Electric Meal Cart

Abstract

To provide an electric catering vehicle capable of taking measures against over-voltage caused by unintended factors such as static electricity while suppressing residual charge.SOLUTION: An electric catering vehicle 10 includes a battery 31 for charging power from an external power source, a motor 18 to which discharging power from the battery 31 is supplied, wheels 17 driven by the motor 18, and a control board 40 for controlling charging / discharging of the battery 31, and the control board 40 includes a control IC 41, a relay 42 for switching between charging and discharging of the battery 31 based on a signal from the control IC 41, and a first Zener diode 43 connected between the relay 42 and the motor 18.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present technology relates to an electric food delivery cart. [Background technology]

[0002] It has been known that electric food delivery carts used in hospitals and other facilities, particularly large and heavy ones, have auxiliary electric functions, an example of which is disclosed in Patent Document 1. The food delivery cart described in Patent Document 1 is equipped with electric drive wheels, and the speed and rotation direction of the drive motor of the drive wheels are controlled in response to handle operation. The food delivery cart also has a battery, and power is supplied to the self-propelled power source from the battery, which is charged before the cart travels. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-103519 Summary of the Invention [Problem to be solved by the invention]

[0004] Electric food delivery carts are often used indoors, where static electricity is easily generated between the carpet or other road surface and the drive wheels. To protect the components from overvoltage caused by unintended factors such as static electricity, it is common for electric control boards for electric food delivery carts to be equipped with a large-capacity capacitor in the electrical path between the battery and the cart.

[0005] However, while providing a large-capacity capacitor on the electric control board can provide a measure against overvoltage, it also requires consideration of residual charge that may occur in the large-capacity capacitor.For example, during inspection and maintenance, in order to perform the work safely, it is necessary to wait until the residual voltage in the large-capacity capacitor is naturally discharged.

[0006] The technology described in this specification was developed based on the above-mentioned circumstances, and aims to provide an electric food delivery cart that can suppress residual charges while taking measures against overvoltage caused by unintended factors such as static electricity. [Means for solving the problem]

[0007] The electric food delivery cart related to the technology described in this specification comprises a battery that charges with power from an external power source, a motor that is supplied with discharged power from the battery, wheels that are driven by the motor, and a control board that controls the charging and discharging of the battery, the control board comprising a control IC, a relay that switches between charging and discharging the battery based on a signal from the control IC, and a first Zener diode connected between the relay and the motor.

[0008] By connecting a first Zener diode between the relay and the motor on the control board, the first Zener diode can be used to deal with overvoltage caused by static electricity, etc. If a large-capacity capacitor were used to deal with overvoltage instead of the first Zener diode, residual charge would be generated in the large-capacity capacitor, but the Zener diode makes it possible to take measures against overvoltage while suppressing the residual charge.

[0009] Furthermore, a load other than the motor is provided to which discharge power from the battery is supplied, and the control board includes a second Zener diode connected between the relay and the load. In this way, even in the current path from the battery to the load other than the motor, the second Zener diode can suppress residual charge and provide a countermeasure against overvoltage.

[0010] The load operates on a drive voltage different from the discharge voltage of the battery, the control board includes a transformer circuit that converts the discharge voltage to the drive voltage, and the second Zener diode is connected between the relay and the transformer circuit. This allows the transformer circuit to supply a voltage power supply corresponding to the drive voltage of the load. Furthermore, the second Zener diode can suppress residual charge in the current path to the transformer circuit while providing a countermeasure against overvoltage.

[0011] The control board further includes an AD conversion circuit between the external power supply and the relay that converts AC voltage from the external power supply to DC voltage, and the second Zener diode is connected between the relay and the transformer circuit and between the AD conversion circuit and the transformer circuit. The AD conversion circuit makes it possible to supply DC voltage, and the second Zener diode suppresses residual charge in the current path from the AD conversion circuit to the transformer circuit, while providing a countermeasure against overvoltage.

