High pressure fuel manifold adapted for fitting between a fuel pump and at least one electromagnetically actuated fuel injection valve

Abstract

 The manifold comprises a body (1) having an internal cavity (2) delimited substantially by a pair of end walls (3, 4) and by a side wall (5); on the first of these end walls there are fixed connectors (6, 7, 8) communicating with the cavity, of which at least one (6) of these is adapted to be connected to a duct communicating with the fuel supply pump and each of the others (7, 8) is adapted to be connected to a corresponding injection valve, the second of these end walls (4) being provided with at least one hole (12) adapted to be connected to a pressure and/or temperature sensor (13).

Description

[0001] The present invention relates to a high pressure fuel manifold which is adapted to be fitted between a fuel pump and at least one electromagnetically actuated fuel injection valve.

[0002] Known manifolds of this type have a substantially tubular form and are delimited by a cylindrical side wall and by a pair of end walls. They further include a plurality of connectors fixed to the said side wall and communicating with the internal cavity thereof; at least one of these connectors is put into communication, via a suitable duct, with the fuel supply pump, whilst each of the others is in communication, via a corresponding duct, with an electromagnetically actuated fuel injection valve. On one of the said end walls there is then fitted a sensor for detecting the pressure and/or the temperature within the said first-defined cavity.

[0003] Manifolds of this type have several disadvantages.

[0004] First of all the resistance to the flow of fluid between each of the connectors and the corresponding fuel injection valve is different. This fact results from the different lengths of the various fuel flow paths which extend between the connectors and the various injection valves; in fact each of these flow paths includes a section within the manifold the length of which obviously depends on the position of the corresponding connector fixed to the side wall of the manifold itself: this length is, in fact, greater for those flow paths which correspond to connectors which are located at a greater distance from the fuel inlet connector of the manifold.

[0005] To overcome this disadvantage the differential resistance between the various flow paths defined above must be compensated by means of different lengths of duct which join the connectors to the fuel injection valves; consequently, as well as a certain constructional complexity, a rather high resistance to the flow of fuel towards the injection valves is experienced.

[0006] Furthermore, a manifold of this type does not lend itself to being utilised on different fuel supply circuits, that is to say those intended for engines of different power having, for example, a different number of cylinders. In fact the axial length of the manifold must be chosen in dependence on the number of connectors to be fixed to its side wall, and therefore this length depends on the overall number of cylinders to be supplied from the manifold.

[0007] Additionally, in manifolds of this type no fuel filtering action takes place, tending to retain particles of metal possibly present within it, preventing these from reaching the injection valves; whenever it is necessary to perform such filtering action suitable means disposed in the supply circuit outside the manifold itself are necessary.

[0008] Finally, manifolds of the known type described above are not normally provided with fuel heating means, and therefore to increase the fuel temperature separate heater means must be fitted in the supply circuit.

[0009] The present invention seeks to provide a high pressure fuel manifold of the type which has been briefly described, which will be free from the disadvantages which have been discussed; it is therefore a first object of the invention to provide a manifold which has a rigorous symmetry in the flow paths for fuel supplied to the injection valves; another object is that of obtaining a high degree of modularity to adapt the manifold to use on engines of different type, in particular those having a different number of cylinders; a further object of the invention is that of providing the manifold with means adapted to exert a certain fuel filtering action and also with fuel heater means.

[0010] This object is achieved by a high pressure fuel manifold adapted to be fitted between a fuel supply pump and at least one electromagnetically actuated fuel injection valve, characterised by the fact that it includes a body provided with an internal cavity delimited substantially by a pair of end walls and a pair of side walls, on a first of the said end walls there being fixed connectors communicating with the said cavity, at least one of which connectors is adapted to be connected to a duct communicating with the said fuel supply pump, each of the others being adapted to be connected to a corresponding fuel injection valve, and the second of the said end walls being provided with at least one hole adapted to be connected to a pressure and/or temperature sensor.

[0011] For a better understanding of the fuel manifold of the present invention a description will now be given, by way of example, with reference to the attached drawings, in which a longitudinal section thereof is represented.

[0012] The fuel manifold of the invention is adapted to be fitted between a fuel supply pump (not shown) and at least one electromagnetically actuated fuel injection valve (not shown); it is particularly adapted to be used in a circuit adapted to supply diesel oil to the electronically controlled injection valves of a diesel engine; as is known, the diesel oil must be supplied to such valves at a very high pressure, of the order of 1500 bar.

[0013] The manifold substantially comprises a body 1 having an internal cavity 2 delimited substantially by a pair of end walls 3 and 4 and by a side wall 5. On the wall 3 there are fixed connectors 6, 7 and 8 communicating with the cavity 2 and of which at least one, that indicated with the reference numeral 6 in the drawing, is connected to a duct 9 communicating with the fuel supply pump; each of the others 7 and 8 is adapted to be connected, via a duct 10 and 11, to a corresponding injection valve; the other end wall 4 is provided with at least one hole 12 which can be connected to a pressure and/or temperature sensor 13.

[0014] Conveniently the hole 12 is formed in an insert 14 which is fixed to the body 1 in any suitable manner, for example by welding; as is clearly seen from the figure, the said insert substantially defines the lower end wall 4 of the body 1.

[0015] Conveniently the sensor 13 is provided with a threaded stem which is screwed into a corresponding threaded section of the hole 12. In correspondence with this hole there is disposed a small magnet 15 of substantially tubular form, which is housed within the said stem and is adapted to be traversed by the fuel to retain metal particles contained in the fuel supplied into the cavity 2.

[0016] In the threaded stem there is formed a duct section 12a which is in communication with a chamber (not shown) of the sensor 13 to act in a known way on a membrane which forms part of the sensor itself.

