JP2006176031A - Grounding mechanism for four-wheel vehicle, four-wheel vehicle, grounding mechanism of four-legs and structure body - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a grounding mechanism for a four-wheel vehicle capable of suitably grounding four wheels by a simple structure, and a four-wheel vehicle for agricultural work provided this. <P>SOLUTION: The grounding mechanism 30 for the four-wheel vehicle is provided with a side frame 33a for supporting front and rear wheels 31a, 32a at a right side; a side frame 33b for supporting front and rear wheels 31b, 32b at a left side; a main frame 22 supported by these in the state that turning of the left and right side frames 33a, 33b is allowed; and a torsion beam 34 for connecting the left and right side frames 33a, 33b and having an intermediate part in a left/right direction connected to the main frame 22. The left and right side frames 33a, 33b are constituted such that they are turned around a virtual rotation center A coincident in the left/right direction and turning positions of both side frames 33a, 33b become a reverse phase by the torsion beam 34. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a four-wheeled vehicle that travels on rough terrain such as an agricultural field, and relates to a four-wheeled vehicle grounding mechanism for grounding the four wheels to a road surface and a four-wheeled vehicle including the same. The present invention also relates to a structure having four legs, such as a chair and a table, to a four-leg grounding mechanism for grounding the four legs, and a structure including the same.

  Conventionally, this type of four-wheeled vehicle for farm work has adopted a rigid type in order to give priority to simplification of structure and weight reduction, and has ensured grounding property only by deformation of tires. However, on road surfaces with rough terrain, steps, and slopes, it is difficult to ensure that all four wheels are in contact with the ground, and there are cases where only three wheels are in contact and become unstable.

  As countermeasures, a system is adopted in which a hinge is arranged at the center of either front or rear axle or a suspension mechanism using a spring is introduced. However, in the former case, a vehicle such as an agricultural tractor or a forklift that performs heavy work has a drawback that its stability is significantly lowered.

Therefore, as a way to ensure both grounding during normal driving and stability during work, hydraulic cylinders are placed at each wheel position and used as a spring by an accumulator during driving, and during work The thing etc. which ensure stability by stopping the flow of oil have been developed (for example, refer to Patent Document 1).
Japanese Patent Laid-Open No. 2000-14212 (FIG. 3)

  Such a vehicle mainly for traveling on rough terrain preferably has a light and simple structure. However, the conventional grounding mechanism for a four-wheeled vehicle using a hydraulic cylinder has a problem that the weight of the hydraulic cylinder increases as much as the hydraulic cylinder and the structure is complicated as a whole.

  An object of the present invention is to provide a grounding mechanism for a four-wheeled vehicle and a four-wheeled vehicle including the grounding mechanism that can appropriately ground four wheels with a simple structure.

  In addition, we focused on the fact that the grounding mechanism of this four-wheeled vehicle can be applied to a four-legged grounding mechanism such as a chair. Accordingly, another object of the present invention is to provide a four-leg grounding mechanism capable of appropriately grounding four legs with a simple structure and a structure including the same.

  The ground contact mechanism for a four-wheel vehicle according to the present invention includes a left side frame that rotatably supports a left front wheel and a rear wheel, a right side frame that rotatably supports a right front wheel and a rear wheel, and a left side frame and a right side. A torsion beam in which the main frame supported by these, the left side frame, and the right side frame are connected in the left-right direction while allowing the side frames to rotate, and the middle portion in the left-right direction is connected to the main frame. The left side frame and the right side frame are configured to rotate around a virtual rotation center that coincides in the left-right direction, and the rotation positions of both side frames are in opposite phases by the torsion beam. It is configured.

  According to this configuration, for example, when the left front wheel rides on a step, the left side frame rotates rearward around the virtual rotation center. At this time, since the right side frame is connected to the left side frame by the torsion beam, the right side frame rotates about the virtual rotation center forward, contrary to the left side frame. Thus, the rotational positions of the left side frame and the right side frame are in opposite phases, and the left and right side frames are kept neutral. Thereby, the grounding property of all four wheels is ensured.

  Therefore, even without providing a spring element such as a general suspension, the four wheels can be properly grounded with respect to a road surface having rough terrain, a step, an inclination, etc. with a simple structure. Although such a configuration is inferior to a suspension having a spring element in terms of ride comfort, it can be superior in terms of grounding performance of the four wheels. In particular, in the case of a four-wheel vehicle in which the position of the center of gravity moves, a suspension having a spring element cannot avoid a change in the inclination of the main frame accompanying a change in the position of the center of gravity. According to the configuration of the present invention, even if the position of the center of gravity moves, the change in the inclination of the main frame (four-wheel vehicle) can be minimized. In addition, the number of torsion beams is arbitrary, and the installation location is also arbitrary.

  In this case, the torsion beam is pivotally connected to the left and right side frames via pins at the left and right ends, and the middle portion in the left and right direction is pivotally connected to the main frame via pins. The axes of the three pins are in the same plane at the non-rotating positions of the left side frame and the right side frame, and the same plane intersects a line connecting the virtual rotation centers of the left side frame and the right side frame. It is preferable.

  According to this configuration, the rotational positions of the left and right side frames can be appropriately reversed in phase, and the grounding property of the wheel can be appropriately ensured. From another viewpoint of the above configuration, the virtual rotation center can be appropriately set according to the pin setting angle. For this reason, characteristics can be set in accordance with applications and factors such as stability and riding comfort of a four-wheel vehicle and wheel diameter.

  In these cases, it is preferable to further include a support mechanism for supporting the main frame on the left side frame and the right side frame.

  According to this configuration, the load of the main frame can be suitably distributed to the side frames.

  In this case, the support mechanism includes an arc cam that is provided on each of the left side frame and the right side frame and has a center at a virtual rotation center, and a cam follower that is provided on the main frame and rolls on the arc cam. It is preferable.

  According to this configuration, when the side frame rotates, the cam follower rolls the arc cam, so that the side frame can appropriately support the main frame in accordance with the rotation operation.

  Similarly, the support mechanism includes a pair of links that form a trapezoidal link in cooperation with the main frame and the left side frame, and a pair of links that form a trapezoidal link in cooperation with the main frame and the right side frame. The reference point to which the left pair of links is directed is a point located near the virtual rotation center of the left side frame, and the reference point to which the right pair of links is directed is near the virtual rotation center of the right side frame. It is preferable that it is a point located in.

  According to this configuration, the design is easier than in the case of the above-described arc cam, and the overall rigidity can be increased. In this case, it is preferable that there is one torsion beam.

  Another ground contact mechanism of the four-wheel vehicle according to the present invention includes a left side frame that rotatably supports a left front wheel and a rear wheel, a right side frame that rotatably supports a right front wheel and a rear wheel, and a left side frame. And a main frame supported by a right side frame via a supporting means, and the supporting means connects the left side frame and the right side frame in the left-right direction and has an intermediate portion in the left-right direction connected to the main frame. The left side frame and the right side frame are allowed to rotate relative to the main frame by the support means so as to rotate about the virtual rotation center that coincides in the left-right direction, and the torsion beams allow the both side frames to be rotated. The rotation position is configured to be in reverse phase. .

  According to this configuration, similarly to the above, the four wheels can be appropriately grounded to the road surface such as a step without having a spring element such as a general suspension. Further, even if the position of the center of gravity of the four-wheel vehicle moves, the change in the inclination of the main frame (four-wheel vehicle) can be minimized. The torsion beam can constitute part or all of the support means for supporting the main frame on both side frames.

