DE8435505U1 - Switching relay - Google Patents

Description

HOFFMANN · EITLE & PARTNERS * -■

PAT E N TAN WÄLT E

DR. ING. E. HOFFMANN (1930-1976) -Dl P L. -ING. W. EITLE · DR.RE R. NAT. K. HOFFMANN · Dl PL.-IN G. W. LEHN

DIPL.-ING. K. FOCHSLE · DR. RER. NAT. B. HANSEN
ARABELLASTRASSE 4 . D-8000 M 0 NCHEN 81 . TEL (089) 911087 . TE LE X 05-29&iacgr;19 (PATH E )

RANCO INC., Dublin, Ohio / USA

Switching relay

The invention relates to a temperature-compensated switching relay with thermally induced switching delay.

Known relays of this type are designed with a movable bimetal part with a heating coil surrounding this bimetal part or with a heating resistor applied to the bimetal part. The movement of the bimetal part takes place continuously, unless additional measures are taken, and not as a snapping process, as is desired for an electrical switching process.
known switching relays are complicated in structure and
relatively difficult to adjust.

The invention is based on the object of creating a temperature-compensated switching relay with a thermally induced switching delay, which is simple and compact in its construction and reliable in its switching effect, including the constancy of the switching delay, and already has a snap action during the switching process.

This object is achieved according to the invention in that
the switching relay is movable between two end positions

■ L'; see &lgr;&igr;: L

res, a switching element carrying a permanent magnet for actuating at least one switching contact, that a first and a second paramagnetic part are provided on opposite sides of the permanent magnet in the direction of movement thereof, that a PTC resistor which can be fed in from a power source is attached to the first paramagnetic part, and that in the end position of the switching element on the second paramagnetic part, the distance of the permanent magnet from the first paramagnetic part is smaller than its distance from the second paramagnetic part.

When the PTC resistor is not switched on, the two paramagnetic parts have essentially the same temperature and therefore the same magnetic conductivity, so that the permanent magnet pulls the switching element into its end position on the first paramagnetic part. If the PTC resistor is now switched on, the first paramagnetic part is heated with a delay time determined by the heat transfer from the PTC resistor to this part, until it loses its magnetic conductivity. The attractive force between the second paramagnetic part and the permanent magnet then predominates and the switching element snaps into its end position on the second paramagnetic part. If the PTC resistor is now switched off, the temperature of the first paramagnetic part decreases with a delay determined by the heat dissipation from this part, until the first paramagnetic part regains its magnetic conductivity and the switching element snaps back into the end position on the first paramagnetic part.

The switching delay time in both directions is

of the heat transfer to and from the first paramagnetic part depends on the ratio of the distances of the permanent magnet from the paramagnetic parts in both positions of the switching element.
5

In the following, the time during which the switching element is in its end position on the first paramagnetic part is referred to as the ON time and the time during which the switching element is in the end position on the second paramagnetic part is referred to as the OFF time.

Both times depend on the ratio of the distances between the permanent magnet and the paramagnetic parts.

According to a further development of the invention, the ratio of the distances between the permanent magnet and the paramagnetic parts is therefore adjustable.

The ratio of the distances between the permanent magnet and the paramagnetic parts can be adjusted in several ways:

If the distance between the two paramagnetic parts is kept constant and the end position of the switching element on the second paramagnetic part is changed, the ON time remains the same and the OFF time changes. If the distance between the two paramagnetic parts is kept constant and the end position of the switching element on the first paramagnetic part is changed, the ON time changes and the OFF time remains constant. In both cases, the sum of the ON time and the OFF time (period) is changed.

With unchanged end positions of the switching element and

By changing the position of the first or second paramagnetic part, the ON time and the OFF time change in opposite directions, their sum remains approximately the same (constant period).
5

If the position of the first or second paramagnetic part is changed while the end position of the switching element on the relevant paramagnetic part is changed at the same time in such a way that the distance to the relevant paramagnetic part in the end position on this paramagnetic part remains unchanged, the ON time and OFF time are changed in the same direction and thus the sum of the two times (period) is changed.

The prerequisite for considering the period is in all cases that the PTC resistor is switched on during the ON time and switched off during the OFF time.

