US3839943A

US3839943A - Electromagnetic injector with assist

Info

Publication number: US3839943A
Authority: US
Inventors: J Ufnalewski
Original assignee: Societe des Procedes Modernes dInjection SOPROMI
Current assignee: Societe des Procedes Modernes dInjection SOPROMI
Priority date: 1972-06-23
Filing date: 1973-06-20
Publication date: 1974-10-08
Anticipated expiration: 1991-10-08
Also published as: RO69041A; FR2190167A5; PL87108B1; GB1440002A; DE2331200A1; JPS4956039A

Abstract

An electromagnetic injector using a fluid pressure assist to obtain a controlled opening movement of the injector and a rapid closing.

Description

ilite rates atent 1 1 3,839,943 Uinniewsiri Oct. 8, 1974 ELECTROMAGNETIC llNJECTOR WITH [58] Field of Search 123/139 E; 91/454; ASSIST 137/6121 [75] inventor: .incek lUi'nalewski, Marly-le-Roi,

France [56] References Cited [73] Assignee: Societe Des Procedes Modernes UNITED STATES PATENTS Dlnjection Sopromi, Clichy, France 3.753.426 8/1973 Lilley 123/139 E 22 F 7 1 June 19 3 Primary ExaminerEdgar W. Geoghegan pp 71,716 Assistant Examiner-William F. Woods Attorney, Agent, or Firm--Darby & Darby [30] Foreign Application Priority Data June 23, 1972 France 72.22729 ABSTRACT An electromagnetic injector using a fluid pressure as- Cl- 91/454, 123/139 E, 137/6121 sist to obtain a controlled opening movement of the [51] lint. 1. F151: 11/08 injector and a rapid closing.

2 10 Claims, 1 Drawing Figure HP 79 :77 78 26 i i ix 72 I 13 35 9 ELECTROMAGNETIC INJECTOR WITH ASSIST The invention relates to an electro-magnetic injector with an assist to aid its switching operation.

BACKGROUND OF PRIOR ART In fuel injectors for internal combustion engines, and also in electromagnetically controlled injectors, it is desired to obtain a relatively slow rise of the injector needle, and a very quick and positive closing of the needle.

It is known to slow the opening movement of the injector needle by means of a damper consisting of a piston sliding in a fluid filled cylinder, and compressing the fluid during the opening movement of the needle. The fluid flows out through a reduced orifice so that the pressure in the cylinder acting on the piston slows the opening movement of the needle.

It is also known to control the movements of the injector needle by the pressure existing in a control, or counterpressure, chamber so that a drop in this pressure causes the opening of the needle by unbalancing the forces acting upon it. The chamber is repressurized to close the needle. The discharge and the repressurizing of the chamber are assured either by a electrically operated valve controlling the chambers discharge orifice, or by an electrically operated valve controlling both the discharge orifice and a supply orifice to the control chamber.

In order for the closing movement of the needle to be quick and positive, it is necessary that the dampers used during needle opening be made inoperative during the closing phase. One of the means used for this purpose consists of a mechanical linkage between the damping piston and the needle, which transmits only forces of compression. The piston then returns slowly to its initial position during the time separating two injections. This arrangement does not permit, simultaneously, great efficiency of the damper and a very high frequency operation of the fuel injector.

Another solution to the problem resides in filling the cylinder of the damper through a non-return, or check, valve consisting of a ball and a spring. But when the damper cylinder is of a substantial capacity, as is desired for good operation a quick closing of the needle allows a very large flow to go through the non-return valve, which can lead to mechanical difficulties for the ball and the spring.

The supply of the control cavity by a high pressure fluid through a small orifice and the discharge through an orifice controlled by an electrically operated valve do not permit a sufficient discharge and a sufficiently rapid repressurizing. And when the injection is of long duration, the consumption of the high pressure fluid is considerable. I

In the case of known devices wherein both orifices, exhaust and supply, are controlled by an electrically operated valve, the operation is such that at the instant of switching, i.e. the moment when the supply orifice must close and the exhaust orifice must open, there is a period of time during which both orifices are partially open. This allows the high-pressure fluid to flow through both orifices. This results in a needless and large consumption of the high-pressure fluid under pressure.

SUMMARY OF INVENTION In order to avoid the drawbacks of known devices, the goal of the invention is the creation of an injector in which the opening movement of the injector needle is slowed in a controlled manner, the closing of the needle is extremely quick and the risk of reopening the injector outlet because of needle bounce is eliminated.