  Another ground contact mechanism of the four-wheel vehicle according to the present invention includes a left side frame that rotatably supports a left front wheel and a rear wheel, a right side frame that rotatably supports a right front wheel and a rear wheel, and a left side frame. And a main frame rotatably supported by the right side frame, a left side frame and a right side frame connected in the left-right direction, and a torsion beam having an intermediate portion in the left-right direction connected to the main frame. The left side frame and the right side frame are configured to be pivotable about the main frame support point that coincides in the left-right direction, and are configured such that the rotational positions of the two side frames are in opposite phases by the torsion beam. It is what.

  According to this configuration, unlike the above-described invention, the left side frame and the right side frame are not configured to rotate about the virtual rotation center, but both the side frames rotate about the support point of the main frame. . At this time, when the both side frames are rotated, the rotation positions of the side frames are opposite to each other by the torsion beam. As a result, as in the case of the above-described invention, the four wheels can be appropriately grounded to the road surface such as rough terrain with a simple structure having no spring element. Similarly, it is possible to appropriately cope with the movement of the center of gravity position of the four-wheel vehicle. Furthermore, since the support points where the side frames support the main frame are used as the direct rotation center, it is not necessary to provide support means such as the above-mentioned arc cams and cam followers, and the torsion beam can be made one. .

  In this case, the torsion beam is pivotally connected to the left and right side frames via pins at the left and right ends, and the middle portion in the left and right direction is pivotally connected to the main frame via pins. The axes of the three pins are in the same plane at the non-rotating positions of the left side frame and the right side frame, and the same plane is a line connecting the support points of the main frames of the left side frame and the right side frame. It is preferable to cross.

  According to this configuration, the rotational positions of the left and right side frames can be appropriately reversed in phase, and the grounding property of the wheel can be appropriately ensured.

  In these cases, it is preferable that the torsion beam is formed in a substantially U-shaped cross section, and the substantially U-shaped opening side is directed outward and downward of the four-wheel vehicle.

  According to this configuration, since the sectional shape of the torsion beam is substantially U-shaped, the torsional rigidity and the bending rigidity of the torsion beam can be increased. Moreover, since the substantially U-shaped opening side of the torsion beam faces outward and downward of the four-wheel vehicle, the drainage can be improved as compared with the case where it is directed upward. The U-shape includes a U-shape and a C-shape.

  Another four-wheel vehicle grounding mechanism of the present invention includes a front axle frame that rotatably supports two left and right front wheels, a rear axle frame that rotatably supports two rear wheels, and a front axle frame and a rear axle. A main frame supported by these in a state in which the rotation of the frame is allowed, a front axle frame and a rear axle frame are connected in the front-rear direction, and a torsion beam having an intermediate portion in the front-rear direction connected to the main frame, The front axle frame and the rear axle frame are configured to rotate about a virtual rotation center that coincides in the front-rear direction, and the rotation positions of the front axle frame and the rear axle frame are in reverse phase by the torsion beam. It is comprised so that it may become.

  According to this configuration, unlike the above-described present invention, the installation direction of the wheels is changed by 90 degrees, and the left and right side frames are changed to the front axle frame and the rear axle frame, and a mechanism corresponding to the rigid axle can be obtained. it can. Similar to the above, the torsion beam functions so that the rotational positions of the front axle frame and the rear axle frame are in opposite phases, so that the four wheels can be properly grounded. As a four-wheel vehicle, it can apply suitably also to what accompanies heavy work, such as a forklift.

  The four-wheel vehicle of the present invention includes the above-mentioned grounding mechanism for the four-wheel vehicle of the present invention.

  According to this configuration, when the four-wheeled vehicle is, for example, a four-wheel vehicle for farm work, the grounding property of the wheel is maintained even when traveling on rough terrain during farm work such as grape seeding, transplantation, fertilization, and harvesting. Can be secured. Moreover, the stability at the time of farm work can be ensured. The four-wheeled vehicle includes not only those for farm work but also so-called strollers such as wheelbarrows and wheelchairs.

  The quadruped grounding mechanism of the present invention is a quadruped grounding mechanism that grounds the front, rear, left, and right four legs, and includes a base, a left unit and a right unit that support the base, a left unit, and a right unit. And a torsion beam that is connected in the left-right direction and whose middle part in the left-right direction is connected to the base. The left unit has left and right front and rear legs, and the unit as a whole is allowed to rotate with respect to the base. The right side unit has right and left legs and supports the base in a state where the entire unit is allowed to rotate with respect to the base. The unit and the right unit are configured to rotate around a virtual rotation center that coincides in the left-right direction, and the rotation positions of both units by the torsion beam. Are those configured to have opposite phases.

  According to this configuration, as in the case of the above-described invention of the grounding mechanism for a four-wheel vehicle, for example, when the left front leg rides on a step or the like, the left unit rotates as a whole to the rear side, The unit is rotated forward by the torsion beam. This keeps both the left and right units neutral. For this reason, the grounding property of all four legs is ensured. Similarly, even when the load position on the base moves, the change in the inclination of the base can be minimized, and for example, the stability of an object placed on the base can be ensured appropriately. Can do.

  In this case, similar to the grounding mechanism of the above-described four-wheel vehicle, the torsion beam is pivotally connected to the left unit and the right unit through the pins at the left and right ends, and the intermediate portion in the left and right direction has the pins. Are pivotally connected to the base, and the axes of the three pins are in the same plane at the non-rotating position of the left unit and the right unit, and the same plane has each virtual rotation center of the left unit and the right unit. It is preferable to intersect the connecting line. Moreover, it is preferable to further include a support mechanism for supporting the base on the left unit and the right unit.

  Preferably, the support mechanism includes an arc cam that is provided in each of the left unit and the right unit and that has a center at the virtual rotation center, and a cam follower that is provided on the base and rolls to the arc cam. Alternatively, preferably, the support mechanism includes a pair of links that form a trapezoidal link in cooperation with the base and the left side unit, and a pair of links that form a trapezoidal link in cooperation with the base and the right side unit, The reference point to which the left pair of links is directed is a point located near the virtual rotation center of the left unit, and the reference point to which the right pair of links is directed is a point located near the virtual rotation center of the right unit. is there.

  By providing these configurations, the same operational effects as those of the invention of the ground contact mechanism of the four-wheel vehicle can be obtained.

  Another four-legged grounding mechanism of the present invention is a four-legged grounding mechanism that grounds four legs, front, rear, left, and right, and includes a base, a left unit and a right unit that support the base, a left unit, and a right unit. And a torsion beam whose middle part in the left-right direction is connected to the base, and the left unit has left and right legs, and the unit as a whole is centered on the support point of the base The right unit has front and rear legs on the right side, and the unit as a whole is configured to be rotatable around the support point of the base. Are matched in the left-right direction, and the left unit and the right unit are configured such that the rotational positions of both units are in opposite phases by the torsion beam. It is intended.

  According to this configuration, unlike the above, both the left and right units do not rotate around the virtual rotation center but rotate around the support point of the base so as to be in opposite phases. Thus, as described above, both the left and right units are kept in neutral, ensuring the grounding property of all four legs and minimizing changes in the inclination of the base. In particular, this is useful in that it is not necessary to provide support means such as the above-described arc cam or cam follower.

  In this case, as described above, the torsion beam is connected to the left unit and the right unit via pins so that the left and right ends can be rotated, and the middle part in the left and right direction can be rotated to the base via the pins. The axes of the three pins are in the same plane at the non-rotating position of the left unit and the right unit, and the same plane may intersect a line connecting the support points of the bases of the left unit and the right unit. ,preferable.

  By having this configuration, the same operational effects as described for the invention of the grounding mechanism of the four-wheel vehicle can be obtained.

  The structure of the present invention includes the above-described quadruped contact mechanism of the present invention.

  According to this configuration, it is possible to provide a structure having a good contact property with four legs. As the structure, for example, furniture such as a chair or a desk can be considered.

