FR2681642A1 - FUEL INJECTION PUMP FOR INTERNAL COMBUSTION ENGINE, COMPRISING A VALVE MEMBER BY FREEZING FLOW SECTIONS OR MAY ESCAPE THE COMPRESSED LIQUID. - Google Patents

Abstract

a) Fuel injection pump for internal combustion engine, comprising a valve member releasing flow sections where the compressed liquid can escape. b) Pump characterized in that the valve (61, 62) comprises a valve member (61) biased by the control pressure, and which is sliding in a cylinder (62) against a restoring force and which releases sections different flow depending on its position, and through which can escape the compressed liquid passing through the discharge pipe.

Description

"Fuel injection pump for internal combustion engine,

  having a valve member releasing flow sections o can escape

the compressed liquid ".

  The present invention relates to a fuel injection pump for internal combustion engines comprising a device for modifying the beginning of the transfer and in which, under the control of a pressure control valve, the control pressure of a liquid The pressure acting on the adjusting member increases with the speed of rotation and thus modifies the beginning of the transfer, a rotational speed regulator which comprises an adjusting sleeve connected to a transfer amount adjusting member of the injection pump. of fuel, and whose operating position depends on the load and the rotational speed of the fuel injection pump, the adjusting sleeve opening or closing a discharge port according to the load, and which, to relatively reduce the control pressure, allows the compressed liquid to escape through

  a discharge line, as well as a valve downstream of the discharge port, which influences flow through the discharge line.

  Such a fuel injection pump is known according to DEAL 39 00 346. This fuel injection pump comprises a device for modifying the start of the transfer and which, controlled by a pressure control valve, increases the pressure of the fuel. controlling a pressurized liquid acting on an adjusting piston as a function of the increasing rotational speed and the adjusting piston modifies the start of the transfer The fuel injection pump further comprises a rotation speed regulator with a sleeve the working position depends on the load and the speed of rotation of the fuel injection pump The adjusting sleeve controls the opening or closing of a pressure-medium outlet according to The discharge port allows the pressurized liquid to flow into a discharge line to relatively reduce the control pressure downstream of the gold. ifice evacuation, is an electrically operated valve that closes the pipe

discharge.

  The control piston urged by the control pressure as a function of the speed of rotation moves the start of the transfer in the direction of advance as a function of the increasing speed of rotation. However, the opening control of the orifice of evacuation through the adjustment sleeve allows the pressurized liquid to escape when the load is low, which decreases the pressure of

  controls and delays the beginning of the transfer accordingly.

  The electrically operated valve closes the discharge line, so that even when the discharge port is opened by the adjusting sleeve, the pressurized liquid can not escape and pressure is applied. higher control which adjusts the start of the transfer in advance direction The valve is controlled according to the temperature of the internal combustion engine and during engine heating, this valve is closed; over a certain

  temperature, this valve is permanently open.

  For some internal combustion engines, it is required that the adjustment according to the load of the beginning of the transfer, depends again on the speed of rotation. Such a modification of the beginning of the transfer is not possible in the pumps.

fuel injection, known.

  The present invention proposes to remedy these drawbacks and concerns for this purpose a fuel injection pump corresponding to the type defined above, characterized in that the valve comprises a valve member urged by the control pressure, and which is slid in a cylinder against a restoring force and which releases different flow sections according to its position, and through which, can escape the compressed liquid

  through the discharge pipe.

  This fuel injection pump has the advantage that the valve allows a modification of the start of the transfer depending on the load and depending on the speed of rotation of the fuel injection pump, and this with simple means. According to a characteristic of the invention, the discharge pipe opens into the cylinder, the valve member having a control groove and the mouth of the discharge pipe in the cylinder is formed as a control opening with which the groove cooperates. of control and which releases a part of the control opening according to

  the position of the valve member.

  According to another characteristic of the invention, the discharge conduit opens into the cylinder, the valve member having a control opening and in that in the cylinder, at the mouth of the discharge line, there is has a control groove which cooperates with the control opening and releases a part of the control opening according to the position of the organ

forming a valve.

  According to another characteristic of the invention, a connection towards the discharge chamber leaves in the valve member of the groove of

  order or opening order.

  According to another characteristic of the invention, the control opening is designed so that after a certain adjustment stroke, determined by the valve member, if the adjustment continues against the return force, the discharge section

decreases again.

  According to another characteristic of the invention, the installation for modifying the beginning of the transfer comprises a regulating piston serving

of valve member.

  Thanks to this realization, it is not

  necessary to have a particular valve.

  According to another characteristic of the invention, there is provided a stroke limitation for the valve member, which is adjustable according to the operating parameters of the internal combustion engine equipped with the fuel injection pump. According to another characteristic of the invention, the restoring force acting on the valve member is variable according to the operating parameters of the equipped internal combustion engine.

  of the fuel injection pump.

