The disclosure relates to a magnetically operated switch for interrupting and/or closing an electrical circuit. The disclosure also relates to the use of such a magnetically operated switch as a state sensor, usable, for example, in a belt lock of a safety belt.
Switches are known devices for interrupting and/or closing electrical circuits. They can include of contacts which are suitable for the respective electrical loading by current or voltage and of an actuation means for bridging the contacts. The actuation device can be of a mechanical or electromechanical nature. These switches are for example rotary, toggle, stepping or momentary contact switches, and/or relays.
In the course of miniaturization, solid-state switches and mechanical microswitches have also been developed. Solid-state switches ordinarily possess source, drain and gate terminals, and are suitable for switching small currents. Microswitches are relatively complex in construction and include contact springs and the like in order to implement the two switching states “on” and “off”. Contact springs are wearing parts which can fatigue and even fail when the switch is intensively used.
Switching devices are known which are based on the magnetic principle. U.S. Pat. No. 6,803,845 describes for example a magnetically operated switch which is used as a monitoring switch in doors or switches. The magnetically operated switch has two current contacts, an electrically conductive, permanent magnetic actuation device and a ferromagnetic attractor component which are located in a housing which is attached for example to a door frame or window frame. A second ferromagnetic attractor component is mounted on the door or on the window wing. In relative movement of the first and second attractor components the actuation means is moved out of a first end position in which for example the circuit is closed, into a second end position in which the circuit is interrupted. This proposed arrangement still includes a relatively large amount of space; when used as a monitoring switch for doors or windows this is of subordinate importance. This arrangement is less well suited for components installed under narrowed space conditions.
In the automobile industry Hall sensors are used for example as proximity state sensors for the state of belt locks of safety belt means. Knowledge of the state of the belt lock is used to indicate to the passengers by a signal that the safety belts have been put on and locked. Since the introduction of safety airbags, information about the closed state of the safety belts can also be important for control of the activation or deactivation of mechanisms for inflating driver and passenger airbags or side airbags.
EP-A-0 861 763 discloses a belt lock with an integrated pretensioned Hall sensor which detects the state of the locking body or ejector for a lock tongue which has been inserted into the belt lock, without contact. Here the Hall sensors with the Hall field are located in the immediate vicinity of the a permanent magnet. By changing the location of the locking body or the ejector which include a ferromagnetic material for this purpose, the magnetic field of the permanent magnet is changed. This changes the signal of the Hall sensor and at the output of the Hall sensor the change of the state can be tapped as a change of voltage. In one alternative version, the Hall sensor with the Hall field is installed without a permanent magnet and for this reason the locking body or ejector is made as a permanent magnet. In this arrangement the change in the position of the locking body or of the ejector is to be detectable by a change of the Hall voltage.
With the belt lock disclosed in EP-A-0 861 763, the Hall sensor is positioned very carefully with respect to the locking element or the ejector. Subsequent installation of the Hall sensor can therefore be relatively complex and expensive. The Hall sensor is moreover relatively sensitive to external stray fields which, for example, can be caused by a magnetic key ring. Optionally even additional shielding is attached; this can further complicate the structure or installation. The susceptibility to external stray fields can also be increased by the signal changes being relatively small due to the comparatively short distances which are traversed in closing or opening of the safety belt lock by the locking body or the ejector. The belt lock version without the pretensioned Hall sensor in which either the locking body or the ejector is made as a permanent magnet is also less practicable. The attainable signal changes can also be relatively small here. Demagnetization can occur over time due to vibrations of the locking body and of the ejector when the safety belt is opened or closed. Ultimately this leads to the Hall sensor becoming ineffective and the state changes of the belt lock no longer being detectable.
A magnetically operated switch is disclosed comprising: at least two electrical contacts; and a permanent magnetic actuation means electrically conductive at least in regions, and located in a common housing with the electrical contacts, the magnetic actuation means in a first end position bridging the electrical contacts in an electrically conductive manner and in a presence of an attractor component which magnetically interacts with the magnetic actuation means, being movable into a second end position in which electrical connection between the two contacts is interrupted, wherein at least one of the electrical contacts contains a ferromagnetic material, and a magnetic attraction force between the ferromagnetic material and the magnetic actuation means is smaller than another magnetic attraction force between the magnetic actuation means and the attractor component.
A belt lock for a safety belt means of a vehicle is disclosed, with the belt comprising: a locking mechanism; and a state sensor which monitors a component which changes position when the locking mechanism is actuated, wherein the state sensor is formed by a magnetically operated switch which includes: at least two electrical contacts; and a permanent magnetic actuation means electrically conductive at least in regions, and located in a common housing with the electrical contacts, the magnetic actuation means in a first end position bridging the electrical contacts in an electrically conductive manner and in a presence of an attractor component which magnetically interacts with the magnetic actuation means, being movable into a second end position in which electrical connection between the two contacts is interrupted, wherein at least one of the electrical contacts contains a ferromagnetic material, and a magnetic attraction force between the ferromagnetic material and the magnetic actuation means is smaller than another magnetic attraction force between the magnetic actuation means and the attractor component.
