WO1995016188A1

WO1995016188A1 - Dosing feeder for fluids, preferably for combustion engine fuel injectors

Info

Publication number: WO1995016188A1
Application number: PCT/SE1994/001186
Authority: WO
Inventors: Magnus Glavmo; Carl Tyrén
Original assignee: Mecel Ab
Priority date: 1993-12-10
Filing date: 1994-12-08
Publication date: 1995-06-15
Also published as: SE9304112D0; SE502160C2; SE9304112L

Abstract

A method and an arrangement for transferring a small volume of fluid along a boundary layer between two tightly contacting elongated bodies (1, 2) from a first end to a second end of said tightly contacting bodies, where at least one of the bodies is made of a giant magnetostrictive material. According to the invention a narrow transversal end section of the magnetostrictive body (1) is exposed to a magnetic field causing a transversal contraction and a longitudinal expansion of the end section thus forming a cavity (9) at one end of the boundary layer. Fluid (5) from a reservoir (4) is replenished into the initially formed cavity induced by the magnetic field at the first end of the bodies, after which the magnetic field is transferred along the bodies towards their second end while conveying said cavity (9) and the fluid contained therein and emitting the fluid (5) at the second end of the bodies. By controlling the strength of the magnetic field initially and during transfer, could dosing and pressurising of the fluid be obtained.

Description

DOSING FEEDER FOR FLUIDS, PREFERABLY FOR COMBUSTION ENGINE FUEL INJECTORS

This invention relates to a method using a magnetostrictive injector or ejector for dosing and forwarding fluids in accordance with the preamble of patent claim 1 and an arrangement implementing the method.

PRIOR ART

Several magnetostrictive fuel injectors are known. Most often the magnetostrictive material is used as a valve member, which by influence of a magnetic field opens or closes a fuel channel. In RD (Research Disclosure), 301019 and 292028; EP,A,189419 and GB,A,2056559, examples of this kind of solutions are shown. In other solutions an oscillating magnetostrictive body is used atomising the fuel, as shown in GB2082251 or SU497410.

OBJECT OF THE INVENTION

The object of the invention is to give directions for a method and an arrangement implementing the method, which by simple measures and means makes it possible to forward and emit small quantities of fluids at high speeds and accurate control, for example in connection with injection of fuel in liquid form into a combustion chamber of Otto- or Diesel engines. The invention is based upon using the properties of magnetostrictive materials, i.e. giant magnetostrictive materials, said properties causing a transverse contraction and a longitudinal expansion when the material is subjected to a magnetic field, for example a material designated as

TERFENOL

A further object is to give directions for a method and an arrangement by means of a predetermined amount of fluid could be dosed within a cavity and during forwarding of said dosed amount of fluid could be pressurised before emitting the fluid.

Yet another object is to give directions for a method and an arrangement by means of a number of consecutive dosed volumes of fluid could be forwarded and at the same time being held separated by the injector/ejector before emitting the separated volumes of fluids. Yet another object is to obtain a simple injector/ejector wherein the magnetostrictive base member is used for establishing the pressure needed for filling of the dosing volume, said base member also forwarding the dosed volume in a controlled manner.

Yet another object is to enable a simple injector/ejector which could pressurise the dosed volume by controlling a magnetic field. FIGURES

A preferred embodiment is described in the following paragraph by reference to attached figures, where

Fig. 1-4 illustrates different phases when using the inventive method in a schematically depicted arrangement according the invention,

Fig. 5 and 6 illustrates schematically how the inventive method is applied when a sequence of cavities filled with fluid is forwarded along a body composed according the invention,

Fig. 7 and 8 illustrates schematically an application of the invention when forwarding a cavity along a body composed according the invention and simultaneously compressing the fluid enclosed in the cavity,

Fig. 9-12 illustrates, equivalent to figure 1-4, different phases when using the inventive method in a modified arrangement according the invention,

Fig. 13 is a cross-section A-A through the arrangement shown in figures 1-12, Fig. 14 illustrates yet another embodiment of the inventive arrangement.

