EP3131101A1

EP3131101A1 - Coil former for an electrical coil, electrical coil comprising such a coil former

Info

Publication number: EP3131101A1
Application number: EP15180749.2A
Authority: EP
Inventors: Bostjan BREMEC; Tadej FLORIJANCIC; Tomaz PIRH
Original assignee: Mahle International GmbH
Current assignee: Mahle International GmbH
Priority date: 2015-08-12
Filing date: 2015-08-12
Publication date: 2017-02-15

Abstract

The invention relates to a coil former (2) for an electrical coil (1),
- comprising a substantially cylindrical basic body (3) having a circumferential wall (4), which basic body is delimited along its axial direction (A) by a first end wall (5a) and a second end wall (5b), which is opposite the first end wall (5a), said end walls both protruding radially beyond the circumferential wall (4),
- comprising a separating element (6), which is arranged axially between the two end walls (5a, 5b) and which projects radially outwards from the circumferential wall (4) so as to form a first and a second axial winding-accommodating region (9a, 9b),
- wherein the separating element (6) has an aperture (17), through which the first axial winding-accommodating region (9a) is connected to the second axial winding-accommodating region (9b).

Description

Electromagnetic coils are used in a variety of forms in vehicle construction. In particular, they are used in starter motors of modern internal combustion engines. Such a coil generally comprises a primary winding, through which an alternating current is passed. In this way, according to Faraday's law of induction, an induced electrical voltage is induced in a secondary winding interacting with the primary winding, and this causes an induced current in the secondary winding. The induced electrical voltage which can be achieved in the coil is dependent on various parameters, in a known manner. Such parameters are, for example, the turns numbers of the primary and secondary windings and the respective electrical resistance of the two windings.
In this case, said windings are typically accommodated in a coil former of the coil, with the result that the two windings can be installed together with the coil former as one unit in the internal combustion engine. The coil former has one or more suitably designed winding-accommodating regions for accommodating the windings.
An object of the present invention consists in demonstrating new approaches in the development of coil formers for electrical coils and in the development of electrical coils comprising such coil formers.
This object is achieved by the subject matter of the independent patent claims. Preferred embodiments are the subject matter of the dependent patent claims.
A coil former according to the invention for an electrical coil comprises a substantially cylindrical basic body, which has a circumferential wall. Said basic body is delimited along its axial direction by a first end wall and a second end wall, which is opposite the first end wall. The two end walls protrude in the radial direction beyond the circumferential wall. In this way, windings wound onto the circumferential wall can be held stably on the basic body. A separating element is arranged axially between the two end walls, said separating element projecting radially outwards from the circumferential wall so as to form a first and a second axial winding-accommodating region. Such a design of the coil former makes it possible to accommodate winding sections of a (first) winding of an electrical coil having a possibly different winding direction physically separately from one another.
In accordance with the invention, the separating element has an aperture, by means of which the first axial winding-accommodating region is connected to the second axial winding-accommodating region. In this way, the first winding section having a first winding direction can be connected electrically easily to the second winding section having a second winding direction, which is opposite the first winding direction. For this purpose, in a simple manner the (first) winding can be passed through the aperture so that there is a transition in the aperture from the first to the second winding section. This additionally enables simple reversal of the winding direction by virtue of the turns of the first winding being wound onto the circumferential wall in the opposite direction in the second winding-accommodating region, starting from the aperture, than in the first winding-accommodating region, starting from the aperture.
By varying the size of the two winding-accommodating regions, for example by varying the axial position of the separating element on the basic body of the coil former, the volume ratio of the two winding-accommodating regions can be varied. If the turns of the first winding have a first winding direction in the first winding-accommodating region, as already explained, and a second winding direction, which is opposite the first winding direction, in the second winding-accommodating region, by virtue of corresponding dimensioning of the volumes of the two winding-accommodating regions the ratio of the number of turns with the first winding direction to the number of turns with the second winding direction can be set or varied.
The induced electrical voltage produced in the coil and the electromagnetic force generated by the coil are dependent on this ratio and can thus be set by selecting the turns ratio without thereby changing the electrical resistance of the coil. The desired electrical resistance can be set by the total number of provided turns in the first winding.
In a preferred embodiment, the two end walls protrude radially outwards beyond the separating element. This ensures that the turns of the winding cannot slide axially from the basic body of the coil former.
In another preferred embodiment, the separating element is in the form of a web extending in the circumferential direction on the circumferential wall. This variant favours an embodiment of the separating element which is particularly simple in design terms and therefore inexpensive. This applies in particular to a variant in which said web is formed integrally on the circumferential wall of the basic body.
In order to connect the first winding section of the first winding which is provided in the first winding-accommodating region electrically to the second winding section which is provided in the second winding-accommodating region, in accordance with an advantageous development it is proposed that the aperture provided in the separating element is in the form of an interruption, preferably a slot-like interruption, provided in the web. Such an interruption in the web, in particular in the form of a slot, makes it possible in a simple manner to pass the first winding from the first winding-accommodating region into the second winding-accommodating region.
Particularly preferably, the separating element can be arranged, in the axial direction, centrally between the two end walls. In this way, the two winding-accommodating regions can be provided with substantially the same dimensions, with the result that the same number of turns can be accommodated in the first accommodating region as in the second winding-accommodating region. The ratio of the number of turns in the first winding section to the number of turns in the second winding section is in this case 1:1. In the case of opposite winding directions of the turns of the first winding in the first and second winding-accommodating regions, the induced voltage produced by the turns increases so that the induced voltage actually produced in the first winding is determined by the turns of the third winding section alone, which is arranged radially outwards on the first two winding sections. The same applies also to the electromagnetic force generated by the coil. The turns of the first and second winding sections therefore serve the purpose of setting the electrical resistance of the first winding.
If the induced voltage induced in the first winding is intended to not be dependent on the third winding section alone but also on the first and second winding sections, in an embodiment which is an alternative to the previous embodiment it is proposed that the separating element is arranged, in the axial direction, at a shorter distance from the first end wall than from the second end wall, or vice versa. In this way, an unequal volume ratio and therefore a different number of turns in the two winding sections is achieved for the two winding-accommodating regions. This results in a net induced voltage produced in the first and second winding sections of the first winding which is different from zero. The same applies also to the electromagnetic force generated by the coil.
In an advantageous development of the invention, in addition to the separating element, at least one additional separating element, which acts as spacer element and protrudes radially outwards from the circumferential wall, is arranged axially in the region between the separating element and the first or second end wall. In this variant, the radius of the separating element differs from the radius of the at least one additional separating element.
In a further preferred embodiment, at least two additional separating elements acting as spacer elements are provided. In this variant, the radii of at least two, preferably of all provided, additional separating elements are different. In this way, the volumes of the two winding-accommodating regions can be varied in a very flexible manner, with the result that the ratio of the turns with the opposite winding direction can also be set easily to the desired value.
The invention also relates to an electrical coil comprising an above-described coil former and a first winding, which is arranged on the circumferential wall and has a first, a second and a third winding section. The first winding section is arranged in the first axial winding-accommodating region. The second winding section is arranged in the second axial winding-accommodating region. The third winding section is arranged radially outwards on the first and second winding sections. A second winding is arranged radially outwards on the third winding section of the first winding. This second winding can act as primary winding of the coil, whereas the first winding can act as secondary winding, in which an induced electrical voltage can be produced.
In a preferred embodiment, a first winding direction of the first winding section extends opposite to a second winding direction and a third winding direction of the second and third winding sections. By selecting the corresponding number of turns of the first, second and third winding sections, both the electrical resistance of the first winding, determined by the total number of turns of the three winding sections, and the inductance of the first winding, determined by the turns ratio of the three winding sections, and therefore the level of the electrical voltage which is or can be induced in the first winding can then be set in a simple manner.
In a further preferred embodiment, an uneven number of winding layers, counted in the radial direction of the coil former, of the first winding section is arranged in the first winding-accommodating region. In this variant, the arrangement is such that the first winding-accommodating region is filled substantially completely (existing interspaces between the individual conductors of the winding are not taken into consideration here) with the first winding section of the first winding. As an alternative or in addition, an uneven number of winding layers, counted in the radial direction, of the second winding section can also be arranged in the second winding-accommodating region. The arrangement of these winding layers is also preferably such that the second winding-accommodating region is filled substantially completely (existing interspaces between the individual conductors of the winding are not considered here) with the second winding section of the first winding.
In an advantageous development of the invention, an uneven number of winding layers, counted in the radial direction of the coil former, of the first winding section can be arranged radially outside the two winding-accommodating regions.
In accordance with an advantageous development, the third winding section can be arranged radially outside the separating element. This enables optimum use of the volume provided by the two winding-accommodating regions for accommodating the first winding.
Particularly little installation space is required by a further preferred embodiment, in accordance with which the second winding section extends between the two end walls beyond the total axial length of the coil former.
Likewise for the purpose of reducing the required installation space, as an alternative or in addition the third winding section and/or the second winding can extend between the two end walls over the total axial length of the coil former.
Particularly preferably, the first winding section is connected to the second winding section via the interruption provided in the separating element. This enables a simple technical implementation of the reversal of the winding direction at the transition from the first to the second winding section, a feature which is essential to the invention.
Particularly expediently, a winding diameter of the first winding can be greater than a winding diameter of the second winding. This makes it possible for the first winding to also be able to carry very high currents induced in the first winding.
Finally, the invention relates to a starter motor of an internal combustion engine comprising at least one above-explained electrical coil.
Further important features and advantages of the invention are set forth in the dependent claims, the drawings and the associated description of the figures with reference to the drawings.
It goes without saying that the features mentioned above and yet to be explained below can be used not only in the respectively specified combination, but also in other combinations or on their own without departing from the scope of the present invention.
Preferred exemplary embodiments of the invention are illustrated in the drawings and will be explained in more detail in the description below, wherein identical reference symbols relate to the same or similar or functionally identical components.
In the drawings, in each case schematically:

