EP1364264A1

EP1364264A1 - Heatable dilation element

Info

Publication number: EP1364264A1
Application number: EP02735114A
Authority: EP
Inventors: Roland Starck; Barbu Scarlat Frunzetti; Wolfgang Richter
Original assignee: Behr Thermot Tronik GmbH; Fritz Eichenauer GmbH and Co KG
Current assignee: Eichenauer Heizelemente GmbH and Co KG; Behr Thermot Tronik GmbH
Priority date: 2001-03-02
Filing date: 2002-03-04
Publication date: 2003-11-26
Also published as: DE10110185A1; JP2005507059A; US7172133B2; DE10110185B4; JP4286000B2; KR20040052487A; KR100880605B1; WO2002086646A1; DE10110185B9; US20040094633A1

Abstract

A dilation working element (1d), in particular for operating a thermostatic valve, comprising a housing (14) and a moving working pin (1b), extending out of the housing, whereby a dilating material and a heating device, with an electrical resistance element applied to a support, are arranged in said housing. According to the invention, the response speed of such a device may be particularly increased, whereby the support (2) comprises a cavity and the resistance heater element is a heat conductor (3) wound around said support.

Description

Heated expansion element

The invention relates to an expansion working element, in particular for actuating a thermostatic valve, with a housing and with a movable working pin which is led out of the housing, wherein expansion material and a heating device with an electrical resistance element attached to a carrier are arranged in the housing.

Engines have increased consumption and emission values, especially in the cold running phase. This phase must therefore be shortened if possible. This is achieved by reducing the amount of coolant circulated during the cold running and warming up phases. For this purpose, the coolant circuit of an internal combustion engine has a main valve 1 which blocks the flow when the coolant is cold and a bypass valve which is then open. Such a valve is regulated on the basis of engine and operating data such as exhaust gas temperature, speed, torque and oil temperature via a gate device for controlling such a thermostatic valve by supplying electrical power to the heating device.

EP 718 738 A2 shows a heating device with a flat carrier on which a thick-film resistor is attached. It is disadvantageous that the thick-film resistor is only in contact with the expansion material, such as expansion material axis, on its side facing away from the support and, moreover, the heating surface is small due to the design of the support. In addition, the stroke of the actuating pin is limited by the central diagonal arrangement of the carrier.

DE 197 05 721 AI shows a generic device in which the PTC element is arranged on the outside of the housing. The heat transfer to the expansion material in the housing is clearly poor. This also applies in principle to the subject matter of DE 42 33 913 AI and DE 44 09 547 C2, in which a PTC element is arranged on the end face in the interior of the housing and has only a small contact area with the expansion material.

In contrast, the invention has for its object to improve a generic device in that at cheaper and safer manufacturing a ^'s response (step response) and intrinsichere reliability is briefly given.

According to the invention, the stated object is achieved in a generic device in that the carrier has a cavity and in that the resistance heating element is a heating conductor which is wound around the carrier.

The configuration according to the invention ensures that the resistance heating element, as the heating conductor itself, is is poor and can therefore be heated up very quickly, the training as a heating conductor allowing a large heat transfer surface to the expansion material, which is supported by the formation of a cavity which is provided in the heating line. This cavity also allows for the large stroke of the actuating pin.

According to the invention, in particular compared to the known thick-film element with the same dimensions, in particular the same outer dimensions of the housing, there is a six times larger heat dissipation area, so that specific heating powers are reduced in a corresponding manner with the same power supply. This significantly reduces the risk of local overheating. In addition, due to the cavity, the heater can be the same

Housing dimensions have a greater axial length without the stroke of the actuating pin being reduced. In this way, uniform expansion of the expansion material is achieved over a large part of the housing height due to its poor thermal conductivity. Overall, the reaction times of the device according to the invention are significantly reduced.

According to a preferred embodiment of the invention it is provided that the heating conductor has a positive coefficient of electrical resistance, i.e. the resistance-temperature characteristic curve increases monotonously in the work area.