  According to the four-wheel vehicle grounding mechanism and the four-wheeled vehicle of the present invention, the four wheels can be appropriately grounded with a simple structure.

  According to the four-leg grounding mechanism and structure of the present invention, the four legs can be appropriately grounded with a simple structure.

  Hereinafter, a grounding mechanism for a four-wheel vehicle according to a preferred embodiment of the present invention will be described with reference to the accompanying drawings. This grounding mechanism of a four-wheel vehicle can be applied to a four-wheeled vehicle driven by a person such as a forklift or a tractor. Here, the grounding mechanism is applied to a four-wheel vehicle for farm work used in a farm work system. An example will be described. Further, an example in which the quadruped grounding mechanism is applied to a desk (structure) having four legs will be described.

  As shown in FIG. 1, the farm work system 1 includes a control vehicle 4 that serves as a parent machine that travels on a paved road 3 outside the farm field 2, and a work vehicle 5 that serves as a child machine that travels within the farm field 2. ing. The control vehicle 4 carries the work vehicle 5 mounted on the carriage part 11. The work vehicle 5 is configured to be able to get on and off the carriage part 11.

  The control vehicle 4 charges the storage battery 14 with electricity generated by the solar power generation module 13 provided on the roof 12, and supplies power to the work vehicle 5 through a cable not shown. The work vehicle 5 includes a motor 21 that receives power supply and drives the front, rear, left and right four wheels (31a, 31b, 32a, 32b). One motor 21 is provided on each of the left and right sides. The right motor 21 drives and rotates the right front and rear wheels 31a and 32a at the same time, and the left motor drives and rotates the left front and rear wheels 31b and 32b at the same time. Thereby, the work vehicle 5 is a vehicle having skid steering, and can mainly move forward and backward and correct the direction.

  On the main frame 22 (machine frame) of the work vehicle 5, a work machine 23 that performs farm work in the farm 2 is mounted via a lateral feed device (not shown). The work machine 23 faces the farm field 2 below from the center of the main frame 22 that is largely opened, and performs farm work such as sowing, transplanting, fertilizing, and harvesting. The lateral feed device moves the work implement 23 in a direction orthogonal to the traveling direction of the work vehicle 5 (the traveling direction of the control vehicle 4).

  When farm work is performed by the farm work system 1, the work vehicle 5 is first transported to a predetermined position by the control vehicle 4, and the work vehicle 5 is lowered from the control vehicle 4 into the farm field 2. Here, after the work machine 23 is driven in synchronization with the forward movement of the work vehicle 5 to perform one line of farm work, the work machine 23 is moved by the lateral feed device, and the work machine 23 is moved to the next line. . From here, the work vehicle 5 is further moved back along the same road (for example, a fence), and the work machine 23 is driven in synchronism with this to perform the farm work of the second line. When such an operation is repeated to complete the farm work on the farm field 2, the work vehicle 5 gets on the control car 4 again and moves to the farm field 2 adjacent by one pitch to perform the next farm work.

  Such a field 2 has uneven ground such as a step, and the work vehicle 5 is desired to ensure the grounding property of the four wheels (31a, 31b, 32a, 32b). Further, an offset load is applied to the work vehicle 5 in accordance with the position of the work machine 23, and the position of the center of gravity of the work vehicle 5 moves. For this reason, it is desired to suppress the change in the inclination of the work vehicle 5 (main frame 22) accompanying the movement of the center of gravity, and to accurately guide the work implement 23 with respect to the ground to ensure stability during work. In view of this, the work vehicle 5 of the present embodiment incorporates the grounding mechanism of the four-wheeled vehicle of the present invention to ensure the grounding property during traveling and the stability during work.

  2 to 5 show the configuration of the work vehicle 5 incorporating the grounding mechanism 30 of the four-wheel vehicle according to the first embodiment. FIG. 2 is a perspective view showing the work vehicle 5 with the right front wheel 31a riding on the step 29. FIGS. 3 to 5 show the work vehicle 5 in a neutral state in which all wheels are on the ground contact surface at the same height. FIG. Except for FIG. 1, details of the motor 21 and the work machine 23 are omitted.

  As shown in FIGS. 2 to 5, the grounding mechanism 30 of the four-wheel vehicle in the work vehicle 5 includes a right side frame 33a that rotatably supports the right front wheel 31a and the rear wheel 32a, and a left front wheel 31b and a rear wheel. A left side frame 33b that rotatably supports 32b, the main frame 22 supported on the upper side of the right side frame 33a and the left side frame 33b in a state in which the right side frame 33a and the left side frame 33b are allowed to rotate; A pair of front and rear torsion beams 34, 34 for connecting the side frame 33b in the left-right direction is provided.

  The ground contact mechanism 30 of a four-wheel vehicle has a left-right symmetric configuration and a front-back symmetric configuration, and the right side frame 33a and the left side frame 33b are sometimes collectively referred to as a side frame 33 for convenience.

  The main frame 22 is formed in a quadrilateral frame shape by a front frame 41, a rear frame 42, a right frame 43, and a left frame 44, and a pair of left and right frames are spanned between the front frame 41 and the rear frame 42. Intermediate frames 45, 45 are provided in parallel to the right frame 43 and the left frame 44.

  The front frame 41, the rear frame 42, and the pair of intermediate frames 45, 45 define the above-described opening for allowing the work machine 23 to face the field 2. Each frame member (41-45) of the main frame 22 is formed of, for example, a metal such as aluminum that is lightweight and has good corrosion resistance, and its framework structure is composed of only rigid joints.

  The side frames 33 (the right side frame 33a and the left side frame 33b) are formed in a rectangular shape in a side view by the upper member 51, the lower member 52, the front member 53, and the rear member 54. The front wheel 31 (31a, 31b) is rotatably supported at the intersection between the front member 53 and the lower member 52, and the rear wheel 32 (32a, 32b) is rotatable at the intersection between the rear member 54 and the lower member 52. It is supported. Each member of the side frame 33 is made of, for example, a metal such as aluminum, and its frame structure is composed of only rigid joints.

  As a result of structural measures described later, the right side frame 33a and the left side frame 33b are interposed via the pair of torsion beams 34 and 34 and the support mechanism 35 so as to rotate around the virtual rotation center A that coincides in the left-right direction. The main frame 22 is supported. The rotational positions of the right side frame 33a and the left side frame 33b are configured to always be in opposite phases by the pair of torsion beams 34, 34.

  Each torsion beam 34 extends in the left-right direction, and is formed of, for example, aluminum in a U-shaped cross section. Each torsion beam 34 has left and right ends connected to the right side frame 33 a and left side frame 33 b, and an intermediate portion in the left and right direction connected to the main frame 22.

  That is, the front torsion beam 34 is rotatably connected to the brackets 71a and 71b fixed to the front end surfaces of the upper members 51 of the left and right side frames 33a and 33b via the pins 72a and 72b. Further, the front torsion beam 34 is rotatably connected to a bracket 71c suspended from the front frame 41 of the main frame 22 via a pin 72c.

  Similarly, the rear torsion beam 34 is rotatably connected to brackets 71a and 71b fixed to the rear end surfaces of the upper members 51 of the left and right side frames 33a and 33b via pins 72a and 72b. Further, the rear torsion beam 34 is rotatably connected to a bracket 71c suspended at an intermediate position of the rear frame 42 of the main frame 22 via a pin 72c.

  As suggested in FIG. 4, the axes of the two pins 72a and 72a of the right side frame 33a are located in a vertical plane including the rotation centers of the right front wheel 31a and the right rear wheel 32a. Similarly, the axes of the two pins 72b and 72b of the left side frame 33b are located in a vertical plane including the rotation centers of the left front wheel 31b and the left rear wheel 32b.

