Auxiliary towing device of electric towing car

Abstract

To provide an auxiliary towing device of an electric towing car that regularly enables the car to tow stably regardless of amounts of loaded cargoes and unevenness on a floor surface.SOLUTION: An auxiliary towing device 1 comprises: a substrate 10 whose one end in a longitudinal direction is connected to an electric towing car 100 horizontally turnably; a hook member 20, provided at the other end in the longitudinal direction of the substrate 10, which has a support plate 21a for supporting a main body part 210 of a truck 200 and hook pins 22 and 22 erected on support plate 21a and can be engaged with the main body part 210 of the truck 200; a frame member 40, connected to the other end in the longitudinal direction of the substrate 10 and extended in the longitudinal direction below the hook member 20, which is provided with a transverse-swing preventing wheel 50 constituted of fixed wheels; a lifting device 30, provided in the substrate 10, which lifts the hook member 20; and a damper mechanism 23, provided in the support plate 21a, which elastically supports the main body part 210 of the truck 200 engaged with the hook member 20.SELECTED DRAWING: Figure 18

Description

[Technical field]

[0001] The present invention relates to a traction auxiliary device that is used by being coupled to an electric towing vehicle in order to tow a cart and transport it on a floor surface. [Background technology]

[0002] Conventionally, carts have been widely used to load and move goods such as merchandise in factories, warehouses, and large stores. However, a considerable amount of force is required to move a cart loaded with goods, making it very difficult for one person to move it alone.

[0003] In order to improve this situation, an electric towing vehicle has been proposed which comprises a vehicle body, a motor housed within the vehicle body, a battery that serves as a power source for the motor, wheels driven by the motor, and a handle for steering the direction of travel, and which tows a bogie by removably connecting it thereto (see Patent Document 1).

[0004] Here, there is a type of cart in which all four wheels are swivel wheels (hereinafter referred to as a "four-wheel swivel cart"). All four wheels of the four-wheel swivel cart can rotate horizontally, making it easy to move in any direction and maneuverable, making it suitable for use in narrow warehouses and stores. However, it has a problem in that it is not suitable for moving long distances because of its poor running stability.

[0005] In view of such problems, a towing auxiliary device has been proposed in the past to improve operability when a four-wheel free-wheeling bogie is towed by an electric towing vehicle, for adding the function of fixed wheels to the four-wheel free-wheeling bogie during towing (see Patent Document 2). This towing auxiliary device improves the running stability when a four-wheel free-wheeling bogie is towed by an electric towing vehicle, and can improve maneuverability. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2006-298157 A [Patent Document 2] European Patent Application Publication No. 2269889 Summary of the Invention [Problem to be solved by the invention]

[0007] The towing assistance device described in Patent Document 2 has a first frame portion and a second frame portion arranged one above the other, with their tips rotatably supported, and a spring provided between the two frames urges the second frame portion downward, thereby pressing the fixed wheel against the floor surface.

[0008] However, with a structure that simply presses the traction auxiliary device described in Patent Document 2 against the floor surface with the force of a spring, there is a risk that the fixed wheels may not be able to obtain sufficient ground contact force depending on the weight of the luggage loaded onto the trolley and the unevenness of the floor surface.

[0009] The present invention has been made in consideration of the above-mentioned problems, and has an object to provide a towing auxiliary device for an electric towing vehicle that always enables stable towing regardless of the amount of luggage loaded or the unevenness of the floor surface. [Means for solving the problem]

[0010] The towing auxiliary device for an electric towing vehicle of the present invention is a towing auxiliary device used by connecting it to an electric towing vehicle configured to electrically drive drive wheels provided on a vehicle body in order to tow a trolley and transport it across a floor surface, and comprises a base whose one end in the fore-and-aft direction is connected to the electric towing vehicle so as to be freely rotatable horizontally, a hook member provided at the other end in the fore-and-aft direction of the base, having a support plate for supporting the main body of the trolley and an upright portion provided on the support plate and capable of engaging with the main body of the trolley, a frame member connected to the other end in the fore-and-aft direction of the base, extending in the fore-and-aft direction below the hook member, and having a lateral run-out prevention wheel consisting of a fixed wheel, a lifting device provided on the base and for raising and lowering the hook member, and a damper mechanism provided on the support plate and for elastically supporting the main body of the trolley engaged with the hook member.

[0011] According to this configuration, when a traction auxiliary device is used to transport a traction dolly with four free-wheeling wheels, the hook member is raised by the lifting device until the support plate receives a load equal to or greater than a predetermined value with the frame member inserted in the lower space between the traction dolly body and the floor surface, so that the anti-sway wheel generates an appropriate grounding force against the floor surface. Furthermore, since the trolley body is elastically supported by a damper mechanism provided on the hook member, an appropriate grounding force is always generated in the anti-sway wheel even if the trolley vibrates up and down due to unevenness of the floor surface. As a result, the anti-sway wheel properly contacts the floor surface, so that the anti-sway wheel reliably functions as a fixed wheel of the trolley, and the trolley can be towed stably regardless of the unevenness of the floor surface, preventing the trolley from swaying laterally when turning, etc. This provides the effect of always enabling stable towing regardless of the load amount or unevenness of the floor surface.

[0012] The lifting device further includes an automatic stop unit that automatically stops the lifting when the hook member receives a load equal to or greater than a predetermined value during the lifting by the lifting device.

[0013] According to this configuration, the automatic stop section automatically stops the ascent when the hook member receives a load equal to or greater than a predetermined value during ascent by the lifting device, thereby automatically and reliably generating an appropriate grounding force between the anti-lateral sway wheel and the floor surface.

[0014] In addition, the lifting device is configured to have an electric motor and a linear motion mechanism driven by the electric motor to move linearly in the vertical direction, and the automatic stop unit detects when it receives a load equal to or greater than the specified value based on a change in the current value in the electric motor.

[0015] According to this configuration, the hook member can be raised and lowered with a simple and compact configuration, and the raising can be automatically stopped by simply and reliably detecting when the hook member receives a load equal to or greater than a predetermined value.