This eliminates the risk of expansion material overheating and thus destruction of the device according to the invention by the self-regulating properties of the heating element. In another preferred embodiment it is provided that the heating conductor has a positive Temperaturkoeffezienten the electrical resistance of> 2 x 10 ^"3 / K. In this way, the coolant of an internal combustion engine is the ^'heating power of the Widerstandsheizele- ments approximately reduced by one third in the usual temperature range, so that the supply of heat by the heating element at high temperatures is less than the heat dissipation by the coolant washing around the expansion material, so that overheating is excluded.

According to a preferred development of the device according to the invention, it is provided that the carrier has an essentially cylindrical outer contour and that the carrier body has a polygonal outer contour, in particular the carrier having a cage-shaped structure. A cage-shaped structure can be formed in that the carrier has longitudinal and transverse ribs. The heating conductor is preferably wound around the longitudinal ribs of the carrier. This ensures all-round contact between the heating conductor and the expansion material, which increases the response speed.

For all-round insulation of the individual heating conductor windings, it is provided that the heating conductor is surrounded by an insulating layer that is resistant to high temperatures. This can be an insulating layer made of polyimide lacquer, ceramic or glass.

In a further preferred embodiment it is provided that the carrier body consists of high temperature resistant material. The carrier can in particular be made of temperature-resistant, permanent plastic, such as polyphenylene sulfide (PPS) or liquid crystal polymer (Liquid Christall Polymer - LCP), a polymer that is self-reinforcing due to the formation of fibers, but also of epoxy resin, such as Araldit ^® , and finally also Ceramics, in particular injection-molded polymer ceramics, ie polymer-bonded ceramics in the initial state.

A heat conductor with a positive temperature coefficient preferably consists of an alloy based on an iron-nickel alloy, which can also have other elements such as chromium. The nickel content is in particular between 65 and 75%, preferably around 70%, the ones content between 25 and 35%, preferably around 30%; the chromium content is optionally in the range of 0.5-2%, preferably approximately 1%.

The specific electrical resistance of such a PTC wire rises from about 0.3 ΩmπArf ¹ at room temperature of 200 largely linearly with the factor C _δ = 1 + .DELTA.T to Be ^¬ humor of resistance at different temperatures, wherein the temperature coefficient α in the largely linear application range is approximately α = 3000 x 10 ^"6 / C °.

In a preferred development of the invention it is provided that the carrier in the housing of its contact parts bearing member by an O-ring seal is because in particular ^¬ sondere the O-ring or is disposed between the housing and supports in an annular shoulder of the support body but the O-ring seal is arranged in a laterally circumferential to a base of the annular groove Trä ^¬ gers. As a result, the carrier can be sealingly connected to the housing. This configuration is particularly advantageous if, as is provided in a further development, contact parts of the carrier are injected into a base. A rational production of the carrier body with the contact parts provided in it and thus the device according to the invention is achieved with a method for producing a carrier for such a device, in which contact parts contact the injection molding machine. stuff for a carrier of a heat conductor in the form of a lead frame.

Further advantages and features of the invention result from the claims and from the following description in which exemplary embodiments of the invention are explained in detail with reference to the drawings. It shows:

1 shows a longitudinal section through an inventive device for controlling a thermostatic valve.

2 shows a perspective illustration of a carrier for the heating conductor with injected

Contact parts;

Fig. 3 is a partially sectioned illustration of the device according to the invention with a different type of seal compared to Fig. 1

Bottom portion;

4 shows a perspective illustration of a heating device according to the invention;

5 shows a side view of a carrier according to FIG.

2;

Fig. 6 shows a section through the object of Fig. 5 along the line I-I

FIG. 7 shows an illustration of a heating conductor carrier during production with a section corresponding to II -II of FIG. 4; 8a and b Alternative configuration of the contact parts with carrier, here plan view of the underside of the carrier and section along the line III-III.

Fig. 9 resistance-temperature characteristics of a preferably used heating conductor material.

A device 1 according to the invention has a substantially cylindrical housing 14 with a pot-shaped lower part 14a and an upper part 14b, which is firmly connected to the housing 14a by flanging the free end face of the housing lower part 14a.

A heating device 1 a is arranged in the area of the lower housing part 14 a facing away from the upper housing part 14 b. An actuating pin 1b is led out through the upper housing part 14b and is surrounded by a membrane 1c within the housing. The further interior of the housing 14 is filled with an expansion element ld, such as expansion wax.

