GB2199893A

GB2199893A - A fuel heater and filter device for diesel engines

Info

Publication number: GB2199893A
Application number: GB08730289A
Authority: GB
Inventors: Alberto Drusi; Franco Martinis
Original assignee: Gilardini SpA
Current assignee: Marelli Europe SpA
Priority date: 1986-12-30
Filing date: 1987-12-30
Publication date: 1988-07-20
Anticipated expiration: 2007-12-30
Also published as: IT8667986A0; FR2609111B1; ES2006030A6; IT1196890B; GB2199893B; FR2609111A1; DE3744134A1; GB8730289D0

Description

9 a 0 ro 1 1 A FUEL HEATER DEVICE FOR DIESEL ENGINES 219.9893 -The present

invention relates to a fuel -heater device and in particular to a device for heating diesel oil for diesel engines.

It is known that, at low temperatures of the order of +20 to - 21. 0 0 C, there is a problem in the supply of diesel oil to diesel engines due to the deposition of paraffins in 10, the filter which is fitted in the fuel supply circuit. To overcome this problem it is sought to increase the temperature of the diesel oil above all in the vicinity of the filter. A first solution provides for the use of electrical resistance heaters installed in or around the filter body, whilst a second solution provides for the use of the engine coolant circuit water and is achie,ved by means of tubes which carry the water in heat exchange with the filter body, and are of relatively great length. Both these solutions have disadvantages in that the first involves a certain current consumption, typically during starting at low temperature, whilst in the second, becAuse of the length of the tubing, the water arrives in the vicinity of the filter at a temperature which is not very high so that the heat exchange with the diesel oil is modest, particularly in the initial stages..

A 1 A 0 1 2 the present invention is that of providing The objezt of t a fuel heater device for diesel engines which will be free from. the stated disadvantages and which will therefore provide a compact and integrated arrangement for heating fuel in the region of the filter, utilising water from the engine cooling circuit.

According to the present invention there is provided a fuel heater device for diesel engines, of the type co.-,.pris.Lng a body within which is installed a f'Llter for the fuel, characterised by the fact that the said body has a cover within which is formed a first set of passages for the fuel and a second set of passages for the water of an engine cooling circuit; there being an exchange of heat between the said sets of passages and the said second set of passages having an inlet opening directly coupled to an outlet opening formed in a pressure region of a thermostat unit for controlling the said engine cooling circuit.

For a better understanding of the present invention a preferred embodiment is now described, purely by way of non-limitative example, with reference to the attached drawings, in which: Figure 1 is a partially sectioned view of a heater device formed according to the principles of the present 1 J 3 invention; Figure 2 is a partially sectioned plan view of the device Figure 1; and Figure 3 is a section taken on the line III-III of Figure 2.

K.

As illustrated in Figure 1, the reference nurieral 1, generally indicates: a fuel heater device for diesel. engines, comprising a filter body 2 within the interior of which is fitted a filter cartridge 3 and which is closed at the top by a cover 4 in which is formed a first set c.' passages for the fuel and a second set of passages for the water of the engine cowling circuit. This second set of passages includes an inlet opening 5 connected directly to a pressure region of a thermostat unit 6 (illust rated in broken outline, ' for controlling the engine cooling circuit. The filter body 2 is made of sheet metal and has a cylindrical form. As already described, within the body 2 there is fitted a filter cartridge 3 which is of known type and has an oveiall annular form because it is wrapped about a hollow support cylinder 7. 'The filter cartridge 3 is closed at the bottom by a small plate 8 having a plurality of small holes 11 formed in correspondence with the cartridge 3, and a central hole 12 in register with the support cylinder 7. In the lower part of the body.61 there is 4 mounted an indicator electrode device 13 of known type which can be operated for draining water possibly present in the fuel and which collects in this lower part of the body 2. The upper edge of the body 2 is folded inwardly and is fixed to a plate 14 having a central threaded through hole 15 coaxial with the cylinder 7 and a plurality of small holes 16 formed in a ring in register with the cartridge 3. An annular seal 17 is positioned between the edge of thle hc;le 15 in the plate 14 and the i 7. Over the plate upper end of the cyl.Lnder a small sheet metal plate 18 having a centra, coaxial with the hole 15 and a plurality of - illustrated for simplicity) formed in a (not corresponding to the ring of holes 16 in the Between the edge of the hole 21 of the small. that of the hole 15 in the plate 14 there is an annular seal 22.

