Charger for electrically charging a moving body

The charger includes first and second connectors, each including an opposing surface. One of the opposing surface of the first connector and the opposing surface of the second connector includes, on a first opposing surface, a male power terminal and a male signal terminal for a power cutoff signal projecting from the first opposing surface, and the other one of the opposing surface of the first connector and the opposing surface of the second connector is provided with a female power terminal which the male power terminal is to be fitted into and a female signal terminal which the male signal terminal is to be fitted into on a second opposing surface. A length of the male signal terminal in a direction in which the male signal terminal projects is shorter than a length of the male power terminal in a direction in which the male power terminal projects.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority from Japanese patent application No. 2018-142109, filed on Jul. 30, 2018, the disclosure of which is incorporated herein in its entirety by reference.

BACKGROUND

The present disclosure relates to a charger.

It is necessary to supply power to moving bodies capable of autonomous movement, such as life support robots, from an external power supply to charge their batteries. For example, Japanese Patent No. 6115502 discloses a charger including a first connector provided on a power supply side and a second connector provided on a moving body side. The charger is configured to be charged in a state in which the first and second connectors are connected to each other by a magnetic force.

SUMMARY

In the charger of Japanese Patent No. 6115502, when the connection between the first connector and the second connector is disconnected, for example, due to a movement of the moving body while charging, an electric arc may occur.

The present disclosure has been made in view of the above circumstances. An object of the present disclosure is to provide a charger capable of effectively preventing an electric arc from occurring even when the connection between the first connector and the second connector is disconnected while charging.

An example aspect of the present disclosure is a charger including: a first connector provided on a power supply side; and a second connector provided on a moving body side. The charger is configured to be charged in a state in which the first connector and the second connector are connected to each other by a magnetic force. The first connector and the second connector include opposing surfaces facing each other. One of the opposing surface of the first connector and the opposing surface of the second connector includes, on a first opposing surface, a male power terminal and a male signal terminal for a power cutoff signal projecting from the first opposing surface, and the other one of the opposing surface of the first connector and the opposing surface of the second connector is provided with a female power terminal which the male power terminal is to be fitted into and a female signal terminal which the male signal terminal is to be fitted into on a second opposing surface. A length of the male signal terminal in a direction in which the male signal terminal projects is shorter than a length of the male power terminal in a direction in which the male power terminal projects.

When the first connector is separated from the second connector, firstly the connection between the male signal terminal and the female signal terminal for the power cutoff signal is disconnected. Then, after the connection between the male signal terminal and the female signal terminal is disconnected, the connection between the male power terminal and the female power terminal is disconnected. That is, when the connection between the first connector and the second connector is disconnected while charging, the connection between the male signal terminal and the female signal terminal is disconnected, and the current supply from the power supply to the first connector is cut off by a current cutoff mechanism before the male power terminal is disconnected from the female power terminals. Thus, when the connection between the male power terminal and the female power terminal is disconnected, the male power terminal and the female power terminal are not conducted, which effectively prevents an electric arc from occurring.

Further, on the first opposing surface, the male signal terminal may be disposed at a central part, and a plurality of the male power terminals may be disposed on a circumference centered on the central part. On the second opposing surface, the female signal terminal may be disposed at a central part, and a plurality of the female power terminals may be disposed on a circumference centered on the central part. When a straight line passing two points of a position of the male signal terminal and a position of the male power terminal on the first opposing surface is defined as a first straight line, a straight line passing two points of an intersection point between the first straight line and an outer edge of the first opposing surface and a leading end of the male signal terminal is defined as a second straight line, and a straight line passing two points of the intersection point and a leading end of the male power terminal is defined as a third straight line, the length of the male power terminal in the direction in which the male power terminal projects and the length of the male signal terminal in the direction in which the male signal terminal projects may be set in such a way that a first angle, which is an elevation angle formed between the first opposing surface and the second straight line, becomes greater than a second angle, which is an elevation angle formed between the first opposing surface and the third straight line.