[0012] Furthermore, there are a plurality of the loads, and the plurality of loads are connected in parallel to the second Zener diode. In this way, even in the current path to the plurality of loads, the second Zener diode can suppress residual charge and provide a countermeasure against overvoltage.

[0013] The control board also includes a charge control circuit between the external power supply and the relay for controlling charging power from the external power supply to the battery, the charge control circuit including a thyristor for controlling the phase of the AC voltage from the external power supply. If a triac were used as the switching element for phase control of the charge control circuit, the triac would be a reverse-conducting element, which raises concerns that the battery might discharge while it is being charged. By using a thyristor, which is a switching element that does not reverse conduct, instead of a triac, it is possible to prevent the battery from discharging while it is being charged. [Effects of the Invention]

[0014] According to the technology described in this specification, it is possible to take measures against overvoltage caused by unintended factors such as static electricity while suppressing residual charges. [Brief explanation of the drawings]

[0015] [Figure 1] Side view of the electric food delivery cart according to the first embodiment [Figure 2] Front view of electric food delivery cart [Figure 3] Circuit diagram showing the schematic configuration of a second control board [Figure 4] An enlarged view of the relay area in Figure 3 when the battery is being charged [Figure 5] An enlarged view of the relay area in Figure 3 during battery discharge [Figure 6] Charging coupler connection circuit [Figure 7] Battery Connection Circuit [Figure 8] Step-down circuit and multiple loads DETAILED DESCRIPTION OF THE INVENTION

[0016] <Embodiment 1> An electric food distribution cart 10 according to the first embodiment will be described with reference to Figures 1 to 8. Note that the symbols F, Rr, L, R, U, and D shown in some of the figures respectively indicate the front and rear in the longitudinal direction of the electric food distribution cart 10, the left and right in the width direction (left-right direction) when viewed from the front, and the top and bottom in the vertical direction (up-down direction). However, these directions are merely defined for convenience and should not be interpreted in a restrictive manner.

[0017] As shown in Figures 1 and 2, electric food delivery cart 10 has an overall rectangular parallelepiped shape and is used to store and transport cooked food to be served (an example of a stored item). Electric food delivery cart 10 generally comprises a storage body 14 that stores the stored items, a machine room 15 located above storage body 14, a control box 20 attached to the front of storage body 14, wheels 16, 17, and a chassis 19 to which wheels 16, 17 are attached.

[0018] The storage cabinet main body 14 is an insulated box whose interior is divided into two compartments in the front-to-back direction by a partition wall, and each compartment is further divided into two compartments in the front-to-back direction by an insulated wall, forming a total of four compartments. As shown in Figure 1, the four compartments in the storage cabinet main body 14 are, from the front, a hot storage compartment 11A, two refrigerator compartments 12A and 12B, and a hot storage compartment 11B. A pair of adjacent hot storage compartments 11A and 12A, and a pair of adjacent hot storage compartments 11B and 12B, are each equipped with a double door 13. Multiple shelves are installed inside the hot storage compartments 11A and 11B and the refrigerator compartments 12A and 12B. When trays with hot and cold foods separated and placed on them are placed on the shelves while penetrating the insulating wall, the hot foods on one tray are stored in the hot storage compartment 11A and the cold foods in the refrigerated storage compartment 12A, respectively, for hot and refrigerated storage. Trays are similarly stored in the other set of hot storage compartment 11B and refrigerated storage compartment 12B.

[0019] The machine compartment 15 houses a heating device 25 that heats the warming compartments 11A and 11B, a cooling device 26 that cools the refrigerator compartments 12A and 12B, and a first control board 27 that controls these devices 25 and 26. The first control board 27 is a printed wiring board on which circuits that control the components of the heating device 25 and the cooling device 26, a memory unit, etc. are mounted, and is provided in a form that is housed in an electrical box.