The heating device la has a carrier 2. This has an actual bobbin 7, which is formed like a cage from longitudinal and transverse ribs 8, 9. The transverse ribs 9 -in the embodiment is only an dargestellt- ^• stabilize the bobbin 7 and prevent while, of winding of the heating wire is formed a constriction of the longitudinal ribs 8. At the upper end of the carrier body is a solid ring 10th The ring 10 has lugs 11, the outer dimensions of which correspond to the inner diameter of the cylindrical lower housing part 14a. On the side of the carrier 2 facing away from the ring 10, a base 4 is formed, the diameter of which also corresponds to the inner diameter of the corresponds to the lower housing part 14a. Base 4 and ring 10 with lugs 11 thus center the carrier 2 in the housing 14. Inside the base 4, a ring shoulder 16 is formed, which receives an O-ring 15 for sealing. ^* An alternative proper sealing of the carrier 2 is shown in FIG. 3. Here is a radially circumferential annular groove 17 is formed on the side of the base 4 of the carrier 2, which also receives an O-ring for sealing. This results in a large contact surface 20 between the carrier 2 and the housing 14 and thus a high level of security also with regard to the large internal pressure prevailing in the housing 14. In addition, in the embodiment of FIG. 3, a sealing compound 19 is introduced in the area of a keyway 18 between the base 4 and the inner wall of the housing 14, which also acts as a seal due to the high internal pressure. In principle, this sealing compound 19 can also be provided in the embodiment of FIG. 1.

Contact parts 5, 6 with inner connection ends 5a, 6a and outer connection ends 5b, 6b are injected into the base 4 of the support 2 and each protrude from the support 2. Around the coil bobbin 7, a heating wire is wound a single layer 3, at both ends thereof are respectively connected to the inner terminal ends 5a, 6a contact parts 5, 6 ^'.

From FIG. 6, which shows the section II of FIG. 5 through the carrier 2, it can be seen that an inner boundary line of the longitudinal and transverse ribs 8, 9 of this exemplary embodiment form a circle, so that the interior of the carrier body 2 is cylindrical. The outer sides or edges of the - in this exemplary embodiment 6- longitudinal - ribs 8 project beyond the outer dimensions of the - in this case one - transverse rib 9 such that the outer connecting line ^" between two adjacent longitudinal ribs 8 outside the outer dimensions of the transverse rib 9 touched even a heating wire 3 wound around the outer sides of the longitudinal ribs 8 does not cross the ribs 9 and therefore, just as in the area of the openings between the longitudinal and transverse ribs 8, 9, can also be washed around on all sides by the wax wax in the area of the transverse ribs 9. By arranging the

In the illustrated exemplary embodiment, the heating wire is guided in longitudinal ribs 8 in the form of a uniform hexagon. Another number of longitudinal ribs 8, for example between 3 and 10, preferably between 4 and 8, is also possible.

The injection of the contact parts 5, 6 into the carrier 2 is indicated in FIG. 7. From FIG. 7 it can be seen that the contact parts 5, 6 are in the form of a lead frame, in which the parts of the lead frame shown in broken lines in FIG. 7 are still present during the spraying process. As can be seen from FIG. 7, a plurality of carriers 2 are simultaneously injected into the mold. After the carrier 2 and the lead frame have been removed from the injection mold, the parts shown in broken lines are removed, so that only the contact parts 5, 6 shown in full lines remain connected to the individual carrier 2. This ensures a rational and well-sealed connection of the contact parts 5, 6 to the outside.

In an alternative embodiment of the contact parts 5, 6, these are not made of flat material, but rather round. The inner ends 5a and 6a are flattened and shaped as a fork 21. The heating wire is attached to it in such a way that it is first wound behind the fork and the end is then passed through the gap 21 of the fork 21. By squeezing the fork tips, the end is securely fixed by melting the layer of insulating material when soldering at this point. The electrical connection is established (see Fig. 8). Fig. 9 shows the monotonically increasing resistance-temperature characteristic of the heating conductor.

