Electric mobile vehicle, method for changing tread width, and method for changing minimum ground clearance

Abstract

To provide an electric transfer device which enables wheels and a drive mechanism of the wheels to be easily attached to or detached from a body frame.SOLUTION: An electric transfer vehicle (1, 2) includes: a body frame (10); and a pair of base plates (20) attached to both sides of the body frame (10) in a vehicle body lateral direction. A pair of wheels (30) located side by side in a vehicle body anteroposterior direction, one motor (40) which rotationally drives the pair of wheels (30), and a transmission mechanism (50) which transmits rotational driving force from the motor (40) to the pair of wheels (30) are attached to each of the pair of base plates (20).SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an electric moving vehicle, a tread width changing method, and a minimum ground clearance changing method.

Background Art

[0002] An automatically traveling electric moving vehicle is provided with a pair of left and right wheels. It is required to make variable the tread width, which is the distance between the centers of the left and right wheels. For example, Patent Document 1 discloses a mechanism for sliding a frame that supports wheels by a bifurcated link that expands by a hydraulic cylinder in a combine, which is an agricultural machine, and moving the wheels outward in the left - right direction. Thereby, even when the amount of paddy in the grain tank increases, the position of the center of gravity of the machine body can be shifted, and work can be performed safely.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, Patent Document 1 only discloses making the tread width variable in a combine, and does not consider replacing the wheels attached to the combine and their drive mechanisms with other main body frames (for example, main body frames having different functions, etc.). Thus, the conventional concept was that the wheels and their drive mechanisms provided in an electric moving vehicle were dedicated to that moving vehicle. Therefore, it was difficult to use the wheels and their drive mechanisms in a wide variety of applications, and if an attempt was made to replace the wheels and their drive mechanisms with other main body frames, the work was complicated.

[0005] The present invention has been made in view of the above-mentioned conventional problems, and its object is to provide an electric mobile vehicle in which the wheels and their drive mechanism can be easily attached to and detached from the main frame. [Means for solving the problem]

[0006] The main invention of this invention for solving the above problems is: An electric mobile vehicle having mutually orthogonal longitudinal and lateral directions of the vehicle body, The main frame and It comprises a pair of base plates attached to both sides of the main frame in the left-right direction of the vehicle body, Each of the pair of base plates has: A pair of wheels positioned side by side in the longitudinal direction of the vehicle body, A single motor that rotates the pair of wheels, A transmission mechanism that transmits rotational driving force from the motor to each of the pair of wheels, It is installed, Each of the pair of wheels is attached to the base plate via a swing arm that pivots around a pivot axis that runs along the left-right direction of the vehicle body. It is an electric mobile vehicle characterized by the following: Other features of the present invention will be made clearer by description in this specification and the accompanying drawings. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide an electric mobile vehicle in which the wheels and their drive mechanism can be easily attached to and detached from the main frame. [Brief explanation of the drawing]

[0008] [Figure 1] This is a schematic side view of the electric mobile vehicle 1. [Figure 2] This is a schematic plan view of a portion of the electric mobile vehicle 1, seen from above. [Figure 3] Figure 3A is a schematic front view of the electric mobile vehicle 1, and Figure 3B is an explanatory diagram showing the state with the base plate 20 removed from the main frame 10. [Figure 4]Figure 4A is a schematic cross-sectional view along line AA in Figure 1, and Figure 4B is a schematic cross-sectional view along line BB in Figure 1. [Figure 5] Figures 5A and 5B illustrate the method for changing the tread width of the mobile vehicle 1. [Figure 6] Figures 6A and 6B illustrate the method for changing the minimum ground clearance of the mobile vehicle 1. [Figure 7] Figures 7A and 7B illustrate the method for changing the minimum ground clearance of the mobile vehicle 1. [Figure 8] This is a schematic side view of the mobile vehicle 2 of the second embodiment. [Figure 9] Figures 9A and 9B illustrate the method for changing the tread width of the mobile vehicle 2 in the second embodiment. [Modes for carrying out the invention]

[0009] The following matters become clear from this specification and the accompanying drawings: (Aspect 1) An electric mobile vehicle having a longitudinal and lateral direction of the vehicle body that are perpendicular to each other, comprising a main frame and a pair of base plates attached to both sides of the main frame in the lateral direction of the vehicle body, wherein each of the pair of base plates is fitted with a pair of wheels positioned side by side in the longitudinal direction of the vehicle body, a motor that rotates the pair of wheels, and a transmission mechanism that transmits rotational driving force from the motor to each of the pair of wheels.

[0010] According to Aspect 1, since a pair of wheels and their drive mechanism are integrated by a base plate, by detaching the base plate from the main body frame, the pair of wheels and the drive mechanism can also be easily detached from the main body frame. Therefore, by replacing the base plate for main body frames with different lengths in the left-right direction of the vehicle body, the tread width of the vehicle body can be easily changed. Also, since there is one motor provided for the pair of wheels, cost reduction can be achieved. Further, by reducing the weight of the drive mechanism (motor) attached to the base plate, the attachment and detachment of the base plate becomes even easier.

[0011] (Aspect 2) The electric moving vehicle according to Aspect 1, wherein the motor is located at the center of the pair of wheels in the front-rear direction of the vehicle body.

[0012] According to Aspect 2, since a heavy motor is provided at the center of the pair of wheels, the center of gravity of the vehicle body is likely to be located at the center, enhancing the stability of the vehicle body. Also, the distance for transmitting the rotational driving force from the motor to the front and rear wheels can be made equal, suppressing the occurrence of large transmission losses of the rotational driving force due to the long distance between one wheel and the motor.

[0013] (Aspect 3) The electric moving vehicle according to Aspect 1 or Aspect 2, wherein each of the pair of wheels is attached to the base plate via a swing arm that swings about a swing axis along the left-right direction of the vehicle body.

[0014] According to Aspect 3, by swinging the swing arm, the vertical position of the wheels with respect to the main body frame becomes variable, and the minimum ground clearance can be easily adjusted. Therefore, it can cope with traveling on a road with large unevenness and changing the wheel size.