  Thanks to these characteristics, the other function parameters of the internal combustion engine are taken into account to modify the beginning of the transfer. The present invention will be described hereinafter with the aid of two exemplary embodiments represented in the drawings. FIG. 1 is a longitudinal section of a first embodiment of an injection pump.

fuel.

  Figure 2 shows on an enlarged scale the

  detail bearing the reference II in Figure 1.

  Figure 3 shows different characteristics of the trajectory of a control piston as a function of the speed of rotation of the

fuel injection pump.

  FIG. 4 shows a second embodiment of the fuel injection pump under

the shape of a simplified view.

  Description of the embodiments

  A fuel injection pump shown in longitudinal section in FIG. 1 and corresponding to the type of dispensing pump, for internal combustion engines, comprises a pump piston 13 driven in rotation and at the same time reciprocating by a d The pump piston 13 operates in a bore 14 of a cylindrical sleeve 16 and delimits in this bore a pump working chamber 17. The working chamber 17 is filled with fuel during operation. the suction stroke of the pump piston 13 via the suction bore 19 and the control grooves 20 made in the pump piston 13, from an internal volume 22 of the fuel injection pump, filled with fuel The suction bore 19 can be closed by an electromagnetic valve 23 to stop the engine equipped with

  this fuel injection pump.

  During the pressure stroke of the pump piston 13, the suction bore 19 being closed, the fuel is transferred under high pressure to a not shown injector equipping a cylinder of the internal combustion engine via a bore longitudinal 25 and a distribution groove 26 connected to this bore, as well as by a

  pressure valve 28 and a pressure line 29.

  The end of the transfer corresponds to the moment when a transverse bore 31 of the pump piston 13 connected to the longitudinal bore 25 is open due to the movement of the piston by a regulating slide 32 serving as a control member of the quantity transferred by the pump. fuel injection, provided on the portion of the pump piston entering the interior volume 22; the working chamber 17 is thus

  discharged to the inner volume 22.

  In the interior volume 22, a transfer pump 34 driven by the drive shaft 10 draws fuel from a reservoir. A pressure-controlled valve 35 controls the pressure in the interior volume 22 and this pressure increases with the rotational speed. of the injection pump

fuel.

  The regulating slide 32 is mounted to slide axially on the piston 13 of the pump and is actuated by a regulator lever 37. The regulator lever 37 can in principle be constituted by a single lever, but in the exemplary embodiments, it is A control lever system 38 having a plurality of levers is provided. The control lever system 38 is pivotally mounted on an axis 40. In the end zone of the control lever system 38 facing the adjustment slide 32, a control spring 41 attached to a control lever 43 The preload of the control spring 41 can be modified by the adjustment lever 43 and its preload increases in the direction of an increasing load when the adjustment lever 43 is adjusted. Regulating lever system 38 is set so that the regulator slide 32 is moved in the direction of the neutral point of the pump piston 13, thereby causing corresponding to the injection of a larger quantity of fuel because of the delayed opening control of the transverse bore 31 during the pressure stroke of the pump piston 13. The control lever system 38 is held in abutment against the adjusting sleeve 44 of a rotational speed regulator 46 by the regulating spring 41 The rotation speed regulator 46 is a centrifugal regulator which comprises flyweights 49 housed in a support 47 The support 47 with the flyweights 49 is driven by the drive shaft 10 by means of a toothed wheel 50 and is fixed axially on a regulator shaft 52 The flyweights 49 rest inside the support 47 and act axially on the sliding adjustment sleeve 44 The adjustment sleeve 44 has at least one discharge orifice 53 connecting a discharge channel 55 passing through the axis 52 of the regulator and the internal volume 22. a number of rotational speed and load ranges, which affect the position of the adjusting sleeve 44 via the adjusting lever 43, the regulating spring 41 and the regulating lever system 38 or having an effect on the rotational speed by the load applied to the internal combustion engine, there is a displacement of the adjustment sleeve 44 which connects the discharge orifice 53 of the discharge channel 55 to the internal volume 22 For other situations of speeds of rotation and the discharge channel 53 is closed. The discharge port 53 and the discharge channel 55 allow fuel to exit the interior volume 22 and thereby reduce the control pressure in the interior volume 22. The The fuel injection pump cam drive has a front cam disk 12 coupled to the pump piston 13 and a roller ring 58 rotatably mounted in the pump body and receiving a pump. roller 56; the front cam disk 12 rolls on this roller ring by being driven by the drive shaft 10 to thereby move the pump piston 13 in rotation and reciprocating manner. The roller ring 58 is coupled to the adjusting piston 61 by a pin 59 which penetrates radially into this ring The adjustment piston 61 is part of a device for modifying the start of the transfer of the fuel injection pump; in Figure 1 the adjusting piston 61 is shown rotated 90-, that is to say, it works

  perpendicular to the plane of the drawing.