Claims

claims

1. Expansion material working element, in particular for actuating a thermostatic valve, with a housing and with a movable working pin which is led out of the housing, expansion material and a

Heating device are arranged with an electrical resistance element attached to a carrier, characterized in that the carrier (2) has a cavity and that the resistance heating element is a heating conductor (3) wound around the carrier.

2. Working element according to claim 1, characterized in that the heating conductor (3) has a positive temperature coefficient of electrical resistance.

Working element according to claim 2, characterized in that the heating conductor (3) has a positive temperature coefficient of the electrical resistance. from> 2 - x 10 ^" ³ / K.

4. Working element according to one of claims 1 to 3, characterized in that the carrier has a substantially cylindrical outer contour.

5. Working element according to one of claims 1 to 3, characterized in that the carrier body (2) has a polygonal outer contour.

6. Working element according to one of the preceding claims, characterized in that the carrier (2) has a cage-shaped structure.

7. Working element according to claim 6, characterized in that the carrier (2) has longitudinal and transverse ribs (8, 9).

8. Working element according to claim 6 or 7, characterized in that the heating conductor (3) is wound around outer edges of the longitudinal ribs (8).

9. Working element according to one of the preceding claims, characterized in that the heating conductor (3) is wound in one layer on the carrier body (2).

10. Working element according to one of the preceding claims, characterized in that the material of the Heizlei ^¬ ters (3) is a nickel-iron alloy.

11. Working element according to one of the preceding claims, characterized in that the heating conductor ^'is covered with a high-temperature-resistant insulating layer. •

12. Working element according to claim 11, characterized in that the heating conductor is made of an insulating layer Is coated with polyimide varnish.

13. Working element according to claim 11, characterized in that the heating conductor is coated with an insulating layer made of ceramic.

14. Working element according to claim 11, characterized in that the heating conductor is coated with a glass insulating layer.

15. Working element according to one of the preceding claims, characterized in that the carrier body (2) consists of high temperature resistant material.

16. Working element according to claim 15, characterized in that the carrier body (2) made of thermoplastic, preferably polyp enylene sulfide (PPS) or. Liquid crystal polymer (Liquid Christall Polymer LCP) exists. ^{• '}

17. Working element according to claim 15, characterized in that the carrier (2) consists of thermosetting plastic, in particular epoxy resin, such as Araldit ^® .

18. Working element according to claim 15, characterized in that the support body (2) consists gekennzeich ^¬ net from spritzgießfähiger polymer ceramic.

19. Working element according to one of the preceding claims, characterized in that in a base (4) of the

Carrier (2) contact parts (5, 6) are injected.

20, working element according to one of the preceding claims, characterized in that the carrier (2) in the housing (14) of its contact parts (5, 6) carrying ends by an O-ring (15) is sealed.

21. Working element according to claim 20, characterized in that the O-sealing ring (15) between the housing (14) and carrier (2) is arranged in a ring shoulder (16) of the carrier body (2).

22. Working element according to claim 20, characterized in that the O-sealing ring (15) is arranged in an annular groove (17) which extends laterally on a base (4) of the carrier (2).

23. Working element according to one of the preceding claims, characterized in that a base (4) of the carrier body (2) has a keyway on its side facing the heating conductor, in which sealing compound is arranged.

24. Working element according to one of claims 17 to 23, there-. characterized in that contact parts (5,6) consist of flat material.

25. Working element according to one of claims 1 to 23, characterized in that contact parts (5, 6) consist of round material.

26. The apparatus according to claim 25, characterized in that the inner end parts (5a, 6a) of the contact parts (5,6) pressed flat and are designed as a fork.

27 Device according to claim 26, characterized in that the heating wire 3 below ^'the' fork on the 'end (5a, 6a) of the contact part (5, 6) wound, guided by the fork (21) and the tip to define the Heating wire edge is compressed.

28. 'Thermostatic valve, in particular for the coolant circuit - running an internal combustion engine, characterized by an expansion element working element according to one of the preceding claims.

29. A method for producing a carrier for a device according to one of claims 1 to 24, characterized in that the contact parts to the one injection -

Tool for a carrier of a heating conductor in the form of a lead frame are supplied.