Controlling the speed of a movable assembly in an electric relay

Abstract

Embodiments in accordance with the present disclosure are directed to apparatuses, systems, and methods for controlling the speed of a movable assembly in an electric relay. In a particular embodiment, an electric relay assembly is disclosed that includes at least one stationary contact and a moveable assembly including a moveable contact coupled to a shaft that is coupled to a plunger. In this embodiment, the plunger is disposed in an actuation channel defined by a magnetic actuation assembly and is configured to move along an actuation pathway. The electric relay also includes a magnetic bridge encircling a portion of the actuation pathway of the plunger.

Description

CONTROLLING THE SPEED OF A MOVABLE ASSEMBLY IN AN ELECTRIC RELAYBACKGROUND

[0001] Electromechanical switching devices, such as contactors and relays, are designed to carry a certain amount of electrical current for certain periods of time. Such devices are particularly important in electric vehicles (EVs). Typically, electric vehicles include one or more high voltage batteries connected, via an electric relay or main contactor, to a vehicle power distribution system for powering an electric motor. An EV relay typically includes an electromechanical switch that opens or closes high current paths between the battery packs and the vehicle power distribution system. The EV relay is used to break high currents in the event of a safety hazard. When a high current condition is detected by the vehicle’s electronics, the current supply to the actuator coil of the EV relay is interrupted. The EV relay opens the circuit, breaking the high current running through the high-voltage system. EV relays need larger gaps to break high currents. Larger gaps create unacceptably high speeds of the movable assembly in the EV relay during closing. The high impact speed creates damage and wear to the EV relay.SUMMARY

[0002] Embodiments in accordance with the present disclosure are directed to apparatuses, systems, and methods for controlling the speed of a movable assembly in an electric relay. In some examples, a magnetic bridge is used to control the speed of the moveable assembly in the electric relay during closing, which allows for larger electrical gaps and thus greater current breaking capabilities. The magnetic bridge causes a magnetic force drop mid-travel of the moveable assembly, which slows and controls the speed of the movable assembly. The dimensions and the position of the magnetic bridge can be used to adjust the dynamic behavior of the movable assembly. Thus, a larger electrical gap and higher breaking capability is achieved without the moveable assembly impacting at a high speed that could result in damage.

[0003] In a particular embodiment, an electric relay assembly is disclosed that includes at least one stationary contact and a moveable assembly including a moveable contact coupled to a shaft that is coupled to a plunger. In this embodiment, the plunger is disposed in an actuation channel defined by a magnetic actuation assembly and is configured to move along an actuation pathway. The electric relay also includes a magnetic bridge encircling a portion of the actuation pathway of the plunger.

[0004] In another embodiment, a method of controlling a speed of a movable assembly in an electric relay is disclosed that includes coupling an electric relay to an electric circuit. The electric relay includes at least one stationary contact and a moveable assembly including a moveable contact coupled to a shaft that is coupled to a plunger. In this embodiment, the plunger is disposed in an actuation channel defined by a magnetic actuation assembly and is configured to move along an actuation pathway. The electric relay also includes a magnetic bridge encircling a portion of the actuation pathway of the plunger. The method also includes applying power to the magnetic actuation assembly. In this embodiment, the magnetic actuation assembly applies a magnetic force to the moveable assembly and the speed of the moveable assembly is controlled by the magnetic bridge.

[0005] These and other features, aspects, and advantages of the present disclosure will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings.BRIEF DESCRIPTION OF THE DRAWINGS

[0006] FIG. 1 shows a side sectional view of an example electric relay for controlling the speed of a moveable assembly in an electric relay in accordance with at least one embodiment of the present disclosure.

[0007] FIG. 2A show s an isometric view of a portion of the example electric relay of FIG. 1 in the open position.

[0008] FIG. 2B shows an isometric view of a portion of the example electric relay of FIG. 1 in the closed position.

[0009] FIG. 3 is a graph illustrating the relationship between force and moving position during the closing operation of a conventional electric relay design and a design incorporating a magnetic bridge in accordance with at least one embodiment of the present disclosure.

