Electric transport dolly

Abstract

To provide an electric transport dolly that can realize more stable traveling by a simple configuration even when traveling in a narrow section.SOLUTION: A dolly includes: a body frame 2 having a loading platform 2A on the top; right and left handle portions 3 each extending rearward from the body frame 2 and having a grip portion 3a at a rear end portion in an extension direction; and two wheels 4 each attached to the body frame 2 and arranged opposite to each other in a right-left direction. One of the two wheels 4 is a drive wheel 4A consisting of an electric wheel 4 incorporating an in-wheel motor 10, and the other is a non-driven follower wheel 4B, and the right-left positions of the two wheels 4 are arranged on an inner side of the positions of the right and left grip portions 3a when viewed from the front.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a technique for an electric transport cart that is a hand-pushed cart. [Background technology]

[0002] An example of a hand-pushed cart is the hand-pushed cart described in Patent Document 1. The hand truck described in Patent Document 1 is a single-wheeled truck, and by using electrically powered wheels, it is possible to assist the worker in pushing the truck by hand. By providing electrically assisted wheels, it has the effect of making it easier to transport loads, even heavy loads. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6970474 Summary of the Invention [Problem to be solved by the invention]

[0004] A hand truck does not have a steering mechanism on the wheels. Therefore, the worker operates the left and right handles to steer the direction of travel of the truck to transport the load. For this reason, the running balance of the truck is important. However, with single-wheeled carts, there is a risk that the center of gravity will be relatively high due to the tendency for them to sway left and right, which poses a risk of them interfering with obstacles on either side when traveling through narrow areas.

[0005] The present invention has been made with the above points in mind, and aims to provide an electric transport cart that can achieve more stable travel of the cart with a simpler configuration, even when traveling through narrow areas to transport loads. [Means for solving the problem]

[0006] In order to solve the problem, one aspect of the present invention comprises a body frame having a loading platform on top, left and right handle portions each extending rearward from the body frame and having a grip portion at the rear end in the extension direction, and two wheels each attached to the body frame and arranged opposite each other in the left-right direction, one of the two wheels being a drive wheel consisting of an electric wheel with an in-wheel motor built in, and the other being a non-driven wheel, and the left-right positions of the two wheels being arranged inside the positions of the left and right grip portions when viewed from the front. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide an electric transport cart that has a simple configuration but provides good operability and assist when transporting loads. Therefore, according to the present invention, even if the load is heavy, the cart can be driven more stably through narrow paths. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a perspective view showing an electric transport cart according to an embodiment of the present invention. [Figure 2] 1 is a perspective view of an electric transport cart according to an embodiment of the present invention, viewed from below. [Figure 3] 1 is a front view showing an electric transport cart according to an embodiment of the present invention. [Figure 4] 1 is a top view showing an electric transport cart according to an embodiment of the present invention. [Figure 5] 1 is a side view showing an electric transport cart according to an embodiment of the present invention. [Figure 6] 6 is a cross-sectional view of FIG. 5 taken along line B-B. DETAILED DESCRIPTION OF THE INVENTION

[0009] Next, an embodiment of the present invention will be described with reference to the drawings. (Basic concept of this embodiment) The electric transport cart of this embodiment is a two-wheeled handcart in which only one wheel is an electric wheel. The hand truck moves forward or backward when the worker pushes or pulls the left or right handles. Furthermore, the hand truck does not have a steering mechanism on the wheels themselves, and the worker steers the truck by operating the left and right handles. The inventors thought that it was necessary to improve the running stability of handcarts when considering the running of handcarts on narrow roads, and investigated a two-wheel handcart, which is more stable than a one-wheeled handcart.

[0010] In this case, the heavier the load, the more driving assistance is required, so the inventors considered driving both the left and right wheels with motors to provide driving assistance. However, the inventors discovered that if both wheels were powered, the maneuverability of the cart would be impaired while traveling. In other words, the operator of a handcart needs to adjust the traveling direction of the cart by operating the left and right handles. However, when considering lateral steering, if both wheels were powered, the operator would need to hold the handles and operate the cart to turn laterally in order to overcome the motor torque from the two motors. For this reason, the inventors discovered that if both wheels were powered, lateral steering could be difficult. Based on this knowledge, in this embodiment, only one of the two wheels is an electrically driven wheel, and the other wheel is a non-driven wheel.