[0015] (Aspect 4) The electric moving vehicle according to Aspect 3, wherein the swinging portion of the swing arm is attached to the main body frame or the base plate via a vibration absorption mechanism that absorbs vertical vibration.

[0016] According to embodiment 4, the oscillation of the swing arm caused by wheel vibration is absorbed by the vibration absorption mechanism, thereby reducing the vibration transmitted to the main frame.

[0017] (Appendix 5) An electric mobile vehicle according to any one of embodiments 1 to 4, characterized in that the transmission mechanism comprises a first annular belt and a second annular belt rotated by the motor, a first driven rotating body fixed to the rotation axis of the front wheel of the pair of wheels and around which the first annular belt is wound, and a second driven rotating body fixed to the rotation axis of the rear wheel of the pair of wheels and around which the second annular belt is wound.

[0018] According to embodiment 5, even if only one motor is provided for a pair of wheels, the rotational driving force of the motor can be transmitted to the front and rear pair of wheels. By adjusting the diameter and number of teeth of the first driven rotating body and the second driven rotating body, the rotational speed of the motor can be adjusted to rotate the wheels.

[0019] (Aspect 6) The electric mobile vehicle according to embodiment 5, characterized in that the transmission mechanism comprises a drive gear fixed to the rotating shaft of the motor, a first driven gear and a second driven gear meshing with the drive gear, the first annular belt rotates by the rotation of the first driven gear, and the second annular belt rotates by the rotation of the second driven gear.

[0020] According to embodiment 6, the rotational speed of the motor can be adjusted to rotate the wheel by adjusting the number of teeth of the first driven gear and the second driven gear relative to the drive gear. The rotational speed of the motor can be adjusted in two stages: the first driven gear and the second driven gear, and the first driven rotating body and the second driven rotating body, which increases the range of adjustment for the rotational speed of the wheel.

[0021] (Aspect 7) A method for changing the tread width of an electric mobile vehicle according to any of embodiments 1 to 6, comprising the steps of: removing the pair of base plates from the main body frame; and attaching the pair of base plates to another main body frame whose length in the left-right direction of the vehicle body is different from that of the main body frame.

[0022] According to embodiment 7, the tread width can be easily changed simply by replacing the base plate on the main frame, which has a different length in the left-right direction of the vehicle body. The variable tread width makes it possible to travel through narrow passages, and when heavy objects are mounted on the main frame, widening the tread width increases the stability of the vehicle body.

[0023] (Pattern 8) A method for changing the minimum ground clearance of an electric mobile vehicle according to Embodiment 4, characterized in that the method is performed for each of the pair of base plates, comprising the steps of: swinging the swing arm attached to the front wheel of the pair of wheels to change the vertical length of the vibration absorption mechanism attached to the swing arm; and swinging the swing arm attached to the rear wheel of the pair of wheels to change the vertical length of the vibration absorption mechanism attached to the swing arm.

[0024] According to embodiment 8, by swinging the swing arm and adjusting the length of the vibration absorption mechanism, the vertical position of the wheel relative to the main frame becomes variable, and the minimum ground clearance can be easily adjusted. Therefore, it can handle driving on roads with large bumps and accommodate changes in wheel size.

[0025] ===First Embodiment=== <<About the configuration of electric mobile vehicle 1>> Figure 1 is a schematic side view of the electric mobile vehicle 1. Figure 2 is a schematic top view of a part of the electric mobile vehicle 1. Figure 3A is a schematic front view of the electric mobile vehicle 1, and Figure 3B is an explanatory diagram showing the state with the base plate 20 removed from the main frame 10. Figure 4A is a schematic cross-sectional view along line AA in Figure 1, and Figure 4B is a schematic cross-sectional view along line BB in Figure 1. To avoid complexity in the drawings, some diagrams omit certain parts. For example, Figure 1 omits the wheel portion 32 of the wheel 30, and Figure 2 omits the upper part of the base plate cover 21. The same applies to Figures 5 and beyond, which will be discussed later.

[0026] In the electric mobile vehicle 1 (hereinafter also referred to as the "mobile vehicle"), the direction in which the vehicle body moves is defined as the longitudinal direction of the vehicle body (hereinafter also referred to as the "longitudinal direction"), the direction perpendicular to it is defined as the lateral direction of the vehicle body (hereinafter also referred to as the "lateral direction"), and the direction along the vertical direction is defined as the up and down direction. The mobile vehicle 1 comprises a main frame 10, a pair of left and right base plates 20, a pair of left and right base plate covers 21, four wheels 30 provided on the front, rear, left and right sides, a pair of left and right motors 40, a pair of left and right transmission mechanisms 50, four swing arms 60 and their pivot axes 61, and four vibration absorption mechanisms 70.

[0027] Each transmission mechanism 50 includes one drive gear 51, a pair of driven gears 52 and their rotating shafts 521, a pair of roller chains 53, a pair of drive-side sprockets 54, and a pair of driven-side sprockets 55. Since the mobile vehicle 1 of this embodiment has a symmetrical configuration in the left-right direction, the following will describe the pair of front and rear wheels 30 on one side in the left-right direction and their drive mechanism, etc.

[0028] The main frame 10 has a top plate portion 11, a support portion 12, and a bottom portion 13. The top plate portion 11 is a plate-shaped member having a horizontal top surface, and is formed so that objects can be placed on its top surface. The bottom portion 13 is a plate-shaped member arranged parallel to the top plate portion 11. The support portion 12 is a plate-shaped member provided between the top plate portion 11 and the bottom portion 13, and supports the top plate portion 11 from below. As shown in Figure 3, the support portion 12 is positioned in the center in the left-right direction of the top plate portion 11 and the bottom portion 13 so as not to interfere with the motors 40 and the like which are arranged on the left and right sides.

[0029] The base plate 20 is a plate-shaped member with its thickness oriented in the left-right direction and planar portions along the front-rear and up-down directions. The pair of base plates 20 are attached to both sides of the main frame 10 in the left-right direction. Specifically, as shown in Figure 3A, the pair of base plates 20 are placed on both sides in the left-right direction of the upper surface of the bottom portion 13 that constitutes the main frame 10.