Other advantages and features of the disclosure will become apparent from the following description of embodiments of a magnetically operated switch. The figures are schematic.
An exemplary magnetically operated switch is disclosed which can have a simple and space-saving structure and which can be economically produced. The magnetically operated switch can be usable as a replacement for known magnetic switches, for microswitches, reed switches or Hall switches. It is also usable under narrow space conditions. The magnetically operated switch can also be suitable for installation in belt lock systems of known safety belt systems.
A magnetically operated switch is disclosed which has at least two electrical contacts and a permanent magnetic actuation means, which is electrically conductive at least in regions, which are located in a common housing. The magnetic actuation means in a first end position bridges the two contacts in an electrically conductive manner and in the presence of an attractor component which magnetically interacts with it can be moved into a second end position in which the electrical connection between the two contacts is interrupted. At least one of the electrical contacts contains (e.g., consists of) a ferromagnetic material (e.g., a base material and/or a coating of a ferromagnetic material). In an exemplary embodiment, the magnetic attraction force between the ferromagnetic contact and the magnetic actuation means is smaller than the magnetic attraction force between the magnetic actuation means and the magnetically interacting attractor component.
In its simplest version, the magnetically operated switch includes (e.g., consists of) two electrical contacts and the permanent magnetic actuation means which in one end position electrically connects the two electrical contacts. In an exemplary embodiment, a sole moving part is the permanent magnetic actuation means which can be moved into the second end position when the attractor component which interacts magnetically with it is present. In this way the electrical connection between the two electrical contacts is interrupted. Pretensioning elements such as for example contact springs or the like can be omitted. The attractor component can be a component of ferromagnetic material or even a magnet or can contain one. The magnetically operated switch does not require a separate second attractor component in order to assume the first switching position since at least one of the electrical contacts is ferromagnetic. In this way the construction of the magnetically operated switch can be made still smaller relative to known switches. For this reason the magnetically operated switch is also very well suited to use under narrowed space conditions. All components of the magnetically operated switch are accommodated in a common housing which can be sealed and insulated very easily; in this way the most varied sealing and insulation requirements for these switches, such as for example IP67, IP68, IP69, can be very easily satisfied. The contact zone is bridged with magnetic force. In this way the contact region can also be made line-shaped. An exemplary prerequisite for this is that the contacts are made elastic; this can generally be done very easily. The costs for the components can be low. The effort for mounting the magnetically operated switch which encompasses only three components in a simple version in the housing is likewise low. In this way the magnetically operated switch can be produced very economically.
The permanent magnetic actuation means can include (e.g., consist entirely of) an electrically conductive material. For example, the magnetic actuation means can be coated with contact material, especially on its contact surface. In this way also relatively strong magnets of SmCo, NdFeB, ceramic materials, hard ferrite and the like can be used.
For reasons of especially good conductivity the contact material can be chosen from the group consisting of silver, gold, other electrically conductive precious metals, nickel, iron and a combination of any two or more of these materials.
In one exemplary version of the disclosure the ferromagnetic electrical contact is made of one of the known contact materials and consists especially of a material from the group consisting of iron, nickel, silver, gold, other electrically conductive precious metals or a combination of any two or more of these materials.
In order to obtain greater flexibility with respect to materials for the electrical contact, the ferromagnetic contact in another exemplary version of the disclosure is coated with a contact material, such as with a material from the group consisting of nickel, silver, gold, other electrically conductive precious metals or a combination of any two or more of these materials.
In the actuation of the magnetically operated switch the permanent magnetic actuation means can be moved completely away from the two electrical ones. One version of the disclosure calls for the second electrical contact to be fixedly (e.g., permanently) connected to the permanent magnetic actuation means.
The switching motion of the permanent magnetic actuation means in the presence of an attractor component which interacts magnetically with it out of its first end position into the second end position can take place in different ways. In one exemplary version of the magnetically operated switch the actuation means can be moved parallel. The parallel displacement within the housing takes place in a controlled guided manner. The walls of the housing are used for guidance here.
In one alternative exemplary version of the magnetically operated switch the permanent magnetic actuation means in the presence of an attractor component which interacts magnetically with it can be pivoted such that the electrical contact to the ferromagnetic contact is interrupted. For example, the second electrical contact can be made as a pivoting axle for the permanent magnetic actuation means. The version with the pivotable actuation means allows very small actuator travels. The actuator travels in the displacement of the actuation means from the first into the second end position are, for example, roughly 0.2 mm to roughly 2 mm (or greater or lesser as desired).