[0017] The cavity 2 has a substantially elongate form and the connector 6 is disposed in a such a way as to open substantially into the centre of the cavity, whilst the other connectors 7 and 8 are disposed peripherally around the first; therefore the connector 6 communicates with the cavity 2 through a substantially axial hole 16 whilst the others open into the cavity through holes 17 and 18 the axes of which form a predetermined angle with that of the hole 16 as is clearly seen from the drawing. Even though in the section shown in the drawing only two connectors 7 and 8 disposed about the connector 6 are visible, it is evident that the number of connectors which are disposed around the central connector 6 can be any number desired depending on the number of injection valves to be supplied by the manifold.

[0018] On the outer surface of the side wall 5 an electrical resistance 19 of annular form can be provided adapted to heat the fuel contained within the cavity 2, or alternatively there may be provided a sleeve 26 with cavities 27 traversed by a liquid to maintain the temperature of the fuel.

[0019] On this outer surface there is formed an annular seat 20 arranged to house the edge of a sheath 21 of cup-shape form adapted to protect the sensor 13. This latter is conveniently provided with a connector 22 intended to be connected to a suitable electrical connection element.

[0020] The manifold described operates in the following manner.

[0021] Fuel is supplied from the injection pump to the connector 6 through the duct 9 and from this flows to the interior of the cavity 2 through the hole 16. The central stream 23 which is thus set up within the interior of the cavity 2 gives rise to a plurality of streams 24 each of which has a substantially parabolic shape as is clearly seen from the drawings; in this way there are formed stream lines 25 with a lower velocity, in correspondence with which the metal particles possibly contained in the fuel are exposed to the attraction exerted by the magnet 15. In this way such particles can be captured by this magnet and deposited on the outer surface thereof; subsequently the streams 24 traverse the holes 17 and 18 directed towards the exit connectors 7 and 8 and therefore towards the injection valves.

[0022] The fuel pressure within the interior of the cavity 2 acts through the hole 12 and the duct section 12a on the sensitive element of the pressure sensor 13. It is evident that, because of the shape of the cavity 2, the pressure which acts within it is constant and transmitted substantially unchanged to the pressure sensor 13.

[0023] In the manifold of the invention the length of the fuel flow paths between the supply connector 6 and each of the outlet connectors 7 and 8 is substantially the same. In this way a perfect symmetry of these flow paths is achieved, which obviously makes it possible to have the same resistance to the passage of fluid through the injection valves and to achieve, overall, a very low resistance to flow.

[0024] Moreover the manifold has a high degree of modularity: in fact on the wall 3 there can be disposed, as well as the inlet connector 6, also a large number of outlet connectors in such a way as to make the manifold suitable to be used on engines of different type; whenever a manifold must be formed with a cavity 2 having greater dimensions it is sufficient to utilise for this purpose a body 1 of greater axial length.

[0025] Further, with the manifold of the invention it is possible to exercise an effective filtering action on metal particles in the fuel which enters into the cavity 2, through the above-described action of the small magnet 15.

[0026] Finally, fuel contained within the cavity 2 can be maintained at a constant temperature with ease and in a continuous manner by the electrical resistance 19 or the heater sleeve 26. The manifold is constructionally very simple and compact and therefore gives rise to a low bulk; it involves few parts which can be easily made and connected together by very simple operations.

[0027] It is evident that the manifold of the invention which has been described above can have modifications and variations introduced thereto, both to the shape and to the arrangement of the various parts, without departing from the scope of the invention itself.

Claims

1. A high pressure fuel manifold adapted to be fitted between a fuel supply pump and at least one electromagnetically actuated fuel injection valve, characterised by the fact that it includes a body (1) having an internal cavity (2) and delimited substantially by a pair of end walls (3, 4) and a side wall (5), on a first (3) of the said end walls there being fixed connectors (6, 7, 8) communicating with the said cavity, at least one (6) of which connectors is adapted to be connected to a duct (9) communicating with the said fuel supply pump, each of the others (7, 8) being adapted to be connected to a corresponding fuel injection valve, and the second (4) of the said end walls being provided with at least one hole (12) adapted to be connected to a pressure and/or temperature sensor (13).

2. A manifold according to Claim 1, characterised by the fact that the said hole (12) is formed in an insert (14) fixed to the said body, the said insert substantially defining the said second end wall (4) of the said body.

3. A manifold according to Claim 1 or Claim 2, characterised by the fact that in correspondence with the said hole (12) there is disposed a small magnet (15) of substantially tubular form adapted to be traversed by fuel and to retain metal particles contained in the fuel which is supplied into the said cavity (2).

4. A manifold according to any preceding Claim, characterised by the fact that the said cavity (2) has an elongate form and the said connector (6) adapted to be connected to the said fuel supply pump is disposed in such a way as to open substantially into the centre of the said cavity (2), the said other connectors (7, 8) being disposed peripherally around the said connector adapted to be connected to the said fuel supply pump in such a way as to achieve flow paths for the said fuel (23, 24) within the said cavity having a substantially parabolic shape, so as to give rise to stream lines (23) having a lower velocity in which the said metal particles in the fuel are exposed to the attractive action exerted by the said small magnet (15).

5. A manifold according to any preceding Claim, characterised by the fact that on the outer surface of the said side wall there are disposed means adapted to maintain the temperature of the fuel contained in the interior of the said cavity (2) at a constant value.

6. A manifold according to any preceding Claim, characterised by the fact that the said outer surface of the said body (1) is provided with an annular seat (20) adapted to house the edge of a cup-shape sheath (21) adapted to protect the said sensor.

Drawing