Three-wheeled electric vehicle

Abstract

To provide a three-wheeled electric vehicle that is able to easily move over even a large step by means of a simple mechanism.SOLUTION: The electric vehicle has: a pair of front wheels 4, 4 disposed in a front part of a vehicle body 3 and having no steering function; and a rear wheel 5 disposed in a rear part of the vehicle body 3, having a steering function and a driving function, and having a diameter smaller than that of the pair of front wheels 4, 4. The steering angle of the rear wheel 5 when one front wheel 4a comes into contact with a step is defined as an angle α formed by a tangent direction and a straight advancing direction of the rear wheel 5 when the rear wheel 5 is circularly moved by making the rotation center of the rear wheel coincide with a ground contact point 8 on the inner wheel side 4a of the front wheel.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a three-wheeled electric vehicle that can overcome even large steps. [Background technology]

[0002] There are legal regulations for electric vehicles known as senior cars, and if they are within the specified range of 120cm in length, 70cm in width, 109cm in height, and a maximum speed of 6km / h, they are considered pedestrians and can be driven on sidewalks. There are also regulations that state that they must be able to overcome steps of 7cm or less and be able to drive on slopes with an incline of 10 degrees or less.

[0003] In areas where barrier-free access is more advanced, steps are becoming smaller, and if the step is about 7 cm, the wheel diameter does not need to be that large, at around 25 to 30 cm. However, in areas where barrier-free access is less advanced, large steps of about 15 cm, such as road curbs, are found everywhere, and the relatively small wheels that can overcome steps of about 7 cm are insufficient, and trying to overcome such a large step would pose a risk of falling, making them completely unusable. For this reason, there is a demand for electric vehicles that can easily and safely overcome even large steps.

[0004] Patent Document 1 discloses an electric vehicle that can easily overcome such large steps (such as stairs), including a six-wheel four-wheel drive vehicle in which the middle and rear wheels are driven by a drive motor or the like, and drive force is transmitted between the middle and rear wheels via a transmission mechanism such as a belt, the left and right middle and rear wheels are driven independently, and the direction is controlled by the difference in rotation between the left and right middle and rear wheels, with the left and right front wheels acting as auxiliary wheels and driven wheels. This six-wheel four-wheel drive electric vehicle can also travel up stairs, escalators, etc. However, it is a six-wheel vehicle with four-wheel drive, and has a very complex mechanism, requiring two independent drive motors, making it expensive. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2020-168314 Summary of the Invention [Problem to be solved by the invention]

[0006] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a three-wheeled electric vehicle that can easily overcome large steps using a simple mechanism. [Means for solving the problem]

[0007] In order to solve the above problem, the three-wheeled electric vehicle according to claim 1 is an electric vehicle characterized by having a pair of front wheels located at the front of the vehicle body and having no steering function, and a rear wheel located at the rear of the vehicle body, having steering and driving functions, and having a smaller diameter than the pair of front wheels. The invention of claim 2 determines the steering angle of the rear wheels when one of the front wheels comes into contact with a step by aligning the center of rotation with the contact point on the inner front wheel side of the rear wheels and setting it as the angle between the tangent direction when the rear wheels are made to move in a circular motion and the straight-ahead direction of the rear wheels. The invention according to claim 3 is provided with an electric motor and a brake coaxially with the rotation shaft of the rear wheel. The invention of claim 4 is a rear wheel steering mechanism in which the rotating shaft of a steering motor is connected to a worm gear via a gear, the worm gear is connected to a worm wheel that meshes with the worm gear, and the rear wheels are connected to the rotating shaft of the worm wheel in a steerable manner. [Effects of the Invention]

