EP2846035B1

EP2846035B1 - Solenoid switch and starter

Info

Publication number: EP2846035B1
Application number: EP14177574.2A
Authority: EP
Inventors: Wei Song; Jian Li
Original assignee: SEG Automotive Germany GmbH
Current assignee: SEG Automotive Germany GmbH
Priority date: 2013-07-26
Filing date: 2014-07-18
Publication date: 2020-01-08
Anticipated expiration: 2034-07-18
Also published as: HUE049297T2; BR102014018234B1; EP2846035A2; CN104347316A; BR102014018234A2; CN104347316B; EP2846035A3

Description

Technical Field

The invention relates to a starter for starting an engine. Meantime, the invention also relates to a solenoid switch that can be used in the starter.

Background Art

It is well known that an engine shall be rotated under an outer force until it can operate using the power of itself. Starting of engine refers to a procedure of the engine which, under the action of the outer force, is transited from a stationary state to a state in which it runs independently. Common engine starting manners comprise manual starting, starting using an assistant gasoline engine and electric starting. Manual starting, in which cable pulling or manual rotating action is involved, is easy but inconvenient, needs too much labor effort, and is thus only applicable in low power engines and is reserved in some vehicles only as a standby option. Starting using an assistant gasoline engine is applicable mainly in high power diesel engines. Electric starting is widely used in modern vehicles for the merits of easy to operate, quick starting, repetitive starting ability, and being remotely controllable. In general, the whole starting procedure of an electric starter comprises the following steps: first, an electric current from a vehicle battery is supplied to a DC motor so that a driving gear of the starter is put into a mechanical movement; then, a transmitting mechanism drives the driving gear into engagement with a toothed ring on a flywheel, and then, when the engine is started, the transmitting mechanism automatically drives the driving gear out of the engagement with the toothed ring. The ON/OFF action of the starter is controlled by a solenoid switch. The solenoid switch generally comprises two stationary terminals and one movable terminal, the movable terminal being able to move relative to the stationary terminals to electrically connect and disconnect the stationary terminals so as to control the close and open of an electric circuit of the starter. The starter comprises a magnetic field (stator) and an armature (rotor). When an electric current flows through a coil of the armature, the whole coil will rotate under the action of a torque force. The DC starter, when energized, generates a counter electromotive force which is in proportion to the rotational speed of the engine and is in reverse proportion to the torque of the engine, and thus the requirements for starting the engine may be met. The starting electric current in the starter is very strong, generally higher than 150 Amperes, and some times even up to thousands Amperes. As a result, the stationary terminals and the movable terminal of the solenoid switch are subjected to a high impact of the strong electric current in the moment of electric connecting, and thus partial high temperature is likely to be generated. In some conditions, the materials of the stationary terminals and the movable terminal may stick to each other, which phenomenon is also called contact welding. When contact welding is happened, in which the materials of the stationary terminals and the movable terminal are stuck to each other and the electric circuit cannot be opened, an electric current of up to thousands Amperes will flow continuously through the solenoid switch, which ultimately results in damage of the solenoid switch or even the whole starter by overheat.
Prior art related with the starter and its solenoid switch can be known from patent publication CN103094010A , which also teaches an improved solution for avoiding contact welding. However, there is still room for making further improvements.
DE 10 2008 002 432 A1 discloses a solenoid switch including two stationary terminals and a movable terminal. One of the terminals can comprise a copper nickel alloy
EP 1 995 745 A1 also discloses a solenoid switch including terminals. Such a terminal can comprise a copper alloy including tellurium, the amount of copper being more than 95%.
Thus, it needs to provide an improved solution to overcome the technical problem found in the prior art.

Summary of the Invention

The invention is mainly aimed at preventing contact welding of the solenoid switch and thus preventing the starter from being damaged by overheat.
For solving the above technical problem, the invention in one aspect provides a solenoid switch which comprises:

a housing;
stationary terminals fixed to the housing; and
a movable terminal adapted to be movable between a first state and a second state, the movable terminal being away from electric contact with the stationary terminals when the movable terminal is in the first state, and the movable terminal being in electric contact with the stationary terminals when the movable terminal is in the second state;
wherein at least one of the stationary terminals and the movable terminal comprises a copper alloy material which contains tellurium and nickel.

