JP7136650B2 - connector - Google Patents

Description

TECHNICAL FIELD The present invention relates to a connector, particularly to a connector useful for vehicles, and to a high-current connector intended to pass a high-current direct current.

A battery mounted on an electric vehicle or the like is generally charged from an external power supply through a charging connector attached to the vehicle. When charging the battery, a DC power supply is used, and the vehicle itself is not equipped with an AC/DC converter, thereby reducing the weight of the vehicle body. It takes about 30 minutes to charge the battery of an electric vehicle even with a high-speed charger. Charging of an electric vehicle starts after a person manually inserts the power plug attached to the charging facility into the connector and sets it. In order to further shorten the charging time, a large current must be applied, but a large amount of heat is generated at the contact resistance generated at the electrode contact portion of the connector. For this reason, it is necessary to increase the size of the connector to increase the amount of current that can flow. However, as the size of the connector increases, the size of the charging cable and power plug also increase, making it difficult to handle manually. For this reason, it has been a major problem to reduce the contact resistance generated in the connector portion and to suppress the heat generated in the contact portion even when a large current is applied.

Conventionally, many technologies related to connectors have been proposed. For example, Patent Document 1 (Japanese Unexamined Patent Application Publication No. 11-168826) describes a connector divided in the axial direction, and describes a contact applying a spring structure. However, this patent document does not disclose details of rod-shaped plug electrodes that are commonly used.

JP-A-11-168826

In view of the above problems, the present invention provides a cylindrical groove in the socket-side electrode portion, preferably hard silver plating on the bottom of the cylindrical groove, and a plurality of contact points in the groove, preferably silver plating. By installing a spring-type contactor with a special coating, the current flowing through each contact point is reduced, thereby reducing heat generation due to contact resistance in the entire connector, thereby solving the problem. be.

The present invention consists of claims 1 to 4 below.
<Claim 1>
In a rod-shaped plug-type connector having a cylindrical shape, a socket-side electrode is provided with a cylindrical groove, the groove has a spring force, and the rod-shaped plug-side electrode to be inserted has 10 or more points of contact. A connector characterized by having a child attached.
<Claim 2>
2. The connector according to claim 1, wherein the surfaces of the contacts are coated with hard silver plating having a hardness of Hv 150 or higher.
<Claim 3>
3. The connector according to claim 1, wherein the bottom of the groove of the socket-side electrode is coated with hard silver plating having a hardness of Hv of 150 or more and a thickness of 20 μm or more.
<Claim 4>
The connector according to any one of claims 1 to 3, wherein the sliding resistance value of the contact surface is 1.4 to 3N.

According to the connector structure of claim 1, various effects represented by the following (1) to (5) can be obtained.
(1) Contact resistance is preferably low due to contacts coated with hard silver plating, and wear of silver-plated surfaces can be minimized.
(2) By having a large number of contact points, the amount of current flowing through each contact is reduced according to the number of contacts, and the amount of heat generated by contact resistance can be reduced.
(3) Since the amount of heat generated is smaller than that of a one-contact type connector, a larger amount of current can be passed through a connector for which temperature rise is specified.
(4) The spring force of the contact is small, and as in claim 4, the slide resistance force on the surface of the contact is as small as 1.4 to 3 N, so that the connector can be easily inserted and removed manually.
(5) It is possible to pass a larger current than a conventional connector in a charging connector such as an electric vehicle where the space is limited, so that the charging time can be shortened.
Further, in the connector according to claim 2, since the surface of the plug-side electrode is coated with hard silver plating, it is possible to further reduce the contact resistance in the contactor, so that a larger amount of current can flow. .
Furthermore, according to the connector of claim 3, since the bottom of the groove of the socket side electrode is coated with a hard silver plating having a hardness of Hv 150 or more and a thickness of 20 μm or more, the corrosion occurs each time the socket side electrode 2 is used. The plug-side electrode 1 described above can be inserted and removed up to 4,000 times, which is estimated from the amount of wear of the hard silver plating of 0.005 μm.
Furthermore, according to the connector of claim 4, since the sliding resistance value of the contactor surface is 1.4 to 3N, the connector can be easily inserted and removed manually.

