GB1601098A - Heating units for the inlet manifolds of internal combustion engines - Google Patents

Description

(54) IMPROVEMENTS IN OR RELATING TO HEATING UNITS FOR THE INLET MANIFOLDS OF INTERNAL COMBUSTION ENGINES (71) I, RONALD GEORGE WEAR ING, a British subject c/o R. G. WEARING LTD., of Dodnor Lane, Industrial Estate, Newport, Isle of Wight (formerly of 3, Manor Way Industrial Estate, Old Woking, QU22 9LA), do hereby declare the invention, for which I pray that a patent may be granted to me, and the method by which it is to be performed, to be particularly described in and by the following statement: The present invention relates to a heating unit for installing in the inlet or induction manifold of an mternal combustion engine, for example of a motor car, for preheating fuel flowing from the carburettor of the engine so as to facilitate starting of the engine under cold climatic conditions.Such units are generally controlled by a thermostatic switch which, upon staring, switches-on the heater when the ambient temperature is less than, for example, -50C, and switches-off the heater when the ambient temperature in the immediate vicinity of the engine rises, say above O"C, when the engine is running and heats-up.

Hitherto, manifold heating units have comprised an insulating body which is installed in the inlet manifold and has a circular open ing corresponding to the inlet or induction passageway. The insulating body is formed in two halves secured together by screws and having a sealing gasket located between the two halves. An annular heating element is fastened in the opening about its periphery by means of small securing wires and one lead wire extends from the heating element to a thermostatic control switch housed in the body at a position outside the manifold. The other lead wire for the heating element is in contact with the manifold and is thereby connected to earth. The lead wire connecting the element to the thermostatic switch is sealed in the bore via which it extends from the opening by means of a lead pellet.

With manifold heating units it is important to prevent leakage of air into the inlet mani fold as this adversely affects the performance of the engine. Whilst the heating unit described above has been used quite extensively, it has proved a problem, because of its construction, to render it completely leak proof when installed in a manifold. Moreover, it is complicated and expensive to manufacture.

It is an object of the present invention to provide a novel construction of manifold heating unit which has less risk of leakage than the hitherto known heating units and which can be produced more efficiently and econo mically.

The invention consists in a manifold heating unit comprising a body made from insulating material and having an opening therethrough corresponding to the passageway in an inlet manifold and means for securing the body to the inlet manifold with its opening in alignment with the manifold passageway, a heating element mounted within said opening, a pas sage extending from said opening outwardly through the body and having a reduced dia meter portion inwardly of its outer end, and a lead wire for the heating element extending through said passage and sealed in said pas sage by means of a ball or pellet of deform able material disposed on the wire and de formed into engagement with the reduced dia meter portion of the passage.

Conveniently the lead-wire passage is formed with a counter-bore or the like at its outer end so that the passage has the required re- duced diameter portion inwardly from its outer end. Also conveniently, the lead wire is sealed in this passage by means of a split lead ball which is of slightly less diameter than the counter-bore. This ball is pinched on to the wire, is inserted into the counter-bore and is then pressed or pressed and spun into contact with the frusto-conical inner end of the counter bore so as to deform the ball into intimate contact with this end and into the reduced diameter portion of the passage leading there from. The inner end of the counter-bore, in effect, forms a seat for the deformed ball which is urged into contact with this seat and into the reduced diameter passage by the induction pressure existing in the inlet manifold.

The passage for the lead wire may extend from the opening in the insulating body to a cavity for containing a thermostatic switch which controls the operation of the heating element, this cavity being located adjacent the periphery of the body so as to be outside the inlet manifold.

Preferably, the opening housing the heating element is circular and the heating element is of substantially annular configuration and is mounted within the opening adjacent its periphery. The element may comprise a coiled heating wire.

A feature of the invention is the manner in which the annular heating element may be secured in the opening in the insulating body.