DESCRIPTION OF AN EXEMPLARY EMBODIMENT

The invention is explained in detail in the following paragraphs by reference to figures 1-4, showing the different phases during application of the invention. The arrangement required for exercising the invention includes a rod shaped body 1 made preferably of a giant magnetostrictive material of the kind that contracts transversely and expands longitudinally when subjected to a magnetic field. Preferably using a material designated as TERFENOL. The rod shaped body is surrounded by a sleeve shaped body 2, preferably made of a non magnetic material, and the rod shaped body is contacting the inner surfaces of the sleeve formed body in a tight manner. The contact surfaces fits tightly either by having the rod shaped body 1 shrink fitted into the sleeve formed body 2 whereby a predetermined grip fit is obtained between the contact surfaces, or having the bodies arranged with a thin fluid film between the contact surfaces, said film forming a dynamic sealing. One end of the sleeve shaped body, preferably the first end located to the right in fig. 1-4, could preferably be terminated by an end wall 3, with the rod shaped body closely contacting the inside of said end wall 3. The end wall 3 further forms at least a part of an enclosing wall for a fluid reservoir 4 attached to the end of the sleeve formed body, said fluid reservoir containing the fluid 5 which is to be forwarded along the bodies 1 and 2. Cuts or narrow channels 6 are arranged in the end wall, also shown in figure 13. The channels 6 lead to the contacting surfaces between the rod shaped body 1 and the sleeve shaped body 2, such that the fluid in the container 4 is connected with said contacting surfaces. The fluid container 4 in the embodiment shown is connected to the surrounding atmosphere through the pipe 7, whereby the fluid in the container is subjected to the surrounding pressure. An alternative solution could use a feeding pump which could pressurise the container 4 in order to kee the container filled and reduce formation of air bubbles.

Around the elongated compounded body 1,2 are a number of closely arranged excitation windings 8 each of the excitation windings being excitable, and thus generating a narrow magnetic field affecti a narrow transversal section of the rod shaped body 1. Influenced by the generated magnetic field th narrow transversal section of the rod shaped body 1 undergoes a contraction transversely and an expansion longitudinal. A cavity 9 is thus formed in the boundary layer between the contacting surfaces of the bodies 1 and 2, whereby fluid 5 is sucked into the cavity 9 assisted by the negative pressure created in the cavity.

By simultaneously deactivation of a number of excitation windings located closest to the container and activation of a corresponding amount of excitation windings located on the other side of the cavity 9, is the cavity and the fluid contained in the cavity brought into motion in the longitudinal direction along the compounded body 1,2.

Figures 1-4 illustrates schematically how the inventive method is applied in order to form a cavity filled with fluid at the part of the compounded body 1-2 being located closest to the container, and forwarding of the filled cavity along the compounded body to its other and second end, where the fluid contained in the cavity is emitted. When the excitation winding or windings located closest to the end wall 3 is activated, as shown in figure 2, the end section of the rod shaped body 1 is subjecte to the generated magnetic field. The end section of the rod shaped body 1 is hereby subjected to a contraction transversally and an expansion longitudinally whereby a cavity is formed between the surrounding sleeve shaped body 2 and the end section of the rod shaped body 1. Fluid from the container 4 is hereby sucked into the cavity through the channels 6 in the end wall 3. Due to that the rod shaped body with its end is in an abutting relationship with the end wall 3 of the sleeve shaped body, the end wall as well as the end part of the sleeve shaped body will be enclosed with the longitudinal expansion movement. The end part of the sleeve shaped body is thus subjected to an elastic elongation. The end part of the sleeve shaped body has been given a thin- walled cross section as schematically shown in the figures, in order to offer lowest resistance possible for the elastic elongation. The sleeve shaped body is preferably made of a non-magnetic material having a high elasticity in the longitudinal direction.

As shown in figure 3 the magnetic field is transferred along the compounded body 1,2 by controlling sequential activation of successive excitation windings, whereby the fluid filled cavity is transferred along the compounded body. When the cavity have reached the other end of the compounded body, the fluid will be emitted through the narrow opening formed at said other end, as shown in figure 4. Figure 1-4 illustrates the application of the inventive principles, forming a cavity filled with fluid and a subsequent transfer of the fluid filled cavity along the compounded body to its other end.

Figure 5 and 6 illustrates the preferred application of the inventive method, whereby a series of cavities filled with fluid is generated in consecutive order and transferred after each other and successively being emitted at the other end of the compounded body.

Figure 7 and 8 illustrates the possibility of pressurising the fluid contained in the cavity/cavities, which will be enabled by the inventive method. By variation of the width of the magnetic field, the volume of the cavity could be decreased during transfer thereof along the compounded body, which result in a pressure increase of the fluid. A corresponding effect could be obtained by decreasing the level of excitation current to the excitation winding/windings during transfer of the cavity along the compounded body.

