EP0898291B1 - Power control apparatus - Google Patents

Abstract

The power control device (11) has a setting device that is adjusted to control the output power of the electric heating appliance. A switch contact (15) is attached to the setting device and contacts a counter-contact (14) in the closed switch position in which the heating appliance is supplied with current and spaced from the counter-contact by a variable distance (D) in the open switch position.

Description

The invention relates to a power control device according to the preamble of claim 1.

Switching between the ON position and the OFF position is carried out in the hereinafter referred to as "clocking", and a single switching operation Called "crack".

Power control devices currently on the market clock with a Click rate of around four to five clicks per minute. By using of consumers on the market (including inductive Loads), which include electrical heating devices, are maximum Cracking rates of less than 2 clicks per minute are required. Furthermore require stricter flicker regulations a larger contact distance of switching contact and counter contact when switched off.

CH 391 057 A describes a control unit with a bimetal switch, which, for example, for a hotplate of an electric cooker can be used. The release path is via a cam disk for a bimetallic element that controls a snap spring, set. Through a second cam disc to which the snap spring strikes in the open position, the counterstop for the Snap spring formed.

DE 36 39 186 describes an electrical switching device in which a position adjustment of an adjustment device the simultaneous adjustment of the power level and the switching hysteresis. The performance level is also called "ED", which means the relative Duty cycle is meant. When changing the position of the adjustment device for changing the power level by turning a Knebels uses a cam disk to hold the entire one on it Adjustment device resting on the cam disk together with the one on it Counterstop changed in position. This allows set the ED between 0% and 100%.

From FIGS. 8 and 9 of DE 36 39 186, in particular from FIG. 9, it can be seen that the click rate at medium power which is around 50% around twice that in the lower Performance range (up to 20%) and high performance range (greater than 80%) can be achieved. A reduction in the cracking rate in the middle range is only possible by increasing the contact distance. However, it is not due to the arrangement of the counterstop possible to increase the tripping path that corresponds to the contact distance or influence without the function of the power control unit adversely affect. At lower performance levels the device switch would no longer be in the OFF position can be solved because of the short time available the triggering bimetal element does not cover the required distance could. Similarly, would be in the high end the bimetal element takes too long with an increased contact distance, to go back from its position of the OFF position of the contact. This would not achieve the desired high level of performance.

TASK AND SOLUTION

The underlying task is therefore to create a power control device that avoids the disadvantages of the prior art, in particular the Switching hysteresis within certain limits can be influenced, so that the cracking rate can be reduced in the medium performance range, the more precise setting of a performance level, especially in the lower and upper area allows and a larger contact distance ensures.

This object is solved by the features of claim 1. The enables the contact distance to be increased beyond the usual Measure regardless of the level of performance, especially in medium performance range, which reduces the cracking rate here. In this way, the one shown in DE 36 39 186 in FIG Curve for the click rate can be changed so that it is the same start and end points are compressed in height, see also Fig. 4. This means that the click rate at medium power (about 50% ED) can be reduced to below two clicks per minute can. Through this position change independent of the performance level the counter-stop and / or the counter-contact can be the click rate generally essentially independent of the level of performance to adjust.

A mechanical power adjustment device is advantageous, in particular also a mechanical contact distance adjustment device, considered. This can be caused by a change in position or distance of assemblies or functional units due to mechanical loading respectively.

The power adjustment device advantageously has a position change of the device switch is a power cam with a varying radius on the outer radius of the device switch by a bias rests elastically pressed. This type of position change has the advantage that any sequence of positions is set in principle can be. In this case, the outer radius determines the position of the device switch.

In the invention, the contact distance adjusting device has a distance cam with a varying radius on the outside radius a device supporting and / or forming the counterstop in the form of an additional spring elastically pressed by a bias is applied. This is a simple way, including changing the position of the counterstop arbitrarily. The additional spring can Be leaf spring, part of which is bent so that it forms the counterstop for the switch contact.

If both cams are mounted on one axis, the with an actuator by a user to adjust the performance level is rotatable, the change in position of both the device switch as well as the counterstop. there it is possible to use a single stepped cam that two mutually independent outer radii accordingly has the two outer radii described above. In progress can be set the rotary movement of the actuator with the axis either only in one direction and in this Case starting with the lowest power, or in both Directions. You can then either use the lowest Power level can be started or by slight twisting in the other direction the highest power level immediately can be set.