Suppose that the lengths of the male power terminals in the projecting direction and the length of the male signal terminal in the projecting direction are set in such a way that the second angle becomes smaller than the first angle. By doing so, when the first opposing surface and the second opposing surface are in contact with each other at only the intersection point, all the pairs of the male power terminals and the female power terminals are connected if the male signal terminal is connected to the female signal terminal. Thus, when the male signal terminal and the female signal terminal are connected to each other, and the first connector and the second connector are conducted, it is possible to prevent one of the pairs of the male power terminals and the female power terminals from being disconnected, and current from being concentrated on another one of the pairs, and thereby preventing the temperature from excessively rising.

Further, the male power terminal may include an elastic member exerting an elastic force in the direction in which the male power terminal projects from the first opposing surface. When a third angle, which is an elevation angle formed between the first opposing surface and the second opposing surface, is smaller than the first angle in a state in which a part of the second opposing surface is physically in contact with the outer edge of the first opposing surface, the elastic force of the elastic member may be set in such a way that a contact resistance between the male power terminal and the female power terminal becomes smaller than a predetermined value.

By doing so, even when the male power terminals and the female power terminals are conducted in a state in which the first opposing surface and the second opposing surface cannot be completely brought close to each other, such as when a foreign matter is sandwiched therebetween, it is possible to effectively prevent the temperature of the parts where the male power terminals are in contact with the female power terminals from excessively rising.

According to the present disclosure, it is possible to effectively prevent an electric arc from occurring even when the connection between the first connector and the second connector is disconnected while charging.

DESCRIPTION OF EMBODIMENTS

Hereinafter, although the present disclosure will be described with reference to an embodiment of the present disclosure, the present disclosure according to claims is not limited to the following embodiment. Moreover, all the components described in the following embodiment are not necessarily indispensable for means to solve problems. For the clarification of the description, the following description and the drawings may be omitted or simplified as appropriate. Throughout the drawings, the same components are denoted by the same reference signs and repeated descriptions will be omitted as appropriate. Further, in the drawings, the dimensions of the components are drawn in a deformed and distorted manner in order to contribute to easy understanding.

First, a configuration of the charger according to this embodiment will be described with reference toFIG. 1.

FIG. 1is a schematic view showing an example of the configuration of the charger1according to this embodiment. As shown inFIG. 1, a charger1includes a charger body2, a first connector3, and a second connector4.

The charger body2has a power supply. The first connector3is provided on the power supply side, i.e., on the charger body2. The charger body2supplies power to the first connector3via a wire5. The second connector4is provided on the moving body6side. The first connector3and the second connector4are connected to each other by a magnetic force.

The moving body6is a common robot (e.g., a life support robot) that includes a battery mounted thereon, acquires power from the battery, and moves autonomously. The moving body6is not limited to an autonomously moving robot, and may be a robot operated via a wireless controller or the like as long as it has a battery mounted thereon.

FIG. 2is a schematic view showing a state in which the first connector3and the second connector4are connected to each other. As shown inFIG. 2, the charger1is configured to be charged in a state in which the first connector3and the second connector4are connected to each other by a magnetic force.

Next, configurations of the first connector3and the second connector4will be described.

FIG. 3is a schematic view for describing an example of the configuration of the first connector3.FIG. 4is a cross-sectional view taken along the line IV-IV ofFIG. 3.FIG. 5is a schematic view for describing an example of the configuration of the second connector4.FIG. 6is a cross-sectional view taken along the line VI-VI ofFIG. 5.

As shown inFIGS. 3 and 4, the first connector3includes a first opposing surface31. The first opposing surface31is provided with male power terminals32and a male signal terminal33for a power cutoff signal. The male power terminals32and the male signal terminal33project from the first opposing surface31. Each of the male power terminal32may include an elastic member35(seeFIG. 4) that exerts an elastic force in a direction in which the male power terminal32projects from the first opposing surface31. A method of setting the elastic force when the male power terminal32has the elastic member35will be described later. The male signal terminal33is disposed, for example, at a central part of the first connector3, and the male power terminals32are disposed, for example, on a circumference centered on the central part of the first connector3. The first connector3is provided with a magnet34which is a permanent magnet.

