FR2766523A1 - FUEL INJECTION VALVE WITH DIRECT INJECTION AND ELECTROVALVE CONTROL FOR MULTI-CYLINDER ENGINE - Google Patents

Abstract

A valve body contains a control piston, a shutter and a high pressure line which can be connected, when the shutter is lifted from its seat, to a supply line leading to a pressure chamber surrounding an injection needle. A bore (7, 8) of the control piston (5) and of the shutter (4) permanently connects a control chamber (9) to the high pressure pipe (11) with the interposition of an inlet throttle. The chamber (9) can be expanded by a solenoid valve (26). The shutter (4) is capable, during injection, of interrupting an expansion connection from a supply line (16) to the return line (25), comprising a throttle. Applicable to internal combustion engines multi-cylinder.

Description

-1 The invention relates to an injection fuel injection valve

  direct and pilot operated by solenoid valve for an internal combustion engine with several cylinders, comprising a control piston and a valve plug cooperating with it in a valve body, a high pressure pipe leading to the valve and being able to be connected, when the shutter is open, that is to say lifted from its seat, to a supply pipe which opens into a pressure chamber surrounding an injection needle, as well as a through bore extending in the piston control valve and shutter and through which a control chamber, delimited by the control piston, is permanently connected to the high pressure pipe with the interposition of an inlet throttle, the control chamber, to which is applied a pressure, which can be relieved by the solenoid valve, which influences the injection, the valve further comprising a return line

  presenting a choke point.

  Such an injector valve, piloted by solenoid valve, is known from document DE 196 12 738 Ai, according to which the control piston, together with the integrated valve shutter, is guided in two parts of the valve body and

  in direct connection with the rear side of the injection needle.

  The shutter is surrounded by an annular chamber into which, on the one hand, the inlet pipe and on the other hand a

choked return line.

  In the case of systems of this type, the high-pressure pipe leading to the injection nozzle is continuously relaxed by the throttled return, more precisely by the permanent connection leading from the supply pipe through the annular chamber to

the return line.

  The object of the invention is to allow a clear improvement in the overall performance of the system.

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  injection, by inexpensive arrangements in the construction of each of the fuel injection valves - of the generic type indicated at the beginning - of an engine. Starting from a valve as specified at the beginning, this is obtained by the fact that, during injection, the valve shutter is capable of interrupting an expansion link leading from the

  supply line to return line.

  lo According to advantageous embodiments of the invention: - the expansion link is produced as a system expansion throttle; the expansion throttle of the system is arranged inside the valve body in a bypass of the supply line and is connected to the return line, through a peripheral groove provided on the valve, also acting valve piston only, outside the injection time; - the expansion throttle of the system is provided in the obturator and can be connected only outside the injection time to an annular chamber surrounding the obturator in the area of the seat of the valve, so that a connection is established expansion leading from the supply pipe, opening into the annular chamber, through the expansion throttle of the system and a longitudinal bore extending in the shutter, up to the return pipe; - The control piston and the shutter, having a smaller diameter, as well as their through holes, are arranged coaxially, end faces directed towards each other of the control piston and the shutter being pressed l one against the other - by sealing the through holes - the through hole arranged in the control piston having

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  an inlet throttle at its end on the control chamber side; - the control piston and the shutter together form, in the region of their end faces directed towards each other, an intermediate chamber of annular shape which is in connection with the return pipe in any position of the control piston ; - the peripheral groove, of shallow configuration, or the longitudinal bore extending into the obturator

  io leads to the annular intermediate chamber.

  The arrangements according to the invention avoid permanent expansion during injection, namely by the connection - which can be controlled - between the supply pipe leading to the injection nozzle and the return pipe connected to the low pressure system. In other words, relaxation takes place only between injections, but not during the injection. The quantity of fuel returned is thus considerably reduced. Other characteristics and advantages of the invention will emerge more clearly from the

  description which follows of two examples of

  non-limiting embodiment, as well as the accompanying drawings, in which: FIG. 1 is an axial section of a fuel injector valve according to the invention; - Figure 2 is an axial section on a much larger scale of the upper part of such a valve; and - Figure 3 is a similar view of an alternative embodiment of the injection valve of

fuel according to the invention.

  A fuel injection valve according to FIG. 1, with direct injection and controlled by a solenoid valve, a valve which is preferably applied to injection systems with accumulation of internal combustion engines with several cylinders, operating according to the principle of the ramp common distribution ("Common-Rail"), consists of a valve body 2 in several parts, of a control piston 5 guided so as to be able to slide longitudinally in a cylindrical step recess 3 formed in the valve body 2 and a valve shutter 4 cooperating with this piston, as well as an injection needle 6 loaded by spring and separated in the space of the shutter 4 and the

io control piston 5.

  The shutter 4 is designed to serve at the same time as a valve piston and arranged on the same axis as the control piston 5 - having a larger diameter - which has a through hole 7, to which a through hole 8 formed in the shutter. The control piston 5 and the valve plug or valve piston 4 are both housed in a part

  in one piece with the body 2 of the valve.