A magnetically operated switch as disclosed herein can be made in another embodiment also as a ganged control switch or as a two-way switch. For this reason in the housing there is at least one other electrical contact. The permanent magnetic actuation means in the presence of an attractor component which interacts magnetically with it can be moved into the second end position in which it then comes into contact with at least one other electrical contact and closes the electrical circuit.
In order to be able to better define the initial end position of the magnetically operated switch, in another exemplary version of the disclosure the two electrical contacts which are electrically connected in the first end position of the permanent magnetic actuation means are made of a ferromagnetic material and/or are coated with one.
Due to a simple structure and small size, exemplary magnetically operated switches as disclosed herein are especially suitable as, for example, a sensor for the closed state of a belt lock of a safety belt means.
In a belt lock equipped with a magnetically operated switch as disclosed herein for a safety belt means of a motor vehicle or the like with a locking mechanism, the magnetically operated switch forms a state sensor which monitors a component which changes its location when the locking mechanism is actuated. In this case the monitored component can be advantageously the lockable lock tongue of the safety belt means which can be inserted into the lock. In this way not just any secondary component which can be moved in locking is monitored, but monitoring is done directly on the safety-relevant component.
In the schematic of
If an attractor component 9 is located in the vicinity of the magnetically operated switch 1 which exerts on the permanent magnetic actuation means 4 a greater magnetic attraction force than the electrical contacts, the permanent magnetic actuation means 4 within the housing is shifted into the second end position in which the electrical circuit between the two electrical contacts 2, 3 is interrupted. The attractor component can be a ferromagnetic component or a magnet or can contain one. If the magnetically interacting attractor component 9 is again moved away from the magnetically operated switch 1, the permanent magnetic actuation means 4 returns again to the first end position and closes the circuit between the two electrical contacts 2, 3. The second end position of the permanent magnetic actuation means 4 and the pertinent location of the attractor component 9 are indicated in
The permanent magnetic actuation means 4 can include (e.g., consist entirely of) an electrically conductive material. For example, it can be coated, especially on its contact surface, with contact material. In this way also relatively strong magnets of SmCo, NdFeB, ceramic materials, hard ferrite, and the like can be used. The larger the magnetic field generated by the permanent magnetic actuation means 4, the greater the distance can be in which the ferromagnetic attractor component 9 is guided to the magnetically operated switch 1. The contact materials can be for example silver, gold, other electrical conductive precious metals, nickel, iron and combinations of two or more of these materials. The ferromagnetic electrical contacts 2, 3 can include (e.g., consist of) these materials of very good conductivity or can be coated with these materials.
The embodiment of the magnetically operated switch shown in
As is apparent from the
In the illustrated versions of the magnetically operated switch, pretensioning elements such as for example contact springs or the like can be omitted. The magnetically operated switch does not require a separate ferromagnetic component in order in the first stable end position of the permanent magnetic actuation means to assume the first switching position since at least one of the electrical contacts is made ferromagnetic. In this way the construction of the magnetically operated switch can be made even smaller relative to the known switches and the magnetically operated switch is also very well suited for use under narrowed space conditions. All components of the magnetically operated switch are accommodated in a common housing which can be sealed and insulated very easily. In this way the most varied sealing and insulation requirements for these switches, such as for example IP67, IP68, IP69, can be very easily satisfied. The contact zone is bridged with magnetic force. In this way the contact region can also be made line-shaped. The prerequisite for this is that the contacts are made elastic; this can generally be implemented very easily. The costs for the components are low. The effort for mounting the magnetically operated switch which encompasses only three components in the simplest version in the housing is likewise small. In this way the magnetically operated switch disclosed herein can be produced very economically.
One exemplary application of the magnetically operated switch is as a sensor for the closed state of a belt lock of a safety belt means which is shown schematically in
The schematic cross section of
A magnetically operated switch 1 which has for example the construction of the embodiment explained using
The magnetically operated switch as disclosed herein can be structured very simply, can be invulnerable to vibration and wear very little.
It will be appreciated by those skilled in the art that the present invention can be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The presently disclosed embodiments are therefore considered in all respects to be illustrative and not restricted. The scope of the invention is indicated by the appended claims rather than the foregoing description and all changes that come within the meaning and range and equivalence thereof are intended to be embraced therein.
Number | Date | Country | Kind |
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192/07 | Feb 2007 | CH | national |
This application claims priority as a continuation application under 35 U.S.C. §120 to PCT/CH2008/000008, which was filed as an International Application on Jan. 7, 2008 designating the U.S., and which claims priority to Swiss Application 192/07 filed in Switzerland on Feb. 6, 2007. The entire contents of these applications are hereby incorporated by reference in their entireties.
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/CH08/00008 | 1/7/2008 | WO | 00 | 8/5/2009 |