GB2614338A

GB2614338A - Damper Accumulator Support

Info

Publication number: GB2614338A
Application number: GB2201467.4A
Authority: GB
Inventors: S Masti Ravish
Original assignee: Delphi Technologies IP Ltd
Current assignee: Delphi Technologies IP Ltd
Priority date: 2021-12-23
Filing date: 2022-02-04
Publication date: 2023-07-05

Abstract

A support 20 for a damper accumulator 10 of a high-pressure fuel pump. The support 20 has a first ring shaped support portion 22 and a second ring shaped support portion 24. The first support portion 22 is configured to contact a first side of the damper accumulator 10 in use, and the second support portion 24 is configured to contact a second side of the damper accumulator 10 in use. The first support portion 22 and the second support portion 24 are connected together via an integrally formed resilient connector 26. The first and second support portions 22, 24 each comprise a wave formation having an amplitude which varies around a circumference of the support potions 22, 24. Reference is also made to a method of forming such a support from a single piece of material. A high-pressure fuel pump having a support is also claimed.

Description

Damper Accumulator Support

Field of the invention

The present disclosure relates to a support for a damper accumulator of a high-pressure fuel pump and to a method of making the support for the damper accumulator. In particular, the present disclosure relates to a wave spacer ring for supporting a damper accumulator in the damper cup of a high-pressure fuel pump and to a method of making a wave spacer ring.

Background to the invention

In gasoline direct fuel injection systems, fuel from a fuel tank pump is supplied first to a high-pressure pump, and then to the fuel injectors. The high-pressure pump typically has a reciprocating plunger which is used to pressurise the fuel. To adjust the fuel pressure during operation, a spill valve of the high-pressure pump may remain open for a portion of the compression stroke of the plunger. In this situation, pressure pulsations can be generated and may propagate upstream of the spill valve resulting in undesirable noise and vibration in the system.

Such pressure pulsations are usually attenuated by a damper accumulator located inside a fuel-filled cup or chamber (herein referred to as 'damper cup'), which is typically mounted on the high-pressure pump. The damper accumulator is typically pre-charged with a gas at a suitable pressure.

The damper accumulator must be firmly supported inside the chamber in order to operate properly. One of the known methods of supporting the damper accumulator is by using a pair of wave spacer rings, with one wave spacer ring being located on either side of the damper accumulator. However, there is the possibility for the spacer rings to be misaligned or misoriented with respect to each other. This is undesirable as such misalignments could lead to unnecessary additional loading and stressing of the flexible walls of the damper accumulator during pump operation, and when pre-loading the damper accumulator during assembly. Such additional loads may also affect the damper accumulator's durability and shorten its fatigue life. Also such unbalanced loads might lead to undesirable mechanical vibration and noise.

The present invention has been devised to address or overcome at least some of the aforementioned problems associated with the prior art.

Statements of the invention

The present invention provides a support for a damper accumulator of a high-pressure fuel pump. The support comprises a first support portion and a second support portion, wherein the first support portion is configured to contact a first side of the damper accumulator in use, and the second support portion is configured to contact a second side of the damper accumulator in use, wherein the first support portion and the second support portion are connected together.

The support of the present invention is advantageous as the first and second support portions are constrained with respect to one another and so remain in place in an intended/preferred alignment or orientation with respect to one another during installation and use.

Optionally the first support portion is configured to contact a first side of a peripheral rim of the damper accumulator in use, and the second support portion is configured to contact a second side of the peripheral rim of the damper accumulator in use. Hence the damper support is firmly supported within the damper cup of the pump by the support without interfering with the operation of the damper accumulator.

The first and second support portions are optionally connected together by a connector. This is advantageous as it allows the mechanical properties/relationship of the connection between the two supports to be selected to best meet the needs of any particular application.

The connector may be a resilient connector so that it can apply a clamping force to the damper accumulator when the damper accumulator is in position within the support to hold the damper accumulator in place before and after installation.