Advantageously, at least one adjustable stop is provided for the switching element at one of its end positions and/or at its other end position.

In a further development of the invention into an embodiment of the switching relay as an energy regulator, the at least one switching contact in the end position of the switching element on the first paramagnetic part closes the feed circuit of the PTC resistor and the stop for the switching element in the end position on the second paramagnetic part is designed as a stop screw with a rotary knob. With this structure, the switching relay becomes an energy regulator for the pulsed switching on and off of a load, for example a hotplate. The on/off switch for the hotplate can also be operated by the stop screw with a rotary knob.

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The control is carried out by changing the OFF time while keeping the ON time constant.

According to a further development of the invention to a further embodiment of an energy regulator, the at least one switching contact closes the feed circuit of the PTC resistor in the end position of the switching element on the first paramagnetic part and an adjusting screw with a rotary knob acting on the second paramagnetic part is provided for adjusting the distance between the first and paramagnetic parts. Here, the control takes place by changing the ON time and OFF time in opposite directions with an essentially constant sum of the two times, i.e. an essentially constant period of energy feed.

A further embodiment of the switching relay according to the invention as a door locking relay is provided in that a latch is provided which the switching element moves when it moves into the end position on the second paramagnetic part in such a way that a door is locked. When an external switch is switched on, the PTC resistor is switched on and the switching element moves the latch into its locking position when it moves into the end position on the second paramagnetic part. The door remains locked as long as the external switch is closed. If the external switch is opened, the release of the lock is delayed by the OFF time. Such a door locking relay is suitable, for example, for locking the door of a washing machine even for a delay time after the drum motor has been switched off.

According to a further development of the door locking device according to the invention

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In the door locking relay, the at least one switching contact closes a load circuit in the end position of the switching element on the second paramagnetic part, for example the circuit of the drum motor in a washing machine. This further development of the door locking relay according to the invention ensures that the load circuit is only switched on when the door is also locked.

It is advantageous to provide an adjusting screw on the second paramagnetic part >i for adjusting the distance between the first and second paramagnetic parts. This adjusting screw can be used to change the ON time and the OFF time in opposite directions.

:· A further development of the invention consists in that the at least one switching contact closes the supply circuit of the PTC resistor in the end position of the switching element on the first paramagnetic part and that a locking device with a locking release button is provided for releasably holding the switching element in the end position on the second paramagnetic part. This results in a switching relay with manual switching on and time-delayed, automatic switching off.

The delay relay designed in this way can be further developed in such a way that an adjusting screw acting on the first paramagnetic part and/or an adjusting screw acting on the second paramagnetic part is provided for adjusting the distance between the first and second paramagnetic parts. The adjusting screws can be used to change the ON time, on the one hand by changing the OFF time in the same direction, and on the other hand by changing the OFF time in the opposite direction.

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Alternatively, an adjustable stop for the switching element in the end position can be provided on the first paramagnetic part. This allows the ON time to be adjusted while the OFF time remains unchanged. 5

According to a further development of the invention, the at least one switching contact in the end position of the switching element on the first paramagnetic part closes the feed circuit of the PTC resistor, and an electro-holding magnet acting on the switching element in the end position on the first paramagnetic part is provided, electrically connected in series with this feed circuit. This design of the switching relay leads to a compressor restart relay with delayed switching on of the compressor after the compressor has previously been working. The compressor restart relay only switches the compressor on when the ON time has elapsed since the compressor was previously switched off. This ensures that there is sufficient time for the inlet pressure in the compressor to be reduced from the previous switching cycle.

Advantageously, a further switching contact is provided which, in the end position of the switching element on the second paramagnetic part, switches on a device for faster reduction of the inlet pressure of a compressor. This can ensure that the inlet pressure of the compressor is reduced more quickly during the OFF time, for example by bridging a throttle point.

A further development of the invention for creating a compressor restart relay consists in that the at least one switching contact in the end position of the switching element

&idiagr;&iacgr;&kgr;&igr; ^r ,

- 13 -

on the first paramagnetic part closes the feed circuit of the PTC resistor, that a spring-loaded lever forms both a stop for the switching element on the side of the second paramagnetic part and a further switching element for a power switching contact closed in the end position of the first switching element on the first paramagnetic part, and that an electro-holding magnet acting on the lever in its end position on the first paramagnetic part is provided, electrically connected in series with the feed circuit of the PTC resistor. Here the load, for example the compressor, is not switched on via the switching contact of the switch that triggers the switching process, for example a thermostat, but via the separate power switching contact.