14 is f ixed 1 hole 21. small holes ring plate 14. plate 18 and positioned The device 1 for the connection of the filter body 2 to the cover 4 includes a hollow cylinder 23 having an outer surface divided into upper and lower regions, separated by an annular projection on which is formed an external thread. In use, the lower region of the cylinder 23 is screwed into the hole 15 of the plate 14 and the intermediate project.ion cooperates with the seal 22. The device 1 includes the cover 4, within which the heat 1 c f exchange takes place between the water and the fuell, which has a hollow cylinder 25 having upper and lower sections respectively ind---a4,-e-- 26 and 27 and divided by a dividing wall 28. The lower section 26 is threaded internally and is sc-rewed onto the upper region of the cylinder 23 and presses on the seal 22. Around the lower section 26 of the cylinder 25 there is defined an annular chamber 31 delimited above by an annular wall 32 of conical form in section, and which extends dcwnwardly from the upper section 27 of the cylinder 25. In a portion of the wall 32 there is formed an opening 33 for the entry of fuel. Within the chamber 31 there are formed several radial ribs 34 which extend from. the unde side of this wall 32. The cover 4 fur-ther has a cylindrical side wall 35 through which the opening 33 passes, and the lower edge of which rests on the small plate 18 with the interposition of an annular seal 39 which is lodged in an annular space in the plate 18 itself.

With reference to Figures 1, 2 and 3, the fuel enters into the chamnber 31 through the opening 33, from where it traverses the holes formed in the small plate 18 and the holes 16 formed inthe plate 14 to flow through the filter cartridge 3, from which it flows through the holes 11 formed in the plate 8 and enters into the interior of 6 the small cylinder -7. From this it traverses the cylinder 23 to flow out intc the interior of the lower section 26 of the cylinder 25. The section 26 is in communication, via an inclined duct 36, with a chamber 37 where there is fitted a thermal expansion valve 41 of known type, the functional characteristic of which will be described hereinbelow. The section 27 is also in communication via a duct 42 with the chamber 37 so that the fuel from the section 26 can enter into the section 27 by traversing the duct 36, the chamber 37 and the duct 42. The section 27 constitutes the fuel outlet opening and for this is threaded internally for a coupling of known type not illustrated. The ducts 36 and 42 are formed close to the dividing wall 28.

is As illustrated in Figures 1, 2 and 3, above the chamber 31 in the cover 4 there is defined an annular chamber 43 delimited below by the wall 32 and above by a plate 44 fixed on the upper section 27 of the cylinder 25. In particular, the peripheral edge of the plate 44 is pressed against the upper edge of the cylindrical side wall 35 and fixed by a ring 49 of Seeger type carried by the section 27. Within the chamber 43 are formed projections 45 which extend upwardly from the wall 32.

As illustrated in Figure 2 the projections 45 describe an arc of a circle and in particular two projections 45 lie 1 p 7 1 i k_l 7 0 on the same circumference centred on the axis of the cylinder 25 and a third projection 45 lies on a circumference concentric to that just described but of greater diameter. Further, this latter projection 45-is of less height than that of the first two. The cover 4 includes an integral. substantially cylindrical portion 46 having a longitudinal axis substant1ally tangential to the s-1de wall 35. Two chambers. are formed within the portion 46, one of which is the chamber 37 hcusing the bulb 41, whilst the other, indicated 47, has the inlet opening 5 which is connected directly (Figure 1j to the outlet opening 51 of the thermostat unit 6. More precisely, water is taken in through the opening 51 from. the cooling circuit in a region under pressure. In the.

chamber 47 there is further formed an aperture 5' for passage of the water from the chamber 47 to the chamber 43. The chambers 43 and 47 are divided by a wall 53 in which is formed a threaded through hole 59 into which is screwed an externally threaded portion of the bulb 41.

This latter includes a stem, an outer portion 55 of which is within the chamber 47. This stem, as is known, has a length which is variable as a function of the temperature of the bulb 41, so that it is sensitive to the temperature of the diesel oil which surrounds it. The projecting portion 55 acts or, a bottom wall 57 of a cup shape valve 58 translatable against the action of a 8 pre-loaded spring ú1 which abuts ont-16 the botton, waIi. E517 and on a plug 62 for closure of the chamber 47. In use, for fuel temperatures greater than, for example, + 230c, the end 55 of the stem has a progressive longitudinal displacement which allows the valve 58 to be displaced towards the plug 62 such that its side wall 63 progressively closes the aperture 52. In the case of fuel temperatures lower than, for example, + 230C, that is to say, during starting and warm up of the engine, the 2 ster. of the bulb 41 is withdrawn leaving the aperture 5... free so that the water from the unit 6 flows into the interior of the chamber 47 and from this to the interior of the chamber 43 where it follows a circular path flowing over the projections 45. The water exits from the chamber 43 through an outlet opening 64 formed in the wall 35 of the cover 4 and returns via an eye coupling (not illustrated) to a depression zone of the unit 6. In the attached drawings the path followed by the fuel is indicated with solid arrows, whilst the path followed by the water is indicated with broken line arrows.

