FR2756594A1 - PISTON PUMP DRIVEN BY THE SHAFT OF AN INTERNAL COMBUSTION ENGINE - Google Patents

Abstract

Piston pump driven by the shaft (5) of an internal combustion engine to supply high pressure fuel. The pump comprises a housing (1) mounted on a wall (3) of the motor. It comprises at least one piston (16) sliding in a housing and defining an active chamber (19) between a low pressure supply range (17) and a high pressure transfer range (18). The chamber (19) is connected alternately with the supply (17) and the discharge (18) in the direction of translation of the piston (16). The length and the number of parts making up the pump are reduced and the replacement assembly for the parts is simplified if the pump is a shaftless assembly which is mounted by an opening (3a) in the wall (3) of the motor on the end. (7) of its tree (5).

Description

The present invention relates to a piston pump driven by the shaft.

  an internal combustion engine for

  supplying high pressure fuel comprising: - a housing which is mounted on a wall of the combustion engine -

  internal tion and, - at least one pump piston sliding in the housing and defining an effective active chamber between a low pressure supply zone and a high pressure transfer zone, - the active chamber being able to be connected alternately with the range of supply or transfer range depending on the

  sliding direction of the pump piston.

  Current pumps of this type have a clean shaft, mounted in the pump housing, with a mirror

  mandating the translational movement of the pistons and

  both a clutch between the pump shaft and that of the

  internal combustion engine. This especially presents the inconvenience

  deny to end up with a pump of great length.

  The object of the present invention is to create a pump which makes it possible to avoid this drawback and which, moreover, uses a smaller number of parts, that is to say of an assembly

  simpler and easier to replace.

  This problem is solved by a pump of the type

  finish above, characterized in that the piston pump is a shaftless assembly, which mounts on one end of the shaft of the internal combustion engine, exiting the engine and passing through an opening in the wall of the combustion engine internal, and which controls a stroke of at least one piston of

  pump through a surface of this end of the shaft.

  Document DE-42 17 910 A1 certainly describes a pump with radial pistons driven by the shaft of an internal combustion engine, namely the camshaft of the engine; in this pump, the piston stroke is controlled by the surface

  of sliding of the shaft and the peripheral surface of an ex-

  centric provided at a free end of the shaft through the

  medial of a translation ring; however, this pump is not a fuel pump, but a hydraulic pump supplying an installation for controlling a camshaft, an automatic clutch or a similar user; moreover, this pump is integrated in the cylinder head; in other words, it is a pump, the parts of which are housed in the cavities of the wall of the cylinder head. This pump does not have its own casing and does not

  is not a set that can relate to the tree.

  If the pump is damaged, it cannot be

  traded globally. On the contrary, it is necessary to disassemble the diff-

  different parts of the cylinder head pump and the

  replace what represents a very important work and can only be done in specialized workshops.

  Contrary to this, the pump according to the invention can be replaced by a few operations, such as for example the loosening of a few screws with the help of which the pump housing is screwed against the wall of the internal combustion engine; the pump can be removed overall from the shaft and replaced by a new pump. This allows between

  others its replacement by a larger cylinder pump

  drée if for example after an increase in the power of the engine for example by a bore of the cylinders, it is necessary a

stronger fuel pump.

  In addition, the pump according to the invention can be controlled independently of the mounting of the motor, in the form

  a complete set, separated using a reference tree

  rence carried out in a corresponding manner to verify proper operation. In the case of the pump according to document DE-42 17 910 A1, it is not possible to carry out such a functional check outside of the mounting of the pump.

on the engine.

  According to a first embodiment of

  the invention, the piston pump is a piston pump

  dials and the end of the shaft is in the form of an eccentric as is known, the peripheral surface of

  the eccentricity controlling the stroke of the pump pistons.

  According to another advantageous characteristic of

  the invention, a cylindrical shaft range centered relative to

  port at the axis of rotation of the shaft is close to the eccentric, this range serving as a rolling surface for two sealing rings spaced from one another, and

  which lean against an intermediate ring placed in an opening in the wall. In this way, the annular gap between the two seals constitutes a leakage collecting chamber sealed by one of the seals against the lubricating oil of the engine.

  fuel and vis-à-vis the fuel through the other seal. This leakage collecting chamber is advantageously connected to a connection allowing the evacuation of the leakage liquid.

  According to a second embodiment of the invention, the piston pump is an axial piston pump and the front surface of the end of the shaft is produced in the form of a nutation surface, inclined, controlling

the stroke of the pump piston.

  Advantageously, the end of the shaft is in the form of a truncated cone and serves as a circulation surface for two seals spaced from one another, and which

  are supported in the opening of the wall.

  According to a preferred embodiment of

  the invention, the shaft is a camshaft of the combustion engine

internal tion.

  According to other characteristics of the invention

  tion: * it is a radial piston pump and the end of

  the tree is in the form of an eccentric, the peripheral surface of which

  rique controls the stroke of the pump piston.

  * the eccentric is close to a cylindrical shaft range, centered on the axis of rotation of the shaft and which serves as

  circulation area for two seals available

  each other, and leaning against a ring

  intermediate placed in the opening of the wall.

  * the intermediate ring is separated in a sealed manner by seals on the one hand with respect to the internal combustion engine and on the other hand with respect to the range

low pressure supply.