It is a sectional view showing composition as a first embodiment of the present invention. 1 is a configuration diagram showing a cross-sectional structure of a contactor attachment portion as a first embodiment of the present invention; FIG. FIG. 4 is a cross-sectional view showing a configuration as a second embodiment of the present invention; FIG. 4a is a plan view showing the planar configuration of the contactor 3 as the first embodiment of the present invention, and FIG. 4b is a cross-sectional view showing the structure of the attached state of the contactor as the first embodiment of the present invention. 4c is a side view showing the side configuration of the contactor as the first embodiment of the present invention; FIG. FIG. 5 is a CC cross-sectional view of FIG. FIG. 6 is a circuit diagram in which the nuclear contact resistance is replaced with an equivalent circuit as the first embodiment of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows a first embodiment of the invention.
FIG. 1 shows a state in which a rod-shaped plug-side electrode 1 is inserted into a socket-side electrode 2 having a hole-like opening. The plug-side electrode 1 and the socket-side electrode 2 are electrically connected via the contactor 3 .
In FIG. 1, the contactor 3 is provided only at one position, but it may be received in a plurality of steps in the hole-shaped opening of the socket-side electrode 2 as required.

FIG. 2 shows how the contactor 3 is mounted.
FIG. 2 shows a cross section of the contactor 3 attached to a groove provided in the socket-side electrode 2 and in contact with the plug-side electrode 1 . The contact 3 has a contact portion plated with hard silver. The hard silver plating is applied so that the hardness of the plating surface is Hv150 or higher.
The hardness Hv is preferably Hv200 or less, more preferably Hv130 to Hv200.
Here, the hardness Hv of the plated surface can be adjusted by controlling the current value when applying the silver plating, or by performing surface effect processing such as peening or roller pressing after applying the silver plating. Peening and roller pressing can also be expected to have the effect of plastically deforming fine cracks on the surface of the plating to close the cracks. It is possible to increase the hardness of the hard silver plating to Hv200 or more by controlling the current during plating, but the residual stress in the plating that makes it Hv200 or more causes fine cracks on the surface of the hard silver plating, resulting in lack of coating. and corrosion. Therefore, the hardness of the hard silver plating used in the present invention is desirably Hv130 to Hv200. The same applies to adjusting the hardness of the groove bottom of the socket-side electrode.
Here, the hardness Hv is a value defined by a method of measuring the hardness of the coating layer with a micro Vickers hardness tester.

The higher the surface hardness of the silver plating, the more durable it will be against abrasion caused by inserting and removing the plug-side electrode. The contact resistance of the contactor 3 is 300 μΩ to 800 μΩ per contact point. The groove provided in the socket-side electrode 2 has a hard silver-plated covering portion 4 having a hardness Hv of 150 or more indicated by diagonal lines at the bottom. The coating thickness of the hard silver plating is 20 μm or more, and the optimum value of the coating thickness is 40 to 50 μm. The contactor 3 is pressed against the surface of the plug-type electrode 1 by a spring force, and current flows through the contact surface A on the plug electrode side in FIG. The contactor 3 is integrally provided with a plate-like posture holding spring 3c for holding the posture so that the contactor 3 does not come out of the groove.
Further, the contactor 3 is provided with a socket-side electrode contact surface B that contacts with the socket-side electrode, and is in contact with the hard silver-plated coating portion 4 . A chamfered portion 3a is provided on the entrance side of the groove to prevent abnormal deposition of silver due to current concentration at the corner during hard silver plating. The chamfered portion preferably has a circular arc shape, but may have a straight chamfered shape.
A thin oxide film on the surface of the contactor 3 is scraped off each time the plug-side electrode 1 is inserted and removed, thereby always maintaining the contact surface in the initial state, thereby preventing an increase in contact resistance due to lamination of the oxide film.
The attitude holding spring 3b prevents the contactor 3 from moving up and down with respect to the plane of the drawing, and has the function of holding it in a stable position in the groove. If the posture holding spring 3b has a small spring force, the contactor 3 will move up and down, so that the hard silver coating of the plug electrode side contact surface A and the socket side electrode contact surface B will be worn out, making it difficult to insert and remove the connector. It leads to a decrease in the number of times.
t in the figure indicates the thickness of the hard silver plating applied to the groove of the socket-side electrode. The hard silver plating coating thickness t is the contact surface with the contactor 3, and is thicker than other plated portions in order to prevent the contact surface with the contactor 3 from changing greatly even if the wear progresses. Thicken the coating. A change in the state of rubbing of the contact surfaces means a change in the number of contact points in a microscopic observation state, that is, a change in electrical resistance at the time of contact.
The contact height hn at the time of contact generated when the plug-side electrode 1 is inserted into the socket-side electrode 2 is closely related to the value of mechanical contact resistance generated when the plug-side electrode is inserted and pulled out. By properly managing the contactor height hn at the time of contact, it is possible to keep the mechanical contact resistance described above within a predetermined range.

