EP3636914A1

EP3636914A1 - A fluid injection assembly for an internal combustion engine

Info

Publication number: EP3636914A1
Application number: EP18199059.9A
Authority: EP
Inventors: Giandomenico Serra
Original assignee: Continental Automotive GmbH
Current assignee: Vitesco Technologies GmbH
Priority date: 2018-10-08
Filing date: 2018-10-08
Publication date: 2020-04-15

Abstract

A fluid injection assembly is disclosed. It comprises an elongate fluid injector (1) having a valve body (2) and a securing element (10) . The valve body (2) is adapted to be located in a bore (5) of a housing (4) of an internal combustion engine. The securing element (10) is located on the valve body (2) and has a projection (16) engageable in a slot (18) of the housing (4) for securing the fluid injector (1) to the housing to locate the fluid injector (1) in a predetermined position. The projection (16) has at least one deformable element (20) projecting from the main body (14) of the projection (16) the deformable element (20) being deformed when the projection (16) is inserted in the slot (18) so that the projection (16) is held with a force fit in the slot (18).

Description

The present disclosure relates to a fluid injection assembly for an internal combustion engine, particularly but not exclusively, for fuel injection assemblies e.g. for a gasoline direct injection internal combustion engine.
Fuel injection assemblies are widely used for injecting fuel into an internal combustion engine, in one form having an injector for each cylinder of a multi-cylinder engine in which the fuel is supplied from a reservoir in the form of a common rail to which each of the injectors is connected. The injectors may be secured directly to a bore in the cylinder head of the engine to project into the combustion chamber. However, such arrangements enable noise generated by the injection and combustion process to be transmitted through the engine to the exterior. In order to reduce noise transmission, a direct mechanical connection between the injector and the engine can be avoided by suspending the injector in a fuel rail injector cup which is itself secured to the fuel rail and the engine. In this way there is no direct mechanical coupling between the injector and the engine components.
However, it is possible for the fuel injector to pivot about the axis of the bore in the cylinder head or the injector cup during assembly or during use due to the vibrations to which the engine and fuel injectors are subjected. In order to achieve the required fuel injection spray pattern into the combustion chamber, the fuel injector should be precisely positioned angularly relative to the bore or the injector cup so that the fuel injector fuel output is in the correct position relative to the combustion chamber.
In known arrangements, this is achieved by means of a further component known as an indexing clip. Such arrangements are shown for example in US 6, 325, 049 B1 which discloses an arrangement in which an interference fit is provided between the projection and a void in the housing. In this arrangement, precision forming of the interengaging surfaces is used to achieve the required engagement force.
The present disclosure seeks to provide a fluid injection assembly which is easier and quicker to assemble, whilst ensuring the correct positioning of the fluid injection spray.
According to the present disclosure there is provided a fluid injection assembly comprising an elongate fluid injector. The fluid injector comprises a valve body and a securing element, the valve body having a longitudinal axis and having a fluid inlet port and a fluid outlet port. In one embodiment, the fluid injection assembly is a fuel injection assembly and the fluid injector is a fuel injector, the valve body having fuel inlet and outlet ports as the fluid inlet and outlet ports, respectively.
The valve body is adapted to be located in a - preferably generally cylindrical - bore in a housing of an internal combustion engine. In one embodiment, the fluid injection assembly comprises the housing and the valve body may expediently be received in the bore.
The securing element is located on the valve body and has a projection engageable in a slot of the housing for securing the fluid injector to the housing to locate the fluid injector in a predetermined position relative to the engine. The projection has at least one deformable element projecting from the main body of the projection, the deformable element being deformed when the projection is inserted in the slot so that the projection is held with a force fit in the slot.
That the projection is engageable in a slot of the housing "for securing the fluid injector to the housing to locate the fluid injector in a predetermined position relative to the engine" means in particular that an angular position of the fluid injector relative to the housing with respect to a rotation around the longitudinal axis is fixed by means of the force-fit connection of the protrusion with the housing when the projection is inserted in the slot. In one development, the force fit connection may also contribute to hold the fluid injector in a predetermined axial position. The fluid injector may additionally be fixed with respect to the housing by means a screw and/or a bolt.
The force fit provides a fastening between the projection and the slot and, therefore, between the injector and the housing, which is achieved by friction after the parts are pushed together. The use of the at least one deformable element enables the injector to be easily engaged with the housing using the projection as a coarse fit or locator and by using the deformable element or elements to engage the securing element with the housing by friction in the desired position. The connection between the securing element and the housing may also be resilient due to the use of the deformable element or elements.
A force fit is designed to maintain a controlled pressure between mating parts, and is commonly used where forces or torques are being transmitted through the joining point. A force fit is achieved by applying a force during component assembly.
An indexing of the injector with respect to the internal combustion engine and combustion chamber may be provided in some embodiments due to the engagement of the securing element with its deformable element or elements in the slot in the housing of the engine. Indexing describes the angular orientation - in particular with regard to rotation around the longitudinal axis - of the injector, e.g. with respect to the combustion chamber of the engine, which enables a correct spray layout of the fuel in the combustion chamber.
