HEATING ELEMENTS FOR FLUIDS

The invention relates to a heating element for fluids, especially for blow-by-gases, with at least one PTC element designed as electric radiator, the via of au & Nkulengu rail; power supply contacts arranged [...] of the heating element can be supplied with electrical power available.

Such heating elements are well known, for example from the nearest State of the Art, EP-A -1,314,862. A heating device for a pressure regulating valve is in this Publication, especially for blow-by-gases, described. The heating device is constructed as an integrally-to-handle and pre-assembled heating element; power supply contacts designed as contact pins are held in the heating element supplied via electrical energy Radiator with. Further heating elements from the US-A -4,406,785 are for diesel fuel, the US-A -6,109,247 and the US-A -4,818,842 known.

To is to be monitored to detect a malfunction, for example, a failure of the heating, , it necessary, the function of the radiator. In particular, the failure of the heating system can lead to serious problems. So can lead, for example, a precipitating in the pressure control valve of the blow-by-circuit to an icing heating, the leads to an excess pressure in the crankcase of a motor vehicle, thus becoming a principal engine trouble. Equally a failure can of a heating system, which is used for preventing the lead [...] of diesel fuel in the filter, for remain lying of a vehicle. Even an increased heat output, as it is possible, for example, by a short circuit locally, can lead to serious problems. To are described to avoid this have been taken, in the various possible solutions State of the Art, hereinafter briefly.

US-A -6,080,973 is shown a flow heater, in which a heater with a current sensor is connected, the measures the current through the radiator. The current sensor is part of a control unit, the resistance of the heater body calculated from the measured current. Over either the resistance or the measured current can be discovered malfunctions of the through-flow heater.

The US-A -5,770,836 disclosed a security monitoring for a thermal blanket, wherein the current through the heating bodies picked up and a voltage divider is supplied at one terminal. If the electrical contact between the power supply lines for the heating element is interrupted contacting problems for example, because of is connected with a resistor of the voltage divider feedback lines, so that a corresponding fault signal can be tapped off at a terminal.

US-A -4,736,091, a control device is described for a radiator, in which the heating radiator is used simultaneously as a temperature sensor. In addition to the heating current is passed through the heating radiator sensor stream a low. Over the voltage drop can be adjusted in the corresponding heating power sensor stream. The sensor stream not substantially for heating the heater body wherein when making.

The JP-A a -06-123249 fuel heating disclosed, wherein the fuel is heated via a radiator. The current consumed by means of a current sensor is detected, so that can be determined, whether the warm-up phase has terminated the heating body.

The 5,451,747 deals with an electric blanket US-A-is provided with wire-shaped radiators. A safety circuit in the event of a short circuit or a disconnection interrupts the power supply of the heat blanket.

The JP-A -07-014661 shows a safety circuit for a radiator, through which both a short circuit and an interruption of the supply of current can be detected.

The US-A -5,272,499 provides for a continuous-flow heater with radiators before, wherein the current through the radiator is monitored, display order are calcified, when the heating bodies.

Another scaling indicator is known from the US-A -4,292,499. Here the differences are connected in parallel by two fly Radiator & Nkulengu rail; currents terminate evaluated.

US-A -3,584,196 is shown a heater for cooking, in which the heating body is connected upstream of a PTC resistor. Via the matched voltage current curves of the PTC resistor and each other of the radiator is automatically regulates the heating power as a function of the heating voltage. From the above-mentioned US-A-Such arrangements are also GB-A -2,358,530 481,842, as well as the, the JP-A -2000-260553, WO-A -86/01064, the US-A -3,737,622 and DE-A -3138547 known.

As State of the Art emerges from the above-mentioned, a plurality of different physical forms for monitoring the operation of heating elements is possible. The from the US-A -5,770,836, the US-A -6,080,973, the US-A -4,736,091, the JP-A -06-123249, the US-A-State of the Art 545,747 and the nearest, the JP-A -07-014661, known devices for monitoring of heating elements on a rather expensive Circuitry as a facing for, on the other hand they permit no compact, easily to manufacturing construction.

