CN1543265A - Electrical heater - Google Patents

Abstract

A die-cast heater (2) for a liquid heating vessel comprises a heating element (4) arranged in substantially a single turn about the periphery of the heater and having overlapping end portions (34). The overlapping end portions (34) allow the heating element (4) to heat substantially the entire periphery of the heater (2). The die-cast element carrier comprises integral bosses (30) which are in direct thermal contact with the heating element (4) and serve as thermal contact locations for bimetallic actuators of a control for the heater (2). The boses (30) smooth out transient fluctuations in the temperature registered by the bimetallic actuators to prevent inappropriate operation.

Description

Electric heater

The application is that application number is that 97195349.X, the applying date to be on May 15th, 1997, application people be Strix Ltd., denomination of invention dividing an application for the application for a patent for invention of " electric heater ".

Technical field

The present invention relates to electric heater, relate in particular to the electric heater that is suitable for forming the liquid heating vessel seat.

Background technology

As everyone knows, in liquid heater, the vessel bottom has at least a part to be made up of the heater of a die casting.Such heater comprises the electrical heating elements of a band guard shield, and this heating element is moulded into a side of aluminum or aluminum alloy dish, and the dish opposite side forms the inner surface of container holder.Typically, such heater and vessel bottom wall are close together by the pinching screw folder, put into a seal simultaneously between the bottom of heater and chamber wall.

Summary of the invention

From first aspect, the invention provides and comprise one by the die casting heater of casting band guard shield heating element in the element bearing part, heating element wherein is mounted at least one circle around the periphery of heater, and overlapping in the end, and heat will be provided by the whole periphery along heater roughly.

Preferably, the heating element quilt is coiled one circle roughly, and the terminals of this heating element are preferably near arranging.This has made things convenient for being connected of terminals and some control unit, for example control unit of describing in the WO 95/34187.

Most preferably, the heating element end of drawing from the bearing part approximate vertical is parallel substantially.

Heating element terminal overlapping roughly to provide heat on 360 ° the scope.Provide heat for making on whole 360 ° scope, heating element must extend beyond 360 °, promptly considers such factor, and " the cold tail " of heating element may extend into the suitable segment distance of heating element from its end.Cold tail can be closely overlapping, because in fact they produce seldom or do not have a heat, thereby prevent the focus localization of heater periphery, be assemblied under the situation of plastic wall container this point at heater especially useful, thereby because may producing enough heat near the plastic wall of container, these focuses damage chamber wall, such as not having liquid and under the situation that heater button closes at one.Therefore, in one embodiment, have only cold portion overlapping in fact.Certainly, depend on that cold tail stretches the degree that is back in the heating element, such assembling is possible, and promptly the heating part of heating element is less than 360 °, for example 330 °～360 ° around the extension of heater periphery.Such layout falls within the scope of the present invention.

When needing heater that a large amount of heat output is provided, in the center of heater, tolerable has the regional area of higher temperature, and does not obviously improve the peripheral working temperature of heater.

Accordingly, in a preferred embodiment, the heating element overlapping end can be by the periphery of heater, and it is inside preferably to be approximately perpendicular to this periphery.The end of inwardly drawing can be provided additional heat with the middle part at heater by at least a portion heating along length.The overlapping part in end can cause providing at the middle part of heater higher partial power's density.Preferably, overlapping end fully extends through the central area of heater haply, and connector lug can be near the peripheral disposition of heater like this, allow heater therein heart zone above have maximum space to arrange the control piece of heater.

Preferred bearing part has the device that for example one or more screws, pillar etc. are installed the responsive to temperature control piece.

In addition, for one or more thermo-responsive control piece actuators are installed, bimetallic actuator for example, bearing part can have one or more thermo-contacts district.In an effective especially embodiment, the thermo-contact district contacts with the heating element direct heat on a boss.Boss plays the effect of heat absorber, takes away heat from heater element, and the temperature of boss will reflect the temperature of heater element more exactly like this.This is to boiling dry or during dry combustion method, before any part of heater was overheated, it was favourable that thermally-responsive controls must be worked.And because the thermal inertia of self, boss fluctuates level and smooth temp of heating element.This fluctuation may cause the bimetallic actuator misoperation.The size of boss and position must be determined by rule of thumb according to desired response times.

Extend in overlapping end under the situation in heater center zone, boss provides a platform on element bearing part datum level, so when the control piece of heater be placed in heating element above the time, the thermo-contact between bimetallic actuator and the heater can be kept.

Being more preferably the boss extending transversely, further is laterally interior to stretching, extension from heating element again.

The structure that heat conduction boss device is considered to a kind of novelty is proposed.From more further viewpoint, the invention provides a kind of heater of die casting thus, it comprises one by the heating element of the band guard shield of casting in the element bearing part, and wherein the element bearing part has a boss that contacts with the heater element direct heat at least.This boss provides a thermo-contact position for the bimetallic actuator of control piece.

According to have the present invention of thermally sensitive control unit who is preferably mounted at the middle part, the present invention includes the heater of a die casting.

Description of drawings

Now by with reference to the accompanying drawings preferred embodiments more of the present invention are described for example, wherein:

Fig. 1 is the plane graph of the die casting heater of first kind of embodiment of the present invention;

Fig. 2 is the cutaway view along Fig. 1 center line 2-2;

Fig. 3 is the profile along Fig. 1 center line 3-3;

Fig. 4 is the plane graph of the die casting heater of second kind of embodiment of the present invention;

Fig. 5 is the partial sectional view along Fig. 4 center line 5-5 that has amplified;

Fig. 6 is the cutaway view along Fig. 4 center line 6-6 that has amplified;

Fig. 7 is the cutaway view along Fig. 4 center line 7-7 that has amplified.