[0016] The device further includes a switching mechanism that switches the anti-lateral sway wheel between a grounding position in which it is in contact with the floor surface and a non-grounding position in which it is separated from the floor surface, and the automatic stop unit automatically stops the ascent when the hook member receives a load of a first predetermined value or more during ascent by the lifting device when the anti-lateral sway wheel is in the grounding position, whereas the automatic stop unit automatically stops the ascent when the hook member receives a load of a second predetermined value or more that is smaller than the first predetermined value during ascent by the lifting device when the anti-lateral sway wheel is in the non-grounding position.

[0017] According to this configuration, when the sway prevention wheel is placed in a ground contact position by the switching mechanism, the automatic stop unit automatically stops the ascent when the hook member receives a load of equal to or greater than a first predetermined value, thereby automatically and reliably generating an appropriate ground contact force for the sway prevention wheel against the floor surface. On the other hand, when the sway prevention wheel is placed in a non-ground contact position by the switching mechanism, the automatic stop unit automatically stops the ascent when the hook member receives a load of equal to or greater than a second predetermined value that is smaller than the first predetermined value, thereby preventing the generation of a force that inhibits the driving force of the electric towing vehicle. [Brief description of the drawings]

[0018] [Figure 1] 1 is a perspective view showing a state in which a bogie is towed using a towing auxiliary device for an electric towing vehicle according to an embodiment of the present invention; [Diagram 2] FIG. 11 is another perspective view showing the state in which the traction assist device is used to tow the dolly. [Diagram 3] FIG. 2 is an enlarged perspective view showing the periphery of a handle of the electric towing vehicle. [Figure 4] FIG. 2 is a perspective view showing the overall configuration of the traction auxiliary device (four-wheel swivel bogie mode). [Diagram 5] FIG. 11 is another perspective view showing the overall configuration of the traction auxiliary device (four-wheel swivel bogie mode). [Figure 6] FIG. 5 is a side view showing the traction auxiliary device of FIG. 4 (four-wheel swivel bogie mode). [Figure 7] 7 is a side view showing a state in which a hook member is raised in the traction auxiliary device of FIG. 6 (in four-wheel swivel carriage mode). FIG. [Figure 8] FIG. 11 is a cross-sectional view of the hook member illustrating the damper mechanism in an uncompressed state. [Figure 9] FIG. 11 is a cross-sectional view of the hook member illustrating a compressed state of the damper mechanism. [Figure 10] FIG. 2 is an explanatory diagram illustrating a schematic configuration of a lifting device. [Figure 11] FIG. 2 is a perspective view showing the overall configuration of the towing auxiliary device (two-wheel fixed carriage mode). [Figure 12] FIG. 12 is a side view showing the traction auxiliary device of FIG. 11 (two-wheel fixed carriage mode). [Figure 13] 13 is a side view showing a state in which a hook member is raised in the towing auxiliary device of FIG. 12 (two-wheel fixed carriage mode). FIG. [Figure 14] FIG. 2 is a block diagram showing an electrical configuration of the traction assist device. [Figure 15] 13 is a flowchart showing a flow of an ascent control. [Figure 16] 13 is a flowchart showing a flow of lowering control. [Figure 17] 1 is a side view showing a state before the hook member is raised in a traction auxiliary device in which a frame member is inserted into a space under a main body portion of a four-wheel swivel bogie. FIG. [Figure 18] 18 is a side view showing a state in which the lifting of the hook member in FIG. 17 has been completed. FIG. [Figure 19] FIG. 11 is an explanatory diagram for explaining a ground contact force acting before the hook member is lifted in the four-wheel swivel carriage mode. [Figure 20] FIG. 13 is an explanatory diagram for explaining a ground contact force acting when the hook member has completed raising in the four-wheel swivel carriage mode. [Figure 21] 1 is a side view showing a state before the hook member is raised in a towing auxiliary device in which a frame member is inserted into a space below a main body portion of a two-wheel fixed dolly. FIG. [Figure 22] 22 is a side view showing a state in which the lifting of the hook member in FIG. 21 has been completed. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a towing auxiliary device for an electric towing vehicle according to one embodiment of the present invention will be described with reference to the drawings.

[0020] <Overall configuration of the towing auxiliary device 1 for electric towing vehicle> First, the overall configuration of the towing auxiliary device 1 of the electric towing vehicle according to the embodiment of the present invention will be described with reference to Figs. 1 to 13. Fig. 1 is a perspective view showing the state in which the towing auxiliary device 1 is used to tow the bogie 200, and Fig. 2 is another perspective view of the same. Fig. 3 is an enlarged perspective view of the periphery of the operation handle 140 of the electric towing vehicle 100. Fig. 4 is a perspective view showing the overall configuration of the towing auxiliary device 1 (four-wheeled bogie mode), and Fig. 5 is another perspective view of the same. Fig. 6 is a side view showing the towing auxiliary device 1 (four-wheeled bogie mode) of Fig. 4, and Fig. 7 is a side view showing the state in which the hook member 20 is raised in Fig. 6. Fig. 8 is a cross-sectional view of the hook member 20 showing the damper mechanism 23 in an uncompressed state, and Fig. 9 is a cross-sectional view of the hook member 20 showing the damper mechanism 23 in a compressed state. Fig. 10 is an explanatory view showing the configuration of the lifting device 30 in a schematic manner. Fig. 11 is a perspective view showing the overall configuration of the towing auxiliary device 1 (two-wheel fixed cart mode), Fig. 12 is a side view, and Fig. 13 is a side view showing the state in which the hook member 20 is raised in Fig. 12. In this embodiment, the direction parallel to the conveying direction is referred to as the front-rear direction, and the horizontal direction perpendicular to the front-rear direction is referred to as the left-right direction.

[0021] The towing auxiliary device 1 for an electric towing vehicle is a towing auxiliary device used in connection with an electric towing vehicle 100 configured to electrically drive drive wheels 120 provided on a vehicle body 110 in order to tow a trolley 200 and transport it across a floor surface FL.