[0020] Heating device 25 is composed of, for example, a drive unit that heats the cord heater and a heating fan. The cord heater is wired to a heating panel attached to the side of warming compartments 11A and 11B, and when the heating fan is driven, warm air is blown into warming compartments 11A and 11B from the vents in the heating panel, heating the inside of warming compartments 11A and 11B.

[0021] Cooling device 26 is composed of, for example, devices that form a known refrigeration cycle and a cooling fan. When cooling device 26 is driven, cold air is blown into the partition wall of refrigerator compartments 12A, 12B and then blown out from the vents in the partition wall into refrigerator compartments 12A, 12B, thereby cooling the interiors of refrigerator compartments 12A, 12B.

[0022] As shown in Figures 1 and 2, the wheels 16, 17 are attached to the bottom surface of a chassis 19 on which the storage body 14 is placed. The wheels 16, 17 are provided in pairs on the left and right sides of the bottom surface, one on the front and one on the back. The front wheel is a swivel wheel 16, and the rear wheel is a drive wheel 17. A motor 18 for driving the drive wheels 17 is provided on the inside (opposite sides) of each of the two drive wheels 17.

[0023] As shown in FIG. 2, the control box 20 is a vertically long cover with an open rear, and is attached to the front of the storage body 14. The control box 20 houses a rechargeable battery 31 and a second control board 40 (auxiliary electric board) that controls the charging and discharging of at least the battery 31. The battery 31 charges with power from an external power source and discharges (supplies) power (voltage power) to multiple loads (motor 18 and loads 32, 33, 34, and 35 other than the motor 18 (FIG. 8)). The control box 20 is detachably attached to the front of the storage body 14. During inspection and maintenance, the control box 20 can be removed, allowing a maintenance worker to replace the battery 31 in the control box 20 and the components and wiring mounted on the second control board 40. The second control board 40 will be described in detail below.

[0024] 1, the control box 20 has a slanted top, and the operation unit 23 and display unit 24 are disposed on this slanted surface. The operation unit 23 includes a key switch 23B (a switch operated by inserting a key and rotating it) for turning on and off the power supply from the battery 31. The display unit 24 includes a lamp 24A for indicating the remaining battery charge of the battery 31. The operation unit 23 and the display unit 24 may be provided integrally as a display device having a touch panel function.

[0025] 1 and 2, handles 21 are rotatably provided on both the left and right sides of the control box 20. The handles 21 are rotatable in the front-to-rear direction (the directions of arrows A and B in FIG. 1) around a handle shaft 22. The handles 21 and the handle shaft 22 are rotatable in the left-to-right direction (the directions of arrows L and R in FIG. 2).

[0026] The electric food delivery cart 10 moves forward when the user rotates the handle 21 forward as shown by arrow A in FIG. 1 and pulls it, and moves backward when the user rotates the handle 21 backward as shown by arrow B and pushes it. Furthermore, the forward acceleration increases as the user rotates the handle 21 forward, and the electric food delivery cart 10 stops when it returns to its initial position (the position shown in FIG. 1). Furthermore, when the user rotates the handle 21 leftward (in the direction of arrow L in FIG. 2), the rotational speed of one drive wheel 17 (i.e., the drive speed of motor 18) becomes greater than the rotational speed of the other drive wheel 17, and the electric food delivery cart 10 moves leftward. Similarly, when the user rotates the handle 21 rightward (in the direction of arrow R in FIG. 2), the rotational speed of the other drive wheel 17 becomes greater than the rotational speed of one drive wheel 17, and the electric food delivery cart 10 moves rightward.

[0027] Next, the second control board 40 will be described in detail. As shown in Figures 3 and 8, the second control board 40 is a printed wiring board on which a microcomputer 41, a relay 42, a motor connection circuit 50, a charge control circuit 60, a battery connection circuit 70, a charge coupler connection circuit 75, an AD conversion circuit 80, and a step-down circuit 90 (an example of a transformer circuit) are mounted. The microcomputer 41 is a control IC that includes a memory unit (ROM, RAM) in which a control program and the like are stored, and a timer unit.