[0010] FIG. 4 is a graph illustrating the relationship between speed and moving position during the closing operation of a conventional electric relay design and a design incorporating a magnetic bridge in accordance with at least one embodiment of the present disclosure.

[0011] FIG. 5 sets forth a flow chart of an example method of controlling the speed of a movable assembly in an electric relay in accordance with at least one embodiment of the present disclosure.DETAILED DESCRIPTION

[0012] The terminology used herein for the purpose of describing particular examples is not intended to be limiting for further examples. Whenever a singular form such as “a”, "an" and “the” is used and using only a single element is neither explicitly or implicitly defined as being mandatory, further examples may also use plural elements to implement the same functionality. Likewise, when a functionality is subsequently described as being implemented using multiple elements, further examples may implement the same functionality using a single element or processing entity. It will be further understood that the terms “comprises”, “comprising”, “includes” and / or “including”, when used, specify7the presence of the stated features, integers, steps, operations, processes, acts, elements and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, processes, acts, elements, components and / or any group thereof.

[0013] It will be understood that when an element is referred to as being “connected” or “coupled” to another element, the elements may be directly connected or coupled via one or more intervening elements. If two elements A and B are combined using an “or”, this is to be understood to disclose all possible combinations, i.e. only A, only B. as well as A and B. An alternative wording for the same combinations is “at least one of A and B”. The same applies for combinations of more than two elements.

[0014] Accordingly, while further examples are capable of various modifications and alternative forms, some particular examples thereof are shown in the figures and will subsequently be described in detail. However, this detailed description does not limit further examples to the particular forms described. Further examples may cover all modifications, equivalents, and alternatives falling within the scope of the disclosure. Like numbers refer to like or similar elements throughout the description of the figures, which may be implemented identically or in modified form when compared to one another while providing for the same or a similar functionality.

[0015] Electric vehicle (EV) relays have a movable assembly that closes and breaks an electric circuit. Typically, the movable assembly is actuated in linear fashion by magnetic coil. The magnetic force is a non-linear function of the magnetic gap, approximately proportional to the gap length on the power of -2. Typically, the open state of the relay is guaranteed by two springs, a return spring and a contact spring. Both springs create the spring response of the system. Typically, the two springs are linear and form a characteristic two stage response.

[0016] During closing, the force difference between the magnetic force and the spring forces causes the movable assembly to accelerate and close the contact. The movable assemblytouches the stationary electrical contacts at high speed. The speed can be calculated by integrating the force difference between the magnetic forces and the spring forces over time. With increasing requirements for breaking capabilities, the EV relays need larger electrical gaps and hence larger magnetic gaps. In one example, EV relays use magnetic gaps in the range of 1.5 to 4mm. With such magnetic gaps, the electrical gaps are also small. The breaking capabilities in such implementations are limited to 2-3kA, whereas modem breaking requirements reach 9kA. To enable pick-up, the ampere turns could be increased. However, this change significantly increases the speed of impact between the movable assembly and the stationary- contacts and increases wear and degradation. A larger electrical gap is required to break high currents, but larger gaps result in speeds that are too fast for the moveable assembly during closing. To limit the damage of the relay during normal operation, the speed of movable assembly should be controlled. One approach is to use progressive springs and match the magnetic forces closely, within a sufficient safety- margin. However, with such an approach, the holding force of the springs will be too high and the needed holding power will be much higher than desirable. Another approach is to use electronics in the relay to create a desirable current supply profile. This approach adds complex electronics in each contactor.

[0017] Embodiments in accordance with the present disclosure provide a mechanism to control and limit the speed of the moveable assembly during closing using a magnetic bridge. The magnetic bridge may be a stationary ring made of magnetic material positioned midtravel of the magnetic gap. In a particular embodiment, the magnetic bridge is made of steel with high magnetic permeability. The magnetic bridge provides a dynamic, tunable, cost- effective mechanism to control the speed of the moveable assembly without added complexity or electronics.

