Patent Application
20200286693
The object concerns an electric contactor (electrical normal open contact), in particular a high-voltage contactor, as well as a motor vehicle with such a contactor.
Electric contactors are well known. Particularly in automotive applications, electric contactors are often designed as relays. Relays are used to switch a first circuit (switch circuit) by means of a control pulse coming from a second circuit (control circuit), in particular to close it. However, the electrical isolation between the switch circuit and the control circuit is also dependent on the dielectric strength of the air. In addition, relays are complex to manufacture and therefore expensive. Finally, relays are subject to wear due to ageing. It is also possible that the switching mechanism of relays is jammed and switching is no longer possible.
In battery or fuel cell powered vehicles, switching is sometimes safety critical. Especially in high-voltage applications, where voltages of 1000V and more can occur, mechanically and electrically reliable switching is necessary. In particular for short-circuiting voltage carrying parts in the event of an accident, it is necessary that an electrical contactor has a low probability of failure. It is also necessary that the electrical contactor always ensures galvanic isolation between the switch circuit and the control circuit when open. In addition, the electrical contactor must remain capable of closing the circuit throughout the service life of a motor vehicle in order to guarantee the necessary safety at all times.
From DE 10 2011 121 958 A1 an electrically well insulating, mechanically fail-safe electric contactor is known. The contactor comprises a first connection lug and a second one, insulated from the first connection lug. By means of a closing element that can be driven by an actuator, an electrical connection can be established between the connection lugs, via which residual capacities can be safely dissipated in the event of an accident.
A disadvantage of the electrical contactor described here, however, is that due to construction-related tolerances and surface contamination, no reproducible and satisfactory contacts can be made between the closing element and the terminal lugs, so that the reduced transmission cross-sections result in insufficiently fast dissipation of residual capacitance, which also adversely operates only under strong heating.
Therefore, the subject matter was based on the object of providing an electrically well insulating, mechanically fail-safe electrical contactor that ensures fast and safe discharge of residual capacities.
This object is solved by an electric contactor according to claim 1. The object is also solved by a motor vehicle according to claim 15.
The electrical contactor has two connection lugs which serve to connect the electrical contactor with electrical cables. The connection lugs are preferably made of a copper material or an aluminium material. The connection lugs can preferably also be nickel-plated and/or tinned, especially in an area where they are connected to energy conductors.
The connection lugs preferably lead into a housing and are arranged isolated from each other in the housing. A guide channel can be arranged inside the housing. This can at least be limited in areas by the connection lugs or their surfaces. In particular, the electrical contactor within the guide channel may have an electrical contact area in which the connection lugs are spaced apart and arranged opposite one another. The opposite ends of the terminal lugs can be shaped to form a receptacle for an electrical contact element.
In particular, the connection lugs can be arranged directly on the edge of the housing. Advantageously, the respective connection lugs can also be arranged at least partially within a recess in the housing.
In order to establish an electrical connection between the connection lugs, it is necessary for the contact element to be guided into the receptacle formed by the connection lugs. For this purpose, the first and second connecting lugs each have at least one recess in the contact region arranged inside the guide housing. There may also be more than one recess in each of the connecting lugs.
By inserting the contact element into the recesses of the terminal lugs, an electrical connection can be established between the terminal lugs.
To this end, the contact element must be electrically conductive at least in part, preferably at least along its surface, so that the contact element electrically connects the terminal lugs to one another as soon as it comes into electrical contact with the two terminal lugs.
The contact element is held in an open position in the guide housing. For this purpose, the contact element can be held in the open position by the guide housing in a form fit manner. In the open position, the contact element is arranged electrically isolated from the connection lugs.
The contact element is displaceable, preferably arranged so as to be transversally displaceable in the guide housing, whereby the contact element in the present arrangement is guided simultaneously in the direction of displacement in the respective recesses of the two connecting lugs when it is displaced. After displacement, the contact element is in a closed position. In the closed position, the electrical contactor is closed, in which an electrical short-circuit is created between the connection lugs by the contact element. The contact element is arranged with contact areas in the closed position in the receptacles of the connection lugs. This is achieved by displacing the contact element in the guide housing.