The underlying purpose of the invention is, to create a heating element, which in particular is suitable for heating fluids in the case of small dimensions and is easy to install.

[...] & Nkulengu rail This problem is solved; for a heating element of the aforementioned type which, as a resistance wire formed in the heating element that, electrically in series with said at least one switched resistor is integrated and that at least one of au & Nkulengu rail Radiator; [...] of the heating element arranged accessible is provided, which is connected to one end of the resistor measuring contact, at which the voltage drop at the resistor or a for the voltage drop in the resistor can be tapped off signal representative.

Through this surprisingly simple solution it is possible, to build a compact heating element with small dimensions, which at the same time allows a confirmation of operation of the heater. The compact form is thereby achieved that the resistor is integrated in the heating element, i.e., with the heating element a constructional, forms integrally handleable and pre-assembled structural unit. The measuring contact enables via said at least one is monitoring the operation, at the in the operation of the heating element of the voltage drop in the resistor can be monitored by conventional voltmeter. As the resistor is connected electrically in series with the heating body is limited the switching plan on simplest arrangements.

The voltage drop at the resistor to zero ab Weakening, so that means that the flow of current through the heater is interrupted. If against the voltage drop across the resistor to a value at that is higher than a measured voltage drop in normal operation, so that means that on a short circuit in the heating element an elevated current fly & Nkulengu rail; t. In both cases via a change of the voltage drop is increasing recognize an operational disturbance. Since both an interruption of the current flow, for example by a contact break, as well as an increase in the current flow, for example by a short circuit, can lead to a serious defect is increased by the [...] & Nkulengu rail; e Structuring the heating element the operational safety.

In practice the monitoring can and the output from the voltage drop in the event of an operational disturbance in a simple way by A- [...] be implemented that upon dropping below a first predetermined limit value for the voltage drop at a second limit value is exceeded for a a the voltage drop alarm signal and representing interruption alarm a representative alarm signal is output a short circuit. The two limit values here lie preferably below or above the fluctuations in the voltage drop at the resistance occurring in normal operation.

A particularly compact construction of the heating element can be [...] & Nkulengu rail; to attain this that the resistance as a resistance wire, for example, as round wire [...] is carried out. Unlike other physical forms of resistance, such as a sheet resistance, and also by the resistance wire are leaving filament currents smallest construction heights [...] & Nkulengu rail at high; en realize, so that the [...] & Nkulengu rail; e design with a series connected, in the heating element integral resistor without gro & Nkulengu rail; e changes in existing heating elements may be installed. The resistance is so small that it does not affect the heat output, but one for the measuring function sufficiently gro & Nkulengu rail; en cutting waste caused.

To may be arranged to supply the electrical energy the heating body is fixed, this between two contact bodies, the resistor preferably on one of the contact body. In order to achieve high output figures at low manufacturing costs, the resistance is preferably by means of welding & Nkulengu rail; en, [...] & Nkulengu rail, for example, ; ene or [...] & Nkulengu rail; en, or by clamping or crimping fixed. While may also be used for fastening the resistance wire soldering method, quite expensive, however, these are partly because of the complicated temperature guidance.

The contact body can substantially [...] disc-shaped, preferably in the form of a contact sheet, be constructed. The contact body can be constructed simultaneously as a heat sink, which heat produced by the heating body uniformly & Nkulengu rail; ig via a greater & Nkulengu rail; of an improved heat transfer and thus distributed in the direction of the surface to be heated fluid.

A contact body, in particular the contact body lying in the direction of the energy supply in front of said at least one heating body, can be divided into two electrically isolated contact body, are bridged by the resistor. The a, first contact body can contact with said at least one of the resistor and the heater and measuring contact be electrically conductively connected. The measuring contact can here be molded in an improvement on the first contact body. Another measuring contact can at the other, second contact body be integrally formed, wherein the other, second power and the resistance can contact a contact body.