In one example the connector is made of the same material as the first and second support portions. The support may be made of a metal, or polymeric and elastomeric materials using any appropriate manufacturing methods.

Optionally the connector is integrally formed with the first and second support portions. This is beneficial for manufacturing cost and efficiency and for durability.

The connector is optionally configured so that the first and second support portions are rotatable with respect to one another. Preferably the first and second support portions are rotatable with respect to one another about an axis which is substantially parallel to a tangent of the first and second support portions.

The first and second support portions may each comprise a gap located between a pair of connectors. This is beneficial as the mechanical compliance of the connection, made up of the pair of connectors, may be readily tuned.

In one example the first and second support portions are substantially ring shaped to allow for receipt of the damper accumulator within the ring-shaped supports. The ring shape may be circular, elliptical, oval, square, rectangular or any other ring shape suitable to the application.

Optionally the first and second support portions each comprise a wave or undulation formation with an amplitude which varies around the circumference of the support portions in a direction parallel to a central axis of the support portions. The wave/undulation may be a regular repeating wave/undulation or may vary without any particular pattern depending on application requirements.

The support portions are optionally orientated with respect to one another so that the first and second support portions are proximate one another at one or more locations around the circumference of the support portions, and spaced apart from one another at one or more locations around the circumference of the support portions.

The first and second support portions may be connected together at a location in which the support portions are proximate one another. Alternatively, the first and second support portions may be connected together at a location in which the support portions are spaced apart from one another In one example the maximum spacing between the first and second support portions in a direction parallel to the central axis of the support portions is located substantially opposite the location at which the support portions are connected together.

Optionally the first support portion is a mirror image of the second support portion. This is beneficial for balanced dynamic behaviour where required. The regions of the support portions wherever in contact with the rim are optionally aligned radially and axially in such a way for best possible coaxiality of reaction forces and support of the damper.

In a further aspect the present invention provides a high-pressure fuel pump, comprising a support as described above.

In another aspect, the present invention provides a method of making a support for a damper accumulator. The method comprises forming a single piece of material into a plurality of rings without separating the single piece of material into separate pieces, wherein each ring is connected to an adjacent ring by a connector portion; and positioning the plurality of rings with respect to one another so that the central axes of the plurality of rings are substantially co-linear.

Forming the support from a single piece of material is beneficial for a material handling and process efficiency perspective.

Optionally the step of forming a single piece of material into a plurality of rings comprises forming a substantially planar shape.

positioning the plurality of rings with respect to one another optionally comprises bending each connector portion.

A wave shape may be formed into one or more of the rings. Brief description of the drawings A non-limiting example of the present invention will now be described with reference to the following drawings in which: Figure 1 shows a sectional side view of the top of a prior art high-pressure pump; Figure 2 shows an isometric view of a damper accumulator located within a support (a non-limiting example of the present invention); Figure 3 shows an isometric view of a damper accumulator before insertion into the support; Figure 4a shows a side view of a single piece of material during a first stage of manufacture of a support; Figure 4b shows a plan view of the single piece of material during the first stage of manufacture; Figure 5a shows a side view of the single piece of material during a second stage of manufacture of the support; Figure 5b shows a plan view of the single piece of material during the second stage of manufacture; Figure 5c shows an isometric view of the single piece of material during the second stage of 20 manufacture; Figure 6a shows an isometric view of the single piece of material during a third stage of manufacture of the support; and Figure 6b shows an isometric view of the finished support. Detailed description Throughout this description, references to top, bottom, peak, and trough portions of the component and other such directional or relative references are made in relation to the orientations of the components shown in the Figures but are not intended to be limiting.

To provide context for the invention Figure 1 shows a portion of a high-pressure pump 1 having a prior art support system for a damper accumulator 10. The prior art support system comprises a pair of wave spacer rings 2, 4 located together with a damper accumulator 10 in the damper cup 5 of the high-pressure pump 1.