The deformation element may have the form of a flap or wing which extends substantially perpendicularly form a side face of the projection in the unmounted state. The element or elements deform upwardly as the projection is pushed downwards into the slot to provide the force fit between the securing element and the housing. In the present context, "upwardly" is the direction parallel to the longitudinal axis from the fluid outlet port towards the fluid inlet port and "downwards" is the opposite direction, i.e. the direction parallel to the longitudinal axis from the fluid inlet port towards the fluid outlet port.
Since the deformable elements deform as the projection is inserted into the slot, a resilient connection is provided between the securing element and the housing. The deformable elements enable any misorientation of the projection in relation to the slot to be compensated by the amount of deformation of the deformable element or elements. Therefore, insertion of the securing element into the slot is simplified and a reliable orientation of the injector with respect to the housing - in case of a fuel injector, thus, in particular with respect to the engine and, in particular, the combustion chamber with which the injector is associated - is achieved.
In an embodiment, the securing element comprises a body that is over moulded to the fluid injector. For example, the securing element is comprised by an actuator module of the fluid injector. The actuator module e.g. extends circumferentially around a portion of the valve body. For example, the valve body extends through a central bore, i.e. a central opening of the securing element.
In embodiments including a single deformable element, the deformable element is arranged on a first surface of the projection and is used to press an opposing second surface of the projection against a surface of the slot. Expediently, the first and second surfaces may extend parallel to the longitudinal axis.
In other embodiments, two deformable elements are disposed on opposite sides of the main body of the projection so as to engage opposed faces of the slot. Expediently, the opposite sides and opposed faces, respectively, may face away from each other in circumferential direction around the longitudinal axis. The two deformable elements provide a self-centring mechanism so that the projection is positioned at the centre of the slot. This enables the projection to be more easily inserted into the slot and arranged in the proper position, since any initial mis-orientation of the projection in relation to the width of the slot is compensated by the two deformable elements.
In some embodiments, the deformable element or elements comprise a generally planar strip(s) extending generally outwardly from the main body of the projection towards the face(s) of the slot when the projection is inserted in the slot.
In another embodiment, the deformable element or elements have a root and an outer extremity and are tapered being thinner, and/or narrower laterally, at their outer extremity than at their root on the projection. In some expedient embodiments, the root merges with the main body and the outer extremity is located at an end of the deformable element remote from the main body.
The deformable elements may be inclined at an angle to the direction of insertion.
The deformable elements may be aligned in the direction of insertion or at an acute angle relative thereto and comprise a triangular planar element increasing in lateral extent the further the element is insertable in the slot in the direction of insertion.
The deformable elements may be formed integrally with the securing element, but in other embodiments the deformable elements are separate components secured to the projection.
In another embodiment, the deformable elements are held resiliently when inserted in the slot so as to be removable. In another embodiment, the deformable elements are permanently deformed when inserted in the slot.
The entire securing element or a portion of the securing element - e.g. the main body of the protrusion - may be formed of steel, an alloy or rubber or a plastics material. The deformable elements may be formed of a different material from other portions of the securing element, in particular in embodiments in which the main body of the protrusion is formed of steel or another alloy.
In an embodiment, the securing element and the deformable element or elements are formed from plastic. For example, the valve body may be overmoulded with the securing element.
A coupling between the injector overmoulding and the cylinder head is provided by way of at least one deformable element. The quantity and dimension of the deformation element(s) can vary depending on the application. The interference between the two components can be selected to set the required insertion force. The insertion force may also depend on the application requirements. For example, the ease of assembly may be less or more important than a high angular position accuracy so that a larger or smaller dimension can be used since different dimensions enable the injector to be blocked in a predetermined angular orientation in different application conditions. The behaviour of the deformation elements or wings can be influenced by adding a smaller or larger draft angle in the horizontal, or vertical direction or both so that the area of the section decreases as the distance from the root of the wing to the extremity of the wing increases. The draft angle can be used to increase the precision of the orientation due to the decreasing stiffness of the wing along its length. A higher precision can be achieved with the same deformation on the two or more wings by way of symmetric geometry. The orientation of the wings may be horizontal, vertical or include a combination of a straight and an inclined portion. A step or abrupt changed in place of a gradual change in orientation may also be used. The deformation of the deformable elements may be permanent or reversible depending on the material used and the amount of deformation that occurs upon insertion.
Embodiments will now be described by way of example with reference to the drawings, in which:

Figure 1 shows a perspective view of an over-moulding adapted to be bonded to a fuel injector,
Figure 2 shows a cross-section of a fuel injector located in a cylinder head,
Figure 3 shows a cross-section along the line B-B of Figure 2,
Figure 4 shows a cross-section along the line C-C of Figure 2,
Figure 5 shows a detail of Figure 3 on a larger scale, and
Figures 6A, 6B and 6C show alternative forms of the over-moulding of Figure 1.