After an accident of a motor vehicle, this not only enables an electrical contact to be established as quickly as possible, but also promises a trajectory that is as reliable as possible when the contact element is moved.
An actuator is preferably provided for displacing the contact element, which actuator allows the contact element to be arranged electrically separated from at least one terminal lug in an open position of the electric closer, whereas the contact element is in electrical contact with both terminal lugs in a closed position of the electric closer and thus short-circuits them to one another.
For a space-saving arrangement of the electrical contactor, it is advantageous that the contact area of the connection lugs is located at a first end of the guide channel and the actuator at a second end of the guide channel opposite the first end.
The actuator is preferably electrically insulated from the connection lugs by the guide housing. For this purpose, the guide housing is preferably made of an electrical insulator, e.g. polyamide, e.g. PA 6.
Also the contact element can be formed at least in parts from an insulator. Only the part of the contact element which serves to electrically short-circuit the connection lugs and comes into mechanical contact with the connection lugs must be electrically conductive.
In order to nevertheless ensure a rapid discharge of residual capacities in the event of an accident, it is advantageous if the contact element is formed at least partially from an electrically conductive material with a high specific electrical conductivity, preferably at least partially from an aluminium material and/or a copper material. It is also proposed that the connection lugs are at least partly made of a conductive material, preferably at least partly of a copper material and/or an aluminium material. The conductive surfaces of the connection lug and contact element are preferably made of the same material, especially in the contact areas.
The contact element is formed in at least one contact region, in which it is held in the recesses in the closed position, as a flat part, in particular as a cuboid flat part. Because the contact areas are formed as flat parts, the contact element with its contact areas can slide into slot-shaped recesses to reach the closed position.
In order to produce high-quality contacting, in particular a particularly low-impedance connection between the terminal lugs, the shape of the contact element is also preferably at least partially substantially complementary, in particular a perfect fit with the recesses of the terminal lugs.
The contact element can be formed from a flat part, in particular from a cuboid flat part.
It has also been recognized that high-quality contacting is not only hindered by design tolerances, but also by the surface quality of the components to be contacted.
In the open position, the contact element rests at the housing, especially at the guide housing. In this position, a surface of the contact element, at least in the area of the contact areas, faces in the direction of the receptacles. This surface has a surface normal. The surface normal of the surface of the contact area facing the recesses in the open position is essentially parallel to the direction of displacement. This ensures that the contact element with the surface facing the recesses is moved in the direction of the recesses. The contact element contacts the recesses in the closed position preferably with other surfaces. In particular, the surface normal of these contact surfaces are perpendicular to the direction of displacement. The contact element preferably contacts the connection lugs with two opposing contact surfaces of the contact element, preferably running parallel to each other. The contact surfaces of the connection lugs, especially in the receptacles, are parallel to each other. The distance between the contact surfaces of the receptacles is preferably equal to the distance between the contact surfaces of the contact element, which may correspond to the height of the terminal element in the contact area.
The contact element preferably has at least four contact surfaces via which an electrical connection can be made between the terminal lugs, in particular both a first and second contact surface and a third and fourth contact surface being arranged substantially parallel to one another and substantially parallel to the direction of movement of the contact element.
The contact areas of the contact element can be spatially separated from each other. The contact element preferably has at least two contact areas which are spaced apart in a direction perpendicular to the displacement direction, preferably also perpendicular to a height direction of the contact element. In particular, the contact areas can be opposite each other in relation to a central axis of the contact element running parallel to the direction of displacement. Thus on both sides of a central axis of the contact element one contact area can be provided, each. The contact areas have the contact surfaces of the contact element, which in the closed position are in direct contact with the contact surfaces of the recesses. The distance between the contact areas can be essentially the same as the distance between the recesses. This ensures that the contact areas in the closed position are both located in the recesses.
When a contact is made between the contact element and the terminal lugs, the contact element can be guided in its movement through the recesses of the terminal lugs. Preferably, the contact element is guided, in particular, simultaneously by both connecting lugs, immediately after an electrical contact is made between the contact element and the connecting lugs.