[0030] Furthermore, the base plate 20 is attached to the bottom 13 by fasteners 203 and is detachable from the main frame 10 (bottom 13). In Figure 3, L-shaped brackets and fastening members (e.g., bolts) are shown as examples of fasteners 203, but the fasteners 203 are not particularly limited and may be, for example, a combination of I-shaped brackets and fastening members that straddle the base plate 20 and the bottom 13, or a combination of female threads embedded in holes provided in the base plate 20 and the bottom 13 and bolts that are screwed into them.

[0031] The base plate cover 21 is shorter in length in the front-to-back direction than the base plate 20 and is attached to the center of the front-to-back direction of the left-to-right outer side of the base plate 20 using fasteners 213 such as bolts. Also, as shown in Figure 4A, the base plate cover 21 is a member with a roughly C-shaped cross-section, and has an upper part 214 and a lower part 215 that are arranged opposite each other in the vertical direction, and a side part 216 that connects the upper part 214 and the lower part 215 on the left-to-right outer side, and the drive gear 51 and driven gear 52 etc are housed in the space enclosed by them.

[0032] The four wheels 30 are positioned on the front, rear, left, and right sides of the main frame 10. Each wheel 30 has a tire 31 made of rubber or the like, a wheel 32 made of metal or the like, and a wheel rotation shaft 33 fixed to the center of the wheel 32 so as not to rotate relative to the wheel 32. As shown in Figure 2, the wheel rotation shaft 33 passes through a bearing 604 (e.g., a ball bearing) provided on the swing arm 60 in the left-right direction and is rotatably supported relative to the swing arm 60. A driven sprocket 55 is also fixedly attached to the wheel rotation shaft 33. As the driven sprocket 55 rotates, the wheel rotation shaft 33 rotates in the left-right direction as its axis, causing the wheel 30 to rotate.

[0033] The motor 40 has a motor rotating shaft 41 and a main body 42. The main body 42 is attached to the base plate 20 by fasteners such as bolts (not shown). The motor rotating shaft 41 passes in the left-right direction through bearings 201 and 211 (e.g., ball bearings) provided on the base plate 20 and the base plate cover 21, respectively, and is rotatably supported relative to the base plate 20 and the base plate cover 21. A drive gear 51 is also fixedly attached to the motor rotating shaft 41. The drive gear 51 rotates in the left-right direction as its axial direction due to the rotation of the motor rotating shaft 41.

[0034] The transmission mechanism 50 has a symmetrical configuration in the front-rear direction with respect to the drive gear 51. A pair of driven gears 52 are positioned in front of and behind the drive gear 51 so as to mesh with the drive gear 51. The front driven gear 52f and the rear driven gear 52b are each fixedly mounted to the driven rotating shaft 521. The pair of front and rear driven rotating shafts 521, like the motor rotating shaft 41, are passed in the left-right direction through bearings 202 and 212 provided on the base plate 20 and the base plate cover 21, respectively, and are rotatably supported relative to the base plate 20 and the base plate cover 21.

[0035] Furthermore, a drive-side sprocket 54 is fixedly attached to each of the front and rear driven rotating shafts 521. The front drive-side sprocket 54f is wrapped around the front roller chain 53f, together with the front driven-side sprocket 55f, which is fixed to the front wheel rotating shaft 33. Similarly, the rear roller chain 53b is wrapped around the rear drive-side sprocket 54b, together with the rear driven-side sprocket 55b, which is fixed to the rear wheel rotating shaft 33.

[0036] A pair of swing arms 60 are provided, one for the front wheel 30f and one for the rear wheel 30b. As shown in Figure 2, each swing arm 60 has a pair of side plate sections 601 and 602 that are spaced apart and facing each other in the left-right direction, and a peripheral wall section 603 that connects them. As shown in Figure 1, the planar shape of the side plate sections 601 and 602 when viewed in the left-right direction is roughly rectangular, with both ends in the front-rear direction forming an arc shape and tapering towards the center in the front-rear direction. The peripheral wall section 603 is provided only on a part of the outer side of the swing arm 60 in the front-rear direction, and surrounds the driven sprocket 55 from three sides: top, bottom, and the outside in the front-rear direction. Therefore, the part of the roller chain 53 on the central side in the front-rear direction (drive sprocket 54 side) is only sandwiched between the pair of side plate sections 601 and 602 and is exposed in the vertical direction.

[0037] The pivot axis 61, which is the center of the swing arm 60's oscillation, is located on the center side of the swing arm 60 in the front-rear direction and, as shown in Figure 2, penetrates a pair of side plates 601 and 602 in the left-right direction. The swing arm 60 is pivotably mounted on the pivot axis 61 and can swing up and down with the left-right direction as the axial direction. One end of the pivot axis 61 is fixed to the base plate 20, and the other end of the pivot axis 61 is fixed to the base plate cover 21.

[0038] Specifically, as shown in Figure 4A, a hollow cylindrical pivot shaft 61 is provided, penetrating the base plate 20, the swing arm 60, and the base plate cover 21 in the left-right direction. A bolt 64 is passed through the pivot shaft 61 from the outside of the base plate cover 21, and a nut 65 is fastened to the bolt 64 protruding from the base plate 20. In this way, the pivot shaft 61 is fixedly attached to the base plate 20 and the base plate cover 21 in a way that prevents it from swinging. The pivot shaft 61 is also passed through bearings 62 (for example, needle bearings or ball bearings) provided on a pair of side plates 601 and 602 of the swing arm 60. Thus, the swing arm 60 is able to swing relative to the pivot shaft 61. It is preferable to provide a spacer 63 between the bearings 62 and the base plate 20 and the base plate cover 21 to suppress the deflection of each component when the bolt 64 and nut 65 are fastened.

[0039] Conversely, the swingarm 60 may be fixedly mounted to the pivot shaft 61, with both ends of the pivot shaft 61 pivotably mounted to the base plate 20 and the base plate cover 21. In any case, the swingarm 60 only needs to be pivotably mounted to the base plate 20. The wheel 30, which is attached to the swingarm 60, also pivots together with the swingarm 60.