Referring now to Figures 1 and 2, Figure 2 in particular illustrates schematically a fluid injector 1 - in the present embodiment a fuel injector - secured in a housing 4 of an internal combustion engine. The fuel injector 1 comprises a valve body 2 extending along a longitudinal axis L from a fuel inlet 8 to a fuel outlet 6, both comprised by the valve body 2. The valve body 2 is depicted as a solid body in the figures for sake of simplicity. However, the valve body 2 is in fact hollow, having a cavity which fluidly connects the fluid inlet 8 to the fluid outlet 6. At the fluid outlet, the valve body 2 has a valve seat and at least one orifice or is fixed to a seat body comprising the valve seat and the orifice (s) . A valve needle and, in the case of the fluid injector 1 being a solenoid injector, preferably also a magnetic armature is/are received in the cavity. Further elements, such as a filter, a spring for biasing the needle, may be comprised by the valve body and are known in principle to the person skilled in the art so that they are not described in further detail here.In the present embodiment, the fuel outlet 6 of the injector is in fluid communication with the combustion chamber of the engine for direct injection of the fuel into the combustion chamber.
The fuel inlet 8 is provided for connecting the fuel injector 1 to a fuel supply. In a multicylinder engine, a fuel injector 2 is supplied for each cylinder of the engine and fuel to the cylinders is provided through the common rail (not shown) comprising a fuel reservoir having a plurality of spaced fuel outlets, one for each fuel injector.
The valve body 2 has bonded thereto securing element 10 which may be an over-moulding which serves to secure the fuel injector 1 to the engine in the correct location to ensure that fuel spray is directed into the combustion chamber in the desired direction and position. In the present embodiment, the over-moulding also forms an electrical connector 11 of an actuator module of the fuel injector 1.
In this example, the fuel injector 1 is shown as being secured directly into the cylinder head which comprises the housing 4, the valve body 2 being received in a cylindrical bore 5 of the housing 4. The housing is a cylinder head in the present embodiment. In other embodiments (not shown), the fuel injector is located in an injector receptacle which forms part of the housing 4. In another embodiment, the fuel injector 1 is secured with the intake manifold - also denoted as inlet manifold - of the internal combustion engine to direct fuel towards the inlet valve or valves of the engine.
Referring now particularly to Figure 1, the securing element 10 includes a central opening 12 in which the valve body 2 of the fuel injector 1 is located. The valve body 2 projects from the central opening 12 in both directions of the longitudinal axis L. The securing element 10 has a main body 14 having a projection 16 extending in a direction radially outwardly from the central opening 12 and in the present embodiment having the same dimension in the axial direction of the bore 12 as the main body 14 of the securing element 10. In the present embodiment, the electrical connector 11 extends away from the central opening 12 in a radial direction opposite to the radial direction in which the projection 16 extends away from the opening 12.
The housing 4 has a slot 18 adapted to receive the projection 16 when the fuel injector 2 is inserted in the housing. As shown particularly in Figure 1, the projection 16 has outwardly extending deformable elements 20 which as shown, particularly in Figure 5, are adapted to be deformed when the fuel injector is inserted in the housing 4 so that the projection 16 enters the slot 18 downwardly from the upper open end 22 of the slot 18. The deformable elements 20 shown in Figures 1 and Figure 5 are deformed as the projection 16 is pushed into the slot 18 so that the projection 16 and hence the securing element 10 and the fuel injector 2 are held securely in the desired location so that the fuel injector 2 is prevented from moving pivotably about its axis .
As shown in Figure 1, the deformable elements 20 comprise a generally planar strip extending at right angles from the two opposing side faces of the projection 16. In this embodiment, two deformable elements 20 are provided. In other non-illustrated embodiments, only one deformable element is provided so that the projection 16 is urged against one side face of the slot 18 by the force of deformation of the one deformable element.
The width W, the length L and the thickness T of the deformable elements 20 depend upon the strength of the interference fit required for the particular installation.
As shown in Figure 6A, in some embodiments, the width W1 at the root of the deformable element 20 where it joins the projection 16 is greater than the width W2 of the outer end or extremity of the deformable element 20, whilst the thickness T1 at the root is greater than the thickness T2 up at the outer end.
Figure 6B shows an arrangement in which the deformable element 20 is essentially triangular when viewed in the radial direction of the injector 2 having its smallest extent at the lowermost part of the deformable element 20 and increasing its dimension towards the upper part of the deformable element 20. In this way, the force of engagement between the projection 16 and the housing increases as the projection 16 is pressed down into the slot 18. In this embodiment, the deformable element 20 lies in a plane parallel to the axis of the bore 12.
Figure 6C shows an alternative arrangement in which the deformable element 20 is located at an acute angle to a plane parallel to the axis of the bore 12. Thus, the orientation of the deformable elements 20 can be horizontal, vertical or inclined relative to the direction of insertion of the projection 16 into the slot 18.
These embodiments illustrate only one deformable element 20 but it will be understood that associated deformable elements of the same design may be located on the other side of the projection 16. It is also possible that more than one deformable element may be located on each side of projection 16 and that these deformable elements may be of different design and shape.
Although the deformable elements 20 are shown as generally having a gradual continuous change in dimensions, it is possible that they may be provided with a stepped shape to give the deformation character required.
As shown, the deformable elements 20 are formed integrally with the securing element 10. The securing element and the deformable elements 20 may be formed of a plastics material. In alternative embodiments, the deformable elements 20 may be formed of a different material from rest of the securing element 10, which may be a rubber or plastics material, which are bonded to the projection 16. In this way, the precise force holding the projection 16 in the precise position required in the housing 4 and hence the force holding the fuel injector 2 in position can be varied to suit the precise requirements of the particular installation.
It therefore enables a very cost effective method of changing the basic design to accommodate the changes necessary for a variety of installations.