[0022] 1 and 2, the electric towing vehicle 100 is configured to include a vehicle body 110 equipped with a pair of drive wheels 120, 120, a drive wheel motor (not shown) mounted on the vehicle body 110 and driving the drive wheels 120, an operating handle 140, and a battery 170. As shown in FIG. 3, the operating handle 140 is equipped with a forward / reverse switch 142, an up push button switch 143, and a down push button switch 144.

[0023] The dolly 200 is a hand-pushed dolly (a so-called hand-pushed basket dolly) equipped with a basket for accommodating luggage, and is configured with a main body 210, a pair of front wheels 220, a pair of rear wheels 230, and a basket part 240 that surrounds the front, rear, and left sides of the main body 210 with a metal fence. There are two types of dolly 200: a four-wheel free-wheel dolly in which all four wheels, the front wheels 220 and the rear wheels 230, are free-wheeling wheels, and a two-wheel fixed dolly in which two free-wheeling wheels are provided as the front wheels 220 and two fixed wheels are provided as the rear wheels 230. The dolly to be transported is not limited to a hand-pushed basket dolly, and may be a dolly without a basket.

[0024] As shown in Figures 4 to 7 and 11 to 13, the traction auxiliary device 1 is configured to include a base body 10, a hook member 20, a lifting device 30, a frame member 40, a pair of lateral runout prevention wheels 50, 50, and a switching mechanism 60.

[0025] The front end of the base body 10 is connected to the electric towing vehicle 100 so as to be horizontally rotatable. Specifically, the base body 10 is configured to include an arm 11 forming the main part of the base body 10, a connecting rotation part 12, and a lifting device support part 13. The arm 11 is made of steel and is a square cylindrical member extending in the front-rear direction. The connecting rotation part 12 is provided on the front end side of the arm 11, and connects the arm 11 to the electric towing vehicle 100 so as to be horizontally rotatable. The lifting device support part 13 is provided on the rear end side of the arm 11, and fixedly supports the lifting device 30.

[0026] The hook member 20 is provided at the rear of the base 10 on the opposite side to the connecting and rotating part 12, and is capable of engaging with the lower part of the cart 200. As shown in Figures 4, 6, etc., the hook member 20 includes a hook member main body 21, a pair of hook pins 22, 22, a pair of damper mechanisms 23, 23, and a pair of connecting guides 24, 24.

[0027] The hook member body 21 includes a support plate 21a, a square tube member 21b, a front plate 21c, and a pair of side plates 21d, 21d, and is configured by joining the respective members together. The support plate 21a is a plate-like member that is arranged horizontally and extends in the left-right direction. The square tube member 21b is a square tube-like member that extends in the left-right direction, and is arranged forward on the upper surface of the support plate 21a and integrated with it. The front plate 21c is a plate-like member that extends in the left-right direction, and is arranged in front of the square tube member 21b on the upper surface of the support plate 21a and integrated with it, and is fixed to the carriage 34. The pair of side plates 21d, 21d are plate-like members that are approximately triangular in side view, and are joined in a vertical position to the left and right end surfaces of the support plate 21a, the square tube member 21b, and the front plate 21c, and are integrated with them.

[0028] The pair of hook pins 22, 22 are made of metal members having a generally cylindrical pin shape, and are provided upright at a distance from each other in the left-right direction near the rear end of the support plate 21a.

[0029] The pair of damper mechanisms 23, 23 are members for elastically supporting the main body 210 of the dolly 200, and are constituted by known spring dampers equipped with coil springs. The pair of damper mechanisms 23, 23 are arranged and fixed at a distance in the left-right direction with their upper portions protruding from the upper surface of the support plate 21a. In this embodiment, the pair of damper mechanisms 23, 23 are arranged adjacent to the front side of the pair of hook pins 22, 22. As shown in Figs. 8 and 9, each damper mechanism 23 is constituted by a coil spring 23a, a cylindrical body 23b that accommodates the coil spring 23a, a core rod 23c that is inserted and arranged at the axis of the coil spring 23a, a bottom plate 23d that is fixed to the lower surface of the cylindrical body 23b and supports the lower end of the coil spring 23a, and a contact plate 23e that is attached to the upper end, which is the free end, of the coil spring 23a.

[0030] The pair of connecting guides 24, 24 are plate-like members having a substantially triangular shape in a side view, which are slightly larger than the pair of side plates 21d, 21d. The pair of connecting guides 24, 24 have adjustment holes 24a, 24a that are long in the front-rear direction formed at two locations, one above the other. The pair of connecting guides 24, 24 can be fixed by adjusting the front-rear direction position relative to the hook member main body 21 by inserting the foot parts of each bolt 24b into the adjustment holes 24a, respectively, and fastening them to the pair of side plates 21d, 21d at any position in the front-rear direction within each adjustment hole 24a. According to this configuration, the pair of connecting guides 24, 24 whose front-rear positions have been adjusted and the pair of hook pins 22, 22 can be connected by sandwiching the frame of the dolly 200 in close contact with each other, so that rattling of the dolly 200 during towing can be prevented.

[0031] The lifting device 30 is provided on the base 10 and lifts the hook member 20, and as shown in Figure 10, is composed of a motor device 31, a linear motion mechanism 32, a lifting body 33, a carriage 34, and a lifting guide 35.

[0032] The motor device 31 is configured to include a lifting motor 31m, a reduction gear unit 31g, and a rotation axis conversion unit 31h, and is fixed to the lifting device support unit 13. The lifting motor 31m is, for example, a permanent magnet type synchronous motor, but may be a DC motor or an induction motor. The lifting motor 31m is driven by power supplied from a battery 170 mounted on the electric towing vehicle 100. The reduction gear unit 31g is a device for reducing the rotation speed input from the lifting motor 31m at a predetermined reduction ratio and outputting it. The rotation axis conversion unit 31h is a device for converting the direction of the rotation axis input from the reduction gear unit 31g by 90 degrees to match the direction of the rotation axis of the screw shaft 32a of the linear motion mechanism 32. An encoder 31e is connected to the rotation axis conversion unit 31h, and is configured to be able to measure the number of rotations of the screw shaft 32a.

