EP1128410A2 - Switching contact for a starter motor - Google Patents

Abstract

The switch contact has relatively movable counter contact (12) and contact elements (14,16). A resistance in the first contact element is larger than one in the second. In a first closed switch state the counter contact element contacts the first contact element and current flows via the first element. In a second state attainable via the first the counter contact element contacts both contact elements and current flows mainly via the second.

Description

The invention relates to a switch contact for a Starter motor with the in the preamble of claim 1 mentioned features.

State of the art

Conventional starter motors are usually single-stage executed, that is, a main stream of the Starter motor is immediately switched through. On such a procedure can on the one hand intervene Difficult starter pinions in an engine sprocket and on the other hand, an increased material load leads to a shortened total operating time.

To remedy this, systems were developed in which over a series resistor a two-stage circuit of the Starter motor is made possible. So there is an additional one Component including cabling necessary. Besides the disadvantage of a resulting increased Manufacturing effort or space requirements becomes the series resistor in such a Embodiment thermally very heavily loaded what turn to early injury and one Overall failure of the starter motor can result.

Advantages of the invention

With the help of the switch contact according to the invention for the starter motor can be a multi-stage for the first time Switching can be realized without an additional Interconnection effort is necessary. The Switch contact can be designed very compact, so that its space requirement is minimal. In addition can significantly reduces the risk of contact welding become.

(a) in einer ersten geschlossenen Schaltstellung das Gegenkontaktelement an dem ersten Kontaktelement anliegt und ein Strom über das erste Kontaktelement fließt sowie

(b) in einer über die erste Schaltstellung erreichbaren zweiten geschlossenen Schaltstellung das Gegenkontaktelement an dem ersten Kontaktelement und dem zweiten Kontaktelement anliegt und ein Strom weitestgehend über das zweite Kontaktelement fließt.

The switch contact according to the invention for the starter motor consists at least of components which can be displaced relative to one another, such as a mating contact element, a first contact element and a second contact element. A resistance of the first contact element is greater than a resistance of the second contact element. The switch contact is designed such that

(a) in a first closed switching position the mating contact element bears against the first contact element and a current flows through the first contact element and

(b) in a second closed switching position which can be reached via the first switching position, the mating contact element bears against the first contact element and the second contact element and a current flows as far as possible via the second contact element.

In a preferred embodiment of the switch contact the first contact element is in an open Switch position and / or at least at the beginning the first switch position in a rest position Holding force applied. This can preferably be such that the first Contact element from a counter contact element facing contact body and a spring element, which is the first contact element in the relaxed Condition moves to the rest position. Preferably is the first contact element in one Insulated bushing with an end stop for the rest position by one to the counter contact element facing inner edge of the insulating sleeve becomes.

It is further preferred that the first contact element or the contact body in the form of a carbon brush realize. If a spring element is provided, then this preferably electrically conductive and / or A strand is assigned to the spring element, the one electrical connection enabled. Furthermore it is advantageous to the second contact element made of copper shape to a very high electrical conductivity to grant.

In a further preferred embodiment of the invention the switch contact can be designed as a wedge contact. The mating contact element is a wedge and the first contact element has a complementary one conical contact shape. The selected geometry enables a self-cleaning effect of the contact surfaces.

It is further preferred to add further contact elements in the Integrate switch contact that starts from the open switch position simultaneously or on top of each other are contactable below. That's the way it is for example conceivable, the first contact element a resistance carbon and a subsequently contacted Another contact element made of high-current coal shape (double carbon contact). The main stream is in of such an embodiment only activated, if the mating contact element on the second contact element, which is generally the best has electrical conductivity. All in all can be by such an embodiment of the Switching contact several closed switching positions, in which a current flows - in the exemplary embodiment three closed switch positions - realize and so a starting process can be essential be made more comfortable.

Further preferred configurations of the invention result from the rest, in the subclaims mentioned features.

drawings

Figur 1

eine schematische Schnittdarstellung durch eine erste Ausführungsform eines Schaltkontaktes mit zwei geschlossenen Schaltstellungen;

Figur 2

einen Ablauf eines Schaltvorganges bei einem Schaltkontakt gemäß Figur 1 in sechs schematischen Schnittdarstellungen;

Figur 3

eine Prinzipdarstellung einer keilförmigen zweiten Ausführungsform des Schaltkontaktes in drei verschiedenen Schaltstellungen und

Figur 4

eine Prinzipdarstellung einer weiteren Ausführungsform des Schaltkontaktes als Kohlen-Doppelkontakt.