[0011] In addition, when traveling through narrow areas, we thought it would be better to have a narrow tread width on both wheels, taking into account interference with obstacles on either side. Furthermore, even if only one wheel is an electrically driven wheel, it is considered better to have a narrow tread width for the two wheels in order to improve steering by operating the left and right handles. In other words, it is considered better to have a narrow tread width for the two wheels in order to suppress turning toward the driven wheels and make it easier to maintain the vehicle posture. From this perspective, in this embodiment, the two left and right wheels are positioned between the left and right handles when viewed from the front (see Figure 1). In addition, in this embodiment, by using only one wheel as an electric drive wheel, it is possible to suppress an increase in the weight of the bogie to assist the driving force, and to avoid making the bogie more complicated despite the good running stability.

[0012] (composition) Next, the configuration of the electric transport vehicle of this embodiment will be described with reference to the drawings. The electric transport cart 1 of this embodiment has a basic structure of a two-wheeled hand truck, as shown in Figures 1 to 6. That is, as shown in Figure 1, the electric transport cart 1 of this embodiment includes a body frame 2, a pair of handle units 3 on the left and right, and two wheels 4 arranged opposite each other in the left-right direction.

[0013] <Body frame 2> The body frame 2 constitutes the body skeleton of the bogie, and its upper part constitutes a loading platform 2 A. This loading platform 2 A may have a mounting support jig (not shown) for loading and supporting a load. In this embodiment, the width of the body frame 2 and the loading platform 2A are narrow so that the vehicle can travel in narrow spaces. Also, the loading platform 2A in this embodiment has a shape in which the length in the front-to-rear direction is longer than the width. Therefore, the handle unit 3 is configured to be farther away from the wheels 4 in the front-to-rear direction.

[0014] Mounting portions 2B that protrude downward are provided on the front side of the body frame 2. The mounting portions 2B are holding portions that support the left and right wheels 4. A pair of opposing mounting portions 2B is provided on the left and right sides for each wheel 4. In this embodiment, as shown in Figures 2 and 3, there are four mounting portions 2B lined up in the left-right direction. The rear of the body frame 2 has left and right legs 2C that protrude downward. The left-right direction is synonymous with the width direction of the carriage.

[0015] <Left and right handles 3> The left and right handle sections 3 are arranged in pairs in the left-right direction, and each handle section 3 has its front end connected to the body frame 2, extends rearward from the body frame 2, and has a grip section 3a at its rear end in the extension direction. In this embodiment, the handle section 3 extends rearward after its front section rises upward, and is at a height that allows an operator to easily grasp the grip section 3a. The operator grasps the left and right grip portions 3a and lifts the handle portion 3 upward to lift the left and right legs 2C, and then operates the left and right handle portions 3 to travel and steer the cart. The rear ends of the left and right handle portions 3 may be connected to each other.

[0016] The distance between the left and right handle portions 3 is set in consideration of the ease of operation by the operator. Furthermore, to enable travel in narrow spaces, the distance L2 between the left and right handle portions 3 is, for example, in the range of 40 cm to 80 cm (see FIG. 4). In this embodiment, the distance L2 is set to 60 cm. Here, the left and right handle units 3 extend rearward. Therefore, the distance from the turning center of the left and right wheels 4 to the grips 3a of the handle units 3 is longer than the distance from the turning center to each wheel 4. Therefore, a leverage equivalent to the arm ratio is applied to the operation of the handle units 3, and the operation load (load applied for steering) can be reduced relative to the resistance from the wheel contact area. In particular, in this embodiment, the tread width L1 between the wheels is reduced, so the operation load can be further reduced relative to the resistance from the wheel contact area.

[0017] <Two wheels 4> This embodiment is an electric transport cart 1 consisting of a two-wheeled cart. The left and right wheels 4 are disposed opposite each other in the left-right direction. Each wheel 4 is mounted on the body frame 2 by attaching both left and right ends of an axle 4a to the mount portion 2B. In this embodiment, one wheel 4A is a driving wheel that is an electric wheel with a built-in in-wheel motor 10. The other wheel 4B is a non-driven wheel. For example, the left wheel is the driving wheel 4A and the right wheel is the driven wheel 4B. The tires of the left and right wheels 4 are, for example, tube tires filled with air. The drive wheels 4A can be driven by in-wheel motors 10. By using in-wheel motors 10 as the drive motors, the amount of protrusion to the left and right is reduced.