[0008] According to the invention of claim 1, the electric vehicle has a pair of front wheels located at the front of the vehicle body and having no steering function, and rear wheels located at the rear of the vehicle body and having steering and driving functions, and having a smaller diameter than the pair of front wheels, so that it is possible to easily overcome even large steps with a simple mechanism. According to the invention of claim 2, the steering angle of the rear wheels when one of the front wheels comes into contact with a step is set to the angle between the tangent direction of the circular motion of the rear wheel and the straight-ahead direction of the rear wheel, with the center of rotation coinciding with the contact point of the inner front wheel, so the electric vehicle can turn around the inner front wheel. At that time, all of the driving force is used to turn the vehicle body, and no force is generated to make the inner wheel go over the step. According to the invention of claim 3, since the electric motor and the brake are provided coaxially with the rotation shaft of the rear wheels, the electric vehicle can be stopped reliably. According to the invention of claim 4, the steering mechanism for the rear wheels is a mechanism in which the rotating shaft of the steering motor is connected to a worm gear via a gear, the worm gear is connected to a worm wheel that meshes with the worm gear, and the rear wheels are connected to the rotating shaft of the worm wheel in a steerable manner, thereby realizing a large steering angle. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a perspective view of a three-wheeled electric vehicle according to an embodiment when traveling straight. [Figure 2] FIG. 2 is a perspective view of the three-wheeled electric vehicle according to the embodiment, as viewed from the bottom side when traveling straight. [Figure 3] 1A and 1B are a plan view and a side view of a three-wheeled electric vehicle according to an embodiment. [Figure 4] FIG. 10 is a side view illustrating the state of the step, with the left front wheel omitted. [Figure 5] FIG. 1 is a perspective view of a three-wheeled electric vehicle according to an embodiment when turning. [Figure 6] FIG. 2 is a bottom view of the three-wheeled electric vehicle according to the embodiment when turning. [Figure 7] FIG. 2 is a perspective view showing the steering mechanism when traveling straight. [Figure 8] FIG. 2 is a perspective view showing the steering mechanism during turning. [Figure 9] FIG. 10 is a bottom view illustrating the state of turning while coming into contact with a step. [Figure 10] FIG. 10 is a side view illustrating how the vehicle climbs over a step. DETAILED DESCRIPTION OF THE INVENTION

[0010] An embodiment of the present invention will now be described in detail with reference to the drawings. A three-wheeled electric vehicle 1 according to the present invention is an electric vehicle driven by a drive motor (electric motor) 2, and comprises a pair of left and right front wheels 4,4 that are located at the front of the vehicle body 3 and have no steering function, and a single rear wheel 5 that is located at the rear of the vehicle body 3 and has a smaller diameter than the pair of left and right front wheels 4,4 and has steering and drive functions. In FIG. 3, the direction of arrow A is the forward direction (straight forward direction).

[0011] A pair of left and right front wheels 4, 4 located at the front of the vehicle body 3 are formed with a large diameter and are driven wheels without steering function. The front wheels have a diameter large enough to overcome a relatively large step 6 (Figs. 9 and 10), for example, a step of about 15 cm in height. For example, a diameter of about 42 cm (about 40 to 45 cm) is sufficient.

[0012] Because the front wheels 4, 4 do not have a steering function, a large space can be secured between the left and right front wheels 4, 4, as shown in Figures 3(a) and 6. This large space can be used as an entrance / exit point. A step 7 is provided at the entrance, and when getting on or off, the front end of the step is inclined downward as shown by the dashed line in Figure 4, so that it functions as a step for getting on and off, and when getting on and off, the front end of the step is inclined upward (Figure 4).

[0013] The rear wheel 5 is provided as a single wheel in the center in the left-right direction at the rear end of the body 3. This rear wheel 5 is structured so that it can turn 360 degrees without any obstacles being placed around it. This rear wheel 5 is formed with a smaller diameter than the front wheels 4 and has steering and drive functions. The diameter of the rear wheel 5 is smaller than that of the front wheels 4, for example, about 32 cm (about 30 to 35 cm). The rear wheel 5 is equipped with an electric motor 2 for driving, and the rear wheel 5 serves as a drive wheel. The rear wheel 5 also has a steering function, and the direction of travel is determined by steering the rear wheel 5. As described above, the three-wheeled electric vehicle 1 according to the present invention is a three-wheeled electric vehicle consisting of a pair of front wheels 4, 4 and a single rear wheel 5, and has a simple mechanism. This makes it inexpensive and easy to maintain.