As is well known in the art, the damper accumulator 10 is supported by wave spacer rings 2, 4 substantially in the centre of fuel space 6 of the damper cup 5. The top wave spacer ring 2 is located between a top surface of the damper accumulator 10 and the upper inner surface of the damper cup 5, and the bottom wave spacer ring 4 is located between a bottom surface of the damper accumulator 10 and the top surface 7 of a top portion 9 of the high-pressure pump 1. The wave spacer rings 2, 4 are substantially ring shaped in plan view (not shown) and each has a wave formation comprising three peaks (which may also be referred to as crests) and three troughs. \Mien installed together with the damper accumulator 10 in the damper cup 5, the top wave spacer ring 2 contacts a top surface of a peripheral rim 12 of the damper accumulator 10, and the bottom wave spacer ring 4 contacts a bottom surface of the peripheral rim 12 of the damper accumulator 10. The wave spacer rings 2, 4 are resiliently deformed when installed in the damper cup 5 so that the damper accumulator 10 is firmly held and pre-stressed by the wave spacer rings 2, 4.

The central axes of the top wave spacer ring 2 and the bottom wave spacer ring 4 are substantially co-linear and the wave spacer rings 2, 4 are intended to be axially aligned and rotationally orientated with respect to one another so that the troughs of the top wave spacer ring 2 substantially align with the peaks of the bottom wave spacer ring 4 (as viewed in relation to Figure 1). The peripheral rim 12 of the damper accumulator 10 is therefore trapped between and supported by the wave spacer rings 2, 4 at three equidistant locations around the peripheral rim 12. The peaks of the top wave spacer ring 2 substantially align with the troughs of the bottom wave spacer ring 4 (as viewed in relation to Figure 1) so that the top and bottom wave spacer rings 2, 4 have maximum spacing between each other at three equidistant locations around the peripheral rim 12 which are angularly offset from the three support positions by about 60°.

As discussed above, during installation and/or use of the high-pressure pump 1 the wave spacer rings 2, 4 can be or become misaligned with respect to one another as they are two separate components. The misalignment can be a rotational misalignment (such that the troughs of the top wave spacer ring are rotationally offset from the peaks of the bottom wave spacer ring 4), or radial lateral misalignment / axial misalignment (such that the troughs of the top wave spacer ring 2 do not contact the rim 12 of the damper accumulator 10 at the same radial distance from the centre of the damper accumulator 10 as the peaks of the bottom wave spacer ring 4). Rotational misalignment of the wave spacer rings 2, 4 can cause undesirable bending of the damper accumulator 10, and radial lateral misalignment can cause a twisting couple on the rim 12 of the damper accumulator 10 which may cause damage by bending and inefficient gripping (the lack of firmness of support) of the damper by the wave springs.

Figure 2 shows an isometric view of a support 20 on which a damper accumulator 10 is mounted. For clarity, like reference numerals have been used throughout to designate like components. The support 20 comprises a top ring 22 and a bottom ring 24 which are connected by two resilient connector pieces 26. As described in greater detail below, the two connector pieces 26 are integrally formed with the material of the top and bottom rings 22, 24.

The top ring 22 is similar in many respects to the prior art wave spacer ring 2 described above and the bottom ring 24 is similar in many respects to the prior art wave spacer ring 4 described above. Specifically, the top and bottom rings 22, 24 each have a ring shape in plan view and each have a wave formation with three peaks and three troughs (relative to the orientation of Figure 2). However, it will be understood that the embodiments 22 and 24 are only a representative! example of spacer support rings and their features are not limited to just three peaks or three troughs of a wave-like formation of the rings. The ring formation may have any convenient number of peaks or troughs and the usage of the term WAVE' is to in generality mean an undulation formation of the spacer support. The usage of three peaks and three troughs are employed here for the ease of explanation of an embodiment of the invention.

As with the example prior art wave spacer rings 2, 4, the peaks and troughs of the top and bottom rings 22, 24 are substantially equally spaced or in general identically arranged around the rings 22, 24. The top and bottom rings 22, 24 may consequently be referred to as top and bottom wave spacer rings 22, 24, and because the top and bottom rings 22, 24 are connected by connector pieces 26, the support 20 may be referred to as a wave spacer ring 20.