The [...] & Nkulengu rail can the heater and the resistor in particular like a housing contact body; en and thus exert a dual function as as regards the protection of the components of the heating element. The contact body can be combined with the at least one heating body further into a stack.

The structural integrity of the heating element may be joined produce To, further the contact body by at least one electrically insulating positive engagement element, for example plastic rivets, with each other.

In the heating element can be integrated further includes an electronic evaluation unit, as a function of the voltage drop at the resistor through which an alarm signal, representative of an operational disturbance in the heating element is, measuring contact can be output to the at least one.

In the following with reference to an embodiment with reference to the drawings the invention is outlined. As from the above description of the with the individual [...] & Nkulengu rail; en Options benefits stated, we can make use of individual features, are present in the embodiment described, also be omitted, if not directly connected with this feature is advantage in concrete application needs.

Fig. 1

a schematic perspective view of an embodiment of a [...] & Nkulengu rail; en heating element;

Fig. 2

a further schematic perspective view of the embodiment of 1 Fig.;

Fig. 3

a schematic perspective view of the inner structure of the embodiment 1 the Fig.;

Fig. 4

a schematic perspective diagram of the inner structure of the embodiment of a first variant 1 Fig.;

Fig. 5

a schematic perspective diagram of the inner structure 1 Fig. of the embodiment of a second variant.

In the following description, for elements and characteristics, the variants have the same or similar at the different Figures and the same or similar structure and/or function, the same reference symbols used.

Fig. [...] & Nkulengu rail 1 shows an embodiment of a; s 1 in a schematic perspective view in a view onto a first heating element end face of the heating element 1 serves for heating a 1st The heating element from blow-by-gas flows, pressure control valve, which is installed in motor vehicles.

As 1 to detect in Fig. is, the fact that the so-called heating element is constructed and a central opening substantially as an annular disc 1 forms from 2, in which for example, a fluid conduit is received. Regarding of the structure of the heating element is cited as a supplement to the following description to the EP-A -1,314,863, relative to their contents in the entire circumference is hereby made.

The heating element 1 has a holding structure 3 on, through which the the individual components is ensured one-pieceness of the heating element 1 and are fastened on the. The retaining structure as a plastic ring carried out in which embodiment described is 3, on the securing means, such as plastic rivets, and 4 are integrally formed in the form of pins [...] holding means.

The heating element 1 has power supply contacts 5a, 5b, for example, in the form of contact lugs or contact pins on, on the energy in the form of electric current can be supplied. The power supply contacts 5a, 5b preferably male contacts from form.

The heating element 1 further comprises two measuring contacts 6a, 6b on, one of which, the measuring contact 6a, 5a is connected directly to said one power, 6a and 5a so that the same signal is present at the power on measuring contact. In the measuring contacts 6a, 6b is a signal representative of the operation state of the heating element 1 tapped, as is explained further below.

All contacts 5a, 5b, 6a, 6b are of au & Nkulengu rail; en accessible arranged and can, as shown in 1 Fig., are adjacent one another, so that they may be contacted by a connector plug at a time. The contacts can, however, also be distributed in circumferential direction depending on the installation situation. The power 5a is in a first, . arcuate contact body 7 away [...], the contact plate may be designed as [...] disc-shaped. In circumferential direction to at least one side of the first contact body 7 is arranged a second contact body 8, except for a different extent in the circumferential direction of the annular heating element 7 is constructed substantially similar to the contact body 1. The 8 can also be made as contact plate contact body. The measuring contact 8 shall be made up in one piece up to the contact body 6b away.

7 and 8 are electrically insulated from one another, the two contact body, by a with an electrically non-conductive material between them, such as a plastic insulator or air, filled gap 9 is provided. Together 8 extend over the entire circumference of the heating element 7 and the two contact body. In particular the contact bodies can form a housing, the inside of the heating element 1 lying protects the components.

In the contact body 10 can be provided a recess 7, an insulating body is received in the, as is described further below.

In Fig. 1 2 a perspective view is represented to that end face of the heating element, the opposite end face 1 represented in the axial direction in Fig..