  As shown in FIG. 5, the axes of the three pins 72a, 72b, 72c in each torsion beam 34 are in the same plane at the non-rotating positions of the right side frame 33a and the left side frame 33b. The same plane intersects a line connecting the virtual rotation centers A of the right side frame 33a and the left side frame 33b. From another viewpoint, this means that the virtual rotation center A of the side frame 33 is set according to the angles of the three pins 72 a, 72 b, 72 c installed on the torsion beam 34.

  By such a mounting structure of the torsion beam 34, the right side frame 33a rotates around its virtual rotation center A, and the left side frame 33b rotates around its virtual rotation center A. At this time, the rotation position of the right side frame 33 a and the rotation position of the left side frame 33 b are in opposite phases by the torsion beam 34.

  6 to 8 show the work vehicle 5 in a state where the side frame 33 is rotated while the main frame 22 is horizontally supported. As shown in these drawings, the left side frame 33b is separated from the right side frame 33a by the pair of front and rear torsion beams 34, 34 as the right side frame 33a rotates rearward around the virtual rotation center A. Conversely, it rotates around the virtual rotation center A forward. Even in this state, the configuration of the work vehicle 5 is bilaterally symmetric and vertically symmetric.

  Returning to FIG. 2 to FIG. The support mechanism 35 constitutes support means for supporting the main frame 22 on the left and right side frames 33a and 33b in cooperation with the torsion beam 34. The support mechanism 35 allows the load on the main frame 22 to escape to the left and right side frames 33a and 33b.

  The support mechanism 35 includes arc cams 81 and 81 provided on the left and right side frames 33 a and 33 b and a roller 82 (cam follower) provided on the main frame 22. The arc cam 81 is formed so as to protrude from a part of the upper end surface (front and rear intermediate portion) of the upper member 51 of each of the left and right side frames 33a and 33b. The arc cam 81 has an arc center at the virtual rotation center A of the side frames 33a and 33b (see FIG. 5).

  Four rollers 82 are provided in a distributed manner with respect to one arc cam 81. A total of eight rollers 82 are rotatably supported by support brackets 83 that are respectively suspended from the right frame 43, the left frame 44, and the pair of intermediate frames 45, 45.

  Each roller 82 is held by each support bracket 83 so as to be rotatable in the same direction as the rotation direction of the wheels (31a, 31b, 32a, 32b), that is, in the same direction as the circumferential direction of the arc cam 81. Each roller 82 is configured to be able to roll on the arc cam 81. Therefore, when the side frame 33 is rotated, the arc cam 81 is also rotated integrally therewith. At this time, each roller 82 rolls the arc cam 81. That is, the side frame 33 continues to support the main frame 22 by the support mechanism 35 even during the rotating operation.

  The operation of the grounding mechanism 30 of the four-wheel vehicle of the present embodiment configured as described above will be briefly described with reference to FIG. As shown in the figure, for example, when the right front wheel 31a rides on the step 29, the right side frame 33a rotates rearward while supporting the main frame 22 via the torsion beam 34 and the support mechanism 35.

  At this time, due to the displacement of the front torsion beam 34, the left side frame 33 b is rotated forward with respect to the main frame 22. That is, the main frame 22 is kept neutral with respect to the left and right side frames 33a and 33b.

  Thereby, not only the grounding property of the right front wheel 31a but also the grounding properties of the other wheels (31a, 32a, 32b) are appropriately ensured. In this way, the four wheels (31a, 31b, 32a, 32b) can be properly grounded without a spring element such as a general suspension. Moreover, even if the work implement 23 moves and the position of the center of gravity of the work vehicle 5 moves by ensuring the contact property of the wheels, the change in the inclination of the main frame 22 (work vehicle 5) is sufficiently suppressed. . For this reason, the stability at the time of farm work can be ensured appropriately.

  As described above, the position of the virtual rotation center A of the side frame 33 can be appropriately set according to the set angles of the pins 72a, 72b, 72c in the torsion beam 34. Properties can be set according to the application and elements such as diameter.

  Further, since the torsional rigidity and bending rigidity can be set independently depending on the cross-sectional shape of the torsion beam 34, the degree of freedom of setting such as the rigidity of the entire mechanism and the restoring force with respect to rotation is high. As the cross-sectional shape of the torsion beam 34, it is preferable that the torsion beam 34 has a substantially U shape as a whole, such as a C shape or a U shape, which has a low torsional rigidity and a high bending rigidity, in addition to the above U shape.

  In addition, the torsion beam 34 shown in FIGS. 2 to 8 has its substantially U-shaped opening side facing upward inside the work vehicle 5, but instead of this configuration, the substantially U-shaped opening side is arranged on the work vehicle. It is preferable to face the outside of 5 below. In the former case, water or the like may stay in the torsion beam 34. However, by using the latter method, the drainage performance of the torsion beam 34 can be improved.

  In addition, when the load applied to the main frame 22 is relatively small, the support mechanism 35 can be omitted. In this case, the main frame 22 is supported on the left and right side frames 33a and 33b by the support means including only the pair of front and rear torsion beams 34 and 34. Further, by providing the support mechanism 35 described above, one of the pair of front and rear torsion beams 34 can be omitted, and another torsion beam can be installed at an arbitrary position. In other words, the number and location of the torsion beams 34 are arbitrary, but the axes of the pins (72a, 72b, 72c) in the torsion beam 34 connect the intersections on the lines connecting the left and right virtual rotation centers A as described above. Is required.

  Next, with reference to FIGS. 9 to 12, the second embodiment of the present invention will be described focusing on the differences from the first embodiment. The main differences between the present embodiment and the first embodiment are that there is only one torsion beam 34 and that the structure of the support mechanism 35 is a trapezoidal link type.

  The torsion beam 34 is provided only on the front side of the work vehicle 5, but of course, the installation position is not limited to this. Similarly to the above, the axes of the three pins 72a, 72b, 72c in the torsion beam 34 are in the same plane at the non-rotating positions of the left and right side frames 33a, 33b, and the same plane is the left and right side frames 33a. , 33b intersect with a line connecting the virtual rotation center A.

  The support mechanism 35 has two sets of trapezoidal link means 101a, 101a on the right side frame 33a side, and two sets of trapezoidal link means 101b, 101b on the left side frame 33b side.

  One of the two sets of trapezoidal link means 101a, 101a on the right side has the upper base of the trapezoid as the right frame 43 of the main frame 22 and the lower base of the trapezoid as the upper member 51 of the right side frame 33a. The link 111c and the rear link 112c are connected by a pair of links. The other is a pair of links consisting of a front link 111d and a rear link 112d between the upper base of the trapezoid as the intermediate frame 45 of the main frame 22 and the lower base of the trapezoid as the upper member 51 of the right side frame 33a. Concatenated with

  In the two pairs of links on the right side, the upper ends and lower ends of the front links 111c and 111d are connected by a rod 114, and the upper ends and lower ends of the rear links 112c and 112d are connected by a rod 115. ing. In this way, by providing two sets of trapezoidal link means 101, 101 per side frame 33, the load on the main frame 22 is more dispersed compared to the case where only one set of trapezoidal link means is provided. 22 can be supported by the side frame 33. The two sets of trapezoid link means 101b, 101b on the left side are configured in the same manner, but the description is omitted because the structure is symmetrical.

  The pair of links 111 c and 112 c (111 d and 112 d) are pivotally supported at their upper ends by the main frame 22 and are pivotally supported by the side frames 33 at their lower ends. A reference point B (a point where the axis of the pair of links intersects) toward which the pair of links 111c and 112c (111d and 112d) is located is a point located in the vicinity of the virtual rotation center A of the side frame 33. More specifically, as shown in FIG. 12, the reference point B and the virtual rotation center A are located in the same vertical plane, but the reference point B is located slightly below the virtual rotation center A.