In use, the fuel follows the path described above, whilst the water in the cooling circuit follows its path only if the aperture 52 is open, that is to say, only if the temperature of the fuel is less than a certain value, for example, 23o C. In this case, the heat exchange between j 1 t.

9 the water and the fuel for the progressive heating of this latter takes place within the cover 4 through the wall 32 which separates the chambers 31 and 43. The provision of the ribs 34 and the projections 45 increases the surface area for heat exchange and therefore allows a greater efficacy of this exchange. Moreover the projections 45 cause a circulation of the water in the chamber 43 in a predetermined directional sense which allows the water to flow over the whole of the wall 322.

From what has been described above the numerous advantages achieved with the structure of the present invention will be evident.

in particular, there is provided within the device 1 a heat exchanger for exchanging heat between the water and the fuel in a compact integrated arrangement. Moreover, it is to be noted that the opening 5 for entry of the water into the cover 4 is directly coupled, that is without the aid of tubing, to the outlet opening 51 of the unit 6. This allows temperature losses in the water to be avoided, which therefore has within the chamber 43 substantially the same temperature that it has when withdrawn, so that the effectiveness of the device is more significant, especially in the initial operating stages of the engine in which the temperature of the 1 1 y low.

water is still relativel The prcvision of the ribE 34 and the projections 45 further allows the heat exchange surfaces to be considerably increased. Further, within the same cover 4 there is provided the control mechanis.-r. fcr closure and opening of the water circulation, which is directly sensitive to the c' the diesel cil thus avoiding excessive temperat L heating of this.

Finally, it is clear that the device 1 described and illustrated, here, can have mod--fications and variations introduced thereto without by this departing from the protective scope of the present invention.

1 m 11 CLA 1 MS 1. A fuel heater device for diesel engines, of the type comprising a body within which a fuel filter is installed, characterized by the fact that the maid body has a cover within which is formed a first set of passages for the fuel and a se-cond act of passages for engine coolant circuit water; there being ar, exchange of heat between the said sets of passages, and the said second set of passages having an entry opening direc-tly coupled to an outlet opening formed in a pressure region of a thermostat unit for control of the engine coolant circuit.

Claims

2. A device according to Claim 1, characterized by the fact that within

the interior of the said cover there are disposed means for controlling the circulation of the water in the maid second set of passages.

3. A device according to Claim 1 or Claim 2, characterised by the fact that the said first act of Passages includes a first, downwardly open annular chamber which is open towards the said filter and by the fact that the maid second set of passages includes a second annular chamber separated from the 1 0 said first chamber 12 by a dividing wall 4. A device according to Clairn 3, characterized by the. within the interior of the said second chamber fact that, there are a plurality of projections extending upwardly from the maid dividing wall in such a way as to increase the heat exchange surface.

5. A device according to Claim 4, characterized by the fact that the said projections describe at least portions of arcs of a circle the centre of which coincides with the axis of the said second chamber in such a way as to define a circular path for the water.

6. A device according to at least one of Claims from 3 to 5, characterised by the fact that within the interior of the said first chamber there is formed a plurality of radial ribs in such a way as to increase the heat exchange surface.

A 7. A device according to Claim 2 or any of Claims from 3 to 6 when dependent on Claim 2, characterised by the fact that a heat sensitive portion of the said water circulation control means is disposed in a region of the said first set of passages.

0 0 Y 13 8. A device according to claim 7, characterized by the fact that the maid water circulation control means include'a thermal expansion bulb installed in a fourth chamber of the zaid cover and an element housed in a third chamber and operable to translate under the action of a rod controlled by the said bulb against the action of spring means to intercept the circulation of the water with a part thereof; the said third chamber being in 1,0 communication with the said second annular chamber and the said water ith associated sections chamber being in series w.

of the said first set of passages.

inlet opening j and the said fourth 1-5 9. A device according to any preceding Claim, characterised by the fact that it includes temporary coaxial connection means between the said body housing the said filter and the said cover - and associated perimetral seal means for the passage of fuel into the different branches of the said first set of passages.

10. A fuel heater device for diesel engines as described and illustrated with reference to the attached drawings.

Published 1988 at The Patent Office, State House. 65'71 High Holborn, London WCIR 4TR Further copies may be obtained from The Patent Office, Sales Branch, St Mary Cray, Orpington, Kent BR5 3RD. Printed by Multiplex techniques ltd, St Maz7 Cray, Kent. Con. 1/87.

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