[0033] The linear motion mechanism 32 is configured by a feed screw mechanism including a screw shaft 32a and a nut 32b screwed onto the screw shaft 32a, and is fixed to the lifting device support part 13. The screw shaft 32a is a shaft member having a helical male screw portion formed on its outer periphery, and is disposed with its axis oriented vertically.

[0034] The screw shaft 32a has a lower end connected to a rotation axis conversion portion 31h of the motor device 31, and an upper end rotatably supported via a ball bearing 32c.

[0035] The nut 32b has a helical female thread portion on its inner circumferential surface that corresponds to the male thread portion of the screw shaft 32a, and is screwed onto the screw shaft 32a. A large number of rolling elements are rollably loaded between the thread grooves of the nut 32b and the screw shaft 32a.

[0036] Since the nut 32b is held by the nut holding portion 33a of the lifting body 33, when the screw shaft 32a is driven to rotate in the forward direction, the nut 32b rises along the screw shaft 32a via the rolling elements loaded in the spiral screw groove.

[0037] On the other hand, when the screw shaft 32a is rotated in the reverse direction, the nut 32b descends along the screw shaft 32a via the rolling elements loaded in the helical thread groove.

[0038] The lifting body 33 is a rod-shaped member whose lower end is connected to the nut 32b via the nut holding portion 33a and whose upper end is connected to the carriage 34, and is disposed with its axis pointing vertically. The lifting body 33 rises as the nut 32b rises along the screw shaft 32a, and descends as the nut 32b descends along the screw shaft 32a.

[0039] The lift guide 35 is a member for guiding the carriage 34 in the vertical direction, and is made of a plate-like member that stands vertically on the upper surface of the rear end of the base body 10 and is fixed to the lift device support part 13.

[0040] The carriage 34 is mainly made of a frame-like member with a U-shaped cross section that matches both the left and right ends of the lifting guide 35, and its front surface is connected to the lifting body 33 at the top by a plate-like member on the left and right, and its rear surface is connected to the front plate 21c of the hook member main body 21 on the left and right. Therefore, the carriage 34 moves vertically upward and downward while being guided by the lifting guide 35 as the lifting body 33 moves upward and downward, and the hook member 20 that is integral with the carriage 34 moves vertically upward and downward.

[0041] The frame member 40 is configured to include a pair of frame member main bodies 41, 41 and a wheel support portion 42. The pair of frame member main bodies 41, 41 are formed by arranging two elongated rectangular tubular members side by side in parallel in the width direction, and extend horizontally rearward from the lower rear end of the base body 10 below the hook member 20. The frame member 40 is configured so that its tilted position can be changed by operating a lever 61.

[0042] The wheel support portion 42 is a portion that rotatably supports a pair of anti-lateral runout wheels 50, 50. The wheel support portion 42 is provided at the rear ends of the pair of frame member bodies 41, 41 with two U-shaped members in plan view that are open to the rear side and arranged side by side in the left-right direction, and a shaft member 42a having an axis oriented in the left-right direction is installed on each of the U-shaped members.

[0043] The pair of sway prevention wheels 50, 50 are supported rotatably around the left-right axis of the shaft member 42a in the wheel support part 42. The U-shaped member in plan view of the wheel support part 42 is immobile, and the pair of sway prevention wheels 50, 50 are fixed wheels that cannot rotate in the horizontal direction.

[0044] The switching mechanism 60 is a mechanism for switching the pair of sway prevention wheels 50, 50 between a grounding position where the wheels are in contact with the floor surface FL and a non-grounding position where the wheels are spaced apart from the floor surface FL. The state where the pair of sway prevention wheels 50, 50 are in the grounding position is suitable for towing a four-wheel free-wheeling dolly, and is referred to as the "four-wheel free-wheeling dolly mode" in this embodiment. The state where the pair of sway prevention wheels 50, 50 are in the non-grounding position is suitable for towing a two-wheel fixed dolly, and is referred to as the "two-wheel fixed dolly mode" in this embodiment. Specifically, the switching mechanism 60 is configured to include a lever 61, a swing link 62, a biasing spring 63, and a mode detection unit 64.

[0045] The lever 61 is a member for changing the position of the frame member 40, and is composed of a lever body 61a, a leg 61c, and an engagement pin 61d. The lever body 61a is made of a metal round bar, and a grip 61b is provided over a predetermined length from the tip. The lever body 61a is attached at its base end to the upper center in the longitudinal direction of the arm 11 via a rotation shaft so as to be rotatable in the front-rear direction. The leg 61c is a relatively short rod-like part connected at a right angle to the rear side of the base end of the lever body 61a, and is integral with the lever body 61a to form an L-shape in a side view. An engagement pin 61d is provided at the tip of the leg 61c so as to protrude in the width direction.

[0046] The swing link 62 is made by processing a steel plate into an elongated shape, and an engagement hole 62a is formed near the upper end with which the engagement pin 61d engages. The engagement hole 62a is an elongated hole bent into a substantially L-shape, and the engagement pin 61d is movably engaged between a first engagement position 62b, which is one end of the elongated hole, and a second engagement position 62c, which is the other end. The lower end of the swing link 62 is supported by the base ends of the pair of frame member main bodies 41, 41 via a rotation shaft 62d so as to be rotatable in the front-rear direction.

[0047] The biasing spring 63 is disposed along the front-rear direction, with one end connected to the upper part of the arm 11 via a mounting bracket and the other end connected to the upper part of the swing link 62. The biasing spring 63 biases the upper end side of the swing link 62 forward (counterclockwise in FIG. 6, etc.) around the rotation shaft 62d.

[0048] The mode detection unit 64 detects the posture of the lever 61, and is configured, for example, with a limit switch, and is disposed near the swing link 62 at the bottom of the base body 10. When the lever 61 is in the vertical posture, the switch 64a is pressed and outputs an ON signal, and when the lever 61 is not in the vertical posture and the switch 64a is not pressed, it outputs an OFF signal.