Embodiment

In each embodiment that illustrates, same reference number is used to indicate same parts.

With reference to figure 1,, the heater 2 of a die casting in this bearing part, has been cast into the heating element 4 of a band guard shield but comprising the element bearing part 3 of a cast aluminium alloy.

Bearing part roughly is circular.Heating element 4 fully extends around the peripheral of container, and its longitudinal axis with dashed lines 6 is indicated in Fig. 1.As shown in Figure 2, the heating element of band guard shield comprises a metal shell 8, for example mild steel, copper or stainless steel have been installed the nichrome or the similar heating resisting metal heater strip 10 of coiling therein, and its is insulated by electric insulation filler and the metal shell 8 such as magnesium oxide 12.The end of heater strip 10 is located to be connected with 16 two at reference icon 14 with the cold tail 18 of so-called heating element.This cold tail is made by copper or similar material, connects the spillikin of the terminals 20 of power supply to overhanging formation from the end of shell.

Can see that from Fig. 1 to Fig. 3 the end of heating element 4 is overlapping and vertically stretch out from bearing part haply in foundry goods, its length is enough to be connected with power supply.We can see in Fig. 1 simultaneously, because the end is overlapping, heating element 4 has extended beyond 360 ° around the periphery of bearing part 3, in fact, the cold tail 18 that it is roughly overlapping heating element 4 this means that the heat that has only in the zone 22 that limits betwixt relatively seldom produces.Therefore, directly heating does not extend to 360 ° of the container periphery fully, and only has about 330 °.Yet, if local overheating takes place when overlapping in the heating part that the periphery that it is exactly heater that overlapping cold tail 18 has an advantage will can not resemble heating element 4 in this zone.

Because heating element 4 is roughly around the bearing part peripheral disposition, so the center 24 of bearing part is empty so that on the bearing part platform installation and control part.Especially, this just is being suitable for an integral type controller type that has overheat protective function and stand-by protection function concurrently of having described in WO95/34187.For holding such controller, bearing part has accepts the fixedly assembling stand 26 of rigging screw etc. of control piece, and bearing part also provides special regional 28 to hold the bimetallic actuator of controller.

Have this custom design controller, the close layout of heating element terminals 20 is particularly advantageous, reduced to minimum because it will connect the total amount of controller and terminals material requested.

Heating element can be installed in a heating vessel bottom or its substrate, for example with following clamp of suitable method with heating element and heating container.

Fig. 4 has shown heater 2 according to second kind of embodiment of the present invention to Fig. 7.Fig. 4 is similar to the heater 1 among Fig. 3 with Fig. 1 to the heater 2 among Fig. 7, will only introduce the different characteristic of this embodiment in detail here.

As shown in Figure 4, the overlapping region 22 of heating element 4 is disposed in 24 li of the central areas of heater in the heater 2.Heating element 4 is roughly circular more than half part around the heater periphery, and overlapping heating part 34 extends into the central area 24 of heater 2 with same direction.2 of indicating with reference number 14 and 16 in Fig. 4 of overlapping heating part 34 and the cold tail 18 of heating element locate to be connected.In Fig. 5, show being connected of cold tail 18 and the overlapping thermal treatment zone 34 in greater detail.Terminals 20 and cold tail 18 are arranged in the heating element 4 peripheral loops near the periphery of heater 2, make heating element 4 not produce under the situation of a focus in the periphery near heater 2, have maximum length.Overlap the central area 24 of heater 2 by heating element 4, guaranteed to obtain the maximum length of heating element in the periphery and the central area 24 of heater 2.Adopt this layout that 3 kilowatts heat output can easily be provided in external diameter for 11 centimetres heater.Fig. 6 and Fig. 7 show the cross-section structure of heater 2.

As can seeing in Fig. 4 and Fig. 6, two boss 30 cross out from the inward flange of heating element 4 peripheral circumference on bearing part 3.Boss 30 all is an entity, as the part of element bearing part 3 by integral casting forming.Boss 30 contacts with shell 8 direct heat of heating element 4, to guarantee from heating element 4 to boss 30 good heat transfer.

The size of boss 30 makes them that enough thermal capacity be arranged, and to serve as the available heat receiver from heating element, is not subjected to the influence of heating element 4 transient temperatures fluctuation substantially.The upper surface of each boss 30 provides a thermo-contact district 28 for the bimetallic actuator of heater controller (not shown), and controller is an integral type controller of describing in WO 95/34187 for example, thereby the thermo-contact district should have corresponding size.Each boss 30 has enough height on the datum level of element bearing part 3, be installed on the heater 2 on the overlapping region 34 of heating element 4 to allow a controller.Be installation and control device on heating element 4, the erection column 26 of controller also is made at a suitable height.

Certainly, without departing from the present invention, can make some change to different embodiment.For example, the upper surface of die-casting element can be handled, such as doing anode treatment, with aesthetic feeling and the corrosion resistance that improves it.And this plate can constitute the whole substrate of container or be the part of substrate.

Claims (1)

1. the heater of a die casting, the heating element that comprises the band guard shield of a casting in the element bearing part, wherein the element bearing part has a boss that contacts with the heating element direct heat at least, and boss provides a thermo-contact district for the bimetallic actuator of controller.

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