According to the invention, the copper alloy material comprises 0.2 wt % to 0.6 wt % of tellurium and 1.0 wt % to 1.5 wt % of nickel, and the copper alloy material comprises 0.1 wt % to 0.5 wt % of phosphorus.
Optionally, the copper alloy material comprises 0.1 wt % to 0.3 wt % of phosphorus, 0.1 wt % to 0.25 wt % of ferrum, 0.15 wt % to 0.3 wt % of zinc and 0.01 wt % to 0.1 wt % of rare earth.
Optionally, each of the stationary terminals comprises a contact portion and a stem portion, the contact portion and the stem portion being formed integrally of the copper alloy material, or the contact portion being formed of the copper alloy material and the stem portion being formed of another material.
Optionally, the housing defines a contacting chamber, the movable terminal and the contact portions of the stationary terminals being arranged in the contacting chamber, and the stem portions of the stationary terminals extending to the outside of the housing through the housing.
Optionally, the stationary terminals have been subjected to cold working.
Optionally, the stationary terminals have been subjected to cold forging.
Optionally, the stem portions of the stationary terminals are formed with screw threads in a rolling process.
Optionally, the solenoid switch further comprises a coil, an elastic element and an armature core magnetically coupled with the coil, the elastic element being elastically pre-deformed to provide an elastic force basing the movable terminal towards the first state, wherein when the coil is energized, the coil generates a magnetic field which acts on the armature core so that the armature core drives the movable terminal to move towards the second state and thus the amount of elastic deformation of the elastic element is increased.
The invention in another aspect provides a starter for starting an engine, the starter comprising a solenoid switch as described above, wherein an electric current of no less than 150 Amperes flows through the stationary terminals and the movable terminal when the movable terminal is in the second state.
In the starter and the solenoid switch according to the invention, at least one of the stationary terminals and the movable terminal comprises a copper alloy material which contains elements like tellurium and thus has a high welding resistance. Thus, the solenoid switch is not likely to become defective even when there is a strong electric current flowing therethrough. In addition, such a copper alloy material, by comprising elements like nickel, has a high tensile strength and a high extendibility. As a result, the material is not likely to become cracked even after a cold working processes, such as cold forging or rolling, and thus it has a high machinability. In addition, the material has good conductive performance and a high electric conductivity.
Other aspects and features of the invention will be apparent when described in details below with reference to the drawings. It is noted that the drawings are given for the purpose of illustrating some possible designs of the invention only, not for limiting the scope of the invention which is defined by the attached claims. It is also noted that the drawings only schematically show related structures and processes of the invention, and thus they are not drawn to scale unless it is specifically pointed out.

Brief Description of the Drawings

For a more complete understanding of the invention, reference is now made to the following description taken in conjunction with the drawings in which like elements are indicated by like reference numerals and in which:

Figure 1 shows a schematic partial sectional view of a solenoid switch according to a possible embodiment of the invention; and
Figure 2 shows a schematic view of stationary terminals and a movable terminal of the solenoid switch shown in Figure 1.