As shown inFIGS. 5 and 6, the second connector4includes a second opposing surface41that is an opposing surface facing the first opposing surface31of the first connector3(seeFIGS. 3 and 4). The second opposing surface41is provided with female power terminals42which the male power terminals32of the first connector3are to be fitted into and a female signal terminal43which the male signal terminal33of the first connector3(seeFIGS. 3 and 4) is to be fitted into. The female signal terminal43is disposed, for example, at a central part of the second connector4, and the female power terminals42are disposed, for example, on a circumference centered on the central part of the second connector4. The second connector4is provided with a magnet44which is a permanent magnet.

In the second connector4, the magnet44is provided at a position corresponding to a position of the magnet34(seeFIGS. 3 and 4) of the first connector3when the first connector3(seeFIGS. 3 and 4) and the second connector4are connected to each other. The magnet44has a polarity opposite to that of the magnet34disposed at a position facing the magnet44when the first connector3and the second connector4are connected to each other. That is, when the first connector3and the second connector4are connected to each other, if one of the polarities of the magnets34and44which are disposed at positions facing each other is an N-pole, the other one of the polarities of the magnets34and44is an S-pole. With such configuration, as shown inFIG. 1, when the moving body6is moved in a direction of the arrow A to reduce the distance between the first connector3and the second connector4which are in a separated state, the first connector3and the second connector4attract each other by the magnetic force as shown inFIG. 2. Then, the first connector3and the second connector4are connected to each other, and the male power terminal32in the first connector3is electrically connected to the female power terminal42in the second connector4.

The charger body2shown inFIGS. 1 and 2is provided with a current cutoff mechanism. When the male signal terminal33(seeFIG. 3andFIG. 4) and the female signal terminal43(seeFIG. 5andFIG. 6) are connected to each other, the current cutoff mechanism is configured in such a way that current is supplied from a power supply to the first connector3. On the other hand, when the male signal terminal33and the female signal terminal43are not connected to each other, the current cutoff mechanism operates in such a way to cut off the current supply from the power supply to the first connector3.

Next, a relationship between the lengths of the male power terminals32and the male signal terminal33in a direction in which the male power terminals32and the male signal terminal33project (hereinafter referred to as a projecting direction) will be described.

FIGS. 7 and 8are schematic views for describing the relationship between the lengths of the male power terminals32and the male signal terminal33in the projecting direction in the first connector3. As shown inFIG. 7, a length h2of the male signal terminal33in the projecting direction is shorter than a length h1of the male power terminal32in the projecting direction.

With such a configuration of the male power terminals32and the male signal terminal33, as shown inFIG. 8, when the second connector4moves in a direction of the arrow B to separate the first connector3and the second connector4from each other, firstly the connection between the male signal terminal33and the female signal terminal43for the power cutoff signal is disconnected. Then, after the connection between the male signal terminal33and the female signal terminal43is disconnected, the connections between the male power terminals32and the female power terminals42are disconnected. That is, when the connection between the first connector3and the second connector4is disconnected while charging, the connection between the male signal terminal33and the female signal terminal43is disconnected, and the current supply from the power supply to the first connector3is cut off by the current cutoff mechanism before the male power terminals32are disconnected from the female power terminals42. Thus, when the connections between the male power terminals32and the female power terminals42are disconnected, the male power terminals32and the female power terminals42are not conducted, which effectively prevents an electric are from occurring.

FIGS. 9 to 11is a schematic view for describing a relationship between lengths of the male power terminals32and the male signal terminal33in the first connector3in the projecting direction. As shown inFIG. 9, in the first opposing surface31, the male signal terminal33is disposed at the central part, and the plurality of male power terminals32are disposed on a circumference centered on the central part. In the second opposing surface41, the female signal terminal43and the plurality of female power terminals42are provided at positions corresponding to the male signal terminal33and the plurality of male power terminals32, respectively, in the first opposing surface31. That is, in the second opposing surface41, the female signal terminal43is disposed at the central part, and the plurality of female power terminals42are disposed on the circumference centered on the central part.