[0018] Exemplary methods and apparatuses for controlling a speed of a moveable assembly in an electric relay in accordance with the present disclosure are described with reference to the accompanying drawings, beginning with FIG. 1. For further explanation. FIG. 1 sets forth a side section view of an example electric relay 100 in accordance with at least one embodiment of the present disclosure. FIG. 2A illustrates an isometric view of a portion 200 of the example electric relay of FIG. 1 in the open position. FIG. 2B illustrates an isometric view of the portion 200 of the example electric relay of FIG. 1 in the closed position. In the example of FIGS. 2A and 2B, the portion 200 includes the magnetic coil 112, the moveable assembly 120, and the magnetic bridge 116 among other components.

[0019] The example electric relay 100 includes stationary contacts 102, 104 and a moveable contact 106 coupled to a shaft 108 that is coupled to a plunger 110. The moveable contact 106, shaft 108, and plunger 110 form at least part of a moveable assembly 120. The electric relay 100 in FIG. 1 is shown in the open position. The example electric relay 100 also includes a magnetic coil 112 (e.g., of a magnetic actuation assembly or armature) that is energized to actuate the moveable assembly 120 by applying a magnetic force to the plunger 110, thus placing the moveable contact 106 in contact with the stationary contacts 102. 104 to allow passage of current through the relay. The magnetic force applied to the plunger 110 forces the plunger 110 upward through an actuation pathway 192 in the actuation channel 118. When the moveable assembly 120 is actuated, the electrical gap E 194 and the magnetic gap M 190 are closed. To aid actuation of the moveable assembly 120. the plunger 110 is disposed in a flux tube 1 14 in the actuation channel 118. When the magnetic coil 112 is deenergized, the moveable contact 106 is pushed out of contact with the stationary contacts 102, 104 via a return spring (e.g., return spring 122 in FIGs. 2A and 2B) to break the current and return to the open position. FIG. 2 A illustrates the return spring 122 with the electric relay in the open position and FIG. 2B illustrates the return spring 122 with the electric relay in the closed position.

[0020] To increase the current specification for the electric relay, as in the amount of current the electric relay 100 is capable of breaking, the electrical gap E 194 must also be increased. This also means an increase in the magnetic gap M 190 between the plunger 110 and a top core 151 of the electric relay. However, as the magnetic gap M 190 increases, the speed of the moveable assembly 120 during actuation also increases. To control or limit the speed of the moveable assembly 120 and thus prevent damage to the electric relay 100, the electric relay 100 also includes a magnetic bridge 116 encircling the magnetic gap M 190 in the actuation channel 118. In some examples, the magnetic bridge 116 is a stationary ring made from magnetic material positioned mid-travel of the magnetic gap M 190. When the plunger passes through the magnetic bridge 116, the magnetic bridge has the effect of limiting the speed of the moveable assembly.

[0021] The magnetic bridge 116 provides a number of advantageous effects compared with a design with no magnetic bridge: a) the initial force is increased, b) mid travel force is decreased, and c) final force is slightly increased. The magnetic force drop mid-travel is used to slow and control the speed of the movable assembly 120. The dimensions and the position of the magnetic bridge can be used to adjust the dynamic behavior of the movable assembly 120. The effect of the magnetic bridge 116 can be tuned through dimensional changes.including adding two or even more magnetic bridges, creating a magnetic bridge with varying thickness and length, and / or adjusting the position in the magnetic gap.

[0022] For further explanation, FIG. 3 sets forth a graph 300 illustrating the relationship between relative force and relative moving position during the closing operation of a conventional electric relay design and a design incorporating a magnetic bridge. The graph includes three curves to illustrate this relationship: load force, original design, and design with a magnetic bridge. The horizontal axis represents the relative moving position of the movable assembly, denoted from 0 to 1, whereas the vertical axis represents the relative force from 0 to 1.

[0023] The load force curve is portrayed using a dashed line, demonstrating how the spring system influences the force experienced by the movable assembly. The original design is depicted by a solid line, indicating the force profile in a relay without a magnetic bridge.