Detailed Description of Possible Embodiments

Some possible embodiments of the invention will be described now in details in conjunction with the drawings so that those skilled in the art can comprehensively understand the subject matters of the invention.
As shown in Figure 1 and Figure 2, a solenoid switch 100 comprises a housing 1, two stationary terminals 21 and 22 and one movable terminal 23. The two stationary terminals 21 and 22 are fixed to the housing 1 in a manner of being separated from each other, and the movable terminal 23 is able to be moved between a first state and a second state. When the movable terminal 23 is in the first state, the movable terminal 23 is away from electric contact with the stationary terminals 21 and 22; on the other hand, when the movable terminal 23 is in the second state, the movable terminal 23 is in electric contact with the stationary terminals 21 and 22. At least one of the stationary terminals 21 and 22 and the movable terminal 23 comprises a copper alloy material, the copper alloy material containing tellurium and nickel.
The housing 1 is insulative, in which a contacting chamber 10 and an armature core chamber 12 are formed, the contacting chamber 10 and the armature core chamber 12 being separated from each other by an insulative separator (fixed core) 14. The stationary terminals 21 and 22 each comprise a contact portion 210 or 220 and a stem portion 212 or 222. The movable terminal 23 and the contact portions 210 and 220 of the stationary terminals 21 and 22 are arranged in the contacting chamber 10, and the stem portions 212 and 222 of the stationary terminals 21 and 22 extend through the housing 1 to the outside of the housing 1. Screw nuts (not designated with reference numerals) are threadingly mounted to the stem portions 212 and 222 respectively, with screw threads of the screw nuts being engaged with screw threads 214 and 224 of the stem portions 212 and 222 to fix the stationary terminals 21 and 22 to the housing 1. Further, the stem portions 212 and 222 extend beyond the nuts by a length to function as connection terminals for connecting with electric cables or wires.
The solenoid switch 100 further comprises a coil 3, an elastic element 4 and an armature core (movable core) 5 magnetically coupled with the coil 3. The coil 3 and the armature core 5 are assembled in the armature core chamber 12. The armature core 5 is mounted coaxially in the coil 3, and the armature core 5 is movable in an axial direction. The elastic element 4 comprises a spring mounted around a push bar 6, and the elastic element 4 is elastically pre-loaded between a first end of the push bar 6 and the separator 14 so that the elastic element 4 is elastically compressively pre-deformed. The movable terminal 23 is fixed to a second end of the push bar 6. The second end of the push bar 6 is opposite to the first end thereof, and thus the elastic element 4 provides an elastic force which biases, via the push bar 6, the movable terminal 23 towards the first state. The movable terminal 23 is kept in the first state when it is not subjected to a magnetic force from the coil 3. On the other hand, when the coil 3 is energized, the coil 3 generates a magnetic field which acts on the armature core 5. This magnetic field attracts the armature core 5 to move it to the right side of Figure 1 in the axial direction, and the armature core 5 in turn pushes the push bar 6 to drive the movable terminal 23 to move to the right side until the movable terminal 23 comes into contact with the stationary terminals 21 and 22 and is thus stopped in the second state, so that electric connection between the two stationary terminals 21 and 22 is established. When the movable terminal 23 is driven to move to the right side, the elastic element 4 is further compressed to increase the amount of elastic deformation of the elastic element 4 so that elastic potential energy is stored. When the coil 3 is deenergized, the coil 3 does not generate the magnetic field which acts on the armature core 5, and the elastic element 4 releases its elastic potential energy to push the push bar 6 and the movable terminal 23 to move to the left side of Figure 1. In other words, by releasing the elastic potential energy of the elastic element 4, the movable terminal 23 is forced to move away from the stationary terminals 21 and 22 so that the electric connection between the two stationary terminals 21 and 22 is broken and the movable terminal 23 returns to the first state.
In a possible embodiment according to the invention, the copper alloy material comprises the following elements and their contents by weight:

copper: ≥ (equal to or higher than) 97 %
tellurium: 0.2 % to 1.0 %, preferably 0.2 % to 0.6 %
nickel: 0.5 % to 3 %, preferably 1.0 % to 1.5 %
phosphorus: 0.1 % to 0.5 %, preferably 0.1 % to 0.3 %
ferrum: 0.1 % to 0.25 %
zinc: 0.15 % to 0.3 %
rare earth (mischmetal): 0.01 % to 0.1 %
other elements: 0.5 %