[0049] Next, the state of each part in each of the four-wheel swivel carriage mode (lateral sway prevention wheels 50 in a ground contact position) and the two-wheel fixed carriage mode (lateral sway prevention wheels 50 not in a ground contact position) will be described.

[0050] 6 and 7, in the four-wheel swivel cart mode, the lever body 61a is in a vertically standing position, and the engagement pin 61d is located at the first engagement position 62b of the engagement hole 62a. Also, the pair of frame member bodies 41, 41 have their tips where the wheel support parts 42 are provided inclined downward at a predetermined angle (e.g., 5°) with respect to the horizontal position, and the pair of lateral runout prevention wheels 50, 50 are in contact with the floor surface FL.

[0051] In the two-wheel fixed dolly mode, as shown in Fig. 12 and Fig. 13, the lever body 61a is in a posture inclined forward at a predetermined angle (e.g., 45°), and the engagement pin 61d is located at the second engagement position 62c of the engagement hole 62a. Also, the pair of frame member bodies 41, 41 have their tips on which the wheel support parts 42 are provided inclined upward at a predetermined angle (e.g., 5°) with respect to the horizontal posture, and the pair of lateral runout prevention wheels 50, 50 are spaced upward by several centimeters from the floor surface FL.

[0052] <Electrical configuration of traction auxiliary device 1> Next, the electrical configuration of the towing auxiliary device 1 will be described with reference to Fig. 14. Fig. 14 is a block diagram showing the electrical configuration of the towing auxiliary device 1. Note that the towing auxiliary device 1 is electrically integrated with the electric towing vehicle 100, but Fig. 14 shows only the electrical configuration related to the towing auxiliary device 1, and does not show the electrical configuration related only to the electric towing vehicle 100.

[0053] As shown in FIG. 14, the traction auxiliary device 1 is configured to include, as electrical components, an up push button switch 143, a down push button switch 144, a battery 170, a control unit 180, an encoder 31e, a lift motor 31m, and a mode detection unit 64.

[0054] The up push button switch 143 and the down push button switch 144 are connected to the CPU 181 of the control unit 180 and receive signals therefrom.

[0055] The battery 170 supplies power to each part of the device including the CPU 181 and the lift motor 31m.

[0056] The control unit 180 is configured to include a CPU 181, a ROM 182, a RAM 183, and a lift motor control circuit 185. The CPU 181 is a known central processing unit, and inputs a lift command, a lower command, and a stop command to the lift motor control circuit 185 based on signal input from the lift push button switch 143 and the lower push button switch 144. The ROM 182 is a known read-only semiconductor memory element, and stores control programs, control data, and the like. The RAM 183 is a known semiconductor memory element that can be read and written randomly, and is used by the CPU 181 as a work area, etc.

[0057] The lift motor control circuit 185 controls the lift motor 31 m to rotate in the normal direction, reverse direction or stop in response to a lift command, a lower command or a stop command input from the CPU 181 .

[0058] The encoder 31e outputs a signal in accordance with the rotation of the screw shaft of the linear motion mechanism 32, and inputs the signal to the CPU 181. The CPU 181 measures the number of rotations based on the signal input from the encoder 31e, and manages the elevation position of the carriage .

[0059] The lift motor 31m rotates in the normal direction, reverse direction or stops based on a command from the lift motor control circuit 185.

[0060] As already described, the mode detection unit 64 outputs an ON signal when the switch 64a is pressed when the lever 61 is in the vertical position, and outputs an OFF signal when the lever 61 is in a position other than the vertical and the switch 64a is not pressed, and is electrically connected to the CPU 181. When the CPU 181 receives an ON signal from the mode detection unit 64, it recognizes the four-wheel swivel carriage mode, and when it receives an OFF signal, it recognizes the two-wheel fixed carriage mode.

[0061] <Lifting control in traction auxiliary device 1> Next, the lifting and lowering control of the traction auxiliary device 1 will be described with reference to Figures 15 and 16. Figure 15 is a flow chart showing the flow of the lifting control, and Figure 16 is a flow chart showing the flow of the lowering control.

[0062] First, the flow of the ascent control will be described with reference to Fig. 15. When the ascent push button switch 143 is pressed, the CPU 181 executes the ascent control process shown in Fig. 15. In the ascent control process, first, in S1 (S represents a step; the same applies to the other steps), it is determined whether or not the current position of the carriage 34 is the upper limit position based on the count of the output of the encoder 31e.

[0063] If the lift motor 31m is at the upper limit position in S1 (S1: Yes), the lift motor control circuit 185 stops the lift motor 31m in S6, and the lift control ends.

[0064] On the other hand, if it is not at the upper limit position (S1: No), in S2, power is supplied from the lift motor control circuit 185 to the lift motor 31m to rotate it forward. When the lift motor 31m rotates forward, the current value CV is measured in S3.

[0065] Next, in S4, it is determined whether it is in the four-wheel independent cart mode based on the signal input from the mode detection unit 64. When an on signal is input from the mode detection unit 64 and it is recognized as the four-wheel independent cart mode in S4 (S4: Yes), in S5, it is determined whether the current value CV is equal to or greater than the first threshold value TH1. Here, when the load value received by the hook member 20 when an appropriate grounding force is generated on the pair of anti-roll wheels 50, 50 is set as the first predetermined value W1, the current value corresponding to the first predetermined value W1 is represented as the first threshold value TH1. That is, when the load received by the hook member 20 (in other words, the load on the lifting motor 31m) changes, the current value of the lifting motor 31m changes, so the current value is used to determine the load value. If the current value CV is not equal to or greater than the first threshold value TH1 (S5: No), it returns to S1. If the current value CV is equal to or greater than the first threshold value TH1 (S5: Yes), in S7, the lifting motor 31m is stopped (i.e., automatically stopped), and the upward control is terminated.