[0024] The design with a magnetic bridge is shown with a dotted line. Initially, the force is greater in comparison to the original design, indicating an increased initial force. As the moving position progresses to the mid-travel region, the force in the design with a magnetic bridge decreases, highlighting a reduction in the mid-travel force. Towards the final stage of movement, the force slightly increases as compared to the original design, reflecting an increment in the closing force.

[0025] This graphical representation differentiates the impact of incorporating the magnetic bridge into the relay design, demonstrating how it modifies the magnetic force profile to control and reduce the speed of the movable assembly upon contact with the stationary electrical contact.

[0026] For further explanation, FIG. 4 sets forth a graph 400 illustrating the relationship between speed and moving position during the closing operation of a conventional electric relay design and a design incorporating a magnetic bridge. The horizontal axis of the chart represents the relative moving position of the movable assembly during closing, ranging from 0 to 1 , with 0 signifying the starting position and 1 indicating the fully closed position. Similarly, the vertical axis represents the relative speed of the movable assembly versus its relative moving position during closing.

[0027] The graph includes two distinct curves: one representing the original design and the other representing the design with the magnetic bridge. The dashed line represents the original design performance. The original design shows a steady increase of the speed of the movable assembly throughout its travel until it nears the fully closed position. The design with the magnetic bridge is represented by a dotted line. This design illustrates a varied speedprofde characterized by an initial rapid speed increase, a subsequent deceleration mid-travel, and a moderate speed increment as it approaches the fully closed position.

[0028] The two curves indicate that the incorporation of the magnetic bridge reduces the midtravel speed, effectively lowering the impact speed at the moment of contact (-0.82 relative position) between the movable assembly and the stationary electrical contact. This results in a controlled and reduced final velocity, which minimizes wear and degradation of the relay components, extending the relay's operational lifespan.

[0029] For further explanation, FIG. 5 sets forth a flow chart of an example method for controlling the speed of a movable assembly in an electric relay. The method includes coupling 502 an electric relay to an electric circuit, the electric relay comprising at least one stationary contact and a moveable assembly including a moveable contact coupled to a shaft that is coupled to a plunger. The plunger is disposed in an actuation channel defined by a magnetic actuation assembly and is configured to move along an actuation pathway. The electric relay also includes a magnetic bridge encircling a portion of the actuation pathway of the plunger.

[0030] In some examples, the electric relay is the electric relay 100 discussed above with respect to FIG. 1 and FIGS. 2A and 2B. For example, the electric relay can be coupled to a high voltage battery and a power distribution system in an electric vehicle, where the electric relay controls when power from the battery is provided to the power distribution system.

[0031] The method of FIG. 5 also includes applying 504 power to the magnetic actuation assembly, wherein the magnetic actuation assembly applies a magnetic force to the moveable assembly, and wherein a speed of the moveable assembly is controlled by the magnetic bridge. In some examples, as discussed above, the magnetic coil is energized to apply magnetic force to the moveable assembly, thus forcing the moveable assembly upward and closing the electrical gap between the moveable contact and the stationary contacts. The magnetic bridge is disposed in the magnetic gap and controls the speed of the moveable assembly as the magnetic gap is closed by modifying the magnetic force acting on the plunger.

[0032] In view of the foregoing, it will be appreciated that an electric relay utilizing a magnetic bridge in accordance with the present disclosure provides a number of advantages, including but not limited to: increased initial (pick up) force; the speed of a moveable assembly is controlled to limit damage to the electric relay;• a larger electrical gap and magnetic gap is achieved, thus allowing for greater breaking capacity of the relay;• eliminates the need for electronics to modulate actuation current or for complex spring arrangements.

[0033] Advantages and features of the present disclosure can be further described by the following statements:

[0034] 1 . An electric relay assembly comprising: at least one stationary contact; a moveable assembly including a moveable contact coupled to a shaft that is coupled to a plunger, wherein the plunger is disposed in an actuation channel defined by a magnetic actuation assembly, the plunger configured to move along an actuation pathway; and a magnetic bridge encircling a portion of the actuation pathway of the plunger.