  According to the configuration of the present embodiment as described above, since the support mechanism 35 is a trapezoidal link type, the actual center of rotation of the side frame 33 is moved by the inclination of the side frame 33. Therefore, as shown in FIGS. 6 to 8 in the first embodiment, even if the side frame 33 is rotated while the main frame 22 is supported horizontally, the configuration of the work vehicle 5 is asymmetrical.

  However, the right side frame 33a and the left side frame 33b try to rotate around the virtual rotation center A that coincides in the left-right direction, and the torsion beam 34 rotates the right side frame 33a and the left side frame 33b. It is the same that it becomes an opposite phase.

  Therefore, also in this embodiment, even when the work vehicle 5 travels on rough terrain, the grounding property of all the wheels (31a, 31b, 32a, 32b) can be appropriately ensured, and the main frame 22 can be secured. Inclination can be suppressed to a minimum, and stability during operation can be appropriately ensured. Further, the rigidity can be increased as compared with the support mechanism 35 such as the arc cam 81 of the first embodiment. Furthermore, stability can be ensured depending on which position the reference point B of the pair of links 111c, 112c (111d, 112d) is set, so that the degree of freedom in design is high.

  In addition, although the case where the number of torsion beams 34 is one was demonstrated, of course, it is also possible to use a pair of front and rear torsion beams 34 as in the first embodiment. However, in this case, since the harshness tends to increase, in the case of the trapezoidal link type as described above, it is preferable to configure with one torsion beam 34.

  Next, a third embodiment of the present invention will be described with a focus on differences from the first embodiment with reference to FIGS. The main difference between the present embodiment and the first embodiment is that there is only one torsion beam 34 and that the right side frame 33a and the left side frame 33b rotate the main frame 22 via the brackets 118a and 118b. Supporting it as possible.

  A total of four brackets 118a and 118b, two on each side, are provided. The two right brackets 118a and 118b are provided at an intermediate position in the front-rear direction of the work vehicle 5 so as to sandwich the right side frame 33a from the outside. The lower ends of the two brackets 118a and 118b are rotatably supported by the lower member 52 of the right side frame 33a, and are connected to each other in the left-right direction by a connecting rod 119. The outer bracket 118 a has an upper end fixed to the right frame 43 of the main frame 22, and forms a T shape in side view in cooperation with the right frame 43. Similarly, the upper end of the inner bracket 118b is fixed to the intermediate frame 45 on the right side of the main frame 22, and forms a T-shape in side view in cooperation with the intermediate frame 45.

  Similarly, the left two brackets 118a and 118b are provided at an intermediate position in the front-rear direction of the work vehicle 5 so as to sandwich the left side frame 33b from the outside. The lower end portions of the two bracket brackets 118a and 118b are rotatably supported by the lower member 52 of the left side frame 33b, and are connected in the left-right direction by a connecting rod 119. The outer bracket 118 a has an upper end fixed to the left frame 44 of the main frame 22, and forms a T shape in side view in cooperation with the left frame 44. Similarly, the upper end of the inner bracket 118b is fixed to the intermediate frame 45 on the left side of the main frame 22, and forms a T-shape in side view in cooperation with the intermediate frame 45.

  The two support points of the brackets 118a and 118b by the right side frame 33a and the two support points of the brackets 118a and 118b by the left side frame 33b coincide with each other in the left-right direction. Reference C shown in FIG. 16 indicates this support point. The right side frame 33a and the left side frame 33b rotate with respect to the main frame 22 around the support point C. At this time, the rotation position of the right side frame 33 a and the rotation position of the left side frame 33 b are in opposite phases by the torsion beam 34.

  The torsion beam 34 is provided only on the front side of the work vehicle 5, but of course, the installation position is not limited to this. Similarly to the above, the axes of the three pins 72a, 72b, 72c in the torsion beam 34 are in the same plane at the non-rotating positions of the left and right side frames 33a, 33b, and the same plane is the left and right side frames 33a. , 33b crosses the line connecting the support points C.

  As described above, in the present embodiment, by using the brackets 118a and 118b, the support points C that support the main frame 22 so as to be directly rotatable by the left and right side frames 33a and 33b are provided. The rotation centers of the side frames 33a and 33b are structurally provided at the virtual rotation center A of the first embodiment. Therefore, as in the first embodiment, even when the work vehicle 5 travels on rough terrain, the grounding properties of all the wheels (31a, 31b, 32a, 32b) can be appropriately ensured, and the main vehicle The stability of the work can be appropriately ensured by minimizing the inclination of the frame 22.

  In addition, the brackets 118a and 118b allow the support means for the rotation of the left and right side frames 33a and 33b to have sufficient rigidity. For this reason, it is not necessary to provide the arc cam and cam follower of the first embodiment and the trapezoidal link means of the second embodiment, and only one torsion beam 34 is sufficient. The lower end of the bracket 118a and the lower end of the bracket 118b are not only connected by the connecting rod 119, but the upper and lower intermediate portions may be connected by a rigid body. By so doing, it is possible to provide the support mechanism for the rotation of the left and right side frames 33a and 33b with even more sufficient rigidity.

  Next, a fourth embodiment of the present invention will be described. Although there is no particular drawing for this embodiment, this embodiment changes the installation direction of each wheel (31a, 31b, 32a, 32b) by 90 degrees in the configuration of the embodiment 1 shown in FIGS. The left and right side frames 33a and 33b are a front axle frame and a rear axle frame.

  That is, the four-wheel vehicle installation mechanism of the present embodiment includes a front axle frame that rotatably supports the left and right front wheels 31a and 31b, and a rear axle frame that rotatably supports the left and right rear wheels 32a and 32b. And a main frame 22 supported by the front axle frame and the rear axle frame in a state where the rotation is permitted. The four-wheel vehicle installation mechanism includes a pair of left and right torsion beams 34 that connect a front axle frame and a rear axle frame in the front-rear direction, and have an intermediate portion in the front-rear direction connected to the main frame 22.

  The front axle frame and the rear axle frame are configured to rotate around a virtual rotation center A that coincides in the front-rear direction, and the rotation positions of the front axle frame and the rear axle frame are reversed in phase by the torsion beam 34. It is comprised so that it may become. The support mechanism 35 including the arc cam 81 and the roller 82 is also provided in the same manner.

  According to the present embodiment, a mechanism corresponding to a rigid axle can be obtained with a simple structure. In this case, the torsion beam 34 functions to have a phase opposite to the rotational position of the front axle frame and the rotational position of the rear axle frame. As a result, the grounding performance of the four wheels (31a, 31b, 32a, 32b) is appropriately ensured, and the inclination of the main frame 22 is suppressed to the minimum, so that the stability during the operation is appropriately secured. Can do. Moreover, as a four-wheel vehicle, it can apply suitably also to what accompanies heavy work, such as a forklift. In the above description, the configuration of the first embodiment has been described as an example. Of course, the configuration of the second embodiment may be applied as described above.

  Next, the frame structure of the frame will be described with reference to FIGS. Although this framework structure can be applied to the connection between members of various structures, here, an example applied to the main frame 22 of this embodiment will be described. The parts of the main frame 22 shown in an enlarged manner in FIGS. 17 and 18 are a front frame 41, a right frame 43, and an intermediate frame 45 parallel thereto. Here, for convenience, the front frame 41 will be described as a horizontal frame 121, the right frame 43 as a vertical frame 122, and the intermediate frame 45 as a vertical frame 122.