[0066] When an off signal is input from the mode detection unit 64 and it is recognized that it is not in the four-wheel independent cart mode (S4: No), that is, in the two-wheel fixed cart mode, in S6, it is determined whether the current value CV is equal to or greater than the second threshold value TH2. Here, when the load value when the hook member 20 is sufficiently engaged with the main body portion 210 of the cart 200 is set as the second predetermined value W2, the current value corresponding to the second predetermined value W2 is represented as the second threshold value TH2. If the current value CV is not equal to or greater than the second threshold value TH2 (S6: No), it returns to S1. If the current value CV is equal to or greater than the second threshold value TH2 (S6: Yes), in S7, the lifting motor 31m is stopped (i.e., automatically stopped), and the upward control is terminated. Note that the CPU 181 (S4 to S7) functions as the automatic stop unit of the present invention.

[0067] Here, the second threshold value TH2 is set to a value smaller than the first threshold value TH1 (TH2 < TH1). That is, when the hook member 20 is lifted in the two-wheel fixed cart mode, the lifting is automatically stopped with a load smaller than that in the four-wheel independent cart mode, so it is possible to prevent the generation of a force that inhibits the driving force of the electric tractor 100.

[0068] Next, the flow of the descent control will be described with reference to Fig. 16. When the descent push button switch 144 is pressed, the CPU 181 executes the descent control process shown in Fig. 16. In the descent control process, first, in S11, it is determined whether or not the current position of the carriage 34 is the lower limit position based on the count of the output of the encoder 31e.

[0069] If it is determined in S11 that the lift motor 31m is at the lower limit position (S11: Yes), the lift motor control circuit 185 stops the lift motor 31m in S13, and the lowering control ends.

[0070] On the other hand, if it is not at the lower limit position in S11 (S11: No), in S12, power is supplied from the lift motor control circuit 185 to the lift motor 31m to rotate it in reverse, and the process returns to S11. Thereafter, S11 to S12 are repeated until S11 becomes No.

[0071] <Operation procedure of the traction auxiliary device 1 and the function of each part> Next, the operation procedure and the action of each part when the traction auxiliary device 1 connected to the electric towing vehicle 100 is used to tow the dolly 200 will be described with reference mainly to Figs. 17 to 22. Fig. 17 is a side view showing the state before the hook member 20 is lifted in the traction auxiliary device 1 in which the frame member 40 is inserted into the space under the main body 210 of the dolly 200, which is a four-wheel free dolly, and Fig. 18 is a side view showing the state in Fig. 17 after the lifting of the hook member 20 is completed. Fig. 19 is an explanatory diagram showing the grounding force acting before the lifting of the hook member 20 in the four-wheel free dolly mode, and Fig. 20 is an explanatory diagram showing the grounding force acting when the lifting of the hook member 20 is completed. Fig. 21 is a side view showing the state before the hook member 20 is lifted in the traction auxiliary device 1 in which the frame member 40 is inserted into the space under the main body 210 of the dolly 200, which is a two-wheel fixed dolly, and Fig. 22 is a side view showing the state in Fig. 21 after the lifting of the hook member 20 is completed.

[0072] First, regardless of whether the dolly 200 is a four-wheel free dolly or a two-wheel fixed dolly, the traction auxiliary device 1 is set to the two-wheel fixed dolly mode at the start of use. If the traction auxiliary device 1 is not in the two-wheel fixed dolly mode when the device is started to be used (i.e., in the four-wheel free dolly mode), an operation to switch to the two-wheel fixed dolly mode is performed using the switching mechanism 60. Specifically, an operator holds the grip portion 61b of the lever body 61a with his / her hand and pushes it forward against the biasing force of the biasing spring 63, so that the lever body 61a is in a forward inclined position and the engagement pin 61d moves to the second engagement position 62c in the engagement hole 62a. As a result, the swing link 62 swings clockwise by a predetermined angle, and accordingly the frame member 40 rotates counterclockwise in FIG. 6, and the pair of lateral runout prevention wheels 50, 50 are set to the two-wheel fixed dolly mode at a predetermined distance from the floor surface FL (FIG. 12). If the two-wheel fixed carriage mode has already been selected before use, there is no need to perform a switching operation in the switching mechanism 60.

[0073] Next, the operator grasps the operating handle 140 of the electric towing vehicle 100 and operates the forward / reverse switch 142 to move the towing auxiliary device 1 together with the electric towing vehicle 100 backward, inserts the frame member 40 into the space below the main body 210 of the dolly 200, and moves backward until the pair of connecting guides 24, 24 abuts against the basket portion 240 of the dolly 200 (see FIG. 21). The operations thereafter differ depending on whether the dolly 200 is a four-wheel swivel dolly or a two-wheel fixed dolly, and will be explained below for each case.

[0074] <<When the cart 200 is a four-wheel swivel cart>> When the dolly 200 is a four-wheeled dolly, an operation for switching to the four-wheeled dolly mode is performed using the switching mechanism 60. Specifically, an operator grasps the grip portion 61b of the lever body 61a with his / her hand and pushes it backward against the biasing force of the biasing spring 63, so that the lever body 61a assumes a vertical position and the engagement pin 61d moves to the first engagement position 62b in the engagement hole 62a. As a result, the swing link 62 swings counterclockwise by a predetermined angle in FIG. 12, and the frame member 40 rotates clockwise accordingly, so that the pair of lateral runout prevention wheels 50, 50 contact the floor surface FL, and an ON signal is input from the mode detection unit 64 to the CPU 181, and the four-wheeled dolly mode shown in FIG. 6 is set.

[0075] Next, the lift push button switch 143 is pressed to lift the carriage 34. When the hook member 20, which is integral with the carriage 34, lifts, the pair of hook pins 22, 22 engage with the lower part of the main body 210 of the dolly 200, and the upper ends of the pair of damper mechanisms 23, 23 abut the lower surface of the main body 210. When the lift push button switch 143 is continuously pressed and the hook member 20 lifts and a load equal to or greater than a predetermined value is detected by the lifting device 30, the lifting is automatically stopped (see FIG. 18). Specifically, in the flowchart of FIG. 15, the current value CV is determined to be equal to or greater than the first threshold value TH1 in S6 (S6: Yes), and the motor is stopped in S7, thereby stopping the lifting of the hook member 20. At this time, when the downward load from the dolly 200 is applied to the hook member 20, it is transmitted to the pair of anti-lateral runout wheels 50, 50 via the frame member 40, and an appropriate grounding force is applied to the floor surface FL.