  By its rear side, the control piston 5 delimits one side of a control chamber 9 into which an inlet throttle 10 of the through hole 7 opens. Due to the provision of the inlet throttle 10, it s '' establishes, on the high pressure end of the valve piston, a higher pressure than in the control chamber 9 when the latter is relaxed, which causes

  lifting the shutter 4 from its valve seat 12.

  The control chamber 9 communicates, through the two coaxial through holes 7, 8, with a high pressure pipe 11 extending radially in the valve body 2. The valve piston is provided with a sealing surface 13 of conical shape. , which is suitable for the intended conical valve seat 12

in the body 2.

  To this conical shape is connected, on the valve piston, a cylindrical nozzle 14 surrounded by an annular chamber 15 from which a supply pipe 16 which opens into a pressure chamber 17

  surrounding the injection needle 6 loaded by spring.

  According to FIG. 2, the supply pipe 16 has a bypass 18 comprising an expansion throttle of the system 19, which cooperates, in the direction of an ascent or descent command, with a peripheral groove 20 formed in the upper part of the valve piston 4. The peripheral groove 20 is connected through an intermediate chamber 21 of shape

  annular to a return pipe 22.

  The intermediate chamber 21 is formed in equal parts by a reduction in section 23 practiced in the control piston and a reduction in section 24 practiced in the valve piston 4 and this chamber

  is significantly larger than the peripheral groove 20.

  In the position shown, the valve piston 4, applied against the seat 12, establishes an open expansion link going from the supply line 16 through the expansion throat of the system 19, the peripheral groove 20 and the intermediate chamber 21 to return line 22

low pressure side.

  As soon as the control chamber 9, which can be connected to an expansion line 25, is expanded by the activation of the solenoid valve 26 (FIG. 1), the valve piston 4 is lifted from its seat 12, because the pressure prevailing on the nozzle 14 of this piston is higher, and the lower distribution edge 20a of the peripheral groove 20 passes over the expansion throttle of the system 19, so that the

  trigger is interrupted during the injection.

  The intermediate chamber 21 of annular shape and the return pipe 22 are - unlike the expansion throttle of the system 19 and the peripheral groove 20 - permanently connected to each other,

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  regardless of the instantaneous position of the piston

valve 4.

  According to FIG. 3, the expansion throttle of the system 19 is not located in the body 2 of the valve, but in the valve piston 4 and is in connection with a longitudinal bore 27 extending in

  this piston and leading to the intermediate chamber 21.

  The expansion throttle of the system 19 has, at a short distance from the end piece 14, a region of radial orientation and can be connected to the annular chamber 15 only when the piston or valve shutter 4 occupies its closed position. The mouth section 19a of the constriction 19 is located in the upper zone of the annular chamber 15, so that the expansion link is already removed after a

  short piston / shutter opening stroke 4.

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Claims (7)

  1. Fuel injection valve with direct injection and solenoid valve control for an internal combustion engine with several cylinders, comprising a control piston and a valve shutter cooperating with it in a valve body, a high pressure pipe leading to the shutter and can be connected, when the shutter is open, that is to say lifted from its seat, to a supply pipe which opens into a pressure chamber surrounding an injection needle, as well as a bore through extending in the control piston and the shutter and through which a control chamber, delimited by the control piston, is permanently connected to the high pressure pipe with interposition of an inlet throttle, the chamber control, to which a pressure is applied, which can be relieved by the solenoid valve, which influences the injection, the valve further comprising a return line present being a choke point, characterized in that, during the injection, the valve shutter (4) is capable of interrupting an expansion link leading from the supply line (16) to the return line ( 22). 2. Fuel injector valve according to claim 1, characterized in that the expansion link is produced as an expansion throttle of the system (19).   3. Fuel injector valve according to claim 2, characterized in that the expansion throttle of the system (19) is arranged inside the 8 2766523   valve body (2) in a branch (18) of the supply line (16) and is connected to the return line (22), through a peripheral groove (20) provided on the shutter (4) , also acting as a valve piston, only in outside the injection time.   4. Fuel injector valve according to claim 2, characterized in that the expansion throttle of the system (19) is provided in the shutter (4) and can be connected only outside the injection time to an annular chamber (15) surrounding the obturator (4) in the area of the seat of the valve, so that a detent connection is established leading from the supply pipe (16), opening into the annular chamber (15), through the expansion throttle of the system (19) and a longitudinal bore (27) extending in the shutter (4), up to the return line (22).   5. Fuel injector valve according to claim 1, characterized in that the control piston (5) and the shutter (4), having a smaller diameter, as well as their through holes (7, 8), are arranged coaxially, end faces directed towards each other of the control piston (5) and   the shutter (4) being pressed against each other -   by sealing the through holes (7, 8) -, the through hole (7) arranged in the control piston (5) having an inlet throttle (10) at its   end of control chamber side.   6. Fuel injector valve according to a   of the preceding claims, characterized in that   the control piston (5) and the shutter (4) together form, in the region of their end faces directed towards one another, an intermediate chamber (21) of annular shape which is in connection with the pipe 9 2766523   return (22) in any position of the control piston (5). 7. Fuel injector valve according to claim 3 or 4, in combination with claim 6, characterized in that the peripheral groove (20), of shallow configuration, or the longitudinal bore (27) extending in the shutter (4) leads to the intermediate chamber (21) of annular shape.