The invention is explained in more detail below in exemplary embodiments with reference to the associated drawings. Show it:

Figure 1

a schematic sectional view through a first embodiment of a switching contact with two closed switching positions;

Figure 2

a sequence of a switching process for a switching contact according to Figure 1 in six schematic sectional views;

Figure 3

a schematic diagram of a wedge-shaped second embodiment of the switching contact in three different switching positions and

Figure 4

a schematic diagram of another embodiment of the switching contact as a carbon double contact.

Description of the embodiments

Figure 1 shows a schematic sectional view a first embodiment of a switch contact 10, as used in a starter motor M of internal combustion engines Can be found. The switch contact 10 consists of a counter-contact element 12, a first contact element 14 and a second contact element 16. The individual components 12, 14, 16 are shiftable relative to each other, that is, in this case is done by appropriate mechanics a displacement of the mating contact element 12 in Direction of the two contact elements 14, 16 allows. If the mating contact element 12 to the Contact elements 14 and / or 16 is present, so a Circuit closed and a flowing current can enable the operation of the starter motor M.

The first contact element 14 is according to the present Embodiment executed in two parts and consists of a contact body 18 on one Counter-contact element 12 facing side and one Spring element 20 on the side facing away from it. The first contact element 18 is also located in FIG an insulating bushing 22. The insulating bushing 22 has a total of three functions. She leads the first Contact element 14 and insulated between them two contact elements 14 and 16. In addition it forms an end stop 24 for the first Contact element 14 by one to the counter contact element 12 facing inner edge of the insulating bush 22 is provided.

The switch body 18 of the first contact element 14 consists of a conventional carbon brush material. This reduces the risk of contact welding during a switching operation. One is also conceivable Execution with a resistance material to additionally to realize a smooth switching on and off. The spring element 20 must be sufficiently electrically conductive to enable an electrical connection. With insufficient thermal strength of the spring element 20 or to low electrical conductivity can the spring element 20 a strand can be assigned.

The second contact element 16 is based on a very good electrical conductor, for example copper, shaped. Accordingly, an electrical resistance of the second contact element 16 much less than an electrical resistance of the first contact element 14.

A sequence of the switching process can be the executions a) to f) of FIG. 2. In a open switch position are the counter contact element 12 and the contact elements 14, 16 so far spaced from each other that no current can flow (Step a)). The contact body 18 of the contact element 14 is such by the spring element 20 force applied to the end stop 24 is present. In a subsequent step b) is now the counter-contact element 12 with one here Mechanics not shown in the direction of the first Move contact element 14. In dependence of the applied voltage and the selected materials arises when falling below a certain A switch-on arc 26 at a distance.

When the mating contact element 12 on the first contact element 14 is present (step c)), a first closed switch position assumed. The first Contact element 14 then represents a resistor RV and the resulting relatively low current flow enables a comfortable, safe engagement of a Starter pinion in an engine ring gear. Will that Mating contact element 12 continues in the direction of Contact elements 14, 16 moved, so one second closed switch position are taken, in which the mating contact element 12 on the second contact element 16 rests (step d). Since the electrical resistance of the second contact element 16 is much less than the RV resistance first contact element 14, almost takes place entire power line through this contact and that first contact element 14 is almost de-energized. With the The starter motor M can now flow the main current a maximum moment on his starter pinion and subsequently transferred to the motor sprocket.

Subsequently, in step e) the counter contact element 12 again in the opposite direction move, a restoring force of the spring element 20 can be exploited. As long as that Mating contact element 12 still on the first contact element 14 is present, this in turn represents the resistance RV represents and the resulting, relatively small Current flow can be started with the starter motor M feasible switching stages can be used. An im Step f) arcing arises with increasing distance of the counter-contact element 12 and of the first contact element 14 deleted and ultimately then the switch contact 10 is again in the open switch position of step a).

Figure 3 is a second alternative embodiment of the switching contact 10 in three different Switch positions. On the presentation the wiring is for reasons of clarity been waived. The switch contact 10 is a wedge contact molded. Here is the counter contact element 12 has a wedge and the first contact element 14 a complementary conical contact form in one Area 28.