[0040] The vibration absorption mechanism 70 is for absorbing vertical vibrations that the wheel 30 receives from the road surface. As shown in Figures 1 and 3, the upper end of the vibration absorption mechanism 70 is attached to the top plate portion 11 of the main frame 10, and the lower end of the vibration absorption mechanism 70 is attached to the swinging portion of the swing arm 60. The vibration absorption mechanism 70 can employ well-known components, such as coil springs, elastic members such as rubber, hydraulic cylinders, air cylinders, etc., either individually or in combination (e.g., suspension).

[0041] The above configuration of the mobile vehicle 1 is merely an example and is not limited thereto. For example, the configuration of the main frame 10 is not limited to the above, and the method of attaching the base plate 20 will differ depending on the configuration of the main frame 10. For example, if the main frame 10 is box-shaped, the base plate 20 may be attached to the left and right sides of the main frame 10. Also, for example, the mobile vehicle 1 may have a configuration without a base plate cover 21. Also, for example, the swing arm 60 may be a plate-shaped member having only one of a pair of side plate portions 601, 602.

[0042] <<Regarding the operation of mobile vehicle 1>> In the mobile vehicle 1 configured as described above, when the left and right motors 40 are activated and the motor rotation shafts 41 of each motor 40 rotate, the drive gear 51 rotates, the front and rear driven gears 52f and 52b that mesh with it rotate, and the front and rear drive-side sprockets 54f and 54b attached to the driven rotation shaft 521 rotate. As a result, a pair of roller chains 53f and 53b extending to the front and rear on both sides of the main frame 10 in the left-right direction rotate, and the front and rear driven-side sprockets 55f and 55b rotate. In this way, the four wheels 30 on the left, right, front, and rear rotate, and the mobile vehicle 1 travels in the front-rear direction.

[0043] The main frame 10 of the mobile vehicle 1 illustrated in this embodiment has a top plate portion 11 with a horizontal upper surface. Therefore, the mobile vehicle 1 functions as an electric trolley, and the user of the mobile vehicle 1 can place objects on the top plate portion 11 and transport them electrically. The electric trolley can be used in a variety of situations, such as transporting harvested produce in agricultural work, transporting parts in factories, or transporting goods in warehouses.

[0044] <<Regarding the attachment and detachment of the wheel 30 and the drive mechanism>> As described above, the mobile vehicle 1 comprises a main frame 10 and a pair of base plates 20 attached to both sides of the main frame 10 in the left-right direction. Each of the pair of base plates 20 is fitted with a pair of wheels 30 (30f, 30b) positioned side by side in the front-to-back direction, a motor 40 that rotates the pair of wheels 30, and a transmission mechanism 50 that transmits rotational driving force from the motor 40 to each of the pair of wheels 30. The wheels 30 and parts of the transmission mechanism 50 (such as the driven sprocket 55) are attached to the base plate 20 via a swing arm 60.

[0045] In other words, in the mobile vehicle 1, a pair of front and rear wheels 30 and their drive mechanisms (motor 40 and transmission mechanism 50) are integrated and mounted on the base plate 20. Therefore, by removing the fasteners 203 (L-shaped brackets and bolts, etc.) and removing the base plate 20 from the main frame 10 as shown in Figure 3B, the pair of wheels 30 and their drive mechanisms (40, 50) can also be removed from the main frame 10 at the same time. Conversely, by attaching the base plate 20 to the main frame 10 using the fasteners 203, the pair of wheels 30 and their drive mechanisms (40, 50) can also be attached to the main frame 10 at the same time.

[0046] Therefore, compared to the case where the pair of wheels 30 and the drive mechanisms (40, 50) are individually and directly attached to the main frame 10, in the mobile vehicle 1 of this embodiment, the pair of wheels 30 and the drive mechanisms (40, 50) can be easily attached to and detached from the main frame 10. As a result, the pair of wheels 30 and the drive mechanisms (40, 50) can be easily swapped with other main frames 10, and the pair of wheels 30 and the drive mechanisms (40, 50) can be used in a wide range of applications.

[0047] For example, the tread width (the distance between the centers of the left and right wheels 30 in the left and right directions) can be easily changed by attaching a pair of wheels 30 and a drive mechanism (40, 50) to a main frame 10 with different lengths in the left and right directions. Furthermore, as in this embodiment, the pair of wheels 30 and drive mechanisms (40, 50) can be easily swapped from the main frame 10, which has a trolley function, to a main frame with a different function, such as a main frame with a seating function (chair), a main frame with a robot arm, or a main frame that carries measuring instruments or medical equipment. Therefore, the mobile vehicle 1 can be used not only as an electric trolley but also for a variety of other purposes. In other words, compared to providing wheels 30 and drive mechanisms (40, 50) for each main frame with a different function, the wheels 30 and drive mechanisms (40, 50) can be used universally on various main frames 10. Furthermore, even if the main frame 10 is damaged, the undamaged wheels 30 and drive mechanisms (40, 50) can be effectively utilized by replacing them with a new main frame 10. In addition, when storing or moving the mobile vehicle 1, the wheels 30 and drive mechanisms (40, 50) can be easily removed from the main frame 10 depending on the available space.

[0048] Furthermore, in the mobile vehicle 1 of this embodiment, one motor 40 is provided for each pair of front and rear wheels 30. Therefore, compared to the case where two motors are provided for each pair of front and rear wheels, the weight of the drive mechanism (motor 40) attached to the base plate 20 can be reduced. Thus, the attachment and detachment of the base plate 20 to the main frame 10 becomes even easier. In addition, reducing the number of motors 40 mounted on the mobile vehicle 1 leads to cost reduction.

[0049] <<How to change tread width>> Figures 5A and 5B illustrate the method for changing the tread width of the mobile vehicle 1, and are schematic front views of the mobile vehicle 1. The "tread width changing method" for changing the tread width of the mobile vehicle 1 with the above configuration has the following steps.