[0076] Here, if the ground contact force at the pair of drive wheels 120,120 and the ground contact force at the pair of lateral runout prevention wheels 50,50 before the hook member 20 is lifted are each F, the generation of the ground contact force is shown in Fig. 19. On the other hand, after the hook member 20 has been lifted, if the downward load by the carriage 200 is W, the upward thrust force generated in the hook member 20 is ΔA, the increase in the ground contact force at the pair of drive wheels 120,120 is ΔA1, and the increase in the ground contact force at the pair of lateral runout prevention wheels 50,50 is ΔA2, the generation of the ground contact force is shown in Fig. 20. At this time, the relationship ΔA=ΔA1+ΔA2 is established, and the ground contact force at the pair of drive wheels 120,120 is expressed as F+ΔA1, and the ground contact force at the pair of lateral runout prevention wheels 50,50 is expressed as F+ΔA2, respectively. In other words, the ground contact force of the pair of lateral runout prevention wheels 50, 50 increases by ΔA2 compared to before the hook member 20 was lifted, and becomes an appropriate ground contact force for stably towing the carriage 200.

[0077] Then, the forward / reverse switch 142 is operated to move the towing auxiliary device 1 connected to the electric towing vehicle 100 forward, thereby towing the bogie 200. At this time, the frame member 40 moves integrally with the bogie 200, and the pair of anti-lateral sway wheels 50, 50 function as two fixed wheels in addition to the four free wheels (front wheels 220, 220 and rear wheels 230, 230) of the bogie 200, thereby effectively preventing lateral sway during turning, etc., and allowing the bogie 200 to be stably towed.

[0078] <<When the dolly 200 is a two-wheel fixed dolly>> As described above, the switching mechanism 60 is once set to the two-wheel fixed carriage mode at the start of use, so that when the carriage 200 is a two-wheel fixed carriage, there is no need to perform a switching operation in the switching mechanism 60.

[0079] Next, the lift push button switch 143 is pressed to lift the carriage 34. This causes the hook member 20 to lift, and the pair of hook pins 22, 22 engage with the lower part of the main body 210 of the dolly 200, while the upper ends of the pair of damper mechanisms 23, 23 come into contact with the lower surface of the main body 210. When the lift push button switch 143 is continued to be pressed to further lift the carriage 34 and a load equal to or greater than a predetermined value is detected by the lifting device 30, the lifting is automatically stopped (see FIG. 22). Specifically, in the flowchart of FIG. 15, the current value CV is determined to be equal to or greater than the second threshold value TH2 in S5 (S5: Yes), and the motor is stopped in S7, so that the lifting of the hook member 20 is automatically stopped.

[0080] Then, the forward / reverse switch 142 is operated to move the towing auxiliary device 1 connected to the electric towing vehicle 100 forward, thereby allowing the bogie 200 to be towed. At this time, the pair of sway prevention wheels 50, 50 are in a non-grounded position separated from the floor surface FL, so that the pair of sway prevention wheels 50, 50 which are fixed wheels on the towing auxiliary device 1 side and the rear wheels 230, 230 which are fixed wheels provided on the bogie 200 do not interfere with each other, allowing the bogie 200 to turn smoothly while preventing sway.

[0081] <Summary of the embodiment> As is clear from the above detailed description, the towing auxiliary device 1 for an electric towing vehicle according to this embodiment is a device used by connecting to an electric towing vehicle 100 configured to electrically drive drive wheels 120 provided on a vehicle body 110 in order to tow a dolly 200 and transport it over a floor surface FL, and is made up of a base body 10 having one end in the front-rear direction connected to the electric towing vehicle 100 so as to be horizontally rotatable, a support plate 21a provided at the other end in the front-rear direction of the base body 10 for supporting a main body 210 of the dolly 200, and a support member 220 standing on the support plate 21a. the hook member 20 having hook pins 22, 22 as upright portions provided thereon and capable of engaging with the main body 210 of the trolley 200; a frame member 40 connected to the other end of the base 10 in the fore-and-aft direction, extending in the fore-and-aft direction below the hook member 20, and having an anti-lateral runout wheel 50 consisting of a fixed wheel provided thereon; a lifting device 30 provided on the base 10 for raising and lowering the hook member 20; and a damper mechanism 23 provided on the support plate 21a for elastically supporting the main body 210 of the trolley 200 engaged with the hook member 20.

[0082] According to this configuration, when the traction auxiliary device 1 is used to transport a four-wheeled swivel-wheeled dolly, the hook member 20 is raised by the lifting device 30 until the support plate 21a receives a load equal to or greater than a predetermined load while the frame member 40 is inserted into the lower space between the main body 210 of the dolly 200 and the floor surface FL, so that the anti-lateral sway wheel 50 generates an appropriate grounding force against the floor surface FL. Furthermore, since the main body 210 of the dolly 200 is elastically supported by the damper mechanism 23 provided on the hook member 20, even if the dolly 200 vibrates up and down due to the unevenness of the floor surface FL, the anti-lateral sway wheel 50 always generates an appropriate grounding force. As a result, the anti-lateral sway wheel 50 properly contacts the floor surface FL, so that the wheel 50 reliably functions as a fixed wheel of the dolly 200, and the dolly 200 can be towed stably regardless of the unevenness of the floor surface FL, thereby preventing the dolly 200 from swaying laterally during turning, etc. This provides the effect of always enabling stable towing regardless of the load of luggage or the unevenness of the floor surface.

[0083] Also, the lifting device 30 further includes a CPU 181 as an automatic stop unit that automatically stops the lifting when the hook member 20 receives a load of a predetermined value (first predetermined value W1) or more during the lifting by the lifting device 30.

[0084] According to this configuration, the CPU 181 as an automatic stop unit automatically stops the ascent when the hook member 20 receives a load of a predetermined value (first predetermined value W1) or more during ascent by the lifting device 30, so that an appropriate ground contact force of the anti-lateral sway wheel 50 against the floor surface FL can be automatically and reliably generated.