If at least one of the two outer radii, preferably the Outer radius at which the device switch is in contact with a Screening or the like is provided at least in sections, can be communicated to a user in this way what setting range it is in. Most of all with actuators mounted frontally under the hob an advantage because in this case the user with Set the desired level of performance with little practice can, without extra on the position of the actuator to have to look.

The outer radii of the cams are advantageous for one Increasing the setting accuracy of the performance at high and low levels of performance and a decrease in cracking rate middle shaped shaped. So follows from the course both cams the setting accuracy, the switching hysteresis and the course of the click rate over the ED.

In a preferred embodiment of the invention, the Outer radius of the power cam at a zero position of the power control unit to be maximum, and itself from this section on in a circumferential direction, the opposite to the direction of actuation of the power control unit is steady to the section of the zero position reduce. The section of the zero position can be one Take radians of about 30 °. This allows the distance of the Device switch to the counter contact, for example, continuously be enlarged, which increases the responsiveness the device switch reduced, so that especially at high ED values the cracking rate is low. The outer radius can between the position for the lowest level of performance and decrease that for the highest by about 30%. at the position for the highest level of performance can Increased additional decrease in the outer radius is an advantage be a significant increase in the To achieve ED value.

The outer radius of the spacer cam is particularly advantageous with a zero position of the power control unit maximum, decreases from this section on a direction opposite to the direction of actuation to a second section that roughly corresponds to the first section lies opposite and has a minimal outer radius, and increases from this point in a third section again to the section of the ZERO position. Consequently the counterstop is adjusted only in the first section roughly proportional to the change in position of the Devices switch. By increasing in the third section Outside radius the counterstop turns back towards it original position at low performance level, so that the setting accuracy in both areas about is equal to. A reduction in the outer radius to about 70% in Area of the second section is particularly advantageous considered for the application of the invention, since the Cracking rate is sufficiently reduced.

The device switch can preferably be a snap switch, especially with a two-part bistable snap spring, be executed, the switching contact against at least one Switch position loaded. This way the contacts safe and reliable both switched and in their respective switch position, i.e. either the ON position or the OFF position. Especially snap springs have the advantage that they switch gear very quickly and thus with a minimum of radio interference or contact erosion carry out.

If the snap spring has a striking fork, the Switching operations of the contacts improved. Particularly advantageous is the use of a two-part impact spring with a Punch fork that shifts in both directions performs particularly quickly. This causes annoying contact erosion or sticking of the contacts avoided and radio interference further decreased.

These and other features of the invention are apparent from Claims also from the description and the drawings , the individual features each individually or more in the form of sub-combinations in one Embodiment of the invention and in other fields be realized and advantageous as well as protectable Can represent designs for which protection here is claimed. The division of the registration into individual Sections and subheadings limit the below these statements made in their general validity.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1

eine Innenansicht eines erfindungsgemäßen Leistungssteuergeräts mit einer Verstelleinrichtung, die an den Außenradien zweier Kurvenscheiben anliegen, wobei der Kontakt eines Geräteschalters geschlossen ist, auf einem niedrigen Leistungsniveau;

Fig. 2

dieselbe Ansicht wie in Fig. 1, wobei ein mittleres Leistungsniveau eingestellt ist;

Fig. 3

die Ansicht aus Fig. 2 mit geöffnetem Schaltkontakt und

Fig. 4

die Kurven der Knackraten entsprechend dem Stand der Technik und der vorliegenden Erfindung.

An embodiment of the invention is shown in the drawings and is explained in more detail below. In the drawings:

Fig. 1

an interior view of a power control device according to the invention with an adjusting device which abuts the outer radii of two cams, the contact of a device switch being closed, at a low power level;

Fig. 2

the same view as in FIG. 1, with an intermediate performance level set;

Fig. 3

the view of FIG. 2 with the switch contact open and

Fig. 4

the curves of the click rates according to the prior art and the present invention.