In figures 1-8 the end wall 3 of the sleeve shaped body is shown as a rigid boundary wall of the container 4. During the longitudinal expansion of the rod shaped body the container likewise will be moved a corresponding distance. Figures 9-12 illustrates schematically an alternative embodiment, where the container is stationary, such that the compounded body when expanded at the end part is pushed into the container 4 thereby pressurising the fluid in the container. The supply duct 6 could for this purpose include a check valve 10 preventing fluid from escaping the container. The pressure build up of the fluid contributes in a rapid filling of the cavity formed by the magnetic field. For the description of the inventive method forming a cavity filled with fluid and transfer of that cavity along the compounded body, reference is made to the description associated with figures 1-8.

The rod shaped body made of giant magnetostrictive material must in a previously known fashion be pretensioned in a direction counteracting the longitudinal expansion when subjected to a magnetic field. The purpose is to eliminate mechanical hysteresis such that no residual change of form of the magnetostrictive body will be obtained when the magnetic field ceases. This kind of pretension could be obtained with a rod made of memory alloy, which stretches through the centre of the magnetostrictive rod, from one end to the other end of the magnetostrictive rod, and attached to end washers arranged at the ends of the rod shaped body. In figures 1-12 the rod shaped body is shown as a massive rod made of giant magnetostrictive material. The rod shaped body could be as a hollow body, i.e. a tube, in order to reduce the amount of material used, with the hollow spaced filled with a non magnetic material. In the figures the excitation windings are arranged at the outside of the compounded body and surrounding it. If the rod shaped giant magnetostrictive body is shaped as a tube, then the excitation windings could be arranged inside the hollow space in the tubular body. This could further reduce the outer dimensions of the arrangement. At the end of the compounded body 1,2 where fluid is expelled, is preferably arranged an excitation winding for generation of a narrow magnetic field influencing a minor part of the end section of the rod shaped giant magnetostrictive rod, for the purpose of calibration of the narrow gap through which the fluid is to be expelled. By controlling the excitation current of said excitation winding the gap size could be controlled to the size needed.

In figure 14 a variant of the inventive arrangement is shown having the rod shaped body of giant magnetostrictive material surrounded by a sleeve shaped body made of an elastic non magnetic material, such as rubber. The rod 1 is arranged inside the sleeve 2 with a certain grip fit between the contacting surfaces and with the end of the rod 1 located towards the container 1 abutting the end wall 3 of the sleeve. The sleeve 2 is at said end flanged and in sealed fashion connected to the container 4 forming an elastic boundary wall of said container. In the end wall 3 of the sleeve 2 is in the same manner as the previously described embodiments arranged a number of cuts or channels 6, connecting the fluid contained in the container 4 with the boundary layer between the contacting surfaces of the rod 1 and the sleeve 2. The compounded body is surrounded, in the same manner as the previously described embodiments, by a number of adjoining excitation windings 8 being arranged for successive activation one after the other for the generation and transfer of cavities 9 filled with fluid along the compounded body, as described in foregoing parts.

In figure 14 is shown, which is applicable also for the other figures, that each separate segment of the excitation winding 8 is selectively magnetisable through some form of control unit 11 , through individual control lines 13. The control unit could possibly be a control system for fuel injection in engines, where sensors 14,15 furnish the control system with necessary inputs regarding engine speed/position respectively load, for determination of amount and timing for each injection. Each individual segment 12 is selectively magnetisable and the generated cavity could hence be transferred by having the right side outermost segments demagnetised at the same time as the left side outermost segments are magnetised, said sequence being repeated until the generated cavity is transferred over the boundary surface to the outlet. Pressurising is obtained if the total number of segments being magnetised is decreased during transfer, whereby the volume of the cavity will be reduced and the contained fluid is pressurised.

The embodiment shown in figure 14 is advantageous due to that the sleeve shaped body 2 is made of an elastic material, i.e. rubber, plastic or other polymeric material, which exhibit high elasticity in the longitudinal direction thereby imparting a low resistance on the longitudinal expansion of the rod 1 when subjected to a magnetic field, in contrast to what could be expected if the sleeve shaped body is made of a metallic material. If the longitudinal elasticity should be maintained with a smaller elasticity transversely or in a radial direction of the sleeve 2, then the elastic sleeve could be reinforced, e.g. by applying a spirally wounded reinforcement of non magnetic material, or by designing the elastic sleeve 2 with a number of adjoining stiffening flanges oriented transversely(not shown).