[0085] The lifting device 30 is also configured to have a lifting motor 31m as an electric motor, and a linear motion mechanism 32 driven by the lifting motor 31m to move linearly in the vertical direction, and the CPU 181 as an automatic stop unit detects that a load of greater than a predetermined value (first predetermined value W1) has been received based on a change in the current value CV in the lifting motor 31m (S3 to S5).

[0086] According to this configuration, the hook member 20 can be raised and lowered with a simple and compact configuration, and the ascent can be automatically stopped by simply and reliably detecting when the hook member 20 receives a load equal to or greater than a predetermined value (first predetermined value W1).

[0087] The device further includes a switching mechanism 60 that switches the anti-lateral runout wheels 50 between a grounded position in which they are grounded on the floor surface FL and a non-grounded position in which they are separated from the floor surface FL. When the anti-lateral runout wheels 50 are in a grounded position (four-wheel swivel carriage mode), the CPU 181, as an automatic stopping unit, automatically stops the ascent when the hook member 20 receives a load of equal to or greater than a first predetermined value W1 during ascent by the lifting device 30 (i.e., when the current value CV is equal to or greater than a first threshold value TH1) (S4, S5, S7). On the other hand, when the anti-lateral runout wheels 50 are in a non-grounded position (two-wheel fixed carriage mode), the CPU 181 automatically stops the ascent when the hook member 20 receives a load of equal to or greater than a second predetermined value W2 that is smaller than the first predetermined value W1 during ascent by the lifting device 30 (i.e., when the current value CV is equal to or greater than a second threshold value TH2 that is smaller than the first threshold value TH1) (S4, S6, S7).

[0088] According to this configuration, when the sway prevention wheel 50 is in a ground contact posture (four-wheel swivel carriage mode), the CPU 181 as an automatic stop unit automatically stops the ascent when the hook member 20 receives a load of equal to or greater than the first predetermined value W1, thereby automatically and reliably generating an appropriate ground contact force of the sway prevention wheel 50 against the floor surface FL. On the other hand, when the sway prevention wheel 50 is in a non-ground contact posture (two-wheel fixed carriage mode), the CPU 181 as an automatic stop unit automatically stops the ascent when the hook member 20 receives a load of equal to or greater than the second predetermined value W2, which is smaller than the first predetermined value W1, thereby preventing the generation of a force that inhibits the driving force of the electric towing vehicle 100.

[0089] <Modification> The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention. For example, in the above embodiment, a feed screw mechanism is used as the linear motion mechanism 32 of the lifting device 30, but the present invention is not limited to this. For example, the linear motion mechanism 32 may be configured as a pinion rack mechanism.

[0090] In the above embodiment, the load applied to the support plate 21a is detected by the current value CV flowing through the lift motor 31m, but this is not limiting. A load sensor may be provided separately on the support plate 21a to detect the load.

[0091] In the above embodiment, the configuration is provided with a switching mechanism 60 that switches the anti-lateral runout wheels 50 between a grounding position in which they are in contact with the floor surface FL and a non-grounding position in which they are separated from the floor surface FL. However, if the trolley 200 is used for towing only a four-wheel swivel trolley, the configuration may not include the switching mechanism 60.

[0092] In addition, in the above embodiment, a hand-pushed cart equipped with a basket for storing luggage (a so-called hand-pushed basket cart) was shown as an example of the cart 200, but this is not limited to this, and it goes without saying that a cart without a basket can also be towed using the towing auxiliary device 1. [Explanation of symbols]

[0093] 1. Towing aid for electric towing vehicles 10 Base 20 Hook member 21a Support plate 22 Hook pin (standing part) 23 Damper mechanism 30 Lifting device 31m Lifting motor (electric motor) 32 Linear motion mechanism 40 Frame members 50 Anti-lateral vibration wheels 60 Switching Mechanism 100 electric towing vehicle 110 Body 120 Drive Wheel 181 CPU (automatic stop section) 200 Carts 210 Main body FL floor surface

Claims

1. A towing auxiliary device used in conjunction with an electric towing vehicle configured to electrically drive drive wheels provided on a vehicle body in order to tow a cart and transport it on a floor surface, a base body having one end in the front-rear direction connected to the electric towing vehicle so as to be horizontally rotatable; a hook member provided at the other end of the base in the front-rear direction, the hook member having a support plate for supporting a main body of the dolly and a standing portion standing on the support plate and capable of engaging with the main body of the dolly; a frame member connected to the other end of the base body in the front-rear direction, extending in the front-rear direction below the hook member, and having a lateral runout prevention wheel formed of a fixed wheel; a lifting device provided on the base for lifting and lowering the hook member; a damper mechanism provided on the support plate and configured to elastically support a main body of the carriage engaged with the hook member; A towing assistance device for an electric towing vehicle.

2. 2. The towing auxiliary device for an electric towing vehicle according to claim 1, further comprising an automatic stop unit that automatically stops the lifting when the hook member receives a load equal to or greater than a predetermined value during lifting by the lifting device.

3. The lifting device is configured to include an electric motor and a linear motion mechanism that is driven by the electric motor and moves linearly in a vertical direction, 3. The towing auxiliary device for an electric towing vehicle according to claim 2, wherein the automatic stop unit detects that a load equal to or greater than the predetermined value has been received based on a change in a current value in the electric motor.

4. A switching mechanism is provided for switching the anti-lateral runout wheel between a grounding position in which the anti-lateral runout wheel is in contact with the floor surface and a non-grounding position in which the anti-lateral runout wheel is separated from the floor surface, The towing auxiliary device for an electric towing vehicle as described in claim 2 or 3, wherein the automatic stop unit automatically stops the ascent when the hook member receives a load of a first predetermined value or more during ascent by the lifting device when the sway prevention wheel is in the ground contact position, and automatically stops the ascent when the hook member receives a load of a second predetermined value or more that is smaller than the first predetermined value during ascent by the lifting device when the sway prevention wheel is in the non-ground contact position.

Images