It is also proposed that the contact element and the recesses of the connecting lugs are shaped and/or dimensioned relative to each other in such a way that a positive connection, in particular a press connection, is formed between the contact element and the connecting lugs during displacement. After displacement, in the closed position, a press fit, a transition fit or a clearance fit may be formed between the contact element and the connection lugs.
For a press fit, it is proposed in particular that the recesses are formed underdimensioned with respect to the contact element or that the contact element is formed overdimensioned with respect to the recesses.
As the recesses are formed to be undersized with respect to the contact element or the contact element is formed to be oversized with respect to the recesses, the surfaces of the components to be contacted can be at least partially freed from impurities or passivations by friction during the contacting, so that a high-quality contacting is ensured in which not only small proportions of the contact surface but preferably the largest part of the contact surface can be used for charge transfer.
In addition to a defined undersize, the contact element can also be tapered, especially wedge-shaped, on its side facing the recesses.
This not only improves contacting by displacing impurities and oxide layers, but a self-locking holding force can also fix the contact element in the recesses of the terminal lugs.
In order to safely prevent the electrical circuit from being reopened after the contactor has been closed, it is also proposed that the receptacle is formed in such a way that the contact element preferably snaps into the receptacle in a closed position of the contactor.
Therefore, snap-in lugs and/or snap-in recesses which are shaped and dimensioned relative to one another in such a way that a positive connection, in particular a snap-in connection between the contact element and the connection lugs, is formed during displacement can also be provided alternatively or cumulatively to slightly underdimensioned recesses or a slightly overdimensioned contact element in the recesses of the connection lugs and the contact element.
The actuator intended for driving the contact element according to the subject matter exerts such a great force on the contact element in the direction of the contact area that it can be displaced in the direction of the contact area. This allows the electric contactor to be moved into its closed position.
In order to achieve the necessary force transmission without losses, the contact element is at least positively, preferably non-positively, in particular materially connected to the displacement element.
The actuator can consist of an actuator element and a displacement element.
The actuator element can be formed as an electrical, hydraulic, pyrotechnical or mechanical actuator element, while the displacement element can, for example, be formed as a displacement carriage or as a piston.
In an embodiment in which the displacement element is formed as a piston, the piston is preferably arranged in the guide housing in such a way that a guide channel is sealed by it. The piston can be cylindrical. It is also possible that the piston is a cuboid guided in the guide housing. The sealing can be such that a space in the guide channel facing the actuator is sealed against a space in the guide channel facing the recess. This is particularly advantageous when the contact element is displaced into the receptacle using compressed air. Sealing can mean that the flow resistance for air in the guide channel through the piston is increased by more than 90%, preferably more than 95%.
The piston is preferably made of an insulating material, in particular polyamide, in particular PA 6. This ensures that the piston of the contact element provides reliable insulation between the conductive part of the contact element and the actuator. Preferably the piston faces the actuator and the contact element faces the recesses of the connecting lugs. The contact element can be moved within the guide housing between the actuator and the contact area of the connection lugs. Preferably the contact element is arranged in an open position of the contactor on the actuator, in particular on the displacement element. The contact element is preferably held in the guide housing in such a way that it can only be moved under the action of force. In particular, the contact element can be arranged in a press fit in the guide housing. The press fit can be such that a force of at least 10 N, preferably 20 N or at least 50 N is required to move the contact element transversally in the guide housing.
A pyrotechnic actuator can be realized, for example, by a thrust piston that can be activated by an electrical ignition pulse. For that a squib is arranged in a sleeve. Inside the sleeve there is a piston which can be displaced along the longitudinal axis of the sleeve and which is displaced in the sleeve by the explosion energy of the squib. The piston is pushed out of the sleeve by the displacement of the piston. The part of the piston pressed out of the sleeve can push the contact element in the direction of the receptacle.
In particular, it is preferred if at least one recess of the connecting lugs is arranged on opposite sides of the guide housing. The recesses can be hook-shaped and/or U-shaped and open in the direction of the contact element. The recesses can have a bottom which can serve as a stop for the contact element so that its maximum movement in the direction of displacement is defined.
The recesses make it possible to ensure a large contact surface of the contact element with the connection lugs despite the simple alignment and design of the electrical contactor.