  As shown in these drawings, the horizontal frame 121 and the pair of vertical frames 122 and 122 are made of a hollow shape and are formed in a square cross-sectional shape. The horizontal frame 121 and the vertical frame 122 are coupled via the screw member 150 and the joint member 151 in a state where the small frame 141 (opening) of the vertical frame 122 is abutted against the side surface 131 of the horizontal frame 121 and they are orthogonal to each other. It is framed by being done.

  As shown in FIG. 18, the screw member 150 is configured by, for example, a cross-recessed machine screw. The screw member 150 includes a screw portion 161 that is screwed into the joint member 151, and a head portion 162 that is integrally connected to the screw portion 161 and has a cross hole. Two holes 132 and 133 for allowing the screw member 150 to pass therethrough are formed in the horizontal frame 121, and one of the holes 132 is a flaw hole that allows the head 162 of the screw member 150 to be inserted. Yes.

  The other hole 133 is formed through the side surface 131 of the vertical frame 122 facing the small opening 141 and has a diameter that allows the threaded portion 161 of the screw member 150 to be inserted and does not allow the head portion 162 to be inserted. ing. Therefore, the screw member 150 inserted from the flaw hole 132 of the horizontal frame 121 can be inserted into the vertical frame 122 side through the screw portion 161 from the other small hole 133, and the opening edge portion of the small hole 133 can be faced. The head 162 can be brought into contact with the inner wall from the inner wall side.

  As shown in FIGS. 18 and 19, the joint member 151 is, for example, a cylindrical member formed corresponding to the vertical frame 122, and is configured to be insertable into the small opening 141 of the vertical frame 122. The joint member 151 is inserted into the fore edge 141 of the vertical frame 122 with its axial direction orthogonal to both the extending direction of the horizontal frame 121 and the extending direction of the vertical frame 122. The joint member 151 is formed of the same metal as the horizontal frame 121 and the vertical frame 122, but both may be different metals.

  A total of four holes 171, 172, 173, and 174 are formed through the peripheral wall of the joint member 151 so as to be evenly distributed in the circumferential direction and located in the same plane. That is, four holes 171, 172, 173, and 174 are provided so as to tie a “cross” in a direction orthogonal to the axial direction of the joint member 151, and these four holes 171, 172, 173, and 174 are connected to the joint member 151. It is formed in the intermediate part of the axial direction. The four holes 171, 172, 173, and 174 have substantially the same diameter, but one of them is formed as a screw hole 171.

  The screw hole 171 is configured so that the screw portion 161 can be screwed together. For this reason, by screwing the screw member 150, the screw member 150 and the joint member 151 move relatively. In addition, although the screw hole 171 was directly engraved in the joint member 151, the screw hole 171 may be comprised with a weld nut. The hole 172 that faces the screw hole 171 is configured so that the threaded portion 161 can be inserted therethrough.

  The joint member 151 of this embodiment is used for the frame of the frame with the screw hole 171 facing the small opening 141 side of the vertical frame 122 and the hole 172 facing the screw hole 171 facing the small hole 133 of the horizontal frame 121. . On the other hand, the two holes 173 and 174 positioned in the direction orthogonal to the screw hole 171 and the hole 172 facing the screw hole 171 face the inner wall at the small opening 141 of the vertical frame 122.

  When the frame is formed, the screw portion 161 of the screw member 150 is guided from the flaw hole 132 of the horizontal frame 121, and the screw portion 161 is inserted from the small hole 133 to the outside of the horizontal frame 121. Subsequently, the screw portion 161 is inserted through the hole 172 of the joint member 151 and the screw portion 161 is screwed into the screw hole 171. The joint member 151 is inserted into the fore edge 141 of the vertical frame 122 and the fore edge 141 of the vertical frame 122 is abutted against the side surface 131 of the horizontal frame 121.

  In this state, the screw member 150 is tightened through the head 162 thereof. By the screwing of the screw member 150, the joint member 151 is attracted to the side surface 131 of the horizontal frame 121 and deformed, and the peripheral wall of the deformed joint member 151 is in close contact with the small opening 141 of the vertical frame 122.

  FIG. 20 shows the relationship between the fore edge 141 of the vertical frame 122 and the joint member 151 in this state. By forming the two holes 173 and 174 in the joint member 151 as described above, the joint member 151 deformed by the tightening of the screw member 150 has the two holes 173 and 174 at the upper and lower peripheral edges. It deforms in the diameter increasing direction in preference to the middle peripheral edge.

  As a result, the joint member 151 is in close contact with the upper and lower corners of the small opening 141 of the vertical frame 122, and the horizontal frame 121 and the vertical frame 122 are coupled via the joint member 151 and the screw member 150. The framework with the vertical frame 122 is completed. The contact pressure can be set by the plate pressure of the tube material of the joint member 151 and the holes 173 and 174, and can be optimized by the material of the joint member 151 and the counterpart frame (122).

  As described above, according to the frame structure of the present embodiment, the orthogonal frames can be appropriately and firmly framed with a simple structure that does not require welding or the like. Various configurations can be added to the above structure, such as providing a washer between the head 162 of the screw member 150 and the horizontal frame 121, or attaching a cap to the small edge of the horizontal frame 121. Moreover, as the screw member 150, not only a small screw but a hexagon bolt etc. can also be used.

  Next, the quadruped contact mechanism and the structure including the same according to the present invention will be described. This four-legged grounding mechanism is obtained by applying the grounding mechanism of the four-wheeled vehicle of the first to third embodiments to a structure having four legs such as a desk. Below, with reference to FIG. 21 and FIG. 22, the example which incorporated the grounding mechanism 30 equivalent to Example 3 in the desk is demonstrated.

  The desk 200 includes a top plate 202 serving as a base, and four legs 204 a, 204 b, 206 a, and 206 b provided on the lower side of the four corners of the top plate 202. The top surface of the top plate 202 is configured to be able to place an object. The four legs 204a, 204b, 206a, 206b are formed in a prismatic shape, for example, and are configured such that the lower end surfaces thereof can be grounded.

  The upper portions of the front and rear legs 204a and 206a on the right side are connected by a square-shaped connecting member 208a extending in the front-rear direction. The connecting member 208a and the top plate 202 are connected by a bracket 208a extending in the vertical direction. An upper end portion of the bracket 208a is fixed to the right side surface of the top plate 202, and a lower end portion thereof is rotatably supported on the outer side surface of the connecting member 208a via a pin 212a. The right unit 214a is composed of the two right legs 204a and 206a and the connecting member 208a. The right unit 214a is configured to support the top plate 202 via a bracket 208a and to be rotatable about a pin 212a that serves as a support point of the top plate 202 as a whole unit.

  Similarly, the upper portions of the left and right leg bodies 204b and 206b are connected by a connecting member 208b, and the connecting member 208b and the top plate 202 are connected by a bracket 208b extending in the vertical direction. The upper end portion of the bracket 208b is fixed to the left side surface of the top plate 202, and the lower end portion of the bracket 208b is rotatably supported on the outer surface of the connecting member 208b via a pin. The left leg unit 214b is composed of the left leg 204b, 206b and the connecting member 208b. The left unit 214b is configured to support the top plate 202 via the bracket 208b and to be rotatable about a pin serving as a support point of the top plate 202 as a whole unit. In this case, the support point (the position of the pin 212a) of the top plate 202 of the right unit 214a and the support point (the position of the pin) of the top plate 202 of the left unit 214b coincide with each other in the left-right direction.

  In addition to the top plate 202, the right unit 214a, and the left unit 214b, the four-leg grounding mechanism 220 incorporated in the desk 200 further includes a torsion beam 222 that connects the right unit 214a and the left unit 214b in the left-right direction. . The left and right ends of the torsion beam 222 are pivotally connected to the front surfaces of the front leg body 204a of the right unit 214a and the front leg body 204b of the left unit via pins 224a and 224b, respectively. Further, the intermediate portion in the left-right direction of the torsion beam 222 is connected to a bracket 226 suspended from the front surface of the top plate 202 via a pin 224c.