With reference to the orientation of Figure 2, the top ring 22 has three peaks 27a, 27b, 27c and three troughs 28a, 28b, 28c, and the bottom ring 24 has three peaks 27d, 27e, 27f and three troughs 28d, 28e, 28f (see also Figure 6b). The two connector pieces 26 are located substantially at the trough 28c of the top ring 22 and at the peak 27d of the bottom ring 24 such that the trough 28c of the top ring 22 and the peak 27d of the bottom ring 24 are resiliently connected together. At this position -and at the other trough/peak pairs 28a/27e and 28b/27f located around the circumference of the rings 22, 24 -the rings 22, 24 are located proximate one another. The distance between the trough/peak pairs 28c/27d, 28a/27e and 28b/27f is indicated in Figure 6b by the letter Id'. The distance Id' is less than the thickness of the rim 12 of the damper accumulator 10 so that when the damper accumulator 10 is located between the top and bottom rings 22, 24 of the support 20, the rim 12 is trapped between the top and bottom rings 22, 24 as a result of the resilient restoring force applied by the two connector pieces 26 as will be described in greater detail below.

The peaks 27a, 27b, 27c of the top ring 22 are located substantially opposite the troughs 28d, 28e, 28f of the bottom ring 24 respectively. The peak/trough pairs 27a/28d, 27b/28e and 27c/28f are spaced apart from one another by distance ID' as indicated in Figure 6b. The distance ID' is greater than the distance between the top surface 7 of the top portion 9 of the high-pressure pump 1 and the top inner surface of the damper cup 5 so that the support 20 is compressed between the top portion 9 and the damper cup 5 when installed in the high-pressure pump 1. It will be understood that the top surface 7 of the top portion 9 and the top inner surface of the damper cup 5 are a specific example case of a general arrangement and that the bearing surfaces for the outer regions of the wave spacer ring 20 could be provided by other parts of the high-pressure pump 1.

Figure 3 shows an isometric view of the support 20 and damper accumulator 10 during assembly. As indicated by arrow 'X', the damper accumulator is inserted into the support 20 between the peak/trough pair 27b/28e of the top and bottom rings 22, 24. It can be seen in Figure 3 that peak/trough pair 27b/28e is located substantially opposite the two connector pieces 26 (and therefore also substantially opposite the trough/peak pair 28c/27d).

During insertion of the damper accumulator 10 into the support 20, the connector pieces 26 resiliently bend open so that the rim 12 of the damper accumulator 10 may be received between the trough/peak pairs 28c/27d, 28a/27e and 28b/27f of the top and bottom rings 22, 24. Therefore, during insertion of the damper accumulator 10 into the support 20 the top and bottom rings 22, 24 rotate with respect to one another about an axis which is substantially parallel to a tangent of top and bottom rings 22, 24. Because the distance 'd' between the trough/peak pairs 28c/27d, 28a/27e and 28b/27f is less than the thickness of the rim 12 of the damper accumulator 10, the resilient connector pieces 26 apply a restorative force to the rim 12 of the damper accumulator thereby holding the rim 12 securely in place between the top and bottom rings 22, 24. As best shown in Figure 2, part of the rim 12 of the damper accumulator 10 is received between the top and bottom portions of the two connector pieces 26 The two connector pieces 26 constrain the relative movement between the top and bottom rings 22, 24 such that the rings 22, 24 cannot translate with respect to one another along the plane of the rim 12 of the damper accumulator 10, or rotate with respect to one another about their substantially co-linear axis A. This is beneficial as the trough/peak pairs 28c/27d, 28a/27e and 28b/27f are consequently held in place with respect to each other thereby alleviating the problems discussed above associated with the prior art.

Figures 4a to 6b illustrate a method of making a support 20. The support 20 may be made of a metal, or polymeric and elastomeric materials using any appropriate manufacturing methods as would be known to those skilled in the art.