FIG. 3 shows a second embodiment of the invention.
In FIG. 3, the hatched portion of the surface of the plug-side electrode 1 shows the state covered with hard silver plating.
This embodiment is a method for minimizing the contact resistance between the contactor 3 and the contact surface A of the plug-side electrode when a large current is passed in a short period of time. In the hard silver plating of the plug-side electrode 1, the oxide film formed on the surface of the hard silver plating is scraped off little by little each time the plug electrode is inserted and pulled out, and the plating surface with low contact resistance is maintained.

FIG. 4a is a plan view showing the planar configuration of the contactor 3 as the first embodiment of the present invention.
In FIG. 4a, a plug-side electrode contact surface A and a socket-side electrode contact surface B are provided continuously in the longitudinal direction of a spring plate-like member. A spring plate having the number of contacts required for energization is cut, rolled into a cylindrical shape, and attached to a required groove. The contactor 3 held in a cylindrical shape is attached with one end open. Electrically, it suffices that each contact is in contact with the plug-side electrode 1 and the socket-side electrode 2 with a required contact pressure.

FIG. 4b is a cross-sectional view showing the structure of the attached state of the contact according to the first embodiment of the present invention. In FIG. 4b, the contactor 3 shows a cross section in a state of being sandwiched between the plug-side electrode 1 and the socket-side electrode 2. FIG. The plug-side contact surface A is in contact with the surface of the plug-side electrode 1 at one location, and the socket-side electrode contact surface B is in contact with the socket-side electrode 2 at two locations. The contact points on the plug-side contact surface A and the socket-side contact surface B may be increased or decreased as necessary.

FIG. 4C is a side view showing the side configuration of the contactor as the first embodiment of the present invention.
FIG. 4C shows a side view of an example in which the pitch of the louvers 3C is 2 mm and the length of the louvers 3C is 3 mm. The paper shows the state before the louver 3C is attached to the groove. Both ends of the louver 3C are brought into contact with the plug-side electrode 1 and the socket-side electrode 2 by being attached to the groove and sandwiched from the top and bottom of the paper. At this time, the louver 3C is tilted more horizontally than the state shown in FIG. 4C, and the spring force applies a predetermined contact pressure to each contact portion to prevent a decrease in contact resistance. The contact pressure of the spring is 4 to 8 N to minimize wear on the silver plating film due to excessive contact pressure. At this time, the slide resistance force on the surface of the contactor becomes a low pull-out force of about 1.4 to 3N. The sliding resistance can be adjusted by adjusting the height hn of the contact, adjusting the hardness of the hard silver plating, and adjusting the spring force of the contact 3 at the time of contact.

FIG. 5 shows the CC section of FIG. In FIG. 5 , the plug electrode 1 is electrically connected to the socket side electrode 2 via the contactor 3 . FIG. 5 shows an example in which the diameter of the plug-side electrode 1 is Φ15. The contactor 3 is in contact with the grooves of the plug-side electrode 1 and the socket-side electrode 2 at 20 points by spring force. When a direct current of 500 A is applied in this state, the current value per contact point is 500 A/20 points=25 A. As the number of contacts increases, the current flowing through each contact decreases, and is expressed by the following formula (1).
Current flowing through one contact = connector current/number of contacts (1)
Actually, the pitch size of the louver determines the size and the number of contacts to be attached to the groove. Therefore, it is important to reduce the pitch of the louver and to maintain the spring force and the thickness of the hard silver plating of each contact in order to keep the contact resistance stable.