The invention is advantageously in all applications where there is a need for high speed and high precision injection of small quantities of dosed amount of fluids, e.g. liquids, to any space. The invention is particularly suitable for utilisation in fuel injectors for combustion engines.

The embodiments shown are only advantageous applications of the inventive method and an applicable arrangement. The invention could be modified in several ways within the scope of the present invention. The bodies (1,2) could for example be constituted as two elongated planar elements, which are only contacting each other along a mainly planar contacting surface, and where the cavity is transferred in-between these planar contacting surfaces. One body, preferably the non magnetostrictive body, could be a rigid fixedly arranged body. Both bodies could also be made of a magnetostrictive material, both of the bodies being subjected to contraction whereby the cavity is formed by a local increase of the volume in the boundary layer where both contacting surfaces are moving away from each other.

The container could also be physically detached from the two bodies and only connected to the contacting surfaces through a flow channel leading to the first end of the bodies where the cavity is formed initially. The first end of the second body (2) could also lack the end wall shown in the embodiments, whereby the first rod shaped body without restrictions could expand longitudinal passed the end part of the second body.

Above mentioned alternatives are examples on embodiments which all are covered within the scope of the independent claims regarding the inventive method and the arrangement for exercising the method.

The bodies 1,2 stretches between two ends over a sufficient length enabling formation of a cavity at one end and during transfer of the cavity being able to maintain the cavity enclosed between the contacting surfaces of the bodies. This is by definition what is intended by the limitation elongated bodies mentioned in the claims. The transfer of the cavity from one end to the other end of the bodies does not necessarily have to take place along the widest extension of the contacting surfaces. Thus the contacting surface between the rod shaped inner body and the sleeve shaped outer body in the embodiments shown, could have a circumference which exceeds the distance between the end parts of the sleeve respectively the rod.

An alternative solution could instead have a reversed polarity of the magnetostrictive properties, in such a manner that a rod is surrounded by a sleeve with a gap between the rod and sleeve. A magnetic field could then instead generate a local enlargement of the rod, said enlargement being transferred by the subsequent transfer of the magnetic field in such a manner that fluid is pushed in front of the enlargement in the gap between the rod and the sleeve. Difficulties arises due to that pretensioning of the rod could be difficult to realise, which pretension is necessary for the rod to recover its initial form without hysteresis.

Claims

1. Method for dosing an amount of fluid in the boundary layer between two tightly contacting elongated bodies (1,2) at one end of the elongated bodies, hereafter named the first end, forming a cavity in the boundary layer between the bodies and transferring the amount of fluid being dosed in the cavity along the boundary layer for further outfeed of the dosed amount of fluid a second end of the elongated bodies characterized in

-at least one of the bodies (1) is made of a magnetostrictive material, preferably a giant magnetostrictive material, and that a narrow transverse section at the first end of the bodies (1) is subjected to influence of a magnetic field of such an order that at least the first magnetostrictive body

(1) contracts in a transverse direction and expands in a longitudinal direction, forming a cavity (9) in the boundary layer between the first body (1) and the second body 82),

-fluid (5) being replenished into said cavity (9) from a source of fluid (4),

-and the magnetic field being transferred along said closely contacting bodies from the first end to the second end while carrying said fluid filled cavity (9) and further outfeeding the fluid (5) at the second end.

2. Method according to claim 1 characterized in that the contraction in the transverse direction and the expansion in the longitudinal direction of the first body simultaneous bring about a corresponding expansion in the longitudinal direction of the corresponding end part of the second body.

3. Method according to claim lor2 characterized in that the fluid (5) is replenished into said cavity (9) from a supply from a reservoir arranged at the first end of said closely contacting bodies (1 ,2), by the action of the negative pressure created when the cavity is formed.

4. Method according to claim 1,2 or 3 characterized in that the fluid is replenished into said cavity (9) from a supply from a reservoir arranged at the first end of said closely contacting bodies (1,2), partly by the action of the negative pressure created when the cavity is formed and partly by the action of a pressure increase in the fluid (5) caused by the expansion of the bodies into the reservoir (4).

5. Method according to any of preceding claims characterized in that a series of adjoining magnetic fields (8) is activated sequentially in predetermined intervals affecting the end part of said first body (2), preferably a magnetostrictive body, and hereby transferring a series of cavities (9) filled with fluid along said closely contacting bodies and sequentially outfeeding the fluid (5) contained in each cavity (9) at the second end of the bodies.