  * it is an axial piston pump and the front surface

  of the end of the tree is shaped like a nuta-

  tion, tilted, controlling the stroke of the pump piston.

  * the end of the tree is shaped like a truncated cone

  front of circulation surface for two seals distant from each other and supported in

the opening of the wall.

  * an annular interval between the two seals, communicating by a leakage connection with the evacuation

leaking liquid.

  * the shaft is a camshaft of the internal combustion engine

  dull. The present invention will be described below from

  in more detail using two examples of realizations

  tion schematically shown in the accompanying drawings in which: Figure 1 is a schematic section of a pump according to the invention in the form of a pump with radial pistons, - Figure 2 is a schematic section of a pump according to

  the invention in the form of an axial piston pump.

  The radial piston pump according to FIG. 1, serves

  side of a high pressure pump for a fuel injection installation of an internal combustion engine comprises a housing 1 fixed by at least two and preferably three screws 2 distributed around the axis X of the following pump

  an angular interval of 120 and of which only one screw appears

  rait in Figure 1, against the wall 3 of the cylinder head of the engine

internal combustion.

  In this wall 3 of the cylinder head, under the reference

  rence 4, there is one or the other camshaft 5 of the internal combustion engine whose axis Y coincides with the axis X of the pump. This shaft has a cylindrical segment 6 centered on the axis Y of the camshaft having a reduced diameter compared to that of the camshaft; then the shaft continues at one end 7 made in the form of an eccentric, penetrating through an opening 3a in the wall 3 of the cylinder head from the inside of the internal combustion engine and extending through an opening 8 of pump housing 1

inside this box 1.

  The housing 1 comprises three chambers 9, directed in the radial direction and distributed in a star around the axis X of the pump. In the sectional view appearing at the

  figure, only one room appears. Each room serves to re-

have a pump element 10.

  Each pump element 10 is housed in a fixing element 11 in the form of a screwed nozzle with a receiving cavity 12 housing a pump cylinder element 13 with a cylinder hole 14 in the form of a through hole. Between the bottom wall of the receiving chamber 12 and the pump cylinder element 13 is a valve element 15 in the form of a cap applied under the effect of a spring in a sealed manner against the front surface of

  the pump cylinder element 13. In the bore 14 of the cy-

  linder of the pump cylinder element 13 is a pis-

  sliding pump tone 16, which fixes an active chamber 19 between a low pressure supply zone 17 and a high pressure transfer range 18; the low pressure supply zone 17 is connected by channels (not shown) of the housing 1 to low pressure inlets 20 supplying the fuel under an upstream transfer pressure; on the other hand, the high pressure transfer pad 18 is connected via the holes 21 in the fixing element 11, an annular channel 22 and a channel 23 to a

central high pressure nozzle 24.

  The pump piston 16 has an inlet channel

  directed in the axial direction of the piston; at its extremi-

  tee opposite to the active chamber 19, this channel communicates by a

  transverse drilling 26 to a low supply zone near

  sion 17. A supply valve 27 in the form of a

  valve is associated with the pump piston 16; following the movement-

  piston 16, this valve establishes or cuts off the communication

  cation between the inlet channel 25 and the active chamber 19.

  At its end opposite to the active chamber 19,

  the pump piston 16 carries a sliding shoe 28,

  held in place against a flat sliding surface 31a of a translation ring 31 by a spring 29 which bears at one end against a fixing element 11 and by the other end against a Belleville spring 30 connected to the sliding shoe 28 The translation ring 31 is itself5 mounted by means of a bearing bush 31b on

  the eccentric end 7 of the camshaft 5.

  In this way, when the camshaft 5 rotates about its axis Y, the peripheral surface 7a of the eccentric 7 controls the stroke of the pump piston 16 by

  through the translation ring 31.

  During the suction stroke (downward movement

  dant) of the pump piston 16, the fuel at the pressure of

  upstream transfer passes from the low supply zone near-

  sion 17 through the transverse bore 26 in the channel

  25 and from there through the feed valve

  tation 27 opened by the vacuum created by the suction stroke of the piston in the active chamber 19, towards this

active chamber 19.

  During the consecutive pressure stroke (upward movement) of the piston 16, the supply valve 27 closes so that the fuel in the active chamber 19 is pressurized. When the pressure reaches a certain

  level, the cap-shaped valve member 15 is raised

  lifts against the load exerted by a spring with respect to the front surface of the pump cylinder element 13 which allows the passage of high pressure fuel passing from the active chamber 19 into the high pressure transfer range 18 and there, through the holes 21 in the element of

  attachment 11, the annular channel 22 and the channel 23 for

  worm at the central high pressure nozzle 24.

  To ensure reciprocal sealing between the cu-

  weary and the low pressure supply zone 17 of the pump housing 1, there are two radial seals 32, 33, spaced from one another for the cylindrical segment 6, centered relative to the axis Y the camshaft 5 as a circulation surface; these seals bear outwardly against an intermediate ring 37 placed in the opening 3a of the wall 3 of the cylinder head and made watertight with respect to the cylinder head by means of O-rings 34, 35 and with respect to the zone of low pressure supply 17. An O-ring 36 ensures

  tightness of the low pressure supply area 17 screws-

vis-à-vis the atmosphere.

  The radial seal 32 ensures

  the sealing for the lubricating oil of the engine of the

  weary while the radial seal 33 achieves

  the tