DE2542584A1 - ELECTRIC SWITCH, - Google Patents

Description

R. 2 8 76 ^

19-9.1975 Rs / Hm

Attachment to

Patent and

Utility model registration

ROBERT BOSCH GMBH, 7 STUTTGART 1

Electric switch

The invention relates to an electrical switch, in particular an ignition breaker switch for motor vehicles, with a rotating control device and with a contact arrangement which is sealed within a gas-tight Housing sits and can be actuated by means of a magnet system is.

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In a known electrical ignition circuit breaker of this type with gas-tight encapsulated protective tube contacts as interrupter contacts, the latter are controlled via the distributor shaft by means of a magnet system, which consists of there is a magnetic rotor with alternating polarity arranged on the distributor shaft and rotatable with it; the protective tube contacts are in each of the two possible polarities of the magnetic field as a result of their opposite polarization closed and open only in the area of the zero crossing of the magnetic field, so that by a magnetic Pole pair two switching processes can be generated (DT-OS 2 302 287).

The invention is based on the object of an electrical switch, in particular an ignition breaker holder for Motor vehicles to create that are maintenance-free and reliable and switches reliably and particularly precisely at every switching frequency. In particular, that of a Magnet system operated switches are designed so that it has a high operating frequency even at very low operating frequencies Switching accuracy guaranteed. For special use as an ignition breaker switch in motor vehicles there is still the special task, the switch also for odd numbers of cylinders, i.e. for odd numbers To be able to use switching cycles. ■ · ,.

This object is achieved according to the invention in that to increase the switching accuracy when used for any Number of switching operations in one switching cycle Control measure taken for the magnetic flux are in such a way that at least the switch-off threshold falls in a range of large changes in flow over time. The magnet system expediently consists of one or more permanent magnets arranged in the rotor and / or in the stator can be because it is particularly successful in terms of operational safety and freedom from maintenance.

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It has proven to be advantageous if the contact arrangement is provided with an asymmetrical alternating magnetic field is acted upon, the switch-on threshold of the contact arrangement only in one direction of the magnetic flux exceeds, wherein the switch-off threshold is placed in a range of large temporal change in flow. on in this way one achieves a high switching accuracy because of the greater temporal value compared to a pulsating magnetic field Flux change in the switching points. This applies in particular to the switch-off threshold, since there is a flat curve, the switching time changes significantly even with small flux fluctuations. The switch-on threshold can the greater the maximum value of the magnetic flux, the more precisely you adhere to.

Details and advantageous embodiments of the invention are shown in the following description with reference to several in FIGS Illustrations of illustrated export games explained in more detail. Show it:

La is a schematic representation of an inventive electrical switch in the closed state, with two permanent magnets arranged in the resting part of the stand, - ^

Fig. Ib an electrical switch according to FIG. La with open. Contacts,

Fig. Ic the schematic course of the magnetic flux in Counter,

Fig. Id a modification of the switch according to Fig. La and Fig. Ib, with two flux guide pieces in the axial direction are arranged on both sides of the rotor,

2a shows a schematic representation of an electrical switch with a permanent magnet at rest Switch part and a permanent magnet rotor magnetized in the circumferential direction,

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Pig. 2b an electrical switch according to FIG. 2a with open contacts,

3 shows a switch according to FIG. 2 with an axially magnetized Rotor and a number of protruding PoI- "corresponding to the desired number of switching cycles pieces on the rotor to which axially offset guide pieces are assigned,

Fig. Ka. the principle of an electrical switch according to the invention with an axially magnetized, permanently magnetic rotor, in which the radially protruding pole pieces for generating an asymmetrical alternating flux are opposed by conducting pieces via cyclically changing air gaps of different sizes,

FIG. 4b shows an arrangement according to FIG. Ka. in the process,

5a shows the principle of an electrical device according to the invention Schalters.mit a permanent magnet with a magnetic shunt part in the stand and

5b shows the course of the magnetic flux in the case of an electrical one Switch according to Fig. 5a «

In Fig. 1 the principle of a switch according to the invention is shown, for example as an ignition breaker switch for a Motor vehicle with five cylinders, i.e. with five ignition processes for one revolution of the distributor shaft 10, can be used is. A guide piece rotor 11 is secured against rotation on the distributor shaft 10 and has five on its outer circumference Has projections 12 made of magnetically conductive material and five indentations 13. The side edges of the protrusions 12 point radially inwards, in order to assign exact switching points define.

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In the resting part of the electrical switch according to Pig. I am a first permanent magnet Ml and a second permanent magnet M2 are arranged in a stationary manner. The magnetic flux tjb 11 of the permanent magnet Ml closes over two flux guide pieces Ll and L2 arranged on the circumference of the guide piece rotor as well via two contact tongues 14 and 15, one sealed in a gas-tight manner Contact arrangement 16, which is designed as a reed contact switch. The magnetic flux φ 2 of the permanent magnet M2 closes directly over the contact tongues 14 and 15 of the contact arrangement 16, the magnets Ml and M2 being polarized so that their flows are directed opposite one another are.

In Fig. La the ignition breaker switch is shown in its switch position with the contact arrangement closed. The guide element rotor 11, which acts as a rotating control device, is positioned in such a way that the flux φ 11 of the magnet Ml is small because of the large air gap to be overcome. The magnet's $ 2 flow. M2 closes without significant counterflow via the contact tongues 14 and 15, which are polarized in opposite directions and attract each other, so that the contact arrangement is closed.

In Fig. Ib the guide piece rotor 11 is moved further in the direction of rotation by such a proportion that two projections 12 are directly opposite the flux guide pieces Ll and L2 with a small air gap. The flux </ t 11 of the magnet Ml flows over the conductive pieces Ll and L2, over the conductive piece rotor 11 and over the contact tongues lh, 15 of the reed contact switch. Opposite to the flux ψ 11, the flux ψ 2 of the magnet M2 is directed. The two magnetic fluxes cancel each other so far that the restoring spring force of the contact tongues 14 and 15 predominates and the contact arrangement 16 opens.

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Pig. lc shows the course of the individual flows Φ 11 and & 2 as well as the course of the resulting flow φ 12. The point in time ta corresponds to the rotor position in Pig. la, the time tb of the runner position in Pig. Ib · The magnetic fluxes ψ 11 and <£> 2 are shown in an idealized sinusoidal form. The figure shows that the inventive arrangement of a permanently magnetic, unchanged flux source φ 2 on the reed contact in conjunction with an oppositely directed, pulsating flux source φ Ί1 results in a resulting flux φ 12 with a change in the direction of flow. The permanently present flux φ 2 must be selected to be large enough to place the switch-on wave (Ein) in an area of large positive change, ie sufficiently far away from the maximum. The pulsating flux <£ 11, which flows through the reed contact in the opposite direction to φ 2, should be greater than the absolute value of φ 2j, the resulting flux φ 12, on the other hand, must not reach the switch-on threshold in the negative range, because for every period of the pulsating flow only one switching operation is desired in order to be able to use the electrical switch for any number of switching operations in a switching cycle. By changing the direction of flow, a large positive change over time is also achieved in the area of the switch-off threshold (off) and thus a high level of switching accuracy. If the switch is intended for an application in which two switching operations are permitted or desired during a period of the pulsating flow <j> 11, the magnitude of <f> 11. can be chosen to be twice as large as that of (^ 2 In this case, the dashed curve £ 12 arises with two switching operations during a period of the pulsating flow q> 11.

In Fig. Id a constructive solution is indicated which allows a simple arrangement with a low overall height. The flux guide pieces Ll and L2 are not over the circumference of the rotor but are offset from one another but are arranged in the axial direction on both sides of the guide return device 11. Even with axial play of the guide piece rotor, the

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Switching point of the contact arrangement 16 not shifted because the size of the total air gap, which the resulting Flux (J) 12 is also determined, remains constant.

The arrangement according to the Pig. la to id owns a number Advantages: A simple, stamped sheet metal part can be used as a runner * the permanent magnets are stationary built in, so that there are no fastening problems. Furthermore, you need little permanent magnet material and the magnets can have simple geometric shapes, which is essential in the manufacture of magnets in terms of price and scrap is.

Fig. 2 shows the basic circuit diagram of an electrical switch, in particular an ignition interrupter holder for motor vehicles, in which a rotor 17 magnetized in the circumferential direction is used as the rotating control device. the Contact arrangement 16 is on the one hand with the magnetic alternating flux φ picked up via flux guide pieces Ll and L2 of the permanent magnet rotor 17 and on the other hand with the constant flux φ 2 of a stationary permanent magnet M2 applied, in a manner analogous to that shown in Fig. Ic Diagram a change of flow direction occurs. 2a shows the contact arrangement 16 in its closed position, Fig. 2b in the open position.

The rotor 17 has five pole pairs, which are indicated with N and S along the circumference. In the arrangement according to FIG. 2a, the flux guide pieces Ll and L2 are each between the north and south poles, so that practically no flux reaches the contact arrangement 16 from the rotor 17, ie the flux φ 12 is approximately zero. In contrast fli.eßt by the permanent magnet M2 a flow $ 2 through the contact tabs 14 and 15 and this magnetized in opposite directions, so that the contact tongues dressed and the contact arrangement is closed 16th In Fig. 2b, the rotor 17 has a

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rotated such an amount that the full flux ψ 12 of the permanent magnetic rotor 17 is removed via the flux guide pieces Ll, L2. The flux $ 12 from the rotor is opposite to the flux φ 2 of the stationary permanent magnet M2 and is so large in magnitude that the resulting flux over the contact tongues Ik and 15 is smaller than the resilient restoring force of the contact tongues; the contact arrangement is open.

As a result, the operation according to corresponding to the arrangement of Fig. 2 to that of FIG. 1. From the rotor is, however, brought no pulsating Gleichfluß but an alternating flux to the contact arrangement in the arrangement according to FIG. 2, the φ 2 by superimposition with the Gleichfluß turn an unsymmetrical alternating magnetic field similar to the flux φ 12 in Fig. Ic results. The flux <fa 2 (FIG. 2) is increased once, with the contact arrangement 16 being closed, and the other time it is canceled or weakened to the extent that the contact arrangement is opened. Since the contact arrangement remains open over a relatively large range of small magnetic fluxes, the flux φ 12 does not have to be strictly equal to the ..Flux φ 2 to open the contact arrangement 16, but the flux λ 12 can be of the order of magnitude between 0.9 ψ 1 and 1.4 φ 1 change without closing the contact arrangement. In order to achieve the steepest possible passage of the resulting flux through the switching points, the flux ^ l2 should, however, be greater than the flux <p 2.

In the case of the structural solution described with reference to FIGS. 2a and 2b, in terms of production engineering, especially in large-scale production, an advantageous embodiment when the permanent magnet systems in the rotor 17 and on the contact arrangement 16 so can be interpreted that their mutual superposition on the contact arrangement leads to an absolutely safe circuit with constant accuracy. For this purpose, the arrangement expediently made so that the magnet M2 is designed so weak on the contact arrangement that it

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alone cannot operate the contact arrangement. This has the advantage that the flux φ 2 when the rotor is at rest can be adjusted so that it does not close the contact with certainty, but assumes the highest possible values. This ensures that the zero crossing of the flux <j) 12 in Figure Ic has a maximum steepness and thus leads to the best switching accuracy. In practice, the adjustment can also be made for something Verify strong magnets by giving the magnet a variable shunt, e.g. in the form of a screwable screw, is approaching.

Fig. 3 shows an arrangement in which the rotor has an axially magnetized permanent magnet disc which on its scope a number of projecting pole piece pairs corresponding to the desired number of switching operations possesses, to which flux guide pieces Ll, L2 arranged at an appropriate distance are assigned. The pole pieces are included denoted by 18 and 19, the axially magnetized permanent magnet disc bears the reference number 20. In this construction, too, according to the embodiment according to FIG. the flux originating from the rotor is superimposed on the flux of the stationary magnet M2, but it is again correspondingly Fig. Ic is a pulsating steady flow. With larger numbers of pole pairs, this arrangement can be more advantageous than circumferential magnetization of the rotor, since increasing number of pole pairs, the control of the necessary switching accuracy to increasing practical difficulties bumps.

A particularly advantageous control is obtained in all of the exemplary embodiments described above when the absolute Maximum values of the changing magnetic flux φ 1 are greater than the constant flux <j> 2; Here, φ 1 stands for the various variable magnetic fluxes in all embodiments. The resulting flow is then subject to a flow direction change, whereby a increased flow change over time in the switching points and

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thus an increased switching accuracy is achieved. For use with odd-numbered shifts in a switching cycle, however, care must be taken that the variable flux is not so great that an actuation of the switching arrangement 16 in both directions of flow he follows.

Fig. 4 shows an electrical switch with a rotating control device, in which the contact arrangement with a magnetic flux <£> taken over flux guide pieces Ll and L2 14 of a permanent magnet rotor 21 is applied will; this contains an axially magnetized permanent magnet disk 22, one of the desired on its circumference Number of switching operations has a corresponding number of protruding pole piece pairs whose pole pieces 23 and 24 as well as the associated flux guide pieces Ll and L2 are arranged offset from one another in the circumferential direction and according to the changing air gap widths in the circuit closed over the flux guide pieces Ll and L2 a magnetic Viechseifluß with different generate large peaks. Fig. 4a shows a schematic Side view of the arrangement, FIG. 4b shows a development the rotor surface. The mode of operation of this arrangement is clear from Fig. 4b:

The flux guide pieces Ll and L2 like first in the excellent Position each face a north and a south pole, which are offset from one another in the circumferential direction are. The magnetic flux of the axially magnetized permanent magnet disk closes over the small air gaps between the pole pieces 23 and Ll, or 24 and L2, and magnetizes the contact tongues 14 and 15 of the contact arrangement 16 opposite polarity, so that * these attract each other and the contact arrangement is closed. With dashed Lines is indicated in Fig. 4b that after a rotation

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of the rotor 21 by half a pole pitch the flux guide Ll opposite the pole piece 24 protruding over the circumference of the permanent magnet disk 22 via a large air gap , while the flux guide piece L2 is opposite the pole piece 23 via an air gap of the same size. Of the Flux φ l4 reduced in accordance with the enlarged air gap has now reversed its direction and the contact tongues l4 and 15 will turn in opposite directions magnetized differently, but the size of the magnetization is not sufficient to generate the elastic restoring force the contact tongues 14 and 15 to overcome .. The contact arrangement is open, as shown in dashed lines in Fig. 4b is indicated. The opposite magnetization in the last described position does not have any effect Connection process, however, is achieved by generating an alternating flow Instead of a pulsating constant flow, the change in flow over time is increased, in particular at the switch-off point, and thus the switching accuracy of the arrangement.

The structural design of the arrangement according to FIG. 4 is such that the two pole faces of the axially magnetized, annular permanent magnet disk 22 are covered with soft iron rings, on the circumference of which protruding lugs protrude as pole pieces 23 and 24. With an equidistant pole sequence NSN, the poles follow one another as shown schematically in Figure 4. Figure 4b illustrates in a solid or dashed figure how the pole pieces 23 and 24 move past the flux guide pieces Ll and L2 leading to the reed contact 16 when the rotor 21 rotates one pole distance each. This construction thus again brings about a flow course as it is shown in Fig. Ic at φ 12. The steepness of the characteristic curve at the switching points can be varied by changing the axial distance between the north and south poles and the flux guide pieces Ll and L2. A reduction in this distance leads to stronger negative values of the flux and thus to greater steepness of the characteristic curve. Such a construction

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does not change the switching point when the rotor 21 has axial play, since the total air gap between the pole pieces changes and the guide pieces does not change. This is another essential prerequisite for practical use the switching device fulfilled.

Fig. 5 shows the schematic representation of a further embodiment of the switch according to the invention, in which the contact arrangement 16 is acted upon by a pulsating magnetic flux φ 15 of a stationary magnet Ml, guided via flux guide pieces Ll, L2, to which on the one hand a magnetic shunt 25 is assigned and its Magnetic flux φ 15, on the other hand, is controlled via an intermittently effective guide piece rotor 26. Similar to the embodiment according to FIG. 1, the guide piece rotor has projections 27 and indentations 28 on its circumference, so that different air gaps arise between the circumference of the guide piece rotor 26 and the flux guide pieces L1 and L2 which take over the magnetic flux.

The arrangement according to FIG. 5a is also suitable for use for any number of switching operations within a switching cycle; the arrangement shown with five VorSprüngen 27 allows five switching operations during one revolution of the rotating control device. This controls the contact arrangement 16, in the illustrated case a reed contact, via a magnet Ml, which is in the stationary part the device and is switched on and off periodically by the sheet metal rotor 26. If the magnetic circuit is closed, so the magnet Ml generates a flux φ 15 »via the contact tongues 14 and 15 which opposes the contact tongues magnetized and thus keeps the contact arrangement closed. In the case of the in Fxg. 5a representation shown the magnetic circuit is open, so that the flux φ 15 drops to a minimum value. The opposite pole magnetization of the

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Contact tongues l4 and 15 is no longer sufficient to overcome the resilient opening force of the contact tongues; the contact arrangement is open. The inventive measure to increase the switching accuracy, by means of which a larger positive change over time is achieved in the area of the shutdown threshold of the arrangement, lies in the use of the magnetic shunt 25. that is, there is practically no residual flow over the contact tongues which could impair the switching accuracy. On the one hand, the magnetic shunt must be so strong that it reliably absorbs the residual flux emitted by the magnet Ml when the circuit is open. This can be achieved by making the air gap to the shunt 25 small compared to the air gap between the flux guide pieces Ll, L2 when the circle is open in the area of the indentations 28.On the other hand, the air gap should be larger than that in the magnetic circuit between the guide pieces Ll, L2 and the projections 27 when the magnetic circuit is closed. By eliminating the residual flow in the contact arrangement 16, the switching accuracy can be increased particularly easily and effectively in this way. Although there is no alternating flow as in the exemplary embodiments discussed above, the pulsating direct flow is changed in such a way that again a sufficiently large change in flow over time is present at least in the area of the switch-off threshold.

The embodiment according to FIG. 5 can be with the simplest Manufacturing means and with little manufacturing effort. The rotor in turn consists from a simple stamped sheet metal part. Furthermore, only a single permanent magnet with a simple geometric shape is used in the stationary part Shape needed.

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Claims (11)

Expectations 1.JElectric switch, especially ignition breaker switch for motor vehicles, with a rotating control device and with a contact arrangement which is gas-tight within a closed housing and can be actuated by means of a magnet system, characterized in that to increase the Switching accuracy when used for any number of switching operations in a switching cycle Control measures for the magnetic flux are taken in such a way that at least the switch-off threshold in a range of greater time River change falls. 2. Switch according to claim 1, characterized in that the contact arrangement (16) with an asymmetrical magnetic An alternating field is applied, which is the switch-on threshold of the contact arrangement only in one direction of the magnetic flux overshoots, wherein the switch-off threshold is placed in a range of large temporal change in flow. 3 · Switch according to claim 1 or 2, characterized by a permanent magnetic magnet system (Ml, M2). 4. Switch according to claim 2 or 3, characterized in that the contact arrangement (16) on the one hand with a pulsating magnetic flux (φ 11) guided via flux guide pieces (Ll, L2) 7098U / 0ÖU -15- a first stationary magnet (Ml) controlled by an intermittently active guide rotor (11) and, on the other hand, acted upon by the opposing constant flux (4> 2) of a second, stationary magnet (M2), whereby a positive direction change occurs (Fig. 1} . 5. Switch according to claim 4, characterized in that the Flux guide pieces (Ll, L2) are arranged in the axial direction on both sides of the LeitStückäufer (11) (Pig. Id). 6. Switch according to claim 2, characterized _s that said contact means (l6) on the one hand with the removed via Flußleitstüeke (ItI, L2) magnetic Viechseifluß a permanent magnet rotor (17) and on the other hand (φ 2) with the constant flow of (^ 12) stationary magnets (M2) - is hit, resulting in a change of flow direction (Fig. 2) ■ 7 »Switch according to claim 6, characterized in that the Fixed magnet (M2) ~ is a permanent magnet. 8. Switch according to claim 6 or 7, characterized in that the rotor (17) is an axially magnetized permanent magnet disc (20) has a number of protruding parts corresponding to the desired number of switching operations on its circumference Pole piece pairs (l8, 19), which in the corresponding Flux guide pieces arranged at a distance (Ll, L2> are assigned (Fig. 3). . . 709814/0044 ~ ^l6 ~ 9. Switch according to one of claims 4 to 8, characterized in that the absolute maximum values (d> 1 max) of the changing magnetic flux (^ D are greater than the constant flux (φ 2). 10. Switch according to claim 2, characterized in that the contact arrangement (l6) is acted upon by a magnetic alternating flux {φ I ¹ I) of a permanent magnetic rotor (21) which is _{removed via flux guide pieces (Ll 3 L2), which has an axially magnetized permanent magnet disk (22} ), which has on its circumference a number of projecting pole piece pairs corresponding to the desired number of switching operations, the pole pieces (23, 24) of which, as well as the associated flux guide pieces (Ll, L2), are offset from one another in the circumferential direction and in accordance with the changing air gap widths in the Generate a magnetic alternating flux with different peak values via the flux guide pieces (Ll, L2) in a closed circuit (Fig. 4). 11. Switch according to claim 1, characterized in that the contact arrangement (l6) is acted upon by a pulsating magnetic flux (φ 15) of a stationary magnet (Ml) guided via flux guide pieces (Ll, L2), to which on the one hand a magnetic shunt (25) is assigned and whose magnetic flux ( rk 15) on the other hand-is controlled via an intermittently effective guide piece rotor (26) (Fig. 5). , { 7098H / Q0U