[0050] Firstly, the process involves removing a pair of base plates 20 from the main frame 10. Secondly, the process involves attaching the pair of base plates 20 to another main frame 10, which has a different length in the left-right direction from the aforementioned main frame 10. The main frame 10, which has different lengths in the left-right direction, refers to the left-right length of the part of the main frame 10 to which the base plate 20 is attached (in this case, the bottom part 13), and is the length of the part that affects the tread width.

[0051] For example, as shown in Figure 5A, a pair of base plates 20 are removed from a main frame 10A whose bottom portion 13 has a shorter left-right length d1. Next, as shown in Figure 5B, the pair of base plates 20 are attached to another main frame 10B whose bottom portion 13 has a longer left-right length d2 than the previous main frame 10A. In this way, the tread width of the mobile vehicle 1 can be changed (in this case, made longer).

[0052] Furthermore, in the case of the mobile vehicle 1 of this embodiment, where the vibration absorption mechanism 70 (upper end) is attached to the main frame 10, when replacing the base plate 20 with another main frame 10, the vibration absorption mechanism 70 is removed from the previous main frame 10A and attached to the subsequent main frame 10B.

[0053] According to the above method for changing the tread width, the tread width can be easily changed simply by attaching and detaching a pair of base plates 20. Because the tread width is variable, for example, even in narrow passages, the vehicle 1 can pass by narrowing the tread width. On the other hand, when transporting heavy loads, widening the tread width increases the stability of the vehicle and prevents it from tipping over.

[0054] Furthermore, according to the above method for changing the tread width, the mobile vehicle 1 does not require a complex mechanism (for example, a mechanism that slides the position of the wheels using a hydraulic cylinder and a bifurcated link) to change the tread width without removing the wheels 30 and the drive units (40, 50). Therefore, the configuration of the main frame 10 can be simplified. However, the main frame 10 may also have a mechanism that allows the length of a part that affects the tread width (for example, the bottom part 13) to be variable in the left-right direction.

[0055] <<Regarding the drive mechanism (motor 40, transmission mechanism 50)>> The motor 40 provided in the mobile vehicle 1 is provided for each pair of front and rear wheels 30, but as shown in Figure 1, it is preferable that the motor 40 is located in the center of the pair of wheels 30 in the front-rear direction. The central part of a pair of wheels 30 in the front-rear direction is defined as the central part 1B of the region (1A, 1B, 1C) obtained by dividing the area from the center of the front wheel 30f to the center of the rear wheel 30b in the front-rear direction into three parts. At least a part of the motor 40 needs to be located in the central part 1B, and preferably the entire motor 40 is located in the central part 1B.

[0056] In this way, by positioning the heavy motor 40 in the center of the mobile vehicle 1, the center of gravity of the mobile vehicle 1 is more likely to be located in the center of the vehicle body. Therefore, the vehicle body is stable and tipping over can be prevented. In addition, the distance from the motor 40 to the front and rear wheels 30f and 30b (the distance over which rotational driving force is transmitted) can be made equal. Therefore, it is possible to prevent the motor 40 from being positioned unevenly on one side of the front or rear wheel 30, which would result in a longer roller chain 53 on one side, leading to increased loss of rotational driving force transmission or the roller chain 53 becoming prone to slack.

[0057] More preferably, the center of the motor rotation shaft 41 should be located at the center of the respective centers of the front and rear wheels 30f and 30b. This makes the center of gravity of the mobile vehicle 1 more stable. In addition, the transmission mechanism 50 and swing arm 60 that transmit rotational driving force to the front and rear wheels 30f and 30b can be configured symmetrically in the front-rear direction. Therefore, the components of the transmission mechanism 50 and the swing arm 60 can be common to both the front and rear sides, reducing the number of types of parts that make up the mobile vehicle 1.

[0058] However, the motor 40 may be located in an area away from the central part 1B of the pair of front and rear wheels 30, without being limited to the above. Also, in the mobile vehicle 1, it is preferable that both the left and right motors 40 are located in the central part 1B, but it is also possible that only one of the motors 40 is located in the central part 1B.

[0059] Furthermore, as previously described, the transmission mechanism 50 includes two roller chains 53 rotated by one motor 40, namely a front roller chain 53f (first annular belt) and a rear roller chain 53b (second annular belt), a front driven sprocket 55f (first driven rotating body) fixed to the wheel rotation shaft 33 of the front wheel 30f and around which the front roller chain 53f is wound, and a rear driven sprocket 55b (second driven rotating body) fixed to the wheel rotation shaft 33 of the rear wheel 30b and around which the rear roller chain 53b is wound.

[0060] According to the transmission mechanism 50 described above, although the mobile vehicle 1 is equipped with only one motor 40 for a pair of front and rear wheels 30f and 30b, the driving rotational force of the motor 40 can be transmitted to the pair of front and rear wheels 30f and 30b. Furthermore, by adjusting the number of teeth (diameter) of the driven sprocket 55 relative to the drive sprocket 54, the rotational speed of the motor 40 can be adjusted to rotate the wheel 30. For example, as shown in Figure 2, by increasing the number of teeth (diameter) of the driven sprocket 55 relative to the drive sprocket 54, the rotational speed of the wheel 30 can be reduced relative to the rotational speed of the motor shaft 41. Thus, the vehicle 1 can be driven at a desired speed.

[0061] In this embodiment, metal roller chains are exemplified as the first and second annular belts, but the system is not limited to these; for example, a toothed rubber belt or a V-belt may be used. Furthermore, the first and second driven rotating bodies may be sprockets (gears) or rotary pulleys, depending on the type of annular belt.

[0062] Furthermore, the transmission mechanism 50 includes a drive gear 51 fixed to the motor 40's rotating shaft (motor rotating shaft 41), and two driven gears 52 that mesh with the drive gear 51, namely, a front driven gear 52f (first driven gear) and a rear driven gear 52b (second driven gear). The front roller chain 53f rotates due to the rotation of the front driven gear 52f, and the rear roller chain 53b rotates due to the rotation of the rear driven gear 52b.