In order to protect the contact element arranged in the guide channel preferably non-positively or materially on the displacement element from unintentional contacting with the connecting lugs, it is proposed that at least one insulation element is arranged between the contact element and the contact region of the connecting lugs for insulating the contact element, the insulation element preferably being formed in two pieces, in particular from two insulation caps.
The contact element has a surface facing in the direction of the connection lugs. The surface normal of this surface is preferably aligned with the direction of displacement. This surface is preferably covered by the insulation element. In particular, insulation elements can be arranged in the contact areas of the contact element.
In order to ensure sufficient insulation by the insulation element even at high voltages, it is proposed that the insulation material of the insulation element, in addition to a specific electrical conductivity of at least less than 10-5 S-cm−1, preferably less than 10-10 S-cm−1, is particularly 10-15 S-cm−1 has a dielectric strength of at least more than 5 kV/mm, preferably more than 20 kV/mm, particularly preferably more than 50 kV/mm. For this purpose, the insulation element may preferably be made of plastic or ceramic.
In accordance with an embodiment, it is proposed that two insulation caps are arranged between the contact element and the contact area of the terminal lugs for insulation of the contact element. These insulation caps are designed in such a way that at least parts of the insulation caps are separated, in particular torn off or sheared off, at the terminal lugs when the electrical contactor is closed. The insulation caps are arranged on the contact element, especially in the contact areas.
In contrast to at least parts of the insulation caps, which are sheared off at the connection lugs, the contact element is accelerated with the displacement element in the direction of the contact area of the connection lugs when the actuator unit is triggered, before the contact element is finally arranged in the recesses of the connection lugs and an electrical contact is established between the connection lugs.
For this purpose, the contact element is preferably arranged and, in particular with respect to the insulating element, designed in such a way that the contact element insulated in the open position with respect to the connecting lugs breaks through the insulating element after the actuator has been triggered. For this purpose, the contact element may preferably have a chisel-shaped taper on its surface facing away from the actuator, especially on the surface facing the connection lugs. The contact element can break through the insulation element at least in the area which, in the open position, borders directly on the recesses of the connecting lugs. Preferably, the insulation element is separated at least in the region of the interface between the insulation element and the surfaces of the contact lugs pointing in the direction of the insulation element.
It is also advantageous if the proposed insulation element not only has excellent insulation properties, but also preferably low breaking strength, in particular low shear strength. Therefore, according to an embodiment, it is proposed that the insulation element be made of a material with a shear strength according to DIN 18137-3 of at least less than 10 N/mm, preferably of at least less than 5 N/mm, particularly preferably of at least less than 1 N/mm.
It is also advantageous if the insulation element has a low breaking and shear strength as well as a low tear strength.
In addition to low breaking, shear and tear strength, it can also be particularly advantageous if the insulation material has predetermined breaking points which are preferably arranged in a potential contact area of the insulation element with the contact element and in a potential contact area with the terminal lugs. This makes it easier to break the insulation element through the contact element and shear it off from the contact lugs when the actuator is triggered.
According to an embodiment, it is proposed that the connection lugs arranged on the electrical contactor each have a connection part pointing out of the guide housing and a part guided in the guide housing, forming at least the receptacle. In particular, the connecting parts are shaped in such a way that electrical power lines can be connected to them in a loss-proof manner. This can be done using screw bolts or screw connections or crimp connections or the like. A soldered or welded connection can also be formed between the connecting parts and the power cables.
In the guide housing, the connection lugs in the area of the receptacle can be arranged electrically non-insulated. This enables the exposed areas of the connection lugs to be electrically short-circuited by means of the contact element.
In accordance with an embodiment, it is proposed that the connection lugs be elastically deformable in the guide housing at least in the area of the recesses. This ensures that the contact element can elastically and/or plastically push the connecting lugs apart in the area of the recesses in order to be moved into the closed position of the contactor. In this case, the connection lugs can spring back elastically and thus at least partially grip the contact element and hold it in the closed position.