[0028] 3 to 5, the relay 42 is connected to the microcomputer 41 and switches between charging and discharging the battery 31 based on a signal from the microcomputer 41. The relay 42 is a so-called power relay, and when a current flows through the coil based on a signal from the microcomputer 41, the movable contact 42A moves due to the action of the electromagnet. This switches the connection destination of the movable contact 42A between the first fixed contact 42B and the second fixed contact 42C.

[0029] As shown in FIG. 3, the motor connection circuit 50 is a circuit connected between the relay 42 and the motor 18. The motor connection circuit 50 includes a connection terminal 51 for the motor 18, a connection terminal 52 for an emergency stop safety device, and two semiconductor switches 53 and 54. The semiconductor switch 53 opens and closes based on operation of the operation unit 23 or a signal from the microcomputer 41. The semiconductor switch 53 functions as a brake for the wheels 16 and 17. When the semiconductor switch 53 is open, the brake is activated and the electric food delivery cart 10 cannot travel; when the semiconductor switch 53 is closed, the brake is released and the electric food delivery cart 10 can travel. The semiconductor switch 54 opens and closes based on a signal from the microcomputer 41. The semiconductor switch 54 functions as a circuit breaker in the current path from the battery 31 to the motor 18. When semiconductor switch 54 is open, the current path to motor 18 is disconnected, preventing electric food delivery cart 10 from traveling, and when it is closed, the current path to motor 18 is connected, allowing electric food delivery cart 10 to travel. Semiconductor switch 54 is closed during normal travel, but if an abnormality such as excessive current is detected while traveling, it is switched to the open state by a signal from microcomputer 41. This disconnects the current path from battery 31 to motor 18, forcibly disabling electric food delivery cart 10 from traveling.

[0030] In addition, a first Zener diode 43 is connected between the motor connection circuit 50 and the movable contact 42A of the relay 42. The provision of the first Zener diode 43 makes it possible to counter overvoltage caused by unintended factors, such as static electricity, in the current path to the battery 31. While it is conceivable to connect a more conventional large-capacity capacitor instead of the first Zener diode 43 as an overvoltage countermeasure element, there is a concern that residual charge generated in the large-capacity capacitor may become a problem. For example, when a worker touches the second control board 40 to replace components or wiring during inspection and maintenance, the worker must wait until the residual voltage in the large-capacity capacitor naturally discharges in order to perform the work safely, which is inefficient. In this regard, the use of the first Zener diode 43 in this embodiment makes it possible to implement overvoltage countermeasures while suppressing residual charge on the second control board 40.

[0031] 3 and 6, the charging coupler connection circuit 75 is a circuit that is connected to a charging coupler (connector) of an external power supply (for example, AC 30V obtained by transforming AC 200V with a transformer). The charging coupler connection circuit 75 includes a connection terminal 76 for connecting to the charging coupler. Furthermore, the charging control circuit 60 and the AD conversion circuit 80 are connected in parallel to the output side of the charging coupler connection circuit 75 (the side opposite to the connection terminal 76).

[0032] The AD conversion circuit 80 converts an AC voltage (e.g., AC 30 V) from an external power supply into a DC voltage (e.g., DC 24 V). As shown in Figures 3 to 5, the input side of the AD conversion circuit 80 is connected to the charging coupler connection circuit 75, and the output side of the AD conversion circuit 80 is connected to the relay 42 and the loads 32, 33, 34, and 35 (Figure 8). When a charging coupler of an external power supply is connected to the charging coupler connection circuit 75 and the battery 31 is being charged, the AD conversion circuit 80 converts the AC voltage from the external power supply into a DC voltage and supplies it to the relay 42 and the loads 32, 33, 34, 35, etc.