FIG. 6 shows a circuit diagram in which the nuclear contact resistance is replaced with an equivalent circuit as the first embodiment of the present invention. In FIG. 6, resistors 5 for one contact are electrically connected in parallel via louvers 3C as many as the number of contact points. For this reason, the resistance 5 per contactor is such that the current flowing through the electrode portion is reduced by the number of contact points. The same voltage is applied to each contact as the voltage V applied between the electrodes.

Next, the amount of heat generated by the connector of the present invention and the conventional single contact will be compared. Assume that the current through the connector is 100A.
The amount of heat generated by a single-contact type connector is expressed by equation (2). Here, I is the current value (A), R is the resistance value of the contact, and T is the elapsed time.
Q=I ² ×R×T (2)
Assume that the current value flowing through the connector is 100 A, the connector of the present invention has 20 contacts, and the contact resistance value at the contact portion is the same as that of a general single contact connector.
The amount of heat generated at a single point of contact in general is expressed by Equation (3).
Q100=100 ² ×R×T (3)
= 10,000 x R x T
Here, Q100 is the amount of heat generated by the connector, R is the contact resistance value, and T is the elapsed time.
The resistance value per contact of the connector of the present invention is represented by the following formula (4) from formula (1).
i 100/20=5(A) (4)

The amount of heat generated by the connector of the present invention is represented by the following equation (5) from equation (2).
Q′100=20×i ² ×R×T (5)
= 20 x 5 ² x R x T
= 500 x R x T

The ratio of the amount of heat generated by the general single-contact connector and the amount of heat generated by the connector of the present invention is expressed by the following equation (6).
Q100/Q'100 = 10,000 x R x T/500 x R x T
= 1/20 (6)
In the connector of the present invention with 20 contacts, the amount of heat generated is 1/20 of that of a single contact type.
To make the amount of heat generated by the connector of the present invention the same as Q100 in the equation (3), it is expressed by the following equation (7).
I′ ² =10,000×R×T/(20×R×T) (7)
I'=√500=22.3(A)
Here, I' indicates the current value per contact when the amount of heat generated is the same as that of Q100.
The current value and ratio in the equation (4) are represented by the following equation (8).
i/I'=22.3/5=4.7 (8)
It can be seen from equation (8) that when the current value per contact is multiplied by 4.7, the amount of heat generated is the same as that of a single contact type connector. In other words, when the allowable temperature of the connector is determined by a specified value, 4.7 times as much current can flow for the same specified temperature.

The connector of the present invention reduces heat generation due to contact resistance in the entire connector by reducing the amount of current flowing through each contact point, and allows a large amount of current to flow. In addition, it is useful as a power supply connector for a motor of a train or the like, or a connector for a power supply connection part of a generator or the like.

REFERENCE SIGNS LIST 1 plug-side electrode 1b hard silver-plated portion 2 socket-side electrode 3 contactor A plug-electrode-side contact surface B socket-side electrode contact surface 3a chamfered portion 3b posture retaining spring 3c louver 4 gap between electrodes 5 per contactor resistance V Voltage applied between electrodes t Thickness of hard silver plating hn Height of contact when connected

Claims (1)

In a rod-shaped plug-type connector having a cylindrical shape, a socket-side electrode is provided with a cylindrical groove, the groove has a spring force, and has 10 or more points of contact with the inserted rod-shaped plug-side electrode. attach the contactor ,
The surface of the contactor is coated with hard silver plating adjusted to a hardness of Hv 150 or more by peening after applying silver plating,
The bottom of the groove of the socket-side electrode is coated with a hard silver plating having a thickness of 20 μm or more, the plating surface of which is adjusted to a hardness of Hv 150 or more by peening after applying the silver plating,
A connector according to claim 1, characterized in that the slide resistance value of the surface of said contact is 1.4 to 3N .

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