InFIG. 9, a plan view of the first connector3is shown on the upper side, and a side view of the first connector3is shown on the lower side. As shown in the upper side ofFIG. 9, a straight line passing two points of a position P1of the male signal terminal33and a position P2of the male power terminal32(32a) on the first opposing surface31is defined as a first straight line L1. As shown in the lower side ofFIG. 9, a straight line passing two points of an intersection point P4of the first straight line L1and an outer edge WI of the first opposing surface31and a leading end P5of the male signal terminal33is defined as a second straight line L2. A straight line passing two points of the intersection point P4and a leading end P6of the male power terminal32(32a) is defined as a third straight line L3. An elevation angle formed between the first opposing surface31and the second straight line L2is defined as a first angle θ1. An elevation angle formed between the first opposing surface31and the third straight line L3is defined as a second angle θ2. In some embodiments, the lengths of the male power terminals32in the projecting direction and the length of the male signal terminal33in the projecting direction be set in such a way that the second angle θ2becomes larger than the first angle θ1(θ1<θ2).

As shown inFIG. 10, the lengths of the male power terminals32in the projecting direction and the length of the male signal terminal33in the projecting direction are set in such a way that the second angle θ2becomes smaller than the first angle θ1(θ1>θ2). An elevation angle formed between the first opposing surface31and the second opposing surface41when the first opposing surface31and the second opposing surface41are in contact with each other at only the intersection point P4is defined as a third angle θ3. When θ1>θ3>θ2holds, although the male power terminal32band the male signal terminal33are in contact with the second opposing surface41of the second connector4, the male power terminal32ais not in contact with the second opposing surface41. That is, although the male power terminal32bis connected to the female power terminal42b, and the male signal terminal33is connected to the female signal terminal43, the male power terminal32ais not connected to the female power terminal42a.

Thus, when θ1>θ2holds, one of the pairs of the male power terminals32and the female power terminals42could be disconnected, and another pair could be connected in some cases. While the first connector3and the second connector4are conducted, when one of the pairs of the male power terminals32and the female power terminals42is disconnected, and another one of the pairs is connected, current may be concentrated on the connected pair, which may cause the temperature to be excessively increased at the connected power terminal pair.

FIG. 10is illustrated in a deformed manner in such a way that the lengths of the male power terminals32(32aand32b) and the male signal terminal33in the projecting direction become longer than a diameter of the first connector3. Therefore, in the second connector4, the positions of the female power terminals42(42aand42b) and the female signal terminal43are drawn in a distorted manner. However, in practice, the lengths of the male power terminals32(32aand32b) and the male signal terminal33in the projecting direction are shorter than the diameter of the first connector3and shorter than the illustration ofFIG. 10. Thus, in the second connector4, distortion of the positions of the female power terminals42(42aand42b) and the female signal terminal43hardly occurs.

On the other hand, as shown inFIG. 11, suppose that the lengths of the male power terminals32and the male signal terminal33in the projecting direction are set in such a way that the second angle θ2becomes larger than the first angle θ1(θ1<θ2). When the first opposing surface31and the second opposing surface41are in contact only at the intersection point P4, the male power terminal32bis in contact with the second opposing surface41of the second connector4if θ1<θ3holds, but the male signal terminal33and the male power terminal32aare not in contact with the second opposing surface41. That is, the male signal terminal33is not connected to the female signal terminal43, and thus the first connector3and the second connector4are not conducted.

Further, when θ1<θ3holds, the male signal terminal33is connected to the female signal terminal43, and the first connector3and the second connector4are conducted. However, when the male signal terminal33is connected to the female signal terminal43, all the pairs of the male power terminals32and the female power terminals42are connected. Thus, when the male signal terminal33and the female signal terminal43are connected to each other, and the first connector3and the second connector4are conducted, it is possible to prevent one of the pairs of the male power terminals32and the female power terminals42from being disconnected, and current from being concentrated on the other pair, and thereby preventing the temperature from excessively rising.