[0035] 2. The electric relay assembly of statement 1, wherein the magnetic bridge is disposed in a magnetic gap between the plunger and a top core of the electric relay assembly.

[0036] 3. The electric relay assembly of statement of 1 or 2, wherein the magnetic bridge is a ring of magnetic material.

[0037] 4. The electric relay assembly of any of statements 1-3, wherein the plunger passes through the magnetic bridge during actuation of the moveable assembly.

[0038] 5. The electric relay assembly of any of statements 1-4, wherein the magnetic actuation assembly includes a magnetic coil encircling the actuation channel.

[0039] 6. The electric relay assembly of any of statements 1-5, wherein the magnetic actuation assembly is energized to apply a magnetic force to the moveable assembly.

[0040] 7. The electric relay assembly of any of statements 1-6, wherein the magnetic force applied to the moveable assembly moves the moveable assembly to close an electrical gap between the moveable contact and the at least one stationary contact.

[0041] 8. The electric relay assembly of any of statements 1-7, wherein the magnetic bridge controls a speed at which the moveable assembly is moved by inducing the magnetic force on the moveable contact during travel through the actuation pathway.

[0042] 9. The electric relay assembly of any of statements 1-8 further comprising one or more additional magnetic bridges encircling one or more portions of the actuation pathway of the plunger.

[0043] 10. A method of controlling a speed of a movable assembly in an electric relay, the method comprising: coupling an electric relay to an electric circuit, the electric relay comprising at least one stationary contact; a moveable assembly including a moveablecontact coupled to a shaft that is coupled to a plunger, wherein the plunger is disposed in an actuation channel defined by a magnetic actuation assembly, the plunger configured to move along an actuation pathway; and a magnetic bridge encircling a portion of the actuation pathway of the plunger; and applying power to the magnetic actuation assembly, wherein the magnetic actuation assembly applies a magnetic force to the moveable assembly, and wherein a speed of the moveable assembly is controlled by the magnetic bridge.

[0044] 11. The method of statement 10. wherein the magnetic bridge is disposed in a magnetic gap between the plunger and a top core of the electric relay assembly.

[0045] 12. The method of statement 10 or 11, wherein the magnetic bridge is a ring of magnetic material.

[0046] 13. The method of any of statements 10-12, wherein the plunger passes through the magnetic bridge during actuation of the moveable assembly.

[0047] 14. The method of any of statements 10-13, wherein the magnetic actuation assembly includes a magnetic coil encircling the actuation channel.

[0048] 15. The method of any of statements 10-14, wherein the magnetic actuation assembly is energized to apply a magnetic force to the moveable assembly.

[0049] 16. The method of any of statements 10-15, wherein the force applied to the moveable assembly moves the moveable assembly to close an electrical gap between the moveable contact and the at least one stationary contact.

[0050] 17. The method of any of statements 10-16, wherein the magnetic bridge controls a speed at which the moveable assembly is moved by inducing the magnetic force on the moveable contact during travel through the actuation pathway.

[0051] 18. The method of any of statements 10-17 wherein the electric relay includes one or more additional magnetic bridges encircling one or more portions of the actuation pathway of the plunger.

[0052] 19. An electric vehicle system comprising: a high voltage battery; a power distribution system; and an electric relay coupling the high voltage battery to the power distribution system, the electric relay comprising: at least one stationary contact; a moveable assembly including a moveable contact coupled to a shaft that is coupled to a plunger, wherein the plunger is disposed in an actuation channel defined by a magnetic actuation assembly, the plunger configured to move along an actuation pathway; and a magnetic bridge encircling a portion of the actuation pathway of the plunger.

[0053] 20. The electric vehicle system of statement 19 wherein the magnetic bridge is disposed in a magnetic gap between the plunger and a top core of the electric relay assembly.