The subject invention relates to an assisted electromagnetic injector for internal combusiton engines, of the type in which a pressure drop in a cavity permits the lifting of the injector needle and a reestablishment of pressure in said cavity causes the downward return of the needle. The injector also utilizes the electromagnetic control of an armature which assures the opening and closing of a valve controlling the high pressure sup ply and the closing and opening, respectively, of an exhaust piping. The injector of the invention includes a first chamber under high pressure and a second chamber separated from the first one by the seat of the valve. A connecting passage system is provided between a second chamber and a cavity which controls the injector needle. A passage having a restriction connects the passage system to a cylindrical cavity which is to be connected to an exhaust passage. A free piston provides the seal between the second chamber and said cylindrical cavity so that upon opening of the valve, the cavity controlling the needle is discharged through the restriction, thus causing a gradual lifting of the injector needle, and that upon closing of the valve, the cavity controlling the needle is repressurized through the passage system, thus causing a quick downward return of the injector needle.

DESCRIPTION OF DRAWING An example of execution of the invention is represented in the single FIGURE of the attached drawing in which one sees a partial longitudinal section of the control device of the injector.

DETAILED DESCRIPTION Referring to the drawing, it can be seen that the ho]- low housing 1 of the injector has, at its upper part, the electrical connections 2 for the electromagnetic control winding, and at its lower part: the atomizing jet 3. The control winding is on a body 4 in the central bore of the main body 1. The winding controls the movements of a movable armature 5 which carries a hollow tubular part 6 whose lower end is chamfered so as to form an active sealing edge 7 bearing on a flat surface 8 of a plug or core 9 fastened in the lower part of housing ll.

It is at the level of this core 9 that the control device for the injector needle is essentially situated. The upper part of this needle, or of its control rod, is represented by numeral 10.

A supply of a high pressure control fluid, for example, another suitable gas, is applied through a tubing 11 and the return to low pressure is through tubing 12. Both

tubings

11 and 12 communicate with passages in the upper part of the injector body. A first passage system l3, l4, 15, 16 is connected to the low pressure return 12 and is always at low pressure. A large annular chamber 17 in the body and passage 18, communicating with the high pressure supply 11, are always under high pressure during the normal operation of the injector.

The tubular part 6 is rigidly connected to the armature 5. It has a first internal chamber 19, to which communication is made by a hole 26 to a first annular chamber 21 formed in the injector body. The high pressure supply passage 18 opens into annular chamber 21. Tube 6 is also formed with a second chamber 22 having a hole 23 through which communication is made to a second annular chamber 24 in the body. A third annular chamber 25 surrounds the flat surface 8 against which bears the sealing edge 7 of tube 6. The low pressure passage opens into chamber 25. A valve seat 26 is provided in tubular part 6 between the two chamber 19 and 22 for the chamfered end of a piston 27. Piston 27 is mounted in a sealed but sliding manner in the upper part of tube 6 and it normally bears against the body 4 carrying the control winding due to the high pressure in chamber 21 and 19. However, in the absence of high pressure in the chamber 19, the piston 27 is pushed against the valve seat 26 by a spring 28 set in a cavity of the body 4.

A free piston 29 is located in the lower part of the tube 6, below the valve seat 26, in a sealed but sliding manner. The lower end of free piston 29 has a reduced diameter which fits into a cylindrical cavity 34) in the core 9. This free piston 29 essentially serves to provide a seal between the chamber 22 of the tube 6 and the cylindrical cavity 30. The purpose of the reduced diameter extension at the lower end of the free piston 29 is to reduce the volume of fluid inside the tube 6, i.e., the volume of fluid undergoing the changes in pressure during the operation of the injector.

The second annular chamber 24 is connected through a passage 31 to a conical chamber 32 in which is located a control needle 33, whose position is adjustable from the outside of housing l, for controlling a restricted passage 37. Up stream of the restriction 37, the conical chamber 32 is connected through a passage 34 to a cavity 35 surrounding the upper part of the injector needle or of its control rod. Downstream of the restriction 37 a passage 36 connects the conical chamber 32 to the cylindrical cavity 30.

The fastening means of the different parts of the injector and the fluid sealing joints are provided in the usual manner.

The operation of the injector is analyzed in the following manner, assuming initially that the high pressure control fluid is not yet supplied (motor stopped) to inlet 11. In the absence of the high pressure control fluid the spring 23 presses the piston 27 against the valve seat 26. This holds the tube 6 and the armature 5 in the lower position, to close off the high pressure chamber 19 thus preventing any flow of control fluid. A buildup of the high pressure fluid in chamber 19 acts on the piston 27 to push it upwardly and it remains against the body 4 as long as the high pressure is maintained. The high pressure fluid quickly passes into the second chamber 22 in tube 6 and from there through hole 23 into the second annular chamber 24. From chamber 24 it goes through passage 31 to the conical chamber 32, the passage 34 and into the cavity 35. The high pressure fluid encounters a delay due to the narrowing 37 as it goes through the passage 36 into the cavity 31 Since the inside diameter of the tube 6 is greater at the level of the piston 27 (chamber 19) than at the level of the piston 29 (cavity 30) the tube is maintained in the lower position and the sealing edge 7 continues to bear against the surface 8 of the core 9. Due to the high pressure in the cavity 35, the needle 10 of the injector is closed. For a more complete explanation of the movement of needle 10, reference is made to US. Pat. No. 3,464,627 which is assigned to the assignee of the subject application.