Hence, the opening in the body has a radial flange at one end and a ring of insulating material is an interference fit in the opposite end. The flange and ring cooperate together to form an annular groove for the heating element and engage opposite sides of the element so as to locate it in position in the opening. Preferably, the adjacent radial faces of the flange and ring are bevelled so that the annular groove formed thereby has diverging radial faces which engage the coils of the heating element and positively trap the element in the groove In order that the present invention may be more readily understood, reference will now be made to the accompanying drawings in which: Figure 1 is an end view of one embodiment of the invention, and Figure 2 is a section on the line II--II of Figure 1.

Referring to the drawings, the manifold heating unit comprises a body 1 moulded from insulating material and having a central circular opening 2 corresponding to the passageway in the inlet or induction manifold of an internal combustion engine. The body is provided with four bolt holes 3 by means of which it may be fastened between adjacent end flanges of an inlet manifold system with the central opening 2 in alignment with induction passageway. Gaskets (not shown) are disposed between the body and the end flanges.

Located adjacent the periphery of the body so as to be outside the manifold end flanges is a cavity 4 for housing a thermostatic control switch (not shown) for a heating element 5.

The heating element 5 is disposed within the central opening 2 adjacent its periphery.

It comprises a coil of heating wire arranged in annular fashion adjacent the periphery of the opening. The periphery of the opening is connected to the switch cavity 4 by means of a passage or bore 6 and the lead wire 7 at one end of the heating element extends through this passage for connection to the thermostatic switch. The passage is formed with a counter-bore or the like 8 at its outer end so that the passage has a reduced diameter portion 9 inwardly of its outer end. The lead wire 7 is sealed in this passage, so as to prevent leakage of air into the manifold via the switch cavity 4 and the passage 6, by means of a split lead ball 10 which is initially of slightly less diameter than the counter-bore 8.The lead ball is pinched onto the lead wire 7 and is then inserted into the counter-bore and seated in position by spinning the ball under pressure with the aid of a suitable tool (not shown) which may be inserted into the bore via a hole 11 in the opposite side of the switch cavity 4. The result of this procedure is to deform the ball into intimate engagement with the frusto-conical inner end of the counter-bore 8 and into the adjacent narrower portion 9 of the passage. This produces an extremely satisfactory seal to prohibit leakage of air into the manifold, the induction pressure within the manifold tending to assist the sealing effect by sucking the deformed ball into contact with the end of the counter-bore.

The lead wire 12 at the opposite end of the heating element extends axially from the opening and its free end is inserted into a small hole 13 in the end face of the insulation body so that when the body is clamped between the end flanges of the manifold, this lead wire makes contact with the adjacent end flange to connect the heating element to earth.

The heating element, itself, is trapped in an annular groove 14 in the periphery of the central opening 2. This groove is formed between a radial flange 15, which is moulded integrally with the body at one end of the opening, and an annular ring 16 of insulating material which has an interference fit in the opposite end of the opening. The adjacent radial faces 17, 18 of the flange and ring are bevelled so that they co-operate together to form an annular groove 14 having inwardly converging radial faces which serve to trap the coils of the heating element within the groove and prevent them from moving radially inwardly into the opening. The ring has a small notch 19 in its outer periphery through which the lead wire 12 extends.

It will be appreciated that, when the heating unit described above is installed in a manifold system, the only connection, through the insulating body, to the outside of the manifold, which might serve as a source of leakage, is the lead-wire passage 6 and this is satisfactorily sealed by the deformed lead ball 10.

The ring 16, which might cause leakage problems, is disposed within the manifold and is sealed by the gaskets between the unit and the manifold end flanges.

Whilst a particular embodiment has been described, it will be understood that modifications can be made without departing from the scope of the invention.

WHAT I CLAIM IS: 1. A manifold heating unit comprising a body made from insulating material and having an opening therethrough corresponding to the passageway in an inlet manifold and means for securing the body to the inlet manifold with its opening in alignment with the manifold passageway, a heating element mounted within said opening, a passage extending from said opening outwardly through the body and having a reduced diameter portion inwardly of its outer end, and a lead wire for the heating element extending through said passage and sealed in said passage by means of a ball or pellet of deformable material disposed on the wire and deformed into engagement with the reduced diameter portion of the passage.