  The adjusting piston 61 is guided in a cylinder 62 and is biased in the direction of a setting in advance of the start of transfer by the control pressure prevailing in the internal volume 29; the displacement in the opposite direction is ensured by the restoring force exerted by a compression spring 64. The side of the adjusting piston 61 biased by the control pressure, is connected by a throttle channel 65 in the adjusting piston with the internal volume 22 to prevent water hammer. In the first embodiment shown in FIGS. 1 and 2, a discharge pipe 67 starts from the discharge channel 55 in the axis of the regulator 52 which opens into the cylinder 62 of FIG.

  the installation to change the start of the transfer.

  The mouth of the discharge line 67 is located at the cylinder 62 which is permanently covered by the adjusting piston 61 and is designed as

  control opening 68 in the cylinder wall 62.

  The adjusting piston 61 is provided in its central zone with an annular control groove 70. Starting from the bottom of the control groove 70, a bore 71 of the adjusting piston 61 leads to a spring chamber 73 delimited in the cylinder 72 by the piston and which contains a compression spring 64 A return pipe 74 as an extension of the discharge pipe 67 starts from the spring chamber 73, and this discharge pipe returns for example to the suction side of the transfer pump 34 The piston in this way, a regulating member 61 forms a valve member urged by the control pressure and releases a discharge section for the fuel escaping from the inner volume 22 through the adjusting sleeve 44 according to

  the position of the valve member.

  The control opening 68 is represented at

  scale enlarged and broken line in Figure 2.

  This opening consists of a first segment 76 turned towards the side of the adjusting piston 61 biased by the control pressure. This segment 76 has the shape of a very crushed triangle in the direction of adjustment of the adjusting piston 61 in the direction This first segment 76 is followed in the direction of further adjustment to the compression spring by a second segment 77 having a substantially constant width. This second segment is followed by a third segment 78 in the form of a triangle. progressively decreasing towards the compression spring 64 The arrangement of the control opening 68 and the control groove 70 can also be chosen inverted with respect to that described above. This means that the control opening 68 is made in the adjusting piston 61 and that the control groove 70 is

  made in the cylinder wall 72.

  By using the adjusting piston 61 to control the discharge section, the start of the load-dependent transfer can be adjusted as a function of the rotational speed. FIG. 3 shows the stroke of the adjustment piston 61 and thus the displacement towards the pressure. advance of the start of the transfer as a function of the speed of rotation The characteristic curve of the stroke of the adjusting piston 61 for the full load is shown in broken lines with the reference a; this corresponds to a discharge orifice 53 of the adjustment sleeve 44 which is permanently closed, so that no fuel can be discharged from the internal volume 22. The characteristic curve of the adjustment piston stroke for the partial load is shown in the line mixed with reference b; this situation corresponds in the embodiment of the invention to a discharge orifice 53 permanently open. The characteristic curve of the adjustment piston path for the variable discharge sections described above is referenced c in FIG. 3 and is shown as a continuous line. The characteristic curve c of the characteristic of the regulating piston leaves the speed rotation or corresponding to the beginning of the adjusting movement, the characteristic curve has full load The control opening 68 is first closed, so that the

  fuel can not escape from the interior volume 22.

  During the path of the adjusting piston 61, the control groove 70 gradually opens the control opening 68. The characteristic curve c thus increases beyond the rotational speed in a less steep manner than the characteristic curve a, since the pressure The control piston 61 is for this part of the characteristic curve c with its control groove 70 beyond the first segment 76 of the internal volume 22 increases only slowly because of the escaping fuel. the control opening 68 For the rotation speed N 2, the characteristic curve c intersects the characteristic curve b for a completely open discharge section. The adjustment piston 61 is at this moment of the characteristic curve c with a groove command 70 directly above the second segment 77 of

the control opening 68.

  During the further movement of the adjusting piston 61, the discharge section decreases again, so that less fuel escapes from the inner volume 22 through the adjusting sleeve 44 of the inner volume 22 as a function of speed. Increasingly, the rotation of the control pressure increases. The stroke of the adjusting piston 61 thus greatly increases with respect to the speed of rotation. The adjusting piston 63 is at this point in the region of the characteristic curve c. and its control groove 70 is above the third segment of the control opening 68 At the rotational speed N 3, the discharge section is completely closed again and from this moment the characteristic curve c coincides with the curve

  characteristic a corresponding to the full load.

  By the appropriate choice of the shape of the control opening 68, it is possible to trace the characteristic curve c of the stroke of the adjusting piston 61 as a function of the rotational speed which

  corresponds to a certain internal combustion engine.