In accordance with an embodiment, it is proposed that the guide housing should have a ventilation opening in the area of the receptacle, especially at one end remote from the actuator. When the contact element is displaced within the guide housing, the space between the receptacle and the contact element is reduced, whereas the space between the contact element and the actuator facing the actuator is increased. The reduction in space between the receptacle and the contact element leads to an increase in pressure. This would result in the contact element in the guide housing being pushed back and, if potentially, the force applied by the actuator would not be sufficient to push the contact element into the receptacle. A ventilation opening can therefore be provided to ensure ventilation. This is preferably provided centrally between the connection lugs in the area of the receptacle.
In the following, the subject matter is explained in more detail using a drawing showing embodiments. In the drawing show:
In the case of an embodiment in which a pneumatic impulse is triggered by the actuator unit 8, the guide channel 14 must be well sealed to the outside. In order to prevent an overpressure from occurring during a displacement of the displacement unit 10, which counteracts the movement in the displacement direction, it is proposed that a vent opening (not shown here) is arranged in the guide channel 14, or that the corresponding space is evacuated.
Furthermore it can be seen in
The contact element 20 is preferably made of a flat part and an electrically conductive material, preferably aluminium or copper.
A more detailed view of the various embodiments of the contact element 20, including the designation of the respective contact areas, contact surfaces and surface normals, is shown in
In the open position, the contact element 20 rests on the housing 12. In this position, the contact element 20 has a surface 20′ facing in the direction of the receptacles 22a, 22b of the connection lugs 4a, b. As can be seen from the arrangement according to
It can also be seen that the contact element 20 has at least two spatially separated contact regions 24a, b, which are spaced apart from one another in a direction perpendicular to the displacement direction indicated by the arrow 30, preferably also perpendicular to a height direction of the contact element 20. The contact areas 24a, b can be designed as shown in
The contact surfaces 26a, 26b, 26c, 26d of the contact areas 24a, 24b of the contact element 20 intended for establishing an electrical contact with the terminal lugs 4a, 4b also have a surface normal 20b each. This respective surface normal runs essentially perpendicular to the surface normal 20a of the surface 20′ of the contact element 20 facing in the direction of the 22a, 22b receptacles.
The contact element 20, which is essentially cuboid in shape according to
The contact surfaces of the connection lugs 22a′, 22a″, 22b′, 22b″ arranged in the recesses 22a and 22b as shown in
The displacement element 10 for insulation is at least partly made of an insulator, preferably at least partly of a plastic.
It can also be seen that two connection parts 2a, 2b of two connection lugs 4a, 4b protrude from the housing 12. The connection lugs 4a, 4b also extend into the interior of the housing 12. Inside the housing 12, the connection lugs 4a, 4b run parallel to each other, parallel to the direction of displacement which runs along the axis II-II up to their contact area 18a, b, in which the connection lugs 4a, 4b each have at least one recess 22a, 22b. The connection lugs 4a, 4b can be arranged directly at the edge of the housing 12. The connection lugs 4a, 4b can also be arranged at least partially within a recess 28a, b of the housing 12.
The recesses 22a, 22b of the connection lugs themselves are preferably hook-shaped and/or U-shaped in the direction of the contact element 20 and have a base.
An insulation element 16 is arranged between the recesses 22a, 22b arranged in the contact region 18a, b of the connection lugs 4a, 4b and the contact element 20 in order to effectively prevent electrical contacting of the contact element 20 with the connection lugs 4a, 4b in the open state of the electrical contactor 1.
The insulation element 16 is preferably made of two parts, in particular two insulation caps 16a, 16b, which are placed on the displacement element 10. The insulation caps 16a, 16b preferably have not only a low electrical conductivity and a high dielectric strength required for insulation purposes, but advantageously also have a low tensile strength, breaking strength and shear strength.
The latter properties are desirable since, when a pulse is triggered by the actuator unit 8, it is preferably provided that the contact element 20 breaks through the insulation caps 16a, 16b during the acceleration of the contact element 20 in the direction of the contact region 18a, b at least in the region which, in the open position, directly adjoins the recesses 22a, 22b of the connecting lugs 4a, 4b. Preferably a separation of the insulation caps 16a, 16b is thus provided at least in the region of the interface between the insulation caps 16a, 16b and the surfaces of the contact flaps 4a, 4b pointing in the direction of the insulation caps 16a, 16b. In particular, the insulation caps 16a, 16b at the connection lugs 4a, 4b are at least partially separated, preferably torn off or sheared off.