At this side is to detect a third contact body 11, the extended portion which extends integrally in the contact portion 5b. The contact body 11 extends in the circumferential direction of the heater body 2 and forms around the entire central opening 1,7 and 8 as the contact bodies, from a housing. The contact body 11 is made as a contact sheet.

The contact body 7,8 and 11 can be made from a metal sheet stamped and deep-drawn.

In Fig. 2 are further positive fixing means 12,13, here in the form of plastic rivets, to detect. The plastic rivets 12,13 are integrally formed on the retaining ring 3 1 in the axial direction through the entire heating element and extending put away. The or the 8 to 12 securing plastic rivets the a contact body 11 the contact body, the contact body 7 at the 11 13 the contact body or the plastic rivets.

To to facilitate the alignment of the contact body may have 7,8 and 11 during assembly, in the form of projections and recesses 14 at predetermined locations positioning aids. The contact body 7,8 and 11 may also be provided at at least one of their edges respectively with bent attachment tabs 15, in the axial direction and hold together the heating element in the axial direction engage around the respective opposite contact body 1. Alternatively, the tabs (not shown) with a latching projection 15 may also be constructed as detent tabs, snaps into the each of the opposed ring in the axial direction.

Fig. 2 shows the heating element 3 in the same perspective representation as Fig. 1, except that the contact body is represented in double dotted lines represented transparent and 11. As can be seen is between the contact bodies 7,8 on the one end face of the heating element 1 on the one hand and the contact body 1, on the other hand, a positioning element 11 on the other end face of the heating element 16 (for example, in ring shape) arranged. The positioning ring with recesses for the rivets 16 is 12,13 provided.

Also it can be seen that between the contact bodies 7,8 on the one hand and the contact body 11, on the other hand, two are arranged in the form of PTC elements 17 Radiator, their location in the heating element by corresponding recesses 16' is fixed in the positioning element 16,17 are inserted into the the heating bodies. The positioning element 16 is preferably made of an electrically insulating material. The location of the positioning element 15 and/or the fastening means 16 can by means of the tabs 12,13 be set. His thickness in the axial direction of the heating element 17 substantially to the thickness of the radiator 1 corresponds to 3 16 lie. at the side of the positioning element in Fig. in the axial direction the contact bodies 7,8 on.

1. a sandwich structure for the heating element occurs Consequently, [...] from the contact body 11, to which the positioning ring 16 and then the contact body 7,8 subsequently & Nkulengu rail; en. As the stack from the contact body 7 is explained held together, 8 and 11 and the positioning ring 15 and/or rivets 17 by means of the tabs together with the radiators 12,13. The width of the contact body 7,8 and/or 11 corresponds to approximately, preferably at least, the width of the heating body 17, so that the contact body 7,8 and/or capable of covering substantially the entire surface of the radiator 11. 7 and 8 are preferably sized contact body The that they in combination at least the heater cover 17, wherein the contact body 7 is electrically isolated from the heating unit 17.

Fig. 4 shows the heating element 1 in the perspective representation of the 3 Fig., except that both the contact element 11 and the positioning ring are represented in double dotted lines 16 and transparent, to release the view of the inner components of the heating element 1.

As in 4 to detect Fig. is, the contact bodies are 7,8 via a resistor 18 connected to each other, having one end at the contact body 7 and with its other end on the contact body 8 is electrically conductive fixed and 5a and the radiators 17 is arranged between said one power. In the embodiment 4 is configured as a resistance wire 18 the resistance the Fig., whose two ends are clamped or crimped. To that end, from the respective contact bodies 7,8 tabs punched out and under wedging of the ends of the resistor 19 18 for respective contact body 7,8 bent back.

Between the resistance wire 18 and the contact bodies 7,8 is mounted an insulating layer 20, which prevents that upon impact of the heating element 18 the contact bodies 1 the wire 7,8 along its longitudinal direction and extends so its resistance reduced. The insulating layer 20 can, so that the axial [...] & Nkulengu rail 1 not unnecessarily building thickness of the heating element; [...], in a corresponding recess of the contact body 7,8 be used. Alternatively, 20 also be used as an insulating layer or an intermediate metallization between-adhesive film. Also the insulating layer can also be constructed as part of the support structure 3.