[0033] As shown in FIGS. 3 to 5, the charge control circuit 60 is a circuit connected between the charge coupler connection circuit 75 and the first fixed contact 42B of the relay 42. The charge control circuit 60 is also connected to the microcomputer 41, and receives signals from the microcomputer 41. The charge control circuit 60 includes a thyristor 61 as a switching element for controlling the phase of the AC voltage from the external power supply. The charge control circuit 60 changes the phase (timing) at which the thyristor 61 is turned on, thereby changing the proportion of on-time per cycle of the AC voltage from the external power supply. In this way, the charge control circuit 60 changes the amount of power supplied from the external power supply and adjusts the output power (i.e., the power input to the first fixed contact 42B of the relay 42).

[0034] It is also possible to use a triac instead of the thyristor 61 as the switching element that performs phase control in the charge control circuit 60. However, because a triac is a switching element that allows reverse conduction, there is a concern that the battery 31 may discharge while it is being charged. In this regard, the thyristor 61 according to this embodiment is a switching element that does not allow reverse conduction, so the battery 31 will not discharge while it is being charged. As a result, it is possible to improve the efficiency of power utilization from the external power source and shorten the charging time of the battery 31.

[0035] 3 and 7, the battery connection circuit 70 is a circuit connected between the relay 42 and the battery 31. The battery connection circuit 70 includes a connection terminal 71 for the battery 31 and a semiconductor switch 72 that operates in conjunction with the battery 31. When a normal battery 31 is connected to the connection terminal 71, the semiconductor switch 72 is closed, allowing the battery 31 to be charged or discharged. On the other hand, when a battery 31 with no remaining charge is connected to the connection terminal 71 or when the battery 31 is connected to the connection terminal 71 with incorrect polarity, the semiconductor switch 72 remains open, preventing charging or discharging.

[0036] 8, the step-down circuit 90 is a circuit connected between the second fixed contact 42C of the relay 42 and the loads 32, 33, 34, and 35. The loads 32, 33, 34, and 35 are connected in parallel to the relay 42. The step-down circuit 90 stably transforms (steps down) the discharge voltage (e.g., DC 24 V) of the battery 31 supplied through the relay 42 and the output voltage (e.g., DC 24 V) of the AD conversion circuit 80 to drive voltages for the loads 32, 33, 34, and 35. The step-down circuit 90 is configured by a regulator and the like.

[0037] The first load 32, the second load 33, and the fourth load 35 are driven by, for example, DC 5V, and the third load 34 is driven by, for example, DC 12V. The first load 32 is a regular device that is operated even when the electric food distribution cart 10 is not in operation (standby) and drives the second control board 40, etc. The second load 33, the third load 34, and the fourth load 35 are supplied with power when a semiconductor switch 91 linked to the operation unit 23 (more specifically, the engine key switch) is turned on. Therefore, the second load 33, the third load 34, and the fourth load 35 are supplied with power only during operation (when the engine key switch is on).

[0038] 3 to 5, a second Zener diode 44 is connected between the loads 32, 33, 34, and 35 and the relay 42, more specifically, between the step-down circuit 90 and the relay 42. In other words, the loads 32, 33, 34, and 35 are connected in parallel to the second Zener diode 44 via the step-down circuit 90. By providing the second Zener diode 44, it becomes possible to deal with overvoltage caused by unintended factors such as static electricity in the current path. Furthermore, similar to the effect of the first Zener diode 43 described above, it is possible to take measures against overvoltage while suppressing residual charge compared to when a large-capacity capacitor is provided.

[0039] Next, the flow of power during charging of battery 31 will be described with reference to Fig. 4. When an external power source is connected to connection terminal 76 of charging coupler connection circuit 75, movable contact 42A of relay 42 is connected to first fixed contact 42B based on a signal from microcomputer 41. As a result, power from the external power source is supplied to battery 31, passing in this order through charging coupler connection circuit 75, charging control circuit 60, relay 42, and battery connection circuit 70, as shown by arrows in Fig. 4. Furthermore, a portion of the power from the external power source branches off to AD conversion circuit 80 connected in parallel to charging control circuit 60, as shown by arrows in Fig. 4, and is supplied to multiple loads 32, 33, 34, and 35 through step-down circuit 90 of Fig. 8.