Figure 1: shows the design of the coil former of an electrical coil 1 according to the invention in a perspective illustration,
Figure 2: shows the coil former from Figure 1 in a longitudinal section along its mid-longitudinal axis,
Figure 3: shows an electrical coil comprising the coil former from Figures 1 and 2 in a longitudinal section along the mid-longitudinal axis of the coil former,
Figure 4: shows a variant of the example in Figure 3.

Figure 1 illustrates the design of the coil former 2 of an electrical coil 1 according to the invention in a perspective illustration. Figure 2 shows the coil former 2 from Figure 1 in a longitudinal section along its mid-longitudinal axis M.
The coil former has a cylindrical basic body 3, which has a circumferential wall 4. The coil former 2 is delimited along its axial direction A, which is defined by the mid-longitudinal axis M of the coil former 2, by a first end wall 5a and a second end wall 5b, which is opposite the first end wall 5a. The two end walls 5a, 5b can protrude in the radial direction R of the coil former 2 beyond the circumferential wall 4, as shown in Figure 1. Corresponding to Figure 1, a separating element 6 is arranged between the two end walls 5a, 5b. The separating element 6 projects radially outwards from the circumferential wall 4 so as to form a first and a second axial winding-accommodating region 9a, 9b. The separating element 6 has an aperture 17, by means of which the first axial winding-accommodating region 9a is connected to the second axial winding-accommodating region 9b.
In the exemplary scenario, the separating element 6 is in the form of a web 7, which extends in the circumferential direction U of the cylindrical basic body 3 on the circumferential wall 4. The web 7 has, in the circumferential direction U, a slot-like interruption 8 (cf. Figure 1), which forms the aperture 17. By means of the interruption 8, the first axial winding-accommodating region 9a is connected to the second axial winding-accommodating region 9b, with the result that a winding can be passed through the aperture 17.
In the exemplary scenario shown in Figures 1 and 2, the separating element 6 in the form of a web 7 is arranged centrally, with respect to the axial direction A, between the two end walls 5a, 5b, with the result that the two winding-accommodating regions 9a, 9b have substantially the same volume. In a variant not shown in the figures, the separating element 6 can be arranged, in the axial direction A, closer at a shorter distance from the second end wall 5b than from the first end wall 5a, or vice versa.
Figure 3 shows, in a longitudinal section, an example of an electrical coil 1 according to the invention comprising the coil former 2 from Figures 1 and 2 in a longitudinal section. As can be seen from Figure 3, a first winding 10 is arranged on the circumferential wall 4. The first winding 10 has a first, a second and a third winding section 11 a, 11 b, 11c, which are formed by a suitable electrical conductor, for example a copper wire. The first winding section 11 a in this case becomes the second winding section 11 b, and the second winding section 11 b becomes the third winding section 11 c. The three winding sections 11 a, 11 b, 11c are formed integrally with one another and are connected electrically to one another directly in this way.