[0014] When going over the step 6, first, the rear wheel 5 is caused to make a circular motion (turn) around the contact point 8 of the front wheel (inner wheel) 4a, which is the first of the pair of front wheels 4, 4 to come into contact with the step 6, and the vehicle body 3 is turned until the other front wheel (outer wheel) 4b comes into contact with the step 6. The steering angle of the rear wheels 5 at this time is set to an angle (α) between the tangent direction when the rear wheels 5 are made to move in a circle with the center of rotation coinciding with the contact point 8 of the inner front wheel 4a and the forward direction of the rear wheels 5. Because the steering angle of the rear wheels 5 when turning is set to α in this way, all of the driving force when turning becomes a force for rotating (turning), and no force is generated that causes the inner front wheel 4a to go over the step 6. Therefore, there is no risk of the vehicle tipping over due to the step 6 when turning. For example, if the wheelbase between the front wheels 4 and the rear wheels 5 is 845 mm and the distance between the rotation centers of the pair of front wheels 4, 4 is 590 mm, the steering angle α is 70.8°.

[0015] In order to ensure such a large steering angle α while also ensuring a large space for the entrance and exit, it is important to use a pair of front wheels 4,4 without a steering function, ensure a large space between the pair of front wheels 4,4 to serve as the entrance and exit, and use the rear wheel 5 as a single wheel with steering and driving functions.

[0016] The steering mechanism for the rear wheels 5 is as follows: The steering mechanism for the rear wheels 5 is a mechanism in which the rotation shaft of a steering motor 10 is connected to a worm gear 12 via gears 11a, 11b, and 11c, the worm gear 12 is connected to a worm wheel 13 that meshes with the worm gear 12, and the rear wheels 5 are connected to a vertical rotation shaft 14 of the worm wheel 13 so as to be steerable (Figs. 7 and 8). The rotation of the rotating shaft of the steering motor 10 is transmitted to the worm gear 12 via gears 11a, 11b, and 11c, and the rotation of the worm gear 12 is transmitted to the worm wheel 13 that meshes with the worm gear 12. The rear wheel 5, which is steerably connected to the vertical rotating shaft 14 of the worm wheel 13, turns and is steered in accordance with the rotation of the worm wheel 13. In this way, by employing a mechanism in which the worm gear 12 and the worm wheel 13 are meshed together, it is possible to achieve a large steering angle while ensuring a large reduction ratio.

[0017] Next, the procedure for the three-wheeled electric vehicle 1 of the present invention to go over a step 6 will be explained. When one of the front wheels 4a contacts the step, first, the electric vehicle 1 is turned on the spot so that the three-wheeled electric vehicle 1 is facing the step 6. More specifically, as shown in Figure 9, when one of the front wheels (the inner front wheel) 4a contacts the step 6 (Figure 9(a)), the steering angle of the rear wheel 5 is set to the above-mentioned steering angle (α), and the three-wheeled electric vehicle 1 is turned around the contact point 8 of the inner front wheel 4a (Figures 9(b) and 9(c)). When the other front wheel (the outer front wheel) 4b also contacts the step 6, the steering angle of the rear wheel 5 is returned to a straight ahead direction (steering angle 0°), so that the three-wheeled electric vehicle 1 is facing the step 6 (Figure 9(d)). Next, from this facing state (Fig. 10(a)), the rear wheel 5 is driven to make the pair of front wheels 4, 4 simultaneously go over the step 6 (Fig. 10(b)). In this way, the rear wheel 5 also goes over the step 6 in turn, and both the front and rear wheels 4, 4, 5 go over the step 6, and the three-wheeled electric vehicle 1 moves up the step 6 (Figs. 10(c)(d)). At this time, because both front wheels 4, 4 go over the step 6 simultaneously while facing the step 6, the vehicle body does not tilt left or right, and there is no risk of tipping over. As a result, the large step 6 can be safely ridden. In the three-wheeled electric vehicle 1 shown in the above specific values, the inclination is 10.2° when the step 6 is 15 cm.