[0040] Next, with reference to Fig. 5, the flow of power when the battery 31 is discharging will be described. When an external power source is not connected to the connection terminal 76 of the charging coupler connection circuit 75, the movable contact 42A of the relay 42 is connected to the second fixed contact 42C based on a signal from the microcomputer 41. As a result, power from the battery 31 passes through the battery connection circuit 70 and the motor connection circuit 50 in this order, as shown by the arrows in Fig. 5, and is supplied to the motor 18. Furthermore, power from the battery 31 passes through the battery connection circuit 70 and the relay 42, as shown by the arrows in Fig. 5, and flows to the step-down circuit 90 in Fig. 8, and is supplied to the plurality of loads 32, 33, 34, and 35 via the step-down circuit 90.

[0041] <Other embodiments> The technology described in this specification is not limited to the embodiments described in the above description and drawings, and for example, the following embodiments are also included in the technical scope of the technology described in this specification.

[0042] (1) The control box 20 may be located in a position other than the front of the storage body 14, as long as it can be removed during inspection work, etc.

[0043] (2) The configuration of the storage body 14 (the number and arrangement of the hot storage compartments 11A, 11B and the refrigeration compartments 12A, 12B) is not limited, and for example, only the hot storage compartments 11A, 11B or only the refrigeration compartments 12A, 12B may be formed. Heating devices and cooling devices are provided as appropriate depending on the required hot and cold functions.

[0044] (3) The front wheels 16 are not limited to swivel wheels, but may be drive wheels equipped with motors 18.

[0045] (4) This technology can be widely applied to electric transport vehicles other than the electric food delivery cart 10. [Explanation of symbols]

[0046] 10: Electric food delivery cart, 17: Drive wheel (wheel), 18: Motor, 31: Battery, 32, 33, 34, 35: Load, 40: Second control board, 41: Microcomputer (control IC), 42: Relay, 43: First Zener diode, 44: Second Zener diode, 60: Charging control circuit, 61: Thyristor, 80: AD conversion circuit, 90: Step-down circuit (transformer circuit)

Claims

1. a battery that charges from an external power source; a motor supplied with discharged power from the battery; a wheel driven by the motor; a control board that controls charging and discharging of the battery, The control board A control IC; a relay that switches between charging and discharging the battery based on a signal from the control IC; An electric food delivery cart comprising: a first Zener diode connected between the relay and the motor.

2. a load other than the motor to which discharge power from the battery is supplied; 2. The electric food delivery cart according to claim 1, wherein the control board includes a second Zener diode connected between the relay and the load.

3. the load operates at a drive voltage whose value is different from a discharge voltage of the battery; the control board includes a transformer circuit that converts the discharge voltage into the drive voltage; 3. The electric food delivery cart according to claim 2, wherein the second Zener diode is connected between the relay and the transformer circuit.

4. the control board includes an AD conversion circuit between the external power supply and the relay, the AD conversion circuit converting an AC voltage from the external power supply into a DC voltage; 4. The electric food delivery cart according to claim 3, wherein the second Zener diode is connected at a position between the relay and the transformer circuit and between the AD conversion circuit and the transformer circuit.

5. The load is plural, 5. The electric food delivery cart according to claim 2, wherein the plurality of loads are connected in parallel to the second Zener diode.

6. the control board includes a charge control circuit between the external power supply and the relay for controlling charging power from the external power supply to the battery; 4. The electric food delivery cart according to claim 1, wherein the charge control circuit includes a thyristor that performs phase control of the AC voltage from the external power source.

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