As indicated by way of illustration in Figure 3, the first winding section 11 a is arranged completely in the first axial winding-accommodating region 9a, and the second winding section 11 b is arranged in the second axial winding-accommodating region 9b. The third winding section 11 c is in turn arranged radially outwards both on the first and the second winding sections 11a, 11b. With respect to the radial direction R of the coil former 2, the third winding section 11c is preferably arranged radially outside the separating element 6. In addition, the third winding section 11c extends between the two end walls 5a, 5b over the total axial length L of the coil former 2. The winding direction of the three winding sections 11 a, 11 b, 11 c of the first winding 10 is indicated by the symbols denoted by the reference signs 12, 13. A first winding direction R₁ of the first winding section 11a accordingly runs in opposition to a second winding direction R₂ and a third winding direction R₃ of the second and third winding sections 11 b, 11c, respectively.
As can be seen in Figure 3, an uneven number of winding layers 18a, counted in the radial direction R, namely by way of example three winding layers 18a, of the first winding section 11 a is arranged in the first winding-accommodating region 9a. The arrangement of the winding layers 18a is such that the first winding-accommodating region 9a is filled substantially completely with the first winding section 11a. Similarly, an uneven number of winding layers 18b, counted in the radial direction R of the coil former 2, of the second winding section 11 b is also arranged in the second winding-accommodating region 9b. In the example shown in Figure 3, by way of example three winding layers 18b are provided. The arrangement of these winding layers is also such that the second winding-accommodating region 9b is filled substantially completely with the second winding section 11 b of the first winding 10.
Finally, an uneven number of winding layers 18c, counted in the radial direction R, of the third winding section 11 c can also be arranged radially outside the two winding-accommodating regions 9a, 9b. In the example shown in Figure 3, only a single winding layer 18c of the first winding 10 is provided by way of example.
The first winding section 11 a is connected to the second winding section 11 b via the interruption 8 (not shown in Figure 3; cf. in this regard Figure 1) provided in the separating element 6. In this way, the reversal of the winding direction R₁, R₂ from the first to the second winding section 11 a, 11 b can also be implemented in a technically simple manner. In addition to the first winding 10, a second winding 14 is also arranged radially outwards on the third winding section 11c.
The second winding 14 can be electrically insulated from the first winding 10 by means of a suitable separating wall 15. Preferably, a winding diameter D₁ of the first winding 10 is greater than a winding diameter D₂ of the second winding 14. The second winding 14 extends, in the same way as the third winding section 11c of the first winding 10, between the two end walls 5a, 5b beyond the total axial length L of the coil former 2.
Figure 4 shows a variant of the example shown in Figure 3. In the example shown in Figure 4, in addition to the separating element 6, 7, four additional separating elements acting as spacer elements 16a, 16b, 16c, 16d are provided. The spacer elements 16a-16d project in the form of a respective web 7 from the circumferential wall 4 in a similar manner to the separating element 6. The spacer elements 16a-16d can be formed as separate component parts or formed integrally on the basic body 3. The radius of each of the spacer elements 16a-16d differs from the radius of the remaining spacer elements 16a-16d and from the radius of the separating element 6. The first spacer element 16a rests on the separating element 6 on the end side. The second spacer element 16b rests on the third spacer element 16c on the end side, and the third spacer element 16c rests on the second end wall 5b on the end side. In variants, the arrangement of the spacer elements 16a-16d with respect to one another, with respect to the separating element 6 and with respect to the two end walls 5a, 5b can vary.