The [...] & Nkulengu rail; e heating element 1 functions as described below: The power to a voltage source 5a is, the power, for example, connected to the ground 5b. The heating current fly & Nkulengu rail; t then by the power for the first contact body 7 7 5a electrically isolated from the other two contact bodies. As the contact body 8,11 and 17, from the heater 1 is disposed in the heating element, fly & Nkulengu rail; t the current via the resistor 18 to the second contact body 8 further, the connected with the radiators 17 is electrically conductive, by the heating bodies 8 are pressed on the contact body 17. The resistor in series with the radiators 17 and 18 is therefore 17 connected in current direction before the heating bodies.

From the contact body 8 fly & Nkulengu rail; t the heating current through the heating body 17 for contact body 11, which is also connected with the radiators 17 is conductive, 11 are pressed by them to the contact body. From the contact body 11 fly & Nkulengu rail; t the heating current [...] & Nkulengu rail; 5b via the protected when using power from.

In the measuring contacts 6a, 6b the voltage drop at the resistor 18 can be tapped off, since the two are connected directly to the ends of the resistor measuring contacts : The contact body 6a and the contact body 7 is directly with the 8 measuring contactmeasuring contact 6b connected directly with the. 6a and 6b is measuring contactmeasuring contacts Between the consequently the voltage drop at the, 7 and 8 occurs between the contact bodies of. Since the contact body 7,8 are connected with each other via the resistor 18, this voltage drop corresponds to the voltage drop at the resistor 18.

Occurs within said heating element is interrupted on a short circuit or the current supply 1, so changes the voltage drop across the measuring contacts 6a, 6b, wherein either a first predetermined limit value for the voltage drop is exceeded or fallen below a second predetermined limit value for the voltage drop. The voltage drop on the resistor 18 is therefore a signal representative for an operational disturbance of the heating element. One of the two limit values detected such a crossing Will, so the are measuring contacts 6a with the, 6b connected measuring device from an alarm signal, the indicative to an operational disturbance in the heating element 1.

The limit values, the lead to the alarm signal, can be determined by tests in a simple manner, in which the voltage drop across the resistor 18 are measured and adjusted mechanical cases of failure and is compared with the voltage drop occurring in the normal operating condition. In operating measuring contacts 6a are the, measuring contacts 6b to an external circuit for monitoring the differential voltage between the 6a, 6b connected.

Fig. 5 shows a variant of the embodiment of the 4 Fig., wherein the monitoring means 1 is integrated in the heating element 21. The power supply contacts 5a 21 is from the heating current to the monitoring means, the voltage drop between the contact bodies and 5b supplied with energy measures 7,8 or the voltage drop falls below predetermined. Where, or by circuits Unrealised limit values stored in the monitoring device, such a voltage placed on the is measuring contact 6b, and serves as a visual indication, for example, actuates the alarm signal. The monitoring device in the form of simple diodes or of a commercial integrated circuit 21 can be carried out for voltage monitoring.

Of course, deviations from the described embodiment and its variants are possible. Thus 17 substantially in the heating element 1 provided the number is the arbitrarily Radiator, except that at least one radiator is provided 17. Also the power can be combined into a single contact measuring contact 5a 6a and the.

Also the realisation [...] & Nkulengu rail is of the; en heating element 1 not limited to an annular configuration of the heating element, but can also be used in a heating element 1, having no central opening 7 with substantially-contiguous base surface 2 but contact body, without is assembled are bridged 2 has opening, and the intermediate resistor 18 to a stack with at least one intervening Radiator and, through the two contact body 7,8,. The base surface of the heating element can bent, for example circular or elliptical in shape, or one or more central openings and with or without [...] polygonal be 2 be constructed.

Alternatively, by the [...] & Nkulengu rail; e heating device 1 in addition to blow-by-gases also combustible fluids, such as diesel fuels are heated.