As shown in Figures 4a and 4b, in a first step, a single piece of material 15 is formed into a planar dumbbell shape comprising two rings 22', 24' connected by two substantially parallel connector pieces 26'). The two connector pieces 26' are separated by a gap 18. In this example embodiment, the single piece of material 15 comprises a wire. The material could also be a tube in an alternative example.

The single piece of material 15 is not cut or separated into separate pieces during manufacture of the support 20. In the example embodiment shown, the ends of the single piece of material meet at junction 17 where they are connected by welding or brazing or any other suitable joining method. In an alternative example, the two ends of the single piece of material 15 are not attached to each other at junction 17. In the example shown, the junction 17 is located at one end of the dumbbell shape substantially in line with the gap 18. However, this is not critical and the junction 17 may be located in any suitable position.

Referring now to Figures 5a to Sc, in a second step the planar rings 22', 24' are formed into a wave shape suitable for the formation of the peaks 27a-27f and troughs 28a-28f described above. For example, the planar rings 22', 24' may be die-pressed to achieve the desired shape. A person skilled in the art will appreciate that other hot or cold forming methods may be used and that die-pressing is not essential. The skilled person will also be able to ascertain an appropriate wave formation to be formed into the rings 22', 24' in order to achieve the desired peak/trough relationship in the finished support 20.

Referring now to Figures 6a and 6b, in a third step the formed rings 22, 24 are positioned with respect to one another so that the central axes of the plurality of rings are substantially co-linear along axis A of the support 20. This is achieved by bending the two connector pieces 26' over a curved anvil 30 so that the two formed rings 22, 24 rotate towards each other as indicated by arrows 'Y'. A person skilled in the art would know how to bend the two connector pieces by using the appropriate methods to generate the support 20 without unduly distorting the formed rings 22, 24.

It will be appreciated that the three method steps described above in relation to figures 4a to 6b need not be the only method steps and that other manufacturing steps may take place before, between or after the three method steps described. For example, the single piece of material 15 may be coated and/or heat treated. The three method steps described in relation to Figures 4a to 6b take place in the order described, but other manufacturing steps may also take place at any suitable point in the manufacturing process.

The method of manufacturing described above is a preferred method only for making the support 20. In an alternative method the two rings 22', 24' may be formed from separate pieces of material (which may originate from the same piece of material) which are then connected by one or more connectors. In such a method the wave formation, or any other suitable formation, may be formed into the rings 22', 24' before or after the rings 22', 24' are connected together.

The single piece of material 15 need not be a wire and need not be bent to form the dumbbell shape depicted in Figure 4b. In one example method the single piece of material 15 may be an elongate piece of material which is cut longitudinally in two locations substantially in the centre of the elongate piece of material to form two equal length slits separated by an un-cut section of the material. The slits may then be opened up and shaped to form the two rings 22', 24'. In such an embodiment the connector piece 26' would consist of one single piece of material joining the two rings 22', 24'.

In another example embodiment the two connector pieces 26' shown in Figure 4b may contact one another such that gap 18 does not exist. If desired and functionally compatible, the two connector pieces 26' may be attached to one another by welding, brazing or any other suitable method.

In yet another embodiment the single of material 15 may be tube-like instead of wire-like.

In the above description the support 20 is described as having two connector pieces 26. It will be understood that the two connector pieces 26 act together and so may be thought of as a single connector. Additionally, the two connector pieces are connectors in their own right such that the support 20 may be considered to have two connectors 26 separated by a gap 18.