DESCRIPTION OF A PREFERRED EMBODIMENT

1 is an internal view of a clocking Power control unit 11 shown for electric heaters. It has a device switch 12, which to the closes contact. This contact is in single from a fixed contact bridge 13 attached rounded counter contact 14 and a switching contact 15, which is attached to the device switch 12. The Switch contact 15 is a commonly used dome-shaped Contact head attached by riveting.

More specifically, the switch contact 15 is one at one end elongated bistable snap spring 16 attached and protrudes both sides over this over. The snap spring has two elongated hairpin-shaped legs 22 on which the Switch contact 15 opposite end 17 on a support 18 are attached. Between the legs 22 of the snap spring 16 runs a snap bracket 19 which is close to the switch contact 15 supporting end of the snap spring bent upwards runs in the direction of the free end 17, and there arched curved under tension against one Abutment 20 is created. This abutment is on one Support plate 21 attached and is preferably part of the carrier 18 also fastened on the support plate 21 educated.

The function of the device switch is basically as follows off: is the point at which the snap bracket 19 abuts the abutment 20, above the level of two hairpin-shaped legs 22 of the snap spring 16, so the snap spring 16 is in a first position. The switching contact 15 becomes against the counter contact 14 pressed. Will now on the free end 17 of the snap spring 16th Pressure exerted and this down according to FIG. 1 deflected, the point approaches the snap bracket 19 in the abutment 20 of the level of the legs 22. Be now the movable legs 22 of the spring 16 under the fixed by the fixed position of the support plate 21 Pressed changeover point, the snap spring snaps over. The means that the switch contact 15 carrying the end of Snap spring 16 abruptly by the snap bracket 19 is bent away below. In this way the switch contact is located 15 no longer on the counter contact 14 and the contact or the device switch 12 is in a second position open.

The switching process of the snap spring 16 is triggered by an actuator in the form of a curved bimetal strip 24. This carries on one of the snap springs 16 opposite top, which is mostly straight, a heating element 25 or the like. With one end, the hook-shaped is bent, the bimetallic strip 24 is exposed End 17 of the snap spring 16. The combination is the two metals that cause the bimetal effect are chosen that the metal with the larger coefficient of expansion the side of the bimetallic strip adjacent to the heating element 25 24 lies. The heating element 25 is only when closed Contact between the switching contact 15 and the counter contact 14 flows through with electricity, as well as parallel connected electrical heating device with power. is the contact closed, the heating element 25 heats the Bimetal strip 24, this changes its shape and presses due to an increasing curvature in the direction of the snap spring 16 on their free end 17. After the expiration of a certain Time given by an increase in heat generation in the Heating element 25 and / or the change in shape of the bimetal strip 24, the free end 17 of the snap spring 16 is so far pressed down that the leg 22 below the Switchover point is whereupon the snap spring snaps and releases the switching contact 15 from the counter contact 14. there the power supply to the heating element 25 and interrupted to the electric heater, and by that As cooling begins, the bimetallic strip 24 migrates again back to its original position. If the Switching point, the snap spring 16 snaps back again, the switching contact 15 bears against the counter contact 14 and the The heating process starts again.

To change the adjustable ones desired by an operator Power must be the power supply for the electric heater be clocked as there is always mains voltage on the electric heating device is present and therefore the performance is not directly changed can be. That means that during a certain Time interval the switched voltage on the electrical heating device is present, and during a certain one of them independent time interval, no voltage is present. The The sum of these two times results in a period. The Ratio of the time interval in which the contact closed and there is voltage on the electric heating device to which Period duration is called relative duty cycle "ED". How from the explanations given above, the Time in the on state from the path that the must return free end 17 until the snap spring 16 snaps.

A change in this path length is thereby known achieved that the support plate 21, the snap spring 16th carries, with a projection 27 against the outer radius one Power cam 28, which is on an axis 29th is pressed. This will make the power adjustment device formed while the axis 29 the actuating means forms.