[0018] The in-wheel motor 10 includes a stator and a rotor rotatably mounted on the outer periphery of the stator (both not shown). An axle 4a is coaxially fixed to the stator. When power is supplied to the in-wheel motor 10, the rotor rotates relative to the stator, and the wheel 4A rotates integrally with the rotor. A one-way clutch (not shown) may be built into the in-wheel motor 10. The one-way clutch is a clutch that mechanically separates the contact points of the coil section to allow the in-wheel motor 10 to run freely when an operator manually moves the cart. The action of this one-way clutch prevents the in-wheel motor 10 from generating resistance torque when the handcart is moved manually, thereby improving the convenience of the handcart. Manual movement refers to a state in which the assist drive force is turned off. However, the in-wheel motor 10 is not limited to the above configuration, and known devices and mechanisms can be applied. Furthermore, the two wheels 4 are, for example, wheels 4 of the same diameter. The treads of the two wheels 4 may be the same or different. For example, the tread on the driven wheel 4B side may be set smaller.

[0019] In this embodiment, the two wheels 4 are positioned inward (toward the center) of the left and right grip portions 3a in a front view. The tread width L1 (see FIG. 3) of the two wheels 4 is preferably set to be equal to or less than half the distance L2 between the left and right grip portions 3a. In this embodiment, the tread width L1 of the two wheels 4 is set to, for example, 30 cm. In this embodiment, the two wheels 4 are arranged symmetrically. However, in consideration of operational stability, the driven wheel 4B may be arranged further outward than the drive wheel 4A in the symmetrical position in the left-right direction. In other words, the distance from the widthwise center of the bogie of the driven wheel 4B may be greater than the distance from the drive wheel 4A. For example, the driven wheel 4B may be arranged 10 mm outward.

[0020] <Battery> The electric transport cart 1 of this embodiment includes a battery 12. The battery 12 is a power supply device that supplies power to the in-wheel motor 10. The battery 12 is configured such that the battery body is housed in a waterproof battery case. The in-wheel motor 10 and battery 12 are electrically connected by a wiring cable that is passed through the axle 4a of the drive wheel 4A. The battery itself is, for example, a secondary battery that can be repeatedly charged and discharged. A dedicated AC / DC charger is used to charge the secondary battery. This charger can be connected to a 100V household outlet and the battery 12, converting 100V AC power into DC power before charging the secondary battery.

[0021] The battery 12 is preferably fixed at a position that minimizes interference between the battery 12 and structures, obstacles, etc. that may be present at the work site of the electric transport vehicle 1. For this reason, in this embodiment, the battery 12 is disposed at the bottom of the loading platform 2A. The battery 12 is also disposed, for example, between the two wheels 4 in the left-right direction when viewed from the front. The battery 12 is disposed, for example, in the center of the loading platform 2A in the width direction. The battery 12 is preferably disposed behind the two wheels 4 when viewed from above. The indicator 12a of the battery 12 is arranged to face the loading platform 2A, and the portion of the loading platform 2A facing the indicator 12a is open (see FIG. 4), making it possible to check the state of the battery 12 from the loading platform 2A side. The battery 12 is electrically connected to a controller (described later) via the wiring cable.

[0022] <Controller 13> The electric transport vehicle 1 of this embodiment includes a controller 13 and an input device 5. The controller 13 is a device that controls the in-wheel motor 10 in response to an operation signal output from the input device 5. For example, when the input device 5 is operated by an operator, a signal (operation signal) corresponding to the operation is output from the input device 5 to the controller 13. The controller 13 includes circuit components including, for example, a controller IC (with built-in memory), power transistors, capacitors, etc. Furthermore, the controller 13 has a waterproof and dustproof case that houses the circuit components. The case may also house wiring cables, etc. It is desirable to fix the controller 13 in a position that minimizes interference between the controller 13 and structures, obstacles, etc. that may be present at the work site of the electric transport vehicle 1. From this perspective, the controller 13 is attached to the bottom of the loading platform 2A.

[0023] In this embodiment, the controller 13 is disposed in the center of the carriage in the width direction. The controller 13 may also be disposed on the opposite side of the drive wheels 4A in the left-right direction. The controller 13 is connected to a plurality of wiring cables extending from the battery 12, the input device 5, and the in-wheel motor 10. That is, the controller 13 is electrically connected to the battery 12, the input device 5, and the in-wheel motor 10 via the plurality of wiring cables.