2. A manifold heating unit as claimed in claim 1, wherein the lead-wire passage is formed with a counter-bore or the like at its outer end so that the passage has the required reduced diameter portion inwardly from its outer end.

3. A manifold heating unit as claimed in claim 1 or 2, wherein the lead wire is sealed within said passage by means of a split lead ball which is of slightly less diameter than the outer end of the passage or counter-bore.

4. A manifold heating unit as claimed in claim 1, 2 or 3, wherein the passage for the lead wire extends from the opening in the insulating body to a cavity for containing a thermostatic switch which controls the operation of the heating element, said cavity being located adjacent the periphery of the body so as to be outside the inlet manifold.

5. A manifold heating unit as claimed in claim 1, 2, 3 or 4, wherein the opening housing the heating element is circular and the heating element is of substantially annular configuration and is mounted within the opening adjacent its periphery.

6. A manifold heating unit as claimed in any one of the preceding claims, wherein the element comprises a coiled heating wire.

7. A manifold heating unit as claimed in any one of the preceding claims, wherein the opening in the body has a radial flange at one end and a ring of insulating material is an interference fit in the opposite end, said flange and ring cooperating together to form an annular groove for the heating element and engaging opposite sides of the element so as to locate it in position in the opening.

8. A manifold heating unit as claimed in claim 7, wherein the adjacent radial faces of the flange and ring are bevelled so that the annular groove formed thereby has inwardly converging radial faces which engage the coils of the heating element and positively trap the element in the groove.

9. A manifold heating unit constructed substantially as hereinbefore described with reference to the accompanying drawings.

10. A method of manufacturing a manifold heating unit as claimed in claim 1, substantially as hereinbefore described.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (10)

**WARNING** start of CLMS field may overlap end of DESC **. the scope of the invention. WHAT I CLAIM IS:

1. A manifold heating unit comprising a body made from insulating material and having an opening therethrough corresponding to the passageway in an inlet manifold and means for securing the body to the inlet manifold with its opening in alignment with the manifold passageway, a heating element mounted within said opening, a passage extending from said opening outwardly through the body and having a reduced diameter portion inwardly of its outer end, and a lead wire for the heating element extending through said passage and sealed in said passage by means of a ball or pellet of deformable material disposed on the wire and deformed into engagement with the reduced diameter portion of the passage.

2. A manifold heating unit as claimed in claim 1, wherein the lead-wire passage is formed with a counter-bore or the like at its outer end so that the passage has the required reduced diameter portion inwardly from its outer end.

3. A manifold heating unit as claimed in claim 1 or 2, wherein the lead wire is sealed within said passage by means of a split lead ball which is of slightly less diameter than the outer end of the passage or counter-bore.

4. A manifold heating unit as claimed in claim 1, 2 or 3, wherein the passage for the lead wire extends from the opening in the insulating body to a cavity for containing a thermostatic switch which controls the operation of the heating element, said cavity being located adjacent the periphery of the body so as to be outside the inlet manifold.

5. A manifold heating unit as claimed in claim 1, 2, 3 or 4, wherein the opening housing the heating element is circular and the heating element is of substantially annular configuration and is mounted within the opening adjacent its periphery.

6. A manifold heating unit as claimed in any one of the preceding claims, wherein the element comprises a coiled heating wire.

7. A manifold heating unit as claimed in any one of the preceding claims, wherein the opening in the body has a radial flange at one end and a ring of insulating material is an interference fit in the opposite end, said flange and ring cooperating together to form an annular groove for the heating element and engaging opposite sides of the element so as to locate it in position in the opening.

8. A manifold heating unit as claimed in claim 7, wherein the adjacent radial faces of the flange and ring are bevelled so that the annular groove formed thereby has inwardly converging radial faces which engage the coils of the heating element and positively trap the element in the groove.

9. A manifold heating unit constructed substantially as hereinbefore described with reference to the accompanying drawings.

10. A method of manufacturing a manifold heating unit as claimed in claim 1, substantially as hereinbefore described.