  According to the development of the injection pump, the support of the compression spring 64 can be adjustable according to other operating parameters such as, for example, the temperature of the internal combustion engine Alternatively, it is also possible to have an adjustable limit of stroke for the adjusting piston 61 which can also be moved according to the parameters of the internal combustion engine. FIG. 4 corresponds to a second embodiment of the fuel injection pump and hereinafter only the variants of the first exemplary embodiment will be described mainly, the other parts already described in the first example

  embodiment being repeated in this second example.

  According to the second exemplary embodiment, the discharge duct 167 comprises a valve 180 after the control shaft, and this valve consists of a piston 181 serving as a closure member working in a cylinder 182. One side of the piston 181 is exposed to the control pressure prevailing in the inner volume 122 and the other side of the piston is biased by the restoring force of a compression spring 184 The piston 181 side exposed to the control pressure is connected to the inner volume The discharge pipe 187 opens into the cylinder 182 and its arrival is made in the wall of the cylinder 182 in the form of a control orifice 187. The piston 181 has a groove. peripheral annular control 188, connected by a bore 190 of a piston 181 to the side of the compression spring 184; a return pipe 174 connects this side, for example to the

  suction side of the transfer pump.

  As in the first embodiment, it is also possible to invert the groove of

  order 188 and the order opening 187.

  The fuel injection pump of the second embodiment also comprises a device for modifying the start of the transfer; however, in this device, the adjusting piston only serves to move the roller ring and the control of the discharge section is provided by the piston 181 of the valve 180 by a suitable choice of the shape of the 187 and by the valve 180, a desired characteristic curve of the stroke of the adjusting piston can be achieved as a function of the

rotation speed.

  It is also possible to provide an adjustable stroke limit for the piston 181 of the valve 180 or an adjustable support of the compression spring 184 which is adjusted according to the operating parameters of the

internal combustion engine.

Claims (8)

R E V E N D I C A T IO N S   1) Fuel injection pump for internal combustion engines having a device for modifying the start of the transfer and in which, under the control of a pressure control valve (35), the control pressure of a liquid compressed on the adjusting member (61) increases with the speed of rotation and thus modifies the beginning of the transfer, a rotational speed regulator (46) which comprises an adjustment sleeve (44) connected to a control member the amount of transfer of the fuel injection pump, the operating position of which depends on the load and the speed of rotation of the fuel injection pump, the adjusting sleeve (44) opening or closing a fuel injection port; discharge (53) as a function of the load, and which, to relatively reduce the control pressure, allows the compressed liquid to escape through a discharge line (67) and a valve (61, 62). 180) downstream of the vent hole acuation (53), which influences the flow rate through the discharge line (67), characterized in that the valve (61, 62; 180), has a valve member (61, 181) biased by the control pressure, and which is slidable in a cylinder (62, 182) against a biasing force and releases different flow sections depending on its position, and through which, can escape the compressed liquid   through the discharge pipe.   2) A fuel injection pump according to claim 1, characterized in that the discharge line (67, 167) opens into the cylinder (62, 182), the valve member (61, 181) having a groove control (70, 188) and the mouth of the discharge line (67, 167) in the cylinder (62, 182) is formed as a control opening (68, 187) with which the control groove (70, 188) co-operates. and releasing a portion of the control opening (68, 187) depending on the position of the valve member (61, 181).  Fuel injection pump according to claim 1, characterized in that the discharge line (67, 167) opens into the cylinder (62, 182), the valve member (61, 181) having an opening control and that in the cylinder (62, 182), at the mouth of the discharge line (67, 167), there is a control groove which cooperates with the control opening and releases a part of the command opening according to the   position of the valve member (61, 181).   4) Fuel injection pump according to   one of claims 1 to 3, characterized in that   a connection (71, 190) to the discharge chamber is provided in the valve member (61, 181) of the control groove (70, 188) or the control opening. ) Fuel injection pump according to   one of claims 2 to 4, characterized in that   the control opening (68, 187) is arranged so that the evacuation section increases against the restoring force during the displacement of the forming member valve (61, 181).   A fuel injection pump according to claim 5, characterized in that the control opening (68, 187) is designed so that after a certain set travel of the valve member (61, 181 ), if the adjustment continues against the return force, the discharge section decreases again.   7) Fuel injection pump according to   one of the preceding claims, characterized in that   what the facility for changing the start of the transfer includes a regulating piston serving valve member (61).   8) Fuel injection pump according to   one of the preceding claims, characterized in that   a stroke limitation is provided for the valve member (61, 181), which is adjustable according to the operating parameters of the internal combustion engine equipped with the pump fuel injection.   9) Fuel injection pump according to   one of claims 1 to 6, characterized in that   the return force acting on the valve member (61, 181) is variable according to the operating parameters of the equipped internal combustion engine   of the fuel injection pump.