[0063] Therefore, by adjusting the number of teeth (diameter) of the driven gear 52 relative to the drive gear 51, the rotational speed of the motor 40 can be adjusted to rotate the wheel 30. In the drawing, the number of teeth (diameter) of the drive gear 51 and the driven gear 52 are shown to be the same, but for example, by increasing the number of teeth (increasing the diameter) of the driven gear 52 relative to the drive gear 51, the rotational speed of the wheel 30 can be reduced relative to the rotational speed of the motor shaft 41. According to the transmission mechanism 50 described above, the rotational speed of the motor 40 can be adjusted in two stages by the drive gear 51, the pair of driven gears 52, and the pair of driven sprockets 55, thereby rotating the wheels 30. As a result, the range of adjustment for the rotational speed of the motor 40 is widened, making it easier to drive the vehicle 1 at the desired speed.

[0064] However, the invention is not limited to the above. For example, the transmission mechanism 50 does not necessarily have to have a drive gear 51 and a pair of driven gears 52, and a pair of front and rear drive-side sprockets 54 may be directly attached to the motor rotating shaft 41. In this case, the range of adjustment for the rotational speed of the motor 40 will be smaller, but the configuration of the transmission mechanism 50 can be simplified. When attaching a pair of front and rear drive sprockets 54 directly to the motor rotation shaft 41, it is advisable to offset the left-right positions of the front drive sprocket 54f and the rear drive sprocket 54b. Conversely, because the transmission mechanism 50 has a drive gear 51 and a pair of driven gears 52, the front and rear drive-side sprockets 54 can be mounted on a separate rotating shaft (driven rotating shaft 521). As a result, the front and rear drive-side sprockets 54 and the roller chain 53 can be positioned at the same location in the left-right direction, and consequently, the transmission mechanism 50 and the swing arm 60 can be configured symmetrically in the front-rear direction.

[0065] <<Regarding minimum ground clearance>> Figures 6A, 6B, 7A, and 7B illustrate the method for changing the minimum ground clearance of the mobile vehicle 1. Figures 6A and 6B are schematic side views of the mobile vehicle 1, and Figures 7A and 7B are schematic front views of the mobile vehicle 1.

[0066] Preferably, the front and rear wheels 30, each attached to a pair of left and right base plates 20, are attached to the base plates 20 via swing arms 60 that pivot around a pivot axis 61 that runs in the left-right direction.

[0067] By doing so, the wheel 30 swings along with the swing arm 60, allowing the vertical position of the wheel 30 relative to the main frame 10 to be changed. This allows the minimum ground clearance of the wheel 30, that is, the vertical distance (h1, h2) from the ground (the lower end of the wheel 30) to the lowest point of the vehicle body (the lower surface of the bottom 13 of the main frame 10), to be adjusted.

[0068] If the minimum ground clearance is variable, for example, when driving on a road with many bumps, the minimum ground clearance h2 can be increased as shown in Figure 6B to prevent contact between the vehicle body (bottom 13) and the road. Also, if the minimum ground clearance is variable, the size of the wheels 30 can be changed. For example, by making the size of the wheels 30 smaller, the driving force of the vehicle 1 can be increased, and by making the size of the wheels 30 larger, the off-road capability of the vehicle 1 can be improved.

[0069] Furthermore, the swingarm 60 is also attached to the base plate 20. Therefore, by attaching and detaching the base plate 20 from the main frame 10, the swingarm 60 can also be attached and detached simultaneously with the wheel 30 and the drive mechanism (40, 50). Thus, attaching and detaching the swingarm 60 to the main frame 10 is also easy.

[0070] More preferably, the swinging portion of the swing arm 60 is attached to the main frame 10 or the base plate 20 via a vibration absorption mechanism 70 that absorbs vertical vibrations. The pivoting portion of the swingarm 60 is the part of the swingarm 60 that pivots relative to the base plate 20 and the main frame 10. Preferably, the vibration absorption mechanism 70 is attached to the part of the swingarm 60 on the opposite side of where the pivot axis 61 is provided, where the pivoting is greater (the part closer to the wheel 30).

[0071] By doing so, the vertical vibrations that the wheels 30 receive from the road surface while the vehicle 1 is in motion are absorbed by the vibration absorption mechanism 70, reducing the transmission of vibrations to the main frame 10. Specifically, the swing arm 60 swings along with the wheels 30 relative to the base plate 20 and the main frame 10, but this swinging is reduced by the expansion and contraction of the vibration absorption mechanism 70, making it less likely to be transmitted to the main frame 10. As a result, objects placed on the main frame 10 can be transported stably. In addition, the ride comfort is improved when a person is riding on the main frame 10.

[0072] In this embodiment, the base plate 20 has a short vertical length, and the upper ends of the base plate 20 and the swing arm 60 are at approximately the same position. Therefore, the upper end of the vibration absorption mechanism 70 is attached to the main frame 10 (top plate portion 11). However, although not shown in the diagram, the base plate 20 may be extended upward and the upper end of the vibration absorption mechanism 70 may be attached to the base plate 20. In this case as well, vibrations from the wheels 30 are less likely to be transmitted to the base plate 20, and vibrations are also less likely to be transmitted to the main frame 10 to which the base plate 20 is attached. According to the base plate 20 of this embodiment, the vertical length is short, which leads to weight reduction and cost reduction of the base plate 20. On the other hand, when the vibration absorption mechanism 70 is attached to the base plate 20 (not shown), when replacing the main frame 10 (for example, in Figure 5A or Figure 5B), the work of replacing the vibration absorption mechanism 70 is not required.

[0073] The method for changing the minimum ground clearance of the mobile vehicle 1 configured as described above comprises the following steps. Firstly, the process involves swinging the swing arm 60f attached to the front wheel 30f to change the vertical length of the vibration absorption mechanism 70 attached to the swing arm 60f. Secondly, the process involves swinging the swing arm 60b attached to the rear wheel 30b to change the vertical length of the vibration absorption mechanism 70 attached to the swing arm 60b. These first and second steps are performed on each of the pair of base plates 20 (on both the left and right sides).