[0024] <Input Device 5> The input device 5 is an operator that accepts operations by an operator using the electric transport cart 1. The controller 13 receives an operation signal from the input device 5 and supplies the power supplied from the battery 12 to the in-wheel motor 10 while appropriately converting and amplifying the power, thereby controlling the driving force and rotation speed of the electric wheels 4. The input device 5 is provided in the vicinity of the grip portion 3 a of the left handle portion 3 . The input device 5 includes, for example, an accelerator lever and a switch section. The accelerator lever is a lever for adjusting the rotation speed of the in-wheel motor 10. The accelerator lever is attached to the main body so that it can tilt relative to the main body, with its base end pivotally supported on the main body. An operator can accelerate or decelerate the electric transport cart 1 by operating the accelerator lever to change its tilt angle.

[0025] Examples of the switch unit included in the input device 5 include a power switch for switching the assist provided by the in-wheel motor 10 on and off, and a mode change switch for switching the operation mode of the assist. By switching the operation mode, it is possible to change the speed range, for example. As the operation mode, for example, the maximum output (maximum speed) can be exemplified in the following five stages. 1st stage: Maximum speed 2km / h 2nd stage: Maximum speed 3km / h 3rd stage: Maximum speed 4km / h 4th stage: Maximum speed 5km / h 5th stage: maximum speed 6km / h

[0026] A display unit may be provided near the input device 5. The display unit is a small liquid crystal display provided to display various information related to the drive wheels 4A. For example, the display unit can display the operation mode of the drive wheels 4A, the remaining capacity of the battery 12, etc. Furthermore, a wiring cable extending from the controller 13 is connected to the input device 5. That is, the input device 5 is electrically connected to the controller 13 via the wiring cable.

[0027] <Brake device> The electric transport cart 1 of this embodiment also includes a brake mechanism 11 and a brake lever 6. In this embodiment, the driving wheel 4A is provided with a roller brake that constitutes the brake mechanism 11. The brake mechanism 11 may also be provided on the driven wheel 4B side. In addition, a brake lever 6 is provided near the grip 3a on the right handle 3 as an operator connected to a brake mechanism 11. When the operator operates the brake lever 6, the brake mechanism 11 is activated, and it becomes possible to apply the brakes to the wheels 4 on which the brake mechanism 11 is provided.

[0028] (Operation etc.) In this embodiment, the two-wheeled vehicle provides improved lateral stability without swaying from side to side compared to a single-wheeled vehicle, making it possible to travel in narrow spaces more easily than a single-wheeled vehicle. Furthermore, by using only one of the two wheels as the drive wheel 4A, it is possible to assist the drive and the operability of the carriage when traveling is ensured. If both wheels are driven wheels 4A, the motor torque increases. Therefore, when a worker operates the cart sideways, the worker must hold down the handle to move forward or backward to overcome the motor torque, which makes it difficult to operate left and right. In other words, with two-wheel drive, the motor drive resistance makes it difficult to turn the cart.

[0029] In contrast to this, in this embodiment, one wheel is designated as the driving wheel 4A, ensuring forward and backward propulsion force, while the other wheel is designated as the driven wheel 4B, making it easier for the bogie to turn. In other words, the load shared by the driven wheel 4B can be reduced, making it easier to turn. Specifically, the turning center is closer to the driving wheel 4A because of the large rotational resistance. Furthermore, if only one wheel is the drive wheel 4A, it becomes easier to turn toward the driven wheel 4B, but straight-line movement can be ensured by the operator applying force in the yawing direction of the vehicle, that is, by the operator applying force to maintain the direction of the cart. In this case, by arranging the drive wheel 4A and the driven wheel 4B close to each other, and particularly by arranging the drive wheel 4A near the center of gravity of the cart, the force that the operator applies in the yawing direction of the vehicle is reduced. Note that the fact that the grip portion 3a is located far from the center of gravity of the cart also contributes to reducing the force that is applied in the yawing direction of the vehicle.

[0030] That is, in this embodiment, assuming that the turning center is between the two wheels 4 in a front view, the moment acting on the wheels 4 is increased by narrowing the wheel spacing (tread width L1) relative to the length from the turning center to the grip portion 3a of the handle portion 3. Also, the rotational resistance of the driven wheels 4B is reduced relative to the driving wheels 4A, for example, to about one-tenth, making it easier for the driven wheels 4B to rotate. As described above, in this embodiment, turning toward the driven wheels 4B is suppressed, and the vehicle attitude is easily maintained, that is, the vehicle is easily oriented in the desired direction. This makes it possible to travel in narrow spaces.