In order to easily break the insulation caps 16a, 16b, the shape of the contact element 20 can also be adapted. For example, contact element 20 may have a chisel-shaped or wedge-shaped taper at its end remote from actuator unit 8.
In addition, it can be advantageous if the insulation caps 16a, 16b have, in addition to a low breaking, shearing and tearing strength, additionally (not shown here) predetermined breaking points which are preferably arranged in a potential contact region of the insulation caps 16a, 16b with the contact element 20 and in a potential contact region with the connecting lugs 4a, 4b, in particular the surfaces of the contact lugs 4a, 4b pointing in the direction of the insulation caps 16a, 16b. Thus the insulation caps 16a, 16b can advantageously be more easily broken through the contact element 20 and sheared off from the connection lugs 4a, 4b when the impulse of the actuator unit 8 is received.
A corresponding movement and contacting is also provided between the contact surfaces 26a, b of the contact element 20 and the contact surfaces 22a′ and 22a″ of the connection lug, which are not shown in this sectional view, after a pulse of the actuator unit 8 has been triggered.
Furthermore, the surface 20′ is visible, which points in the direction of the receptacles 22a and 22b when the contact element 20 is installed. The surface normal 20a of this surface is also shown, which runs essentially parallel to the direction of displacement when the contact element 20 moves from the open position to the closed position.
In addition, the two surfaces 20b and 20c, each arranged perpendicular to the surface 20a, together with their respective surface normal values, can be recognized. The surface normal 20b is perpendicular to the wide surface of the contact element 20. The surface normal 20c is perpendicular to the outward facing surface of the contact element 20.
In addition to an embodiment formed as a cuboid flat part in accordance with
In the closed position the contact element 20, in particular the contact areas 24a, b of the contact element 20, are arranged in the recesses 22a, 22b of the connection lugs.
An electrical contact is established between the two terminal lugs 4a, 4b via the direct contact of the contact surfaces of the contact element 26a, b, c, d with the contact surfaces of the recesses 22a′, 22a″, 22b′, 22b″, so that electrical charge can be dissipated safely and reliably via the two interconnected terminal lugs 4a, 4b.
In this position, the contact element 20 is arranged in the mounting of the connection lugs 4a, 4b and thus closes them short. By short-circuiting the connection lugs 4a, 4b, it is possible to allow the discharge of residual capacities, as may be necessary in the event of an accident with a motor vehicle. It can be seen that the insulation caps 16a, 16b have been partially separated at the connection lugs 4a, 4b, whereby only the sheared off remainders of the insulation caps 16a′ and 16b′ remain at the contact surfaces between the connection lugs 4a, 4b and the insulation caps 16a, 16b. The remaining part of the insulation caps 16a, 16b is finally arranged between the contact element 20 and the wall of the housing 12.
The displacement is triggered by the actuator unit 8. After initiation of an electrical impulse, for example, another electrical, mechanical, hydraulic or pneumatic impulse is triggered in the actuator unit 8, which accelerates the displacement unit 10 together with the contact element 20 arranged in the direction of the contact area 18a, b of the connection lugs 4a, 4b. The displacement unit 10 can be formed as a displacement carriage or as a piston which pushes the contact element 20 in the direction of displacement into the receptacle.
During this movement, the contact element 20 first breaks through the insulation caps 16a, 16b arranged between the actuator unit 6 and the contact area 18a, b, before the contact element 20 is finally inserted into the recesses 22a, 22b of the connection straps 4a, 4b.
With the help of the electric closer 1 it is possible to establish a fast and high quality electrical connection between the connection lugs in order to guarantee a fast and safe removal of residual capacities.
The proposed electrical make contact 1 is not only electrically well insulated and mechanically fail-safe, but also allows a reproducible and satisfactory contact between the contact element and the terminal lugs.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2017 106 117.7 | Mar 2017 | DE | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2018/051570 | 1/23/2018 | WO | 00 |