The pressing is done by an approximately right-angled one resilient metal element 31 which with one leg on the Housing of the power control device 11 is attached and on the other leg of the support plate 21 is attached. This metal element 31 is biased so that the support plate 21 against the outer radius of the power cam 28 is present. According to the description, this power cam has 28 a variable radius. Through a Rotation of an operator on the axis 29 depends on set position of the projection 27 at another Instead of on the outer circumference of the power cam 28, and depending on the radius of the disc at this point the support plate 21 and thus the snap spring 16 in one specific position to the counter contact 14 and the bimetallic strip 24th

The radius is in a position with a low power level the power cam large so that the free end 17 is close to the bimetallic strip 24 and this already after a short time, switching the snap spring 16 and so a separation of the contacts 14 and 15 can cause. In a The power cam shows a position with high power 28 a small radius so that the free end 17th is located at a greater distance from the bimetallic strip 24. As a result, this has a larger path (corresponds to one longer period) to move the snap spring 16 to Bring to snap.

When the contact is open, the switching contact 15 lies with it on the side facing away from the counter contact 14 on a counter stop 33 at. The distance between the switch contact 15 and the counter-stop 33 is designated D and determines how far the spring 16 after actuation of its free end 17 snapped. The larger D is, the lower they are Leg 22 after snapping below the abutment 20th and consequently the bimetallic strip 24 must continue upwards hike to reach the switch point.

According to the present invention, the variable contact pitch D achieved in that the counterstop 33 part is a wiper spring 34 which has an angled end is attached to the housing of the power control device 11 and the other free end 35 is slightly hook-shaped is. It lies on the outer radius of a second distance cam 36, which is adjacent to the first cam 28 is located on the axis 29. So the distance adjustment device educated.

According to the description, the distance cam plate 36 also a variable radius. By the resilient Attachment of the wiper spring 34 to the housing becomes this in every position against the outer radius of the distance cam 36 pressed. The counter stop 33 thus changes its position depends on the radius of the distance cam 36th

The shape of the cams 28 and 36 is as follows described: The power cam 28 has one for such applications known course of the outer radius. In a ZERO position of the power control device 11 is the Radius maximum to continuously decrease up to a place for maximum performance 38 where he has an additional Has indentation inwards. This indentation 38 not only increases the middle one due to its reduced radius Power output once again considerably, but gives you Users the clearly noticeable feedback that the top one Power level is set. After the indentation 38 is the section 37 of the ZERO position.

The course of the distance cam 36 corresponds to Area of section 37 that of the power cam 28. The radius then takes up to a second section 39 about from section 37 more than at Power cam 28 to continue from there again to climb to a third section, the Indentation 38 corresponds. That means that the radius first decreased and then enlarged.

Through the course of the distance cam described above 36 the contact distance D is small in the areas in which a high setting accuracy and a safe Function of the device switch is required. These are the lower and the upper performance range. In the medium performance range in which the requirements for setting accuracy but the cracking rate is lower contact distance D is greater.

FIG. 2 shows the power control device 11 from FIG. 1 shown again. However, the setting is Power from a low power in Fig. 1 by Twisting the axis 29 changed to a medium power Service. This can be seen from the fact that the projection 27 and the end of the wiper spring 34 in each section 39 the corresponding cam, the ZERO position section 37 is roughly opposite. In comparison to Fig. 1 can be clearly seen that the end 35 of the Grinder spring 34 a good distance away from the snap spring 16 is located as the projection 27 of the support plate 21. Furthermore, one can see that the legs 22 of the snap spring 16 a little further above the switchover point on Abutments 20 are as in Fig. 1. This means that the free end 17 of the snap spring 16 further down must be pressed until the snap spring snaps. The The function is the same as in FIG. 1.

3 shows the power control device 11 with the power setting from Fig. 2, but in a position in the snap spring 16 is snapped and the switch contact 15 has separated from the counter contact 14. The switch contact 15 is now with its back on the counter stop 33 at. It can clearly be seen that the legs 22 of the snap spring 16 lie below the abutment 20. Based on this Fig. 3 can be the inventive adjustment of the contact distance through the movable counter contact 33 particularly represent well. Due to the changing radii of the Cam discs 28 and 36 are not only the device switch 12 changed its position to the bimetal strip 24, but also the relative position between the counterstop 33 and the support plate 21 or the point at which the counter-stop 33 is closest to the support plate 21.