When an electrical control signal is received by the winding situated in body 4, the armature 5 is lifted. This lifts the tube 6. The pressure at the level of the sealing edge 7 begins a discharge towards the low pressure passage 14 to tubing 12.

The valve seat 26 in the tube 6 then bears against the lower end of piston 27, interrupting the circulation of high pressure fluid within tube 6 below chamber 19. The

chambers

22, 32 and 35 then discharge through the restriction 37. This discharge is therefore gradual, as well as the rise of injector needle whose upper part 10 rises gradually.

At the end of the control signal the armature 5 and the tube 6 drop once again. The high pressure is applied suddenly to the cavity 35 through the

direct connection

31, 32, 34, which causes the sudden closing of the injector needle 10.

Thus, in the injector according to the invention, the opening and closing of the injector needle 10 is controlled by the discharge and the pressurizing of the cavity 35. The opening movement of the injector needle 10 is slowed in controlled manner by the position of the control needle 33 in the restriction 37. The closing of the injector needle 10 is sudden and any risk of reopening because of needle bounce is eliminated. The volume of fluid undergoing the changes of pressure is very small owing to the presence of the free piston 29 which, in addition, assures the separation between the second chamber 22 and the cavity 30 situated downstream of the restriction 37. Owing to this arrangement the free piston is practically always driven back to the bottom of the cavity 30. Finally the restriction 37 partially closes off the connection which might temporarily exist between the source of high pressure and of low pressure during the switchovers.

What is claimed is:

1. An electromagnetic injector comprising a body formed with a first cavity (35), an injector needle (10) having a portion mounted in said body in fluid communication with said first cavity to move in a first direction in response to a pressure drop in said first cavity and in a second direction opposite said first direction in response to the resumption of pressure in said first cavity, electromagnetically controlled armature means (5), inlet means (11) for applying high pressure fluid to the body and means (12) on the body providing a low pressure return, a bore formed in said body, a tubular member (6) located in said bore and attached to said armature means for movement therewith, valve means (27) movable within said tubular member, a first chamber (19) and a second chamber (22) formed in said tubular member and a seat (26) formed on said tubular member between said first and second chambers for said valve means (27 means (18, 20) providing communication between said high pressure inlet means and said first chamber, first means (31-34) for providing fluid flow communication between said second chamber (22) of said tubular member and said first cavity (35), a second cavity (30) formed in said body, means (31, 32, 36) providing fluid flow communication between said second chamber (22) of said tubular member and said second cavity, second means (25, 14) providing communication between said second cavity (30) and said low pressure return (12), third means (36) having flow restriction means (37) therein for providing communication between said first and said second means, a free piston (29) movable within said tubular member (6) to form a seal between said second chamber (22) and said second cavity (30), means engaging said valve and acting in the absence of the high pressure for holding the valve (27) against said seat (26) to block communication between said first and second chambers (19,22) and to hold said tubular member in a position to seal off communication between said third and said second means, means on said valve responsive to the application of high pressure to said first chamber 19) to move said valve (27 out of said sealing relationship with said seat to provide communication for the high pressure fluid from said first to said second chamber (22) and then through said second means (31-34) to said first cavity (35) to pressurize the cavity (35) and to move the injector needle in said second direction, said armature means (5) being responsive to the application of a control signal to move said tubular part in a first direction out of the sealing relationship between said second cavity (30) and said second means (25,14) to provide a discharge path which is gradual in time from said first cavity to said low pressure return through said third means (36) including the restriction (37) and said second means to cause said needle to move in said first direction, the movement of said tubular part in said first direction by said armature means in response to said control signal also restoring the sealing relationship of said valve between said first and second chambers.

2. An injector as in claim 1 wherein said second means (31-34) includes a chamber (32) containing a needle (33) adjustable from the outside of the injector and defining the restriction (37) of the third means (36).

3. An injector as in claim 1 wherein said seat (26) of 40 5. An injector as in claim 1 wherein the free piston (29) is dimensioned with respect to the interior of the tubular member to reduce the volume of fluid distributed inside the tubular member between the second chamber (22) and the second cavity (30).