Here, too, a further switching contact can be provided which, in the end position of the switching element on the second paramagnetic part, switches on a device for faster reduction of the inlet pressure of a compressor.

For both compressor restart relays, the setting or adjustment of the OFF time is essential. It is therefore advantageous to provide an adjusting screw that engages with the switching element or lever to adjust the end position of the switching element on the second paramagnetic part. When this adjusting screw is adjusted, the ON time remains unchanged, while the OFF time is changed.

Finally, the compressor restart relay is fitted with a spring-loaded push button that engages the switching element for manually moving the switching element into its

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End position provided on the first paramagnetic part. This push button allows manual switching on of the compressor for testing purposes even if the compressor has just been working. 5

The invention is explained in more detail below using exemplary embodiments and the drawings. The drawings show

Fig. 1 is a schematic representation of the arrangement

the essential parts of a switching relay according to the invention,

Fig. 2 and 3 are schematic representations of different positions of the parts shown in Fig. 1.

each other with different adjustment changes of the distances between the parts,

Fig. 4 is a representation of a first embodiment of the switching relay according to the invention as

Energy regulator,

Fig. 5 is a schematic representation of a second embodiment of the switching relay according to the invention as an energy regulator,

Fig. 6 is a schematic representation of a third

Embodiment of the switching relay according to the invention as a door locking relay, 30

Fig. 7 is a schematic representation of a fourth

Embodiment of the switching relay according to the invention as a switch-on relay with delayed switch-off,

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Fig. 8 is a schematic representation of a fifth

Embodiment of the switching relay according to the invention as a switch-on relay with delayed switch-off,
5

Fig. 9 is a schematic representation of a sixth embodiment of the switching relay according to the invention as a compressor restart relay, and

Fig. 10 is a schematic representation of a seventh

Embodiment of the switching relay according to the invention as a compressor restart relay.

In Figs. 1 to 3, the essential parts of the switching relay according to the invention are shown schematically in their various positions relative to one another. A switching element 1 carries a permanent magnet 2. The switching element 1 with permanent magnet 2 is arranged between a first paramagnetic part 3 and a second paramagnetic part 4 and can be moved between the two paramagnetic parts 3, 4. The first paramagnetic part 3 carries a PTC resistor 5 that can be fed from a power source. In Figs. 1 to 3, the switching element 1 with permanent magnet 2 is shown in its end position on the second paramagnetic part 4 in solid lines and in its end position on the first paramagnetic part in dashed lines.

As long as the PTC resistor 5 is not fed, i.e. does not receive any current, both the first paramagnetic part 3 and the second paramagnetic part 4 are magnetically conductive and the switching element 1 with the permanent magnet 2 is in its end position at the first

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paramagnetic part 3. If the PTC resistor 5 is now switched on, the first paramagnetic part 3 is heated by it until it loses its magnetic conductivity, the effect of the second paramagnetic part 4 predominates and the permanent magnet 2 with the switching element 1 is moved into its end position on the second paramagnetic part 4. If the PTC resistor 5 is switched off during this movement, the first paramagnetic part 3 cools down again, regains its magnetic conductivity and causes the permanent magnet 2 and thus the switching element 1 to move back into the end position on the first paramagnetic part 3.

In Fig. 1 the individual parts are shown in their basic positions. The time during which the switching element 1 with the permanent magnet 2 is in the end position on the first paramagnetic part 3 is referred to as the ON time t - (t" in Figs. 2 and 3), the time during which the switching element 1 with the permanent magnet 2 is in the end position on the second paramagnetic part 4 is referred to as the OFF time t _Af) (t _A in Figs. 2 and 3). In the end position of the switching element 1 on the second paramagnetic part 4 the distance of the permanent magnet 2 to the first paramagnetic part 3 is A~ (A in Figs. 2 and 3) and its distance to the second paramagnetic part 4 is B» (B in Figs. 2 and 3). In the end position of the switching element 1 on the first paramagnetic part 3, the distance of the permanent magnet 2 to the first paramagnetic part 3 is A» ¹ (A' in Fig. 2 and 3) and its distance to the second paramagnetic part 4B _n ¹ (B' in Fig. 2 and 3). The distance A or A„ must always be smaller than the distance B or B _Q so that the desired force effects

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for the function of the switching relay. Any pre-tensioning force of the switching element 1 is to be considered equivalent when determining or changing the distances.