Claims

Coil former (2) for an electrical coil (1),
- comprising a substantially cylindrical basic body (3) having a circumferential wall (4), which basic body (3) is delimited along its axial direction (A) by a first end wall (5a) and a second end wall (5b), which is opposite the first end wall (5a), said end walls both protruding radially beyond the circumferential wall (4),

- comprising a separating element (6), which is arranged axially between the two end walls (5a, 5b) and which projects radially outwards from the circumferential wall (4) so as to form a first and a second axial winding-accommodating region (9a, 9b),

- wherein the separating element (6) has an aperture (17), through which the first axial winding-accommodating region (9a) is connected to the second axial winding-accommodating region (9b).
Coil former according to Claim 1,
characterized in that
the two end walls (5a, 5b) protrude radially outwards beyond the separating element (6).
Coil former according to Claim 1 or 2,
characterized in that
the separating element (6) is in the form of a web (7) extending in the circumferential direction (U) on the circumferential wall (4).
Coil former according to Claim 3,
characterized in that
the aperture (17) is in the form of an interruption (8), preferably a slot-like interruption, provided in the web (7).
Coil former according to one of the preceding claims,
characterized in that
- the separating element is arranged centrally, in the axial direction (A), between the two end walls (5a, 5b), or in that

- the separating element (6) is arranged, in the axial direction (A), at a shorter distance from the first end wall (5a) than from the second end wall (5b), or vice versa.
Coil former according to one of the preceding claims,
characterized in that
in addition to the separating element (6), at least one additional separating element, which acts as spacer element (16a, 16d) and protrudes radially outwards from the circumferential wall (4), is arranged axially in the region between the separating element (6) and the first or second end wall (5a, 5b), wherein the radius of the separating element (6) differs from the radius of the at least one additional separating element.
Coil former according to Claim 6,
characterized in that
at least two additional separating elements acting as spacer elements (16a-16d) are provided,
wherein the radii of at least two, preferably of all provided, additional separating elements are different.
Electrical coil (1),
- comprising a coil former (2) according to one of the preceding claims,

- comprising a first winding (10), which is arranged on the circumferential wall (4) and has a first, a second and a third winding section (11 a, 11 b, 11 c),

- wherein the first winding section (11 a) is arranged in the first axial winding-accommodating region (9a), and the second winding section (11 b) is arranged in the second axial winding-accommodating region (9b), and the third winding section (11c) is arranged radially outwards on the first and second winding sections (9a, 9b),

- wherein a second winding (14) is arranged radially outwards on the third winding section (11 c) of the first winding.
Electrical coil according to Claim 8,
characterized in that
a first winding direction (R₁) of the first winding section (11a) extends opposite to a second winding direction (R₂) and a third winding direction (R₃) of the second and third winding sections (11 b, 11 c).
Electrical coil according to Claim 8 or 9,
characterized in that
- an uneven number of winding layers (18a), counted in the radial direction (R) of the coil former (2), of the first winding section (11a) is arranged in the first winding-accommodating region (9a) in such a way that the first winding-accommodating region (9) is filled substantially completely with the first winding section (11 a) of the first winding (10),
and/or in that

- an uneven number of winding layers (18b), counted in the radial direction (R) of the coil former (2), of the second winding section (11 b) is arranged in the second winding-accommodating region (9b) in such a way that the second winding-accommodating region (9b) is filled substantially completely with the second winding section (11 b) of the first winding (10).
Electrical coil according to Claim 10,
characterized in that
an uneven number of winding layers (18c), counted in the radial direction (R) of the coil former (2), of the third winding section (11c) is arranged radially outside the two winding-accommodating regions (9a, 9b).
Electrical coil according to one of Claims 8 to 11,
characterized in that
the third winding section (11c) is arranged radially outside the separating element (6).
Electrical coil according to one of Claims 8 to 12,
characterized in that
the third winding section (11c) and/or the second winding (14) extend(s) between the two end walls (5a, 5b) beyond the total axial length (L) of the coil former (2).
Electrical coil according to one of Claims 8 to 13,
characterized in that
the first winding section (11a) is connected to the second winding section (11 b) via the interruption (8) provided in the separating element (6).
Electrical coil according to one of Claims 8 to 14,
characterized in that
a winding diameter (D₁) of the first winding (10) is greater than a winding diameter (D₂) of the second winding (14).
Starter motor of an internal combustion engine comprising at least one electrical coil (1) according to one of Claims 8 to 15.