[0054] It will be understood from the foregoing description that modifications and changes may be made in various embodiments of the present disclosure without departing from its true spirit. The descriptions in this specification are for purposes of illustration only and are not to be construed in a limiting sense. The scope of the present disclosure is limited only by the language of the following claims.

Claims

CLAIMSWhat is claimed is:

1. An electric relay assembly comprising: at least one stationary contact; a moveable assembly including a moveable contact coupled to a shaft that is coupled to a plunger, wherein the plunger is disposed in an actuation channel defined by a magnetic actuation assembly, the plunger configured to move along an actuation pathway; and a magnetic bridge encircling a portion of the actuation pathway of the plunger.

2. The electric relay assembly of claim 1, wherein the magnetic bridge is disposed in a magnetic gap between the plunger and a top core of the electric relay assembly.

3. The electric relay assembly of claim 1, wherein the magnetic bridge is a ring of magnetic material.

4. The electric relay assembly of claim 3, wherein the plunger passes through the magnetic bridge during actuation of the moveable assembly.

5. The electnc relay assembly of claim 1. wherein the magnetic actuation assembly includes a magnetic coil encircling the actuation channel.

6. The electric relay assembly of claim 1, wherein the magnetic actuation assembly is energized to apply a magnetic force to the moveable assembly.

7. The electric relay assembly of claim 6, wherein the magnetic force applied to the moveable assembly moves the moveable assembly to close an electrical gap between the moveable contact and the at least one stationary contact.

8. The electric relay assembly of claim 7, wherein the magnetic bridge controls a speed at which the moveable assembly is moved by modifying the magnetic force acting on the plunger during travel through the actuation pathway.

9. The electric relay assembly of claim 1 further comprising one or more additional magnetic bridges encircling one or more portions of the actuation pathway of the plunger.

10. A method of controlling a speed of a movable assembly in an electric relay, the method comprising: coupling an electric relay to an electric circuit, the electric relay comprising at least one stationary' contact; a moveable assembly including a moveable contact coupled to a shaft that is coupled to a plunger, wherein the plunger is disposed in an actuation channel defined by a magnetic actuation assembly, the plunger configured to movealong an actuation pathway; and a magnetic bridge encircling a portion of the actuation pathway of the plunger; and applying power to the magnetic actuation assembly, wherein the magnetic actuation assembly applies a magnetic force to the moveable assembly, and wherein a speed of the moveable assembly is controlled by the magnetic bridge.

11. The method of claim 10, wherein the magnetic bridge is disposed in a magnetic gap between the plunger and a top core of the electric relay assembly.

12. The method of claim 10, wherein the magnetic bridge is a ring of magnetic material.

13. The method of claim 12, wherein the plunger passes through the magnetic bridge during actuation of the moveable assembly.

14. The method of claim 10, wherein the magnetic actuation assembly includes a magnetic coil encircling the actuation channel.

15. The method of claim 10, wherein the magnetic actuation assembly is energized to apply a magnetic force to the moveable assembly.

16. The method of claim 15, wherein the force applied to the moveable assembly moves the moveable assembly to close an electrical gap between the moveable contact and the at least one stationary contact.

17. The method of claim 1 , wherein the magnetic bridge controls a speed at which the moveable assembly is moved by modifying the magnetic force acting on the plunger during travel through the actuation pathway.

18. The method of claim 10 wherein the electric relay includes one or more additional magnetic bridges encircling one or more portions of the actuation pathway of the plunger.

19. An electric vehicle system comprising: a high voltage battery; a power distribution system; and an electric relay coupling the high voltage battery to the power distribution system, the electric relay comprising: at least one stationary contact; a moveable assembly including a moveable contact coupled to a shaft that is coupled to a plunger, wherein the plunger is disposed in an actuation channel defined by a magnetic actuation assembly, the plunger configured to move along an actuation pathway; and a magnetic bridge encircling a portion of the actuation pathway of the plunger.

20. The electric vehicle system of claim 19 wherein the magnetic bridge is disposed in a magnetic gap between the plunger and a top core of the electric relay assembly.

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