[0031] In addition, by arranging the left and right wheels between the left and right handle sections 3 when viewed from the front, the wheels 4 are prevented from interfering with obstacles such as walls, making it easier to travel in narrow spaces. As described above, in this embodiment, while achieving both the driving (travel) assist property and the guarantee of steering performance, by using a drive motor for only one wheel, that is, by solving the problem of electrification with a single motor, it is possible to suppress an unnecessary increase in weight and avoid an unnecessary complication of the bogie configuration. For example, compared to using drive wheels 4A for both wheels 4, the number of motors used can be reduced, and accordingly the cost of the battery 12 and the controller 13 can be kept low.

[0032] Furthermore, the indicator 12a of the battery 12 can be seen through a gap in the loading platform 2A, so that the replacement time for the battery 12 can be known and the replacement can be easily carried out. Furthermore, by arranging the battery 12 and the controller 13 below the loading platform 2A, the battery 12 and the controller 13 are protected from external obstacles, and by arranging the battery 12, which is a heavy object, below the loading platform 2A, the stability of the center of gravity of the cart is improved.

[0033] To reduce the storage space required for the trolley, the trolley is sometimes stored with the loading platform 2A upright. In this case, the front of the trolley is placed on the ground and the trolley is leaned up against the ground. This operation is performed with the brakes applied. Considering such leaning, a heavy object may be placed on the left-right opposite side of the in-wheel motor 10. In this case, the weight balance in the left-right direction is improved, and when the loading platform 2A is stored upright, the cart is less likely to tip over and is easier to handle. The heavy object may be a battery 12 or the like. Also, a brake mechanism 11 may be placed on the driven wheel 4B, and the brake mechanism 11 may be the above-mentioned heavy object. Furthermore, it is preferable that the battery 12 is oriented so as to be openable upward when the loading platform is in an upright position, and the indicator 12a is provided so as to face the loading platform 2A side (see FIGS. 4 and 5). On the other hand, by placing the heavy battery 12 near the center of the loading platform 2A, operability and workability are improved.

[0034] (others) The present disclosure may also have the following configuration. (1) Disclosure 1 is a vehicle comprising a body frame having a loading platform on top, left and right handlebars each extending rearward from the body frame and having a grip at a rear end in the extending direction, and two wheels each attached to the body frame and arranged opposite each other in the left-right direction, One of the two wheels is a drive wheel that is an electric wheel with a built-in in-wheel motor, and the other is a non-drive driven wheel, The left and right positions of the two wheels are arranged inside the positions of the left and right grip portions when viewed from the front. Electric transport cart. (2) Disclosure 2 is an electric transport cart in which the distance between the driven wheels and the center position in the width direction of the cart is greater than the distance between the drive wheels and the center position in the width direction of the cart. (3) Disclosure 3 provides a battery that supplies power to the in-wheel motor under the loading platform, The battery is disposed between the two wheels in a left-right direction when viewed from the front. Electric transport cart. [Explanation of symbols]

[0035] 1 Electric transport cart 2 Body frame 2A Cargo bed 2B Mounting section 2C Legs 3 Handle 3a Grip 4 wheels 4a Axle 4A Drive wheels 4B Driven wheel 5 Input Devices 6. Brake lever 10 In-wheel motor 11 Brake mechanism 12 Battery 12a Indicator 13 Controller

Claims

1. a body frame having a loading platform on top; left and right handlebars each extending rearward from the body frame and having a grip at a rear end in the extending direction; and two wheels each attached to the body frame and arranged opposite each other in the left-right direction; One of the two wheels is a drive wheel that is an electric wheel with a built-in in-wheel motor, and the other is a non-drive driven wheel, The two wheels are positioned in the left-right direction on the inside of the positions of the left and right grip portions when viewed from the front. Electric transport cart.

2. a distance from the center position of the bogie in the width direction of the driven wheels to the center position of the bogie in the width direction of the driven wheels being greater than ...

2. The electric transport cart according to claim 1.

3. a battery for supplying power to the in-wheel motor is disposed below the loading platform; The battery is disposed between the two wheels in a left-right direction when viewed from the front.

3. The electric transport cart according to claim 1 or 2.

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