6. In an assisted electromagnetic fuel injector for internal combustion engines, said injector being of the type including a body having a cavity therein, first means including valve means for supplying fluid under pressure to said cavity, second means also including said valve means for providing a discharge of the fluid under pressure from said cavity, an injector needle in fluid communication with said cavity and controlled by the pressure therein such that a pressure drop in the cavity permits movement of the needle in a first direction and resumption of pressure in the cavity causes a movement of the needle in a second direction opposite from said first direction, said injector also including electromagnetically controlled armature means for operating said valve means to control the supply of fluid under pressure by said first means to said cavity and the discharge of the fluid from said cavity by said second means, the improvement comprising said first means includes a first fluid supply path and said second means including a second fluid discharge path having at least a portion separate from said first: path, said armature means operating said valve means to control the communication of said first and said second paths with said cavity.

7. An injector as in claim 6 wherein said second path includes a restriction means for controlling the discharge of fluid from said cavity to thereby control the speed of movement of the injector needle in said second direction, and means located outside of the injector for adjusting the amount of restriction provided by said restriction means.

8. An injector as in claim 7 wherein said restriction means is located in said second path between said valve means and the cavity.

9. An injector as in claim 6 wherein said valve means includes a tubular member located in said body, a free piston mounted in a sealed but sliding manner within said tubular member for controlling the opening and closing of said first and second paths.

10. An injector as in claim 9 wherein said free piston is dimensioned to reduce the volume of fluid inside said tubular member.

Claims

1. An electromagnetic injector comprising a body formed with a first cavity (35), an injector needle (10) having a portion mounted in said body in fluid communication with said first cavity to move in a first direction in response to a pressure drop in said first cavity and in a second direction opposite said first direction in response to the resumption of pressure in said first cavity, electromagnetically controlled armature means (5), inlet means (11) for applying high pressure fluid to the body and means (12) on the body providing a low pressure return, a bore formed in said body, a tubular member (6) located in said bore and attached to said armature means for movement therewith, valve means (27) movable within said tubular member, a first chamber (19) and a second chamber (22) formed in said tubular member and a seat (26) formed on said tubular member between said first and second chambers for said valve means (27), means (18, 20) providing communication between said high pressure inlet means and said first chamber, first means (31-34) for providing fluid flow communication between said second chamber (22) of said tubular member and said first cavity (35), a second cavity (30) formed in said body, means (31, 32, 36) providing fluid flow communication between said second chamber (22) of said tubular member and said second cavity, second means (25, 14) providing communication between said second cavity (30) and said low pressure return (12), third means (36) having flow restriction means (37) therein for providing communication between said first and said second means, a free piston (29) movable within said tubular member (6) to form a seal between said second chamber (22) and said second cavity (30), means engaging said valve and acting in the absence of the high pressure for holding the valve (27) against said seat (26) to block communication between said first and second chambers (19,22) and to hold said tubular member in a position to seal off communication between said third and said second means, means on said valve responsive to the application of high pressure to said first chamber (19) to move said valve (27) out of said sealing relationship with said seat to provide communication for the high pressure fluid from said first to said second chamber (22) and then through said second means (31-34) to said first cavity (35) to pressurize the cavity (35) and to move the injector needle (10) in said second direction, said armature means (5) being responsive to the application of a control signal to move said tubular part in a first direction out of the sealing relationship between said second cavity (30) and said second means (25,14) to provide a discharge path which is gradual in time from said first cavity to said low pressure return through said third means (36) including the restriction (37) and said second means to cause said needle to move in said first direction, the movement of said tubular part in said first direction by said armature means in response to said control signal also restoring the sealing relationship of said valve between said first and second chambers.

3. An injector as in claim 1 wherein said seat (26) of said tubular member (6) for said valve (27) is internal of said tubular member.

4. An injector as in claim 1 wherein the end of the tubular member (6) is chamfered to form a sealing edge (7), a seat (8) formed on a portion of the valve body opposite said sealing edge (27), said edge (7) and said seat (8) forming a seal between said second cavity (30) and said second means (25,14) when said valve (27) is open.

5. An injector as in claim 1 wherein the free piston (29) is dimensioned with respect to the interior of the tubular member to reduce the volume of fluid distributed inside the tubular member between the second chamber (22) and the second cavity (30).

6. In an assisted electromagnetic fuel injector for internal combustion engines, said injector being of the type including a body having a cavity therein, first means including valve means for supplying fluid under pressure to said cavity, second means also including said valve means for providing a discharge of the fluid under pressure from said cavity, an injector needle in fluid communication with said cavity and controlled by the pressure therein such that a pressure drop in the cavity permits movement of the needle in a first direction and resumption of pressure in the cavity causes a movement of the needle in a second direction opposite from said first direction, said injector also including electromagnetically controlled armature means for operating said valve means to control the supply of fluid under pressure by said first means to said cavity and the discharge of the fluid from said cavity by said second means, the improvement comprising said first means includes a first fluid supply path and said second means including a second fluid discharge path having at least a portion separate from said first path, said armature means operating said valve means to control the communication of said first and said second paths with said cavity.