If one takes the position of the power cam 28 as given and varies the radius of the distance cam 36 in the central area 39, so you can see that this the switching contact 15 in its position to the counter contact 14 changes. Furthermore, the distance between the Legs 22 and the abutment 20. By the variable Counter stop 33 can both be set to the point which the snap spring 16 closes the contacts again as also the contact distance between the switching contact 15 and the mating contact 14. This distance corresponds to that Distance D between the rear of the switch contact 15 and the counter stop 33. In the illustrated in the figures The course of the cams 28 and 36 is the contact distance D small in the lower and upper performance range, in medium performance range, however, large.

The wiper spring 34 is preferably made of the same resilient Material like the snap spring 16 made. The counter attack 33 is the right-angled turn of a Section formed in the direction of the switching contact 15. He can through a cutout in the support plate 21st protrude.

4 is a diagram 40 showing the click rates above the ED shows a dashed click rate curve 41 a power control device according to the prior art shown. It begins at a starting point 46 with a low click rate of about one click per minute, is in its course with increasing ED first in a curve curved at the top and reaches one at its uppermost point 42 Cracking rate of over 4 cracks per minute. From an ED of about 50 percent, curve 41 drops again to one Endpoint 47 with a click rate of approximately one click per Minute.

The solid click rate curve 44 of the invention Power control device 11 also begins at the starting point 46, but rises less sharply to a top one Point 45, the at less than two pops per minute lies, and falls from there to the end point 47. Man clearly sees the reduction in the cracking rate in the medium performance range.

The choice of starting and ending points 46 and 47 for the same Cracking rates are arbitrary, but can be seen as cheap. By varying the radii of the two cams the click rate curve can be adjusted to a large extent. It other courses than curved curves are also conceivable, for example linear. For this only the outer radius of the Distance cam 36 can be designed accordingly.

Claims (9)

1. Power control unit with an adjusting device for an appliance switch (12) contained therein, particularly for electric heating appliances, whose position change leads to a change of a settable power level and which carries a switching contact (15), which engages in an "on" position on an opposite contact (14) and in particular supplies the electric heating appliance with power, and in an "off" position engages with a variable contact separation (D) with respect to the opposite contact on a counterstop (33), in which the adjusting device has a power adjusting device for the power level and a contact separation adjusting device separate therefrom, together with actuating means (29) for the actuation thereof, in which the contact separation adjusting device has a separation cam disk (36) with a varying radius, characterized in that onto the external radius of the separation cam disk is elastically pressed by a pretension a device carrying and/or at least partly forming the counterstop (33) and which is in the form of an additional spring (34).
2. Power control unit according to claim 1, characterized in that both the power adjusting device and the contact separation adjusting device can be simultaneously operated with common actuators (29).
3. Power control unit according to claim 1 or 2, characterized in that the power adjusting device, particularly also the contact separation adjusting device, is constructed mechanically, preferably by position changes due to mechanical action.
4. Power control unit according to one of the preceding claims, characterized in that the power adjusting device for changing the position of the appliance switch (12) has a power cam disk (28) with varying radius, on whose external radius is elastically pressed by a pretension the appliance switch.
5. Power control unit according to claim 1 or 4, characterized in that both cam disks (28, 36) are fitted to a spindle (29), which can be turned with an actuator by a user.
6. Power control unit according to claim 4 or 5, characterized in that the external radius of the power cam disk (28) is at a maximum for a zero position (37) of the power control unit and as from this portion decreases continuously to the zero position portion in a circumferential direction opposed to a preferred actuating direction of the power control unit.
7. Power control unit according to claim 5 or 6, characterized in that the external radius of the separation cam disk (36) is at a maximum at the zero position (37) of the power control unit, decreasing from this portion in a direction opposed to the preferred actuating direction to a second portion (39), which roughly faces the first portion and has a minimum external radius and from here increases again in a third portion to the zero position portion.
8. Power control unit according to one of the preceding claims, characterized in that the appliance switch (12) is constructed as a snap-action switch, particularly with a two-part, bistable snap-action spring (16), which loads the switching contact (15) against at least one switching position.
9. Power control unit according to claim 8, characterized in that for improving the switching processes of the contacts (14, 15), the snap-action spring (16) has an impact fork.

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