To set the ON time t" and the OFF time t _A , the ratio of the distances between the permanent magnet 2 and the paramagnetic parts 3, 4 can be conveniently adjusted. This adjustment can be made by changing the positions of the two end positions of the switching element 1 with permanent magnet 2 and/or adjusting the paramagnetic parts 3, 4. Various adjustment options are shown in Figs. 2 and 3 and are described in more detail below in relation to their effects in connection with inward adjustments.

According to Fig. 2a, the end position of the switching element 1 with permanent magnet 2 on the second paramagnetic part 4 can be adjusted with the position of the paramagnetic parts 3, 4 unchanged. Compared to the values A _n , B _n , A ', B ', t Q and t _n , the distance A is reduced and the distance B is increased, while the distances A' and B' remain the same. The ON time t remains the same, the OFF time t becomes shorter; the switching period becomes shorter.

According to Fig. 3a, the end position of the switching element 1 with permanent magnet 2 on the first paramagnetic part 3 can be adjusted while the position of the paramagnetic parts 3, 4 remains the same. The distances A and B remain the same, the distance A ¹ becomes larger and the distance B ¹ becomes smaller. The ON time t becomes smaller, the OFF time t remains the same; the switching period becomes smaller.

According to Fig. 2b, only the first paramagnetic part 3 is adjusted. The distance A becomes smaller, the distance B

- 18 -

remains the same, while the distance A' becomes smaller and the distance B ¹ remains the same. The ON time t becomes longer, the OFF time t, becomes smaller; the switching period remains essentially the same.
5

According to Fig. 3b, only the second paramagnetic part 4 is adjusted. The distance A remains the same, the distance B becomes smaller, while the distance A ¹ remains the same and the distance B ¹ becomes smaller. The ON time t_, becomes smaller and the OFF time t becomes longer; the switching period remains essentially the same.

According to Fig. 2c, both the first paramagnetic part 3 and the end position of the switching element 1 with permanent magnet 2 on the first paramagnetic part 3 are adjusted in the same direction. The distance A is reduced and the distance B remains the same, while the distance A ¹ remains the same and the distance B ¹ is reduced. The ON time t" and the OFF time t are both reduced.

According to Fig. 3c, the second paramagnetic part 4 and the end position of the switching element 1 with permanent magnet on the second paramagnetic part 4 are adjusted in the same direction. The effect is the same as described in Fig. 2c.

Figs. 4 to 10 show different embodiments of a switching relay according to the invention. In all of these embodiments, the switching element is designed as a pivoting lever. Furthermore, in all embodiments, at least one switching contact 6 is provided, which is actuated by the switching element 1.

Fig. 4 shows an embodiment of the switching relay as an energy regulator. The switching contact 6 closes in the end position of the switching element 1 on the first paramagnetic part 3

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the supply circuit of the PTC resistor 5. A switch 7 connects both the PTC resistor 5 and a load 8 in parallel, for example the hotplate of a stove, to an electrical energy source, while the switching element 1 is in its end position on the first paramagnetic part 3. As soon as the first paramagnetic part 3 has been heated by the PTC resistor 5 to such an extent that it loses its magnetic conductivity, the switching element 1 snaps into the end position on the second paramagnetic part 4.

This opens the switching contact 6 and switches off the energy supply to both the PTC resistor 5 and the load 8. Once the first paramagnetic part 3 has cooled down again and regained its magnetic conductivity, the switching element 1 snaps back into the end position on the first paramagnetic part 3 and the cycle begins again.