LikeFIG. 10,FIG. 11is illustrated in a deformed manner in such a way that the lengths of the male power terminals32(32aand32b) and the male signal terminal33in the projecting direction become longer than the diameter of the first connector3. For this reason, in practice, distortion of the positions of the female power terminals42(42aand42b) and female signal terminal43like the one shown inFIG. 1lhardly occurs in the second connector4.

Next, a method of setting the elastic force when the male power terminal32includes the elastic member35is described below. In the following description, a reference is made also toFIG. 2as appropriate.

FIG. 12is a schematic view for describing the method of setting the elastic force when the male power terminal32includes the elastic member35. As shown inFIG. 12, when a foreign matter M is sandwiched between the first connector3and the second connector4, the first opposing surface31of the first connector3and the second opposing surface41of the second connector4cannot be completely brought close to each other. Specifically, only a part of the second opposing surface41is in physical contact with the outer edge of the first opposing surface31. However, when the third angle θ3is smaller than the first angle θ1(when θ1>θ3holds), the male signal terminal33and the female signal terminal43are connected to each other, and the first connector3and the second connector4are conducted. Then, current flows through all of the pairs of the male power terminals32and the female power terminals42.

The elastic member35is, for example, a coil spring, and is in an expanded state when the male power terminals32are not fitted into the female power terminals42. When the male power terminals32are fitted into the female power terminals42, the elastic member35exerts the elastic force in a direction in which the male power terminals32projects from the first opposing surface31. That is, when the male power terminals32are inserted into the female power terminals42, the male power terminals32are pressed against the female power terminals42by the elastic force of the elastic member35. The closer the first opposing surface31is to the second opposing surface41, the greater the elastic force of the elastic member35becomes, and the stronger the male power terminals32pressed against the female power terminals42. Then, an electrical contact resistance between the male power terminals32and the female power terminals42is reduced. The smaller the contact resistance, the smoother the current flows between the male power terminals32and the female power terminals42.

When the first opposing surface31cannot be completely brought close to the second opposing surface41, such as when the foreign matter M is sandwiched therebetween, the electrical contact resistance between the male power terminals32and the female power terminals42is larger than that when the first opposing surface31and the second opposing surface41are completely brought close to each other. That is, current is hard to flow between the male power terminals32and the female power terminals42. For this reason, when the male power terminals32and the female power terminals42are conducted in a state in which the electrical contact resistance between the male power terminals32and the female power terminals42is larger than the predetermined value, the temperature of parts where the male power terminals32are in contact with the female power terminals42may excessively rise.

In order to prevent this, when the third angle θ3is smaller than the first angle θ1in a state in which a part of the second opposing surface41is in physical contact with the outer edge of the first opposing surface31, the elastic force (an elastic coefficient) of the elastic member35is set in such a way that the contact resistance between the male power terminals32and the female power terminals42becomes smaller than the predetermined value. By doing so, even when the male power terminals32and the female power terminals42are conducted in a state in which the first opposing surface31and the second opposing surface41cannot be completely brought close to each other, such as when the foreign matter M is sandwiched therebetween, it is possible to effectively prevent the temperature of the parts where the male power terminals32are in contact with the female power terminals42from excessively rising.

LikeFIG. 10,FIG. 12is illustrated in a deformed manner in such a way that the lengths of the male power terminals32(32aand32b) and the male signal terminal33in the projecting direction become longer than the diameter of the first connector3. For this reason, in practice, distortion of the positions of the female power terminals42(42aand42b) and female signal terminal43like the one shown inFIG. 12hardly occurs in the second connector4.

The present disclosure is not limited to the above embodiment and can be appropriately modified without departing from the scope of the present disclosure.

In the above embodiment, as shown inFIGS. 3 to 6, although the opposing surface of the first connector3including the male power terminals32and the male signal terminal33is defined as the first opposing surface, and the opposing surface of the second connector4including the female power terminals42and the female signal terminals43is defined as the second opposing surface, the configurations thereof may be reversed. That is, the opposing surface of the first connector3may be defined as the second opposing surface including the female power terminals42and the female signal terminal43, and the opposing surface of the second connector4may be defined as the first opposing surface including the male power terminals32and the male signal terminal33.