On the left side of Figure 3 is the switch contact 10 shown in the open switch position. Subsequently, it is closed in a first Switch position and on the right side then in a second closed switching position shown. In the first closed switch position is the counter-contact element 12 in Area 28, but is not yet on the second Contact element 16 on. Here too, a material from the selected first contact element 14 such that be Resistance is greater than that of the second contact element 16, so that after closing the circuit current flow occurring is relatively low and used to engage the starter pinion can. The current initially flows over a resistance range R of the first contact element 14, then over a portion of the second contact element 16 and is subsequently on the spring element 20th transfer.

During the start-up process of the mating contact element 12 in the conical contact shape can be created Frictional forces for self-cleaning of the contact surfaces be used. On a resistance range R opposite side of the first contact element 14 is also a according to this embodiment Spring element 30 is provided next to the spring element 20 the necessary restoring force is available can put.

If the wedge-shaped counter-contact element 12 in the move second closed switching position, see above it rests on the second contact element 16. On Current flow is now due to the lower electrical resistance almost exclusively over this component and the actual starting process can in this switching position by the flow of the main current be made possible.

In a further alternative embodiment, such as it can be seen in Figure 4, in addition to the first and second contact element 14, 16 also a further contact element 32 may be present. Here too is for the sake of clarity on a representation the necessary wiring been. The further contact element 32 consists of a contact body 34 and a spring element 36. The Contact body 34 is based on a high-current carbon realized. Of course, the spring elements 20 and 36 are sufficiently high have electrical conductivity. The contact body 18 of the first contact element 14 consists of a Resistance coal.

If the counter-contact element 12 in the direction of Move contact elements 14, 16 and 32, so it hits first on the first contact element 14 and one first closed switch position can be assumed in which only a very small current flows. The mating contact element 12 subsequently meets the further contact element 32. Because of the electrical resistance of the contact body 34 is less than that electrical resistance of the contact body 18 flows now a slightly higher current through the further contact element 32. Only after the counter-contact element 12 on the second contact element 16, which is the least has electrical resistance, is present Main stream flow. In total, there are three different ones closed switch positions can be realized.

Claims (11)

Switching contact for a starter motor of internal combustion engines, which comprises at least relatively displaceable components, such as a mating contact element, a first contact element and a second contact element, wherein a resistance of the first contact element is greater than a resistance of the second contact element and in that (a) in a first closed switching position, the mating contact element (12) abuts the first contact element (14) and a current flows through the first contact element (14) and (b) in a second closed switching position which can be reached via the first switching position, the mating contact element (12) bears on the first contact element (14) and the second contact element (16) and a current flows largely via the second contact element (16). Switching contact according to claim 1, characterized in that the first contact element (14) is held in an open switching position and / or at least at the beginning of the first switching position in a rest position by applying a holding force. Switching contact according to claim 2, characterized in that the first contact element (14) consists of a contact body (18) facing the counter-contact element and a spring element (20) which moves the first contact element (14) into the rest position in the relaxed state. Switching contact according to one of claims 2 or 3, characterized in that the first contact element (14) or the contact body (18) is a carbon brush. Switching contact according to one of claims 3 or 4, characterized in that the spring element (20) is electrically conductive and / or a strand is assigned to the spring element (20). Switching contact according to one of the preceding claims, characterized in that the second contact element (16) is made of copper. Switching contact according to one of the preceding claims, characterized in that the first contact element (14) is accommodated in an insulating bush (22), an end stop (24) for the rest position being formed by an inner edge of the insulating bush (22) facing the counter-contact element (12) becomes. Switching contact according to one of the preceding claims, characterized in that the switching contact (10) is a wedge contact. Switching contact according to claim 8, characterized in that the counter-contact element (12) is designed as a wedge and the first contact element (14) has a complementary conical contact shape. Switching contact according to one of the preceding claims, characterized in that further contact elements (32) are provided which can be contacted simultaneously or in succession starting from the open switching position. Switching contact according to claim 10, characterized in that the first contact element (12) consists of a resistance carbon and a further contact element (32) contacted subsequently consists of high-current carbon (carbon double contact).

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