  As described in the above embodiments (Embodiment 1 and Embodiment 3), the axes of the three pins 224a, 224b, and 224c in the torsion beam 222 are the same in the non-rotating positions of the right unit 214a and the left unit 214b. In the plane. The same plane intersects a line connecting the support points of the top plate 202 of the right unit 214a and the left unit 214b. With such a mounting structure of the torsion beam 222, the right unit 214a and the left unit 214b are rotated in opposite phases by the torsion beam 222.

  As described above, according to the present embodiment, for example, when the right front leg body 204a rides on a step or the like (as shown in FIG. 21), the right unit 214a rotates as a whole on the rear side, Forward turning power is applied by a torsion beam 222 connected to the left unit 214b. Thereby, the top plate 202 is kept neutral with respect to the left and right units 214a and 214b.

  Therefore, the desk 200 of the present embodiment can ensure the grounding property of all four legs 204a, 204b, 206a, 206b even when placed on uneven ground such as a step. For this reason, the desk 200 is prevented from wobbling due to the influence of the ground plane. In addition, even when placed on rough terrain, a change in the inclination of the top plate 202 can be suppressed, so that the stability of the object placed on the top plate 202 can be appropriately ensured.

  In the description of the present embodiment, “front / rear / left / right” is arbitrary. That is, if the way of viewing is changed, for example, the right unit 214a is a front unit, and the left unit 214b is a rear unit. In any case, the grounding property of the four legs 204a, 204b, 206a, 206b on the front, rear, left and right is still maintained. The number of torsion beams 222 is sufficient as described in the third embodiment. However, the number of the torsion beams 222 and the positions of the torsion beams 222 can be appropriately changed, for example, by providing the torsion beams 222 on the rear side of the desk 200. . The shape of the torsion beam 222 is preferably substantially U-shaped in cross section, but may be flat as in this embodiment.

  In the above description of the present embodiment, the example in which the grounding mechanism 30 of the four-wheeled vehicle of the third embodiment is applied to the four-legged grounding mechanism 220 has been described, but of course the grounding of the four-wheeled vehicle of the first and second embodiments is described. The mechanism 30 can also be applied to a quadruped grounding mechanism 220. Since these application examples are the same, although not particularly illustrated, the following is a summary.

  For example, a four-legged grounding mechanism 220 to which the grounding mechanism 30 of the four-wheeled vehicle of the first embodiment is applied includes the top plate 202, the right unit 214a, the left unit 214b, and the torsion beam 222, but does not include the brackets 208a and 208b. . However, at least two torsion beams 222 are provided at the front and rear, for example. Therefore, the right unit 214a and the left unit 214b rotate around a virtual rotation center that coincides in the left-right direction. Further, a support mechanism is provided between the top plate 202 and the right unit 214a, and between the top plate 202 and the left unit 214b. Consists of an arc cam and a cam follower.

  Specifically, an arc cam having a center at the center of virtual rotation is formed on the upper end surface of the connecting member 208a of the right unit 214a and the upper end surface of the connecting member 208b of the left unit 214b. A roller serving as a cam follower is held by a support bracket (for example, reference numeral 83 in FIG. 1) suspended from the top plate 202, and rolls on the arc cam in the same direction as the circumferential direction of the arc cam. With such a configuration, the right unit 214a and the left unit 214b support the top plate 202 in a state where the top plate 202 is allowed to rotate, and the torsion beam 222 causes the rotation positions to be opposite to each other.

  Similarly, a four-legged grounding mechanism 220 to which the grounding mechanism 30 of the four-wheel vehicle of the second embodiment is applied includes the top plate 202, the right unit 214a, the left unit 214b, and the torsion beam 222, but the bracket 208a, It does not have 208b. Accordingly, the right unit 214a and the left unit 214b rotate around the virtual rotation center that coincides in the left-right direction. Further, a support mechanism is provided between the top plate 202 and the right unit 214a, and between the top plate 202 and the left unit 214b. Consists of trapezoidal links.

  Specifically, the support mechanism cooperates with the top plate 202 and the connecting member 208a of the right unit to form a trapezoidal link, and the support mechanism cooperates with the top plate 202 and the connecting member 208b of the left unit. A pair of links constituting the link. The side surface of the top plate 202 becomes the upper base of the trapezoid, and the outer side surfaces (or inner side surfaces) of the connecting members 208a and 208b become the lower base of the trapezoid. The reference point to which the pair of links on the right side and the left side is located is located near the virtual rotation center of each of the right and left units 214a and 214b (for example, slightly below the virtual rotation center). With such a configuration, the right unit 214a and the left unit 214b support the top plate 202 in a state where the top plate 202 is allowed to rotate, and the torsion beam 222 causes the rotation positions to be opposite to each other.

1 is an external perspective view showing a four-wheel vehicle for farm work according to an embodiment. It is an external appearance perspective view which shows the four-wheel vehicle which concerns on Example 1, and shows the state which one wheel got on the level | step difference. 1 is a plan view illustrating a configuration of a four-wheel vehicle according to a first embodiment. 1 is a front view illustrating a configuration of a four-wheel vehicle according to a first embodiment. 1 is a right side view illustrating a configuration of a four-wheel vehicle according to a first embodiment. FIG. 4 is a plan view similar to FIG. 3, showing a state in which the side frame is rotated while the main frame is horizontally supported. FIG. 5 is a front view similar to FIG. 4, illustrating a state in which the side frame is rotated while the main frame is horizontally supported. FIG. 6 is a right side view similar to FIG. 5, showing a state in which the side frame is rotated while the main frame is horizontally supported. FIG. 4 is an external perspective view similar to FIG. 2, showing a four-wheel vehicle according to a second embodiment. FIG. 6 is a plan view showing a configuration of a four-wheel vehicle according to a second embodiment. FIG. 6 is a front view illustrating a configuration of a four-wheel vehicle according to a second embodiment. FIG. 6 is a right side view illustrating a configuration of a four-wheel vehicle according to a second embodiment. FIG. 4 is an external perspective view similar to FIG. 2, showing a four-wheel vehicle according to a third embodiment. FIG. 6 is a plan view illustrating a configuration of a four-wheel vehicle according to a third embodiment. FIG. 6 is a front view illustrating a configuration of a four-wheel vehicle according to a third embodiment. FIG. 6 is a right side view illustrating a configuration of a four-wheel vehicle according to a third embodiment. It is an expansion perspective view which expands and shows the framework of some frames of a four-wheeled vehicle. It is a disassembled perspective view which decomposes | disassembles and shows the framework of the flame | frame of FIG. It is a perspective view which shows the joint member used for the frame of a flame | frame. It is a figure which shows the edge of the flame | frame of the state fixed with the joint member. FIG. 12 is an external perspective view showing a desk incorporating a quadruped grounding mechanism according to a sixth embodiment. It is an external appearance perspective view similar to FIG. 21, and is a figure which shows the desk of a rotation state.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Agricultural work system, 2 Farm field, 3 Paved road, 4 Control vehicle, 5 Work vehicle, 22 Main frame, 30 Four-wheeled vehicle grounding mechanism, 31a Right front wheel, 31b Left front wheel, 32a Right rear wheel, 32b Left rear wheel, 33a Right side frame, 33b Left side frame, 34 torsion beam, 35 support mechanism, 72a, 72b, 72c pin, 81 arc cam, 82 roller, 111c, 112c link, 111d, 112d link, 118a, 118b bracket, 200 desk (structure) ), 202 Top plate (base), 204a Right front leg, 204b Left front leg, 206a Right rear leg, 206b Left rear leg, 214a Right unit, 214b Left unit, 220 Quadruped contact mechanism, 222 Torsion beam, A Virtual center of rotation, B reference point, C support point