[0074] For example, to increase the minimum ground clearance h2 from a low minimum ground clearance h1 as shown in Figures 6A and 7A to a higher minimum ground clearance h2 as shown in Figures 6B and 7B, the free end (the end opposite to the pivot axis 61) of the swing arm 60 attached to each wheel 30 is swung downward. In this way, the position of the swing arm 60 and the wheel 30 is lowered relative to the main frame 10. In addition, the vertical length of the vibration absorption mechanism 70 is increased.

[0075] The vibration absorption mechanism 70 also includes connecting members that connect the main body of the vibration absorption mechanism 70 (such as the coil spring and cylinder) to the swing arm 60 and the main frame 10. Therefore, changing the vertical length of the vibration absorption mechanism 70 means changing the length of the main body of the vibration absorption mechanism 70 (for example, extending the coil spring as shown in Figure 6B) and changing the length of the connecting members.

[0076] Furthermore, as shown in Figures 6A and 6B, swinging the swing arm 60 downwards causes the positions of the front and rear wheel pair 30f and 30b to shift slightly towards the center in the front-to-rear direction. Therefore, the length of the roller chain 53 can be used as is without adjustment. Since the change in the wheelbase (the length in the front-to-rear direction from the center of the front wheel 30f to the center of the rear wheel 30b) at this time is small, it does not significantly affect driving stability.

[0077] According to the above method for changing the minimum ground clearance, the vertical position of the wheel 30 relative to the main frame 10 can be adjusted simply by swinging the swing arm 60 and adjusting the length of the vibration absorption mechanism 70, thereby easily changing the minimum ground clearance. Furthermore, there is no need to, for example, replace the wheel 30 with one of a different size in order to adjust the minimum ground clearance, and the desired function of the wheel 30 (driving force and off-road capability) can be maintained.

[0078] Furthermore, when the swing arm 60 is swung, not only the wheel 30 but also a part of the transmission mechanism 50 attached to the swing arm 60 (the driven sprocket 55 and the roller chain 53 wrapped around it) swung. The swing arm 60 swung around the pivot axis 61, but the roller chain 53 swung around the drive sprocket 54. Therefore, as shown in Figure 6B, the inclination of the swing arm 60 and the inclination of the roller chain 53 with respect to the horizontal direction are different. Thus, as shown in Figure 2, in the swing arm 60, on the central side in the front-rear direction (the drive sprocket 54 side), it is preferable not to provide a peripheral wall portion 603 between the pair of side plate portions 601 and 602 to prevent interference between the swing arm 60 and the roller chain 53.

[0079] Furthermore, as shown in Figure 4A, the swing arm 60 and roller chain 53 are housed within the space of the base plate cover 21. Therefore, in order to prevent interference with the base plate cover 21 when the swing arm 60 and roller chain 53 swing, it is advisable to ensure vertical space between the swing arm 60 and roller chain 53 and the base plate cover 21 (lower part 215). In addition, the swing arm 60 has a shape that tapers towards the center in the front-to-back direction, corresponding to the vertical length of the roller chain 53. From this point of view as well, it can be said that interference between the swing arm 60 and the base plate cover 21 can be prevented.

[0080] Furthermore, the configuration is not limited to the above, and the vibration absorption mechanism 70 does not necessarily have to be attached to the swing arm 60. For example, the swing arm 60 may be fixed to the pivot shaft 61, and the pivot shaft 61 may be fixed to the base plate 20 and base plate cover 21 with fastening members (bolts and nuts, etc.). Then, before driving, the fastening members may be loosened to allow the pivot shaft 61 and swing arm 60 to swing relative to the base plate 20 and base plate cover 21 to adjust the minimum ground clearance (vertical position of the wheel 30), and then the fastening members may be tightened to fix the position of the pivot shaft 61 and swing arm 60 to the base plate 20 and base plate cover 21 while driving. In this case as well, the minimum ground clearance can be easily changed simply by swinging the swing arm 60. In this case, it is preferable to provide a vibration absorption mechanism (coil spring, rubber damper, etc.) between the main frame 10 and the base plate 20 to absorb vibrations of the wheel 30 while driving.

[0081] ===Second Embodiment=== Figure 8 is a schematic side view of the mobile vehicle 2 of the second embodiment. Figures 9A and 9B are explanatory diagrams of a method for changing the tread width in the mobile vehicle 2 of the second embodiment, and are schematic front views of the mobile vehicle 2.

[0082] The mobile vehicle 2 of the second embodiment, like the mobile vehicle 1 of the first embodiment, is equipped with a pair of base plates 20 attached to both the left and right sides of the main frame 10. Each base plate 20 is fitted with a pair of front and rear wheels 30 (30f, 30b), a motor 40, and a transmission mechanism 50 that transmits rotational driving force from the motor 40 to each of the pair of wheels 30.

[0083] However, the mobile vehicle 2 of the second embodiment does not have a swing arm 60. Therefore, the wheel 30 is directly attached to the base plate 20. Specifically, as shown in Figure 9A, the wheel rotation shaft 33 of the wheel 30 passes through a bearing 204 provided on the base plate 20, and the wheel 30 is rotatably supported relative to the base plate 20. Therefore, as shown in Figure 8, the base plate 20 is a member that is long in the front-rear direction. Similarly, the base plate cover 21 is also a member that is long in the front-rear direction, and it is preferable that the base plate cover 21 covers the drive gear 51 and a pair of driven gears 52, as well as a pair of front and rear roller chains 53f, 53b and a pair of front and rear driven sprockets 55f, 55b. Therefore, as shown in Figure 9A, the wheel rotation shaft 33 passes through the base plate cover 21 and through a bearing 217 provided on the base plate cover 21, and the wheel 30 is rotatably supported relative to the base plate cover 21.

[0084] In the mobile vehicle 2 of the second embodiment, the front and rear pair of wheels 30 and the drive mechanism (40, 50) can also be easily attached to and detached from the main frame 10 at the same time by attaching and detaching the base plate 20 from the main frame 10 using a fastening device (not shown). Therefore, as shown in Figures 9A and 9B, the tread widths D1 and D2 of the wheels 30 can be easily changed by swapping the base plate 20 between main frames 10A and 10B, which have different lengths d1 and d2 in the left-right direction (here, the length between the support parts 12 of the main frame 10). In addition, since there is only one motor 40 for the front and rear pair of wheels 30, the drive mechanism (motor 40) can be made lighter and less expensive.