The support 20 described herein comprises two rings 22, 24 connected together by one or more connectors. It will be appreciated that the support 20 may comprise more than two rings with each ring being connected to a neighbouring ring by a connector and positioned so that the axis of each ring is substantially co-linear. The support 20 may comprise more than one ring configured to be located above the damper accumulator 10 in use and more than one ring configured to be located below the damper accumulator 10 in use. Provided that the top ring or rings are connected to the bottom ring or rings the benefits of the improved support 20 may be realised. It is not necessary that the number of rings configured to be located above the damper accumulator 10 in use match the number of rings configured to be located below the damper accumulator 10 in use. In addition, it is not necessary that every ring be formed into a wave formation and some of the rings may remain planar or may be formed into another suitable shape. Indeed, in cases where multiple rings are used above and below the damper accumulator 10 in use, none of the rings need be formed, the support instead being provided by the resilient connectors between the rings. Finally, any ring configured to be located above or below the damper accumulator 10 in use may have different radial depths and/or axial heights. If the rings are configured to be located above or below the top/bottom surface of the damper accumulator 10, the rings may in fact be discs. This is an example of a vertical cascading arrangement of wave spacer spring supports for an application using more than one damper in a vertical arrangement. There can also be an example of a horizontally cascaded arrangement of supports and dampers depending on the orientation of the damper cup 5 in use.

It will be understood that the above-described embodiment is an example only and that many different configurations are possible without departing from the scope of the invention.

Claims

Claims 1. A support (20) for a damper accumulator (10) of a high-pressure fuel pump (1), the support (20) comprising a first support portion (22) and a second support portion (24), wherein the first support portion (22) is configured to contact a first side of the damper accumulator (10) in use, and the second support portion (24) is configured to contact a second side of the damper accumulator (10) in use, wherein the first support portion (22) and the second support (24) portion are connected together.
2. A support (20) as claimed in claim 1, wherein the first (22) and second (24) support portions are connected together by a connector (26).
3. A support (20) as claimed in claim 2, wherein the connector (26) is a resilient connector.
4. A support (20) as claimed in claim 3, wherein the connector (26) is made of the same material as the first (22) and second (24) support portions.
5. A support (20) as claimed in claim 4, wherein the connector (26) is integrally formed with the first (22) and second (24) support portions.
6. A support (20) as claimed in any preceding claim, wherein the first (22) and second (26) support portions are substantially ring shaped.
7. A support (20) as claimed in claim 6, wherein the first (22) and second (24) support portions each comprise a wave formation with an amplitude which varies around the circumference of the support portions (22, 24) in a direction parallel to a central axis (A) of the support portions (22, 24).
8. A support (20) as claimed in claim 7, wherein the support portions (22, 24) are orientated with respect to one another so that the first (22) and second (24) support portions are proximate one another at one or more locations (28c, 27d) around the circumference of the support portions (22, 24), and spaced apart from one another at one or more locations (27a, 28d) around the circumference of the support portions (22, 24).
9. A support (20) as claimed in claim 8, wherein the first (22) and second (24) support portions are connected together at a location (28c, 27d) in which the support portions (22, 24) are proximate one another.
10. A support (20) as claimed in claim 8 or 9, wherein a maximum spacing (D) between the first (22) and second (24) support portions in a direction parallel to the central axis (A) of the support portions (22, 24) is located (27b, 28e) substantially opposite the location (28c, 27d) at which the support portions (22, 24) are connected together.
11. A support (20) as claimed in any preceding claim, wherein the first support portion (22) is a mirror image of the second support portion (24).
12. A method of making a support (20) for a damper accumulator (10), the method comprising: forming a single piece of material (15) into a plurality of rings (22, 24) without separating the single piece of material (15) into separate pieces; wherein each ring (22, 24) is connected to an adjacent ring (22, 24) by a connector portion (26); and positioning the plurality of rings (22, 24) with respect to one another so that the central axes (A) of the plurality of rings (22, 24) are substantially co-linear.
13. A method as claimed in claim 12, wherein the step of forming a single piece of material (15) into a plurality of rings (22, 24) comprises forming a substantially planar shape (22', 24', 26').
14. A method as claimed in claim 12 or 13, comprising forming a wave shape into one or more of the rings (22, 24).
15. A high-pressure fuel pump (1) comprising a support (20) as claimed in any one of claims 1 to 11.