Claims

A fluid injection assembly, comprising an elongate fluid injector (1) having a valve body (2) and a securing element (10), the valve body (2) having a longitudinal axis and comprising a fluid inlet port (8) and a fluid outlet port (6),
wherein
- the valve body (2) is adapted to be located in a bore (5) of a housing (4) of an internal combustion engine

- the securing element (10) is located on the valve body (2) and has a projection (16) engageable in a slot (18) of the housing (4) for securing the fluid injector (1) to the housing to locate the fluid injector (1) in a predetermined position, and

- the projection (16) has at least one deformable element (20) projecting from a main body (14) of the projection (16) the deformable element (20) being deformed when the projection (16) is inserted in the slot (18) so that the projection (16) is held with a force fit in the slot (18) .
A fluid injection assembly according to claim 1, wherein the securing element comprises a moulded body, in particular molded to the valve body (2).
A fluid injection assembly according to claim 1 or claim 2, wherein two deformable elements (20) are disposed on opposite sides of the main body of the projection (16) so as to engage opposed faces of the slot.
A fluid injection assembly according to one of claims 1 to 3, wherein the deformable element or elements (20) comprise a generally planar strip(s) extending generally outwardly from the main body of the projection (16) towards the face (s) of the slot when the projection (16) is inserted in the slot (18) .
A fluid injection assembly according to one of claims 1 to 4, wherein the element or deformable elements (20) have a root and an outer extremity and are tapered being thinner and/or narrower laterally at their outer extremity than at their root on the projection (16).
A fluid injection assembly according to one of claims 1 to 5, wherein the deformable element or elements (20) are inclined at an angle to the direction of insertion.
A fluid injection assembly according to one of claims 1 to 6, wherein the deformable element or elements (20) are aligned in the direction of insertion or at an acute angle relative thereto and comprise a triangular planar element increasing in lateral extent the further the element is insertable in the slot (18) in the direction of insertion.
A fluid injection assembly according to any one of claims 1 to 7, wherein the deformable element or elements (20) are formed integrally with the projection (16).
A fluid injection assembly according to any one of claims 1 to 8, wherein the deformable element or elements (20) are separate components secured to the projection (16).
A fluid injection assembly according to any one of claims 1 to 9, wherein the deformable element or elements (20) are held resiliently when inserted in the slot (18) so as to be removable.
A fluid injection assembly according to any one of claims 1 to 9, wherein the deformable element or elements (20) are permanently deformed when inserted in the slot (18).
A fluid injection assembly according to any one of claims 1 to 11, wherein the securing element (10) is formed of steel, an alloy or a plastics material.
A fluid injection assembly according to any one of claims 1 to 11, wherein the securing element (10) and the deformable element or elements (20) are formed of a plastics material.
A fluid injection assembly according to any one of the preceding claims, wherein the valve body (20) extends through a central opening (12) of the securing element (20) .
A fluid injection assembly according to any one of the preceding claims, wherein the fluid injection assembly comprises the housing (4) with the bore (5) and the slot (18) and either the housing is comprised by a cylinder head of the engine so that the fluid injector (1) is secured to the cylinder head and oriented in the predetermined position relative to a combustion chamber of the engine or the housing is comprised by an intake manifold of the engine for injection into the manifold so that the fluid injector (1) is secured to the intake manifold and oriented in the predetermined position relative to the intake manifold.