solenoid switch

movable terminal

stationary terminals

solenoid switch

In a possible embodiment, the contact portions 210 and 220 are formed integrally with the corresponding stem portions 212 and 222 of the single copper alloy material, respectively. The stationary terminals 21 and 22 have been subjected to cold forging to form hexagonal contact portions 210 and 220 and cylindrical stem portions 212 and 222, and screw threads 214 and 224 are formed on the outer peripheries of the stem portions 212 and 222 of the stationary terminals 21 and 22 in a rolling process. Thanks for the high comprehensive performance of this copper alloy material, the stationary terminals 21 and 22 are not likely to become cracked even after a cold working processes, such as cold forging or rolling, and thus they have a high machinability. In addition, the solenoid switch 100 is not easy to become defective by contact welding even when a strong electric current flows through it.
In another possible embodiment, the contact portions 210 and 220 are formed of the copper alloy material, while the stem portions 212 and 222 are formed of another material (for example, pure copper). That is to say, the contact portions 210 and 220 and the corresponding stem portions 212 and 222 are formed separately, and then they are connected together, such as by riveting or welding. In this way, the contact portions 210 and 220 have a high welding resistance to prevent contact welding, while the stem portions 212 and 222 have a high machinability and a high electric conductivity by using a suitable material (for example, pure copper).
In an embodiment according to the invention, stationary chamfers 216 and 226, which are oblique with respect to the axial direction, are formed respectively at tip ends of the two contact portions 210 and 220 which are closer to the movable terminal 23. Corresponding moving chamfers 230, which are oblique with respect to the axial direction, are formed at a tip end of the movable terminal 23 which is closer to the stationary terminals 21 and 22. A through hole 232 is formed in the movable terminal 23, the through hole 232 extending through the movable terminal 23 in the axial direction, and the push bar 6 being fixed in the through hole 232. When the movable terminal 23 is in the second state, the moving chamfers 230 of the movable terminal 23 contact directly with the stationary chamfers 216 and 226 of the contact portions 210 and 220 to establish satisfactory electric contact between the stationary terminals 21 and 22 and the movable terminal 23.
According to the invention, a starter (not shown) for starting an engine is provided, which comprises the solenoid switch 100 according to the invention. When the movable terminal 23 is in the second state, an electric current of no less than 150 Amperes may flow through the stationary terminals 21 and 22 and the movable terminal 23. Optionally, when the movable terminal 23 is in the second state, an electric current of no less than 200 Amperes flows through the stationary terminals 21 and 22 and the movable terminal 23. Further optionally, when the movable terminal 23 is in the second state, an electric current of no less than 400 Amperes flows through the stationary terminals 21 and 22 and the movable terminal 23.
It is noted that, as can be understood by those skilled in the art, directional terms "right" and "left" are used here in order to facilitate the description, which indicate only relative positional relations, not absolute positional relations. Further, as can be understood by those skilled in the art, "axis" used here means a line around which an object is symmetrical, and in particular, means a central axis of a revolution object.

Claims

A solenoid switch (100) comprising:
a housing (1);

stationary terminals (21, 22) fixed to the housing (1); and

a movable terminal (23) adapted to be movable between a first state and a second state, the movable terminal (23) being away from electric contact with the stationary terminals (21, 22) when the movable terminal (23) is in the first state, and the movable terminal (23) being in electric contact with the stationary terminals (21, 22) when the movable terminal (23) is in the second state;

wherein at least one of the stationary terminals (21, 22) and the movable terminal (23) comprises a copper alloy material which contains tellurium and nickel, characterised in that

the copper alloy material comprises 0.2 wt % to 0.6 wt % of tellurium, 1.0 wt % to 1.5 wt % of nickel and 0.1 wt % to 0.5 wt % of phosphorus.
The solenoid switch (100) according to claim 1, wherein the copper alloy material comprises 0.1 wt % to 0.3 wt % of phosphorus, and further comprises 0.1 wt % to 0.25 wt % of ferrum, 0.15 wt % to 0.3 wt % of zinc and 0.01 wt % to 0.1 wt % of mischmetal.
The solenoid switch (100) according to claim 1, wherein each of the stationary terminals (21, 22) comprises a contact portion (210, 220) and a stem portion (212, 222), the contact portion (210, 220) and the stem portion (212, 222) being formed integrally of the copper alloy material, or the contact portion (210, 220) being formed of the copper alloy material and the stem portion (212, 222) being formed of another material.
The solenoid switch (100) according to claim 3, wherein the housing (1) defines a contacting chamber (10), the movable terminal (23) and the contact portions (210, 220) of the stationary terminals (21, 22) being arranged in the contacting chamber (10), and the stem portions (212, 222) of the stationary terminals (21, 22) extending to the outside of the housing (1) through the housing (1).
The solenoid switch (100) according to claim 3, wherein the stationary terminals (21, 22) have been subjected to cold working.
The solenoid switch (100) according to claim 3, wherein the stationary terminals (21, 22) have been subjected to cold forging processing, or the stem portions (212, 222) of the stationary terminals (21, 22) are formed with screw threads (214, 224) in a rolling process.
The solenoid switch (100) according to claim 1, further comprising a coil (3), an elastic element (4) and an armature core (5) magnetically coupled with the coil (3), the elastic element (4) being elastically pre-deformed to provide an elastic force basing the movable terminal (23) towards the first state, wherein when the coil (3) is energized, the coil (3) generates a magnetic field which acts on the armature core (5) so that the armature core (5) drives the movable terminal (23) to move towards the second state and thus the amount of elastic deformation of the elastic element (4) is increased.
A starter for starting an engine, comprising a solenoid switch according to any one of claims 1 to 7, wherein an electric current of no less than 150 Amperes flows through the stationary terminals (21, 22) and the movable terminal (23) when the movable terminal (23) is in the second state.