[0085] Furthermore, since the mobile vehicle 2 of the second embodiment does not have a swing arm 60, adjusting the minimum ground clearance becomes more difficult compared to the mobile vehicle 1 of the first embodiment. However, in the mobile vehicle 2 of the second embodiment, the weight of the parts attached to the base plate 20 can be reduced by the absence of the swing arm 60. As a result, attaching and detaching the base plate 20 from the main frame 10 becomes even easier. In addition, since the mobile vehicle 2 of the second embodiment has fewer parts than the mobile vehicle 1 of the first embodiment, the configuration can be simplified and costs can be reduced.

[0086] Furthermore, Figure 8 illustrates a mobile vehicle 2 in which a base plate 20 is attached below the support portion 12 of the main frame 10. In this case, it is preferable to provide a vibration absorption mechanism 70 (such as a coil spring or rubber damper) between the support portion 12 of the main frame 10 and the base plate 20 in the vertical direction. This reduces the vertical vibrations that the wheels 30 receive from the road surface and suppresses the transmission of vibrations to the main frame 10. In addition, in the mobile vehicle 2 of the second embodiment, the weight of the components located below the vibration absorption mechanism 70, namely the base plate 20 and the components attached to it (wheels 30, motor 40, transmission mechanism 50), is reduced by the amount of the swing arm 60. Therefore, the unsprung weight can be reduced, and the vibration of the main frame 10 can be further reduced. However, the invention is not limited to this, and in the mobile vehicle 2 of the second embodiment, the base plate 20 may be mounted on the bottom portion 13 of the main frame 10, similar to the mobile vehicle 1 of the first embodiment.

[0087] The embodiments described above are provided to facilitate understanding of the present invention and are not intended to limit its interpretation. The present invention can be modified and improved without departing from its spirit, and equivalents thereof are also included. [Explanation of symbols]

[0088] 1, 2 Mobile vehicle (electric mobile vehicle), 10 Main frame, 11 Top plate, 12 Support part, 13 Bottom part, 20 base plates, 21 Base plate cover, 30 wheels, 31 tires, 32 wheels, 33 Wheel rotation axle (rotation axle), 40 motors, 41 Motor rotating shaft, 42 Main body, 50 transmission mechanism, 51 Drive gear, 52 Driven gears (first driven gear, second driven gear), 53 Roller chain (first annular belt, second annular belt), 54 Drive sprocket, 55 Driven sprocket (first driven rotating body, second driven rotating body), 60 Swingarm, 61. Pivoting axis, 70 Vibration absorption mechanism,

Claims

1. An electric mobile vehicle having mutually orthogonal longitudinal and lateral directions of the vehicle body, The main frame and It comprises a pair of base plates attached to both sides of the main frame in the left-right direction of the vehicle body, Each of the pair of base plates has: A pair of wheels positioned side by side in the longitudinal direction of the vehicle body, A single motor that rotates the pair of wheels, A transmission mechanism is attached to each of the pair of wheels that transmits rotational driving force from the motor, An electric mobile vehicle characterized in that the pair of wheels are each attached to the base plate via a swing arm that pivots around a pivot axis along the left-right direction of the vehicle body.

2. An electric mobile vehicle according to claim 1, An electric mobile vehicle characterized in that the motor is located in the center of the pair of wheels in the longitudinal direction of the vehicle body.

3. An electric mobile vehicle according to claim 1 or 2, An electric mobile vehicle characterized in that the swinging portion of the swing arm is attached to the main frame or the base plate via a vibration absorption mechanism that absorbs vertical vibrations.

4. An electric mobile vehicle according to claim 1 or 2, The aforementioned transmission mechanism is A first annular belt and a second annular belt are rotated by the motor mentioned above. A first driven rotating body is fixed to the rotation axis of the front wheel of the pair of wheels, and the first annular belt is wrapped around it, An electric mobile vehicle characterized by having a second driven rotating body fixed to the rotation axis of the rear wheel of the pair of wheels, and around which the second annular belt is wrapped.

5. An electric mobile vehicle having mutually orthogonal longitudinal and lateral directions of the vehicle body, The main frame and It comprises a pair of base plates attached to both sides of the main frame in the left-right direction of the vehicle body, Each of the pair of base plates has: A pair of wheels positioned side by side in the longitudinal direction of the vehicle body, A single motor that rotates the pair of wheels, A transmission mechanism is attached to each of the pair of wheels that transmits rotational driving force from the motor, The aforementioned transmission mechanism is A first annular belt and a second annular belt are rotated by the motor mentioned above. A first driven rotating body is fixed to the rotation axis of the front wheel of the pair of wheels, and the first annular belt is wrapped around it, It has a second driven rotating body which is fixed to the rotation axis of the rear wheel of the pair of wheels and around which the second annular belt is wrapped, The aforementioned transmission mechanism is A drive gear fixed to the rotating shaft of the motor, It has a first driven gear and a second driven gear that mesh with the aforementioned drive gear, The first annular belt rotates due to the rotation of the first driven gear, An electric mobile vehicle characterized in that the second annular belt rotates due to the rotation of the second driven gear.

6. A method for changing the tread width of an electric vehicle according to claim 1 or 2, The steps include removing the pair of base plates from the main frame, The steps include: attaching the pair of base plates to another main frame whose length in the left-right direction of the vehicle body is different from that of the main frame; A method for changing tread width, characterized by having the following features.

7. A method for changing the minimum ground clearance of an electric mobile vehicle according to Claim 3, The steps include: swinging the swing arm attached to the front wheel of the pair of wheels, thereby changing the vertical length of the vibration absorption mechanism attached to the swing arm; The steps include: swinging the swing arm attached to the rear wheel of the pair of wheels, thereby changing the vertical length of the vibration absorption mechanism attached to the swing arm; A method for changing the minimum ground clearance, characterized by performing the following for each of the pair of base plates.

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