6. Method according to any of preceding claims c h a r a c t e ri z e d in that the cavity (9) formed at the first end is generated by a magnetic field with a predetermined order of strength, said magnetic field is, during transfer from the first end to the second end of the bodies during an initial phase of said transfer, maintained at a constant order of strength of said magnetic field at least until the cavity no longer is connected to the reservoir (4), after which the strength of the magnetic field (8) is decreased in order of strength during a later phase of the transfer of the magnetic field from one end of the bodies to the second end, whereby the volume of the cavity is decreased and hence pressurising the fluid before outfeeding the fluid at the second end of the bodies.

7. Arrangement for exercising the method specified in claims 1-6 c h a r a c t e ri z e d in that the arrangement includes; -a first elongated body (1) stretching from a first end to a second end, which first body is closely contacting a second elongated body (2) in such a manner that a boundary layer is formed between the bodies and their respective first and second ends, and where at least one of the bodies is made of a magnetostrictive material, preferably a giant magnetostrictive material,

-a plurality of excitation coil segments arranged closely to the elongated bodies (1,2) for the purpose of magnetising narrow segments of the bodies between the first and second ends of the bodies, causing a contraction transversely and expansion longitudinally and thus forming a cavity (9) in the boundary layer,

-a reservoir (4) containing fluid and connected through channels (6) with the boundary layer between the bodies at their first end, and -means for bringing the magnetic field into motion along the elongated bodies (1,2) from the first end to the second end thereof, while carrying the cavity formed by said magnetic field at the first end and replenished with fluid by said reservoir, towards the second end, which cavity (9) is transferred in the boundary layer outfeeding the fluid (5) at the second end.

8. Arrangement according to claim 7 c h a r a c t e r i z e d in that the first elongated body is rod shaped and is closely contacting the inner surface of a sleeve shaped second elongated body.

9. Arrangement according to claim 7 or 8 c h a r a c t e r i z e d in that only the rod shaped body is made of a magnetostrictive material and the other body is made of a non magnetic material.

10. Arrangement according to claim 9 characterized in that the end part of the magnetostrictive body being located at the first end of the bodies, is physically connected with the corresponding end part of the non magnetic body (2) in order to connect the end part of the non magnetic body together with the expansion movement caused by the magnetostrictive action of the first body

11. Arrangement according to claim 10 characterized in that the end part of the first rod shaped body (1), located at the first end of the bodies, is arranged in an abutting relationship with an end wall (3) of the corresponding part of the sleeve shaped second body (2), such that the end wall (3) forms at least one boundary wail of a reservoir (4) for fluid connected to the second body, which reservoir through channels (6) is connected with the boundary layer located closest to the first end of the rod (2) and the sleeve (2).

12. Arrangement according to claim 11 characterized in that the end part of the sleeve (2) located closest to the end wall (3) of the sleeve (2) is construed to be able to deform elastically and take pan in the longitudinal expansion movement of the rod (1).

13. Arrangement according to any of preceding claims characterized in that a series of excitation windings (8) each of them being separately magnetisable, are arranged adjoining each other as seen in the longitudinal direction of the first body ( 1 ), and where each section of the excitation winding is arranged when activated to generate a narrow magnetic field affecting the first body, and that a control unit is arranged for sequential activation of each section of the excitation winding (8) in a consecutive order, starting at the first end.

14. Arrangement according to claim 13 characterized in that the excitation windings (8) are surrounding the sleeve externally, with the rod (3) arranged inside the sleeve.

15. Arrangement according to claim 8 or 9 characterized in that the rod have a tubular form, with the excitation windings being arranged inside the hollow space of said rod.

16. Arrangement according to any of the claims 8-14 characterized in that the rod shaped body (1) is clamped against the interior surface of the sleeve shaped body (2), with a predetermined grip fit between the contacting surfaces.

17. Arrangement according to any of the claims 8-14 characterized in that the rod shaped body (1) is tightly contacting the interior surface of the sleeve shaped body (2), with a thin film of fluid between the contacting surfaces.

18. Arrangement according to any of the claims 8-17 characterized in that the sleeve shaped body (2) is made of a material exhibiting a high elasticity in the longitudinal direction of the sleeve (2), preferably rubber.

19. Arrangement according to claim 18 characterized in that the elastic sleeve shaped body (2) is provided with transversely arranged reinforcements in order to reduce the elastic deformation in the transversal direction of the sleeve.