# US 8,786,388 B2 · Electromagnetic switch for a starting device, and method for switching the electromagnetic switch

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- Number: US 8,786,388 B2
- Document ID: US8786388B2
- Status: Granted
- Kind: B2
- Application number: 13/126,298
- Filed: 2009-10-27
- Published: 2011-11-17
- Granted: 2014-07-22
- Earliest claimed: 2008-10-27
- Assignees: Robert Bosch GmbH
- Applicants: Houman Ramezanian; Claus Kramer; Michael Froehlich-Schlapp
- Inventors: Houman Ramezanian; Claus Kramer; Michael Froehlich-Schlapp
- Web page: https://patentgrep.com/patent/US8786388B2

## CPC

- H01H 50/54: Contact arrangements
- F02N 11/087: {Details of the switching means in starting circuits, e.g. relays or electronic switches}
- H01H 1/06: characterised by the shape or structure of the contact-making surface, e.g. grooved
- H01H 1/18: with subsequent sliding
- H01H 50/546: {for contactors having bridging contacts}
- H01H 51/065: {Relays having a pair of normally open contacts rigidly fixed to a magnetic core movable along the axis of a solenoid, e.g. relays for starting automobiles (details H01H50/20)}
- H01H 50/60: moving contact being rigidly combined with movable part of magnetic circuit {(for polarised relays H01H51/2254, H01H51/2281)}
- H01H: ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES (contact cables H01B7/10; electrolytic self-interrupters H01G9/18; emergency protective circuit arrangements H02H; switching by electronic means without contact-making H03K17/00)
- F02N: STARTING OF COMBUSTION ENGINES; STARTING AIDS FOR SUCH ENGINES, NOT OTHERWISE PROVIDED FOR

## Abstract

The invention relates to an electromagnetic switch (16) for a starting device (10), comprising two contacts (180, 181) that are electroconductively inter-connected by a mobile contact bridge (184). At least one of the two contacts (180, 181) preferably comprises a contact surface (300) fixed to a contact stud (150, 151). According to the invention, a) the contact surface (300) is at least essentially flat, and an edge (279) of the contact bridge (180, 181), is arranged in such a way that, (184), providing electrical contact between the contact bridge (184) and the contact once it has come into contact with the contact surface (300), it enables a linear contact between the contact (189, 181) and the contact bridge (184), or b) the contact surface (300) comprises bumps lying essentially in one plane, and an edge (279) of the contact bridge (184), providing electrical contact between the contact bridge (184) and the contact (180, 181), is arranged in such a way that, once it comes into contact with the contact surface (300), it enables essentially a multiple-point contact between the contact (180, 181) and the contact bridge (184), or c) a surface (318) of the contact bridge (184), oriented towards the contact (180, 181), and a longitudinal axis (312) of the contact stud (150, 151), form an angle (β) oriented towards a central axis (315) of the switch (16) and larger than 90°, or d) a surface (318) of the contact bridge (184), oriented towards the contact (180, 181), and a longitudinal axis (312) of the contact stud (150, 151), form an angle (β) which is radially outwardly oriented towards a central axis (315) of the switch (16) and is larger than 90°. The invention also relates to a method for switching an electromagnetic switch, preferably a starting device (10), comprising two contacts (180, 181) that are connected by a mobile contact bridge (184). When the contact bridge (184) is contacted by at least one of the two contacts (180, 181), a rubbing movement is generated between the contact bridge (184) and the contact surface (300) of the contact (180, 181).

## Claims

### Claim 1

An electromagnetic switch (16) for a starting device (10), comprising two contacts (180, 181) that are electroconductively interconnected by a mobile contact link (184) that moves along a movement axis of a switching pin (177) and has a contact edge (279) and a central flat section (270) with a hole (226), wherein at least one of the two contacts (180, 181) comprises a contact surface (300) fixed to a contact pin (150, 151) having a longitudinal axis (312) that is a central axis of the contact pin (150, 151), characterized in that the contact surface (300) has fluting in the shape of an annular fluting (310) and an outer flat section (276) of the contact link (184) glides or rubs along a surface (420) of a wave-like contour (303) of the annular fluting (310) during a switching operation or, respectively, when providing contact, and wherein the outer flat section (276) has a face (318) that points toward the contact surface (300), and wherein during a switching operation there is a current passage area, with the longitudinal axis (312) being disposed between the current passage area and the movement axis of the switching pin (177), and with the current passage area being disposed between the contact edge (279) and the longitudinal axis (312), and further wherein an angle (β) of greater than 90 degrees exists between the face (318) and the longitudinal axis (312) and points toward a central axis (315) of the switch (16).

### Claim 2 (depends on 1)

The electromagnetic switch according to claim 1, characterized in that the central flat section (270) is oriented perpendicular to the switching pin (177) and wherein the outer flat section (276) is adjoined to the flat section (270) so as to point away from said switching pin (177), wherein the outer flat section (276) is inclined or bent in a direction of the contacts (180, 181).

### Claim 3 (depends on 1)

The electromagnetic switch according to claim 1 , characterized in that the contact link (184) is guided in a bearing by means of the switching pin (177) and said contact link (184) has a region comprising an enlarged cross-section (290) between the switching pin (177) and the edge (279) of the contact link (184) and has a region of reduced cross-section (293) between the region comprising the enlarged cross-section (290) and the switching pin (177).

### Claim 4 (depends on 1)

The electromagnetic switch (16) according to claim 1, characterized in that a necked-down portion is present between the central flat section (270) and the outer flat section (276).

### Claim 5 (depends on 1)

The electromagnetic switch (16) according to claim 1, characterized in that the outer flat section(276) has an approximately circular contour.

### Claim 6 (depends on 1)

The electromagnetic switch according to claim 1, characterized in that the wave-like contour (303) has a sinusoidal form.