Claims (19)

A left side frame that rotatably supports the left front wheel and the rear wheel;
A right side frame that rotatably supports the right front wheel and the rear wheel;
In a state in which the left side frame and the right side frame are allowed to rotate, a main frame supported by these,
The left side frame and the right side frame are connected in the left-right direction, and a torsion beam whose middle portion in the left-right direction is connected to the main frame,
The left side frame and the right side frame are configured to rotate around a virtual rotation center that coincides in the left-right direction, and the rotation positions of the side frames are in opposite phases by the torsion beam. A grounding mechanism for four-wheeled vehicles. The torsion beam is pivotally connected to the left side frame and the right side frame via pins at the left and right ends, and the middle portion in the left and right direction is pivotable to the main frame via pins. Connected,
The axes of the three pins are in the same plane at the non-rotating positions of the left side frame and the right side frame,
The ground contact mechanism for a four-wheel vehicle according to claim 1, wherein the same plane intersects a line connecting virtual rotation centers of the left side frame and the right side frame.   The grounding mechanism for a four-wheel vehicle according to claim 1, further comprising a support mechanism for supporting the main frame on the left side frame and the right side frame. The support mechanism is
An arc cam provided on each of the left side frame and the right side frame, having a center at the virtual rotation center;
A cam follower provided on the main frame and rolling on the arc cam;
The grounding mechanism for a four-wheeled vehicle according to claim 3, comprising: The support mechanism is
A pair of links constituting a trapezoidal link in cooperation with the main frame and the left side frame;
A pair of links constituting a trapezoidal link in cooperation with the main frame and the right side frame;
The reference point to which the pair of links on the left side is directed is a point located in the vicinity of the virtual rotation center of the left side frame,
The ground contact mechanism for a four-wheel vehicle according to claim 3, wherein the reference point toward which the pair of right links are directed is a point located in the vicinity of the virtual rotation center of the right side frame. A left side frame that rotatably supports the left front wheel and the rear wheel;
A right side frame that rotatably supports the right front wheel and the rear wheel;
A main frame supported by a support means on the left side frame and the right side frame,
The support means includes a torsion beam that connects the left side frame and the right side frame in the left-right direction and has an intermediate portion in the left-right direction connected to the main frame.
The left side frame and the right side frame are allowed to rotate with respect to the main frame by the support means so as to rotate about a virtual rotation center that coincides in the left-right direction, and the torsion beams allow the both side frames to be rotated. A grounding mechanism for a four-wheeled vehicle configured so that the rotational position is in an opposite phase. A left side frame that rotatably supports the left front wheel and the rear wheel;
A right side frame that rotatably supports the right front wheel and the rear wheel;
A main frame rotatably supported by the left side frame and the right side frame;
The left side frame and the right side frame are connected in the left-right direction, and a torsion beam whose middle portion in the left-right direction is connected to the main frame,
The left side frame and the right side frame are configured to be rotatable around a support point of the main frame that coincides in the left-right direction, and the rotation positions of the two side frames are in opposite phases by the torsion beam. A grounding mechanism for four-wheeled vehicles. The torsion beam is pivotally connected to the left side frame and the right side frame via pins at the left and right ends, and the middle portion in the left and right direction is pivotable to the main frame via pins. Connected,
The axes of the three pins are in the same plane at the non-rotating positions of the left side frame and the right side frame,
The ground contact mechanism for a four-wheel vehicle according to claim 7, wherein the same plane intersects a line connecting the support points of the main frame of the left side frame and the right side frame.   The grounding mechanism for a four-wheeled vehicle according to any one of claims 1 to 8, wherein the torsion beam is formed in a substantially U-shaped cross section and an opening side of the substantially U-shaped is directed downward and outward of the four-wheeled vehicle. . A front axle frame that rotatably supports the left and right front wheels,
A rear axle frame that rotatably supports the left and right rear wheels;
In a state in which the front axle frame and the rear axle frame are allowed to rotate, a main frame supported by these,
The front axle frame and the rear axle frame are coupled in the front-rear direction, and a torsion beam having an intermediate part in the front-rear direction connected to the main frame,
The front axle frame and the rear axle frame are configured to rotate around a virtual rotation center that coincides in the front-rear direction, and the rotation positions of the front axle frame and the rear axle frame are in reverse phase by the torsion beam. A grounding mechanism for a four-wheeled vehicle configured to be.   A four-wheeled vehicle comprising the grounding mechanism for a four-wheeled vehicle according to any one of claims 1 to 10. A four-legged grounding mechanism that grounds the four legs on the front, rear, left and right,
Base and
A left side unit and a right side unit supporting the base;
The left side unit and the right side unit are coupled in the left-right direction, and a torsion beam whose middle portion in the left-right direction is connected to the base,
The left unit has front and rear legs on the left side, and supports the base in a state where the entire unit is allowed to rotate with respect to the base.
The right unit has front and rear legs on the right side, and supports the base in a state where the entire unit is allowed to rotate with respect to the base.
The left unit and the right unit are configured to rotate around a virtual rotation center that coincides in the left-right direction, and are configured such that the rotational positions of the two units are in opposite phases by the torsion beam. Quadruped grounding mechanism. The torsion beam is pivotally connected to the left unit and the right unit via pins at the left and right ends, and a middle portion in the left and right direction is pivotally connected to the base via a pin.
The axes of the three pins are in the same plane at the non-rotating position of the left unit and the right unit,
The quadruped contact mechanism according to claim 12, wherein the same plane intersects a line connecting the virtual rotation centers of the left unit and the right unit.   The quadruped contact mechanism according to claim 12 or 13, further comprising a support mechanism for supporting the base on the left unit and the right unit. The support mechanism is
An arc cam provided on each of the left unit and the right unit, and having a center at the virtual rotation center;
A cam follower provided on the base and rolling on the arc cam;
The four-legged grounding mechanism according to claim 14, comprising: The support mechanism is
A pair of links forming a trapezoidal link in cooperation with the base and the left side unit;
A pair of links constituting a trapezoidal link in cooperation with the base and the right unit;
The reference point to which the pair of left links are directed is a point located in the vicinity of the virtual rotation center of the left unit,
15. The quadruped contact mechanism according to claim 14, wherein the reference point to which the pair of right links is directed is a point located in the vicinity of the virtual rotation center of the right unit. A four-legged grounding mechanism that grounds the four legs on the front, rear, left and right,
Base and
A left side unit and a right side unit supporting the base;
The left side unit and the right side unit are coupled in the left-right direction, and a torsion beam whose middle portion in the left-right direction is connected to the base,
The left unit has left and right front and rear legs, and is configured to be rotatable around the support point of the base as a whole unit,
The right unit has front and rear legs on the right side, and is configured to be rotatable around the support point of the base as a whole unit,
The support points of the base of the left unit and the right unit coincide in the left-right direction,
The left-hand unit and the right-hand unit are quadruped grounding mechanisms configured such that the rotational positions of the two units are in opposite phases by the torsion beam. The torsion beam is pivotally connected to the left unit and the right unit via pins at the left and right ends, and a middle portion in the left and right direction is pivotally connected to the base via a pin.
The axes of the three pins are in the same plane at the non-rotating position of the left unit and the right unit,
18. The quadruped contact mechanism according to claim 17, wherein the same plane intersects a line connecting the support points of the base of the left unit and the right unit.   A structure provided with the quadruped contact mechanism according to any one of claims 12 to 18.

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