[0018] The same procedure is used when descending a step 6. First, the three-wheeled electric vehicle 1 is turned so that it faces the step 6. In this state, the rear wheels 5 are driven and the vehicle moves forward so that the left and right front wheels 4, 4 simultaneously descend the step 6. Next, the rear wheels 5 also descend the step 6, and the three-wheeled electric vehicle 1 descends to the bottom of the step 6. Because the left and right front wheels 4, 4 simultaneously descend the step 6, the vehicle maintains balance between the left and right sides, allowing it to descend the step 6 safely without risk of tipping over.

[0019] The driving electric motor 2 and brake (electromagnetic brake) 15 are provided coaxially with the axle of the rear wheels 5 on both the left and right sides of the rear wheels 5, with the rear wheels 5 interposed between them. In this way, the electric motor 2 and brake 15 are provided coaxially with the rotational axis of the rear wheels 5, so the vehicle can be stopped reliably. In addition, since the electric motor 2 and brake 15 are provided on both the left and right sides of the rear wheels 5, left and right balance can be maintained.

[0020] The numerical values ​​shown above are merely examples and are not limiting. In the diagram, reference numeral 16 denotes a seat, reference numeral 17 denotes a backrest, and reference numeral 18 denotes an armrest. A switch 19 and a display 20 are provided at the tip of the armrest 18, and the switch 19 controls both drive and steering. An emergency stop button is also provided at the top end of the switch 19. The display 20 displays the remaining battery level, tilt angle, various abnormalities, etc. Reference numeral 21 denotes a rearview mirror. Reference numeral 22 denotes a suspension that reduces vibration of the seat 16. The power sources for the drive electric motor 2, steering motor 10, etc. are supplied from a battery (not shown). Because the drive and steering systems are concentrated on the rear wheel side, there is a large amount of free space in the center of the vehicle body, and a heavy battery can be installed at the lowest part of this center, which results in a lower center of gravity and makes the electric vehicle less likely to tip over. [Explanation of symbols]

[0021] 1. Three-wheeled electric vehicle 2. Drive motor (electric motor) 3. Body 4 front wheels 4a Inner circle 4b outer ring 5 rear wheels 6 steps 7 steps 8 Inner ring grounding point 10 Steering motor 11a, 11b, 11c gears 12 Worm gear 13 Worm wheel 14 Worm wheel rotation axis 15 Brake (electromagnetic brake) α Rear wheel steering angle when turning A Forward direction

Claims

1. A three-wheeled electric vehicle having a pair of front wheels located at the front of the vehicle body and having no steering function, and a rear wheel located at the rear of the vehicle body, having steering and driving functions, and having a smaller diameter than the pair of front wheels.

2. 2. The three-wheeled electric vehicle of claim 1, wherein the steering angle of the rear wheels when one of the front wheels comes into contact with a step is set to the angle between the tangent direction of the rear wheels when the rear wheels are made to move in a circular motion with the center of rotation coinciding with the contact point on the inner front wheel side.

3. 3. The three-wheeled electric vehicle according to claim 1, further comprising an electric motor and a brake, which are arranged coaxially with the rotational shaft of the rear wheels.

4. The three-wheeled electric vehicle according to any one of claims 1 to 3, wherein the steering mechanism for the rear wheels is a mechanism in which the rotating shaft of the steering motor is connected to a worm gear via a gear, the worm gear is connected to a worm wheel that meshes with the worm gear, and the rear wheels are connected to the rotating shaft of the worm wheel so as to be steerable.

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