A stop screw 9 with a rotary knob 10 is provided as a stop for the switching element 1 in the end position on the second paramagnetic part 4. In addition, an adjusting screw 11 can be provided as an indirect stop for the switching element 1 in the end position on the first paramagnetic part 3. The stop screw 9 with a rotary knob 10 can be used to adjust the switching element 1 as described in connection with Fig. 2a, while the adjusting screw 11 can be used to adjust the switching element as described in connection with Fig. 3a. In the first case, the ON time t_ remains unchanged and the OFF time t is changed, while in the second case the ON time t” is changed and the OFF time t _A remains unchanged. In both cases, the ratio of the ON time t to the OFF time t and thus the on and off times of the load 8 are changed in relation to one another. It is an automatic pulse feed of the load 8. The switch 7 can be connected to the

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Stop screw 9 together with rotary knob 10 must be integrated in one component.

Fig. 5 shows another embodiment of the switching relay as an energy regulator. Here, instead of the stop screw 9 with rotary knob 10, an adjusting screw 12 with rotary knob 13 is provided, which engages the second paramagnetic part 4 to adjust the distance between the first paramagnetic part 3 and the second paramagnetic part 4. Furthermore, an adjusting screw 14 engaging the first paramagnetic part 3 can be provided to adjust the distance between the first paramagnetic part 3 and the second paramagnetic part 4. Turning the adjusting screw 12 leads to the adjustment of the ON time t and the OFF time t with an essentially constant switching period as described in connection with Fig. 3b, while adjusting the adjusting screw 14 leads to a corresponding change in the times as described in connection with Fig. 2b.

Fig. 6 shows a switching relay that is designed as a door locking relay for the door of a drum washing machine, for example. Here, a latch 15 is provided, which the switching element 1 moves when it moves to the end position on the second paramagnetic part 4 in such a way that a door 16 is locked. When an external switch 17 is switched on, the PTC resistor 5 is switched on and the switching element 1 moves the latch 15 into its locking position when it moves to the end position on the second paramagnetic part 4. The door 16 remains locked as long as the external switch is closed. If the external switch 17 is opened, the locking is released by the OFF time t.

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delayed. Such a door locking relay is suitable, for example, for locking the door of a washing machine with a delay time after the drum has been switched off.
5

The at least one switching contact 6 is preferably arranged in the door locking relay in such a way that in the end position of the switching element 1 on the second paramagnetic part it closes a load circuit L, for example the circuit of the drum motor in a washing machine. This ensures that the load circuit L is only switched on when the door 16 is also locked. The door locking relay also has an adjusting screw 18 acting on the second paramagnetic part 4 for adjusting the distance between the first paramagnetic part 3 and the second paramagnetic part 4. With this adjusting screw 18, the ON time t and the OFF time t can be changed in opposite directions, as described in connection with Fig. 3b.

The adjustment of the OFF time t is essential here.

Fig. 7 shows another embodiment of the switching relay as a delay relay with manual switch-on and time-delayed, automatic switch-off.

Here, the switching contact 6 closes the feed circuit of the PTC resistor 5 in the end position of the switching element 1 on the first paramagnetic part 3, and a locking device 19" with a locking release button 20 is provided for releasably holding the switching element 1 in the end position on the second paramagnetic part 4. By operating the locking release button 20, the locking device 19 is released and a load M, for example a motor, is connected to a power source in series with the PTC resistor 5. After the

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During the ON time t _E , the delay relay opens the circuit via the switching contact 6 and both the PTC resistor 5 and the load M are switched off. The locking device 19 holds the switching element 1 in the end position on the second paramagnetic part 4 until it is released by the locking release button 20 to carry out the next cycle.

Furthermore, an adjusting screw 21 acting on the second paramagnetic part 4 or alternatively an adjusting screw 22 acting on the first paramagnetic part 3 is provided for adjusting the distance between the first paramagnetic part 3 and the second paramagnetic part 4. The ON time t" can be adjusted using both adjusting screws, namely with the adjusting screw 21 as described in connection with Fig. 3b and with the adjusting screw 22 as described in connection with Fig. 2c.

Fig. 8 shows a further embodiment of a corresponding delay relay, in which, instead of the setting screws 21 and 22, an adjustable stop for the switching element 1 in the end position is provided on the first paramagnetic part 3 in the form of an indirectly acting stop screw 23. This allows the ON time t_ to be adjusted while the OFF time t remains unchanged, as is the case

Hey A

described in connection with Fig. 3a.

A particularly important embodiment of the switching relay 0 as a compressor restart relay is shown in Fig. 9.

In this compressor restart relay, the switching contact 6 closes the feed circuit of the PTC resistor in the end position of the switching element 1 on the first paramagnetic part 3

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5 and electrically connected in series with this feed circuit, an electro-holding magnet 24 acting on the switching element 1 in the end position on the first paramagnetic part 3 is provided. When an external switch 25 is closed, for example the switch in a thermostat, the electro-holding magnet 24 and the PTC resistor 5 are fed from an energy source when the first paramagnetic part 3 is cold. At the same time, a compressor C is switched on. This state is maintained due to the effect of the electro-holding magnet 24 until the switch 25 is opened again. Closing the switch 25 again when the first paramagnetic part 3 is still warm only leads to the compressor C being switched on again when the ON time t_ has elapsed since the compressor C was previously switched off. This ensures that there is sufficient time for the inlet pressure in the compressor C to be reduced from the previous switch-on cycle.

A further switching contact 26 can be expediently provided in the compressor restart relay, which in the end position of the switching element 1 on the second paramagnetic part 4 switches on a device 27 for the faster reduction of the inlet pressure of the compressor C. This can ensure that the inlet pressure of the compressor C is reduced more quickly during the OFF time t-, for example by bridging a throttle point.

With the compressor restart relay according to Fig. 9, the full power of the compressor C is switched via the switch 25, however, the switching relay has the advantage that it is fail-safe, i.e. in the event of failure of the PTC resistor 5 and/or interruption of the coil of the electro-holding magnet

-2A-

24, switching on the compressor C is possible in any case.

Fig. 10 shows a further embodiment of a compressor restart relay in which the full power of the compressor is not switched directly via the switch 25. Here, the switching contact 6 closes the feed circuit of the PTC resistor 5 in the end position of the switching element 1 on the first paramagnetic part 3. A spring-loaded lever 28 forms both a stop for the switching element 1 on the side of the second paramagnetic part 4 and a further switching element for a power switching contact 29 closed in the end position of the first switching element 1 on the first paramagnetic part 3. The electro-holding magnet 24, which acts on the lever 28 in its end position on the first paramagnetic part 3, is electrically connected in series with the feed circuit of the PTC resistor 5. Here, the load, for example the compressor C _1, is not switched on via the switching contact of the switch 25 that triggers the switching-on process, but via the separate power switching contact 29.

In both compressor restart relays, the setting or adjustment of the OFF time t- is essential. An adjusting screw 30 is therefore provided which engages with the switching element 1 or lever 28 for setting the end position of the switching element 1 on the second paramagnetic part 4. When this adjusting screw 30 is adjusted, the ON time t remains unchanged, while the OFF time t _A is changed, as described in connection with Fig. 2a.

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Finally, each compressor restart relay can be provided with a spring-loaded pushbutton 31 acting on the switching element 1 for manually moving the switching element 1 into its end position on the first paramagnetic part 3. This pushbutton 31 enables the compressor C to be switched on manually for testing purposes, even if the compressor C has just been running.

Claims (17)

HOFFMANN · EITLE & PARTNER ^r ·■<*- - PAT E N TAN WALT E DR. ING. E. HOFFMANN (19301976) . Dl PL.-ING. W. EITLE . DR. RE R. NAT. K. HOFFMAN N ■ DI PL.-1 N G. W. LEHN DIPL.-ING. K.FOCHSLE . DR. RER. NAT. B. HANSEN ARABELLASTRASSE 4 · D-8000 M D N C H E N 81 · TE LE FON (089) 911087 . TE LE X 05-29619 (PATH E ) RANCO INC., Dublin, Ohio / USA Switching relay - &Mgr;*=»&Phi; CLAIMS 1. Temperature compensated switching relay with thermally induced switching delay, characterized in that it has a switching element (1) which can be moved between two end positions and carries a permanent magnet (2) for actuating at least one switching contact (6), that a first and a second paramagnetic part (3, 4) are provided on opposite sides of the permanent magnet (2) in the direction of its movement, that a PTC resistor (5) which can be fed from a power source is attached to the first paramagnetic part (3), and that in the end position of the switching element (1) on the second paramagnetic part (4), the distance (A) of the permanent magnet (2) from the first paramagnetic part (3) is smaller than its distance (B) from the second paramagnetic part (4). 2. Switching relay according to claim 1, characterized in that the ratio of the distances (A/B, A'/B ¹ ) of the permanent magnet (2) from the paramagnetic parts (3, 4) is adjustable. 3. Switching relay according to claim 1 or 2, characterized in that an adjustable stop is provided for the switching element (1) at one of its end positions and/or at its other end position. 4. Switching relay according to claim 3, characterized in that the at least one switching contact (6) closes the feed circuit of the PTC resistor (5) in the end position of the switching element on the first paramagnetic part (3) and that the stop for the switching element in the end position on the second paramagnetic part is designed as a stop screw (9) with a rotary knob (10). 5. Switching relay according to claim 1, 2 or 3, characterized in that the at least one switching contact (6) in the end position of the switching element (1) on the first paramagnetic part (3) closes the feed circuit of the PTC resistor (5) and that an adjusting screw (12) with a rotary knob (13) engaging the second paramagnetic part (4) is provided for adjusting the distance between the first and second paramagnetic parts (3, 4). 6. Switching relay according to claim 1 or 2, characterized in that a latch (15) is provided which the switching element (1) displaces when moving into the end position on the second paramagnetic part (4) in such a way that a door (16) is locked. 7. Switching relay according to claim 6, characterized in that the at least one switching contact (6) closes a load circuit in the end position of the switching element (1) on the second paramagnetic part (4). 8. Switching relay according to claim 6 or 7, characterized in that an adjusting screw (18) engaging the second paramagnetic part (4) is provided for adjusting the distance between the first and second paramagnetic parts (3, 4). 9. Switching relay according to claim 1 or 2, characterized in that the at least one switching contact (6) in the end position of the switching element (1) on the first paramagnetic part (3) closes the supply circuit of the PTC resistor (5) and that a locking device (19) with a locking release button (20) for releasably holding the switching element (1) in the end position is provided on the second paramagnetic part (4). 10. Switching relay according to claim 9, characterized in that an adjusting element acting on the first paramagnetic part (3) screw (22) and/or an adjusting screw (21) engaging the second paramagnetic part (4) is provided for adjusting the distance between the first and second paramagnetic parts (3, 4). 5 11. Switching relay according to claim 9, characterized in that an adjustable stop (stop screw 23) for the switching element (1) in the end position is provided on the first paramagnetic part (3). 12. Switching relay according to claim 1 or 2, characterized in that the at least one switching contact (6) in the end position of the switching element (1) on the first paramagnetic part (3) closes the feed circuit of the PTC resistor (5), and that electrically connected in series with this feed circuit a switching element (1) in the end position on the first paramagnetic part (3) acting electro-holding magnet (24) is provided, 13. Switching relay according to claim 12, characterized in that a further switching contact (26) in the end position of the switching element (1) on the second paramagnetic part (4) switches on a device (27) for faster reduction of the inlet pressure of a compressor (C). 14. Switching relay according to claim 1 or 2, characterized in that the at least one switching contact (6) in the end position of the switching element (1) on the first paramagnetic part (3) closes the feed circuit of the PTC resistor (5), that a spring-loaded lever (28) both a stop for the switching element (1) on the side of the second paramagnetic part (4) as well as another switching element for a power switching contact (29) closed in the end position of the first switching element (1) on the first paramagnetic part (3), and that an electro-holding magnet (24) acting on the lever (28) in its end position on the first paramagnetic part (3) is provided, electrically connected in series with the supply circuit of the PTC resistor (5). 15. Switching relay according to claim 14, characterized in that a further switching contact (26) in the end position of the switching element (1) on the second paramagnetic part (4) switches on a device (27) for faster reduction of the inlet pressure of a compressor (C). 16. Switching relay according to claim 12 or 14, characterized in that an adjusting screw (30) engaging with the switching element (1) or lever (28) is provided on the second paramagnetic part (4) for adjusting the end position of the switching element (1). 17. Switching relay according to claim 12 or 14, characterized in that a spring-loaded push button (31) acting on the switching element (1) is provided for manually moving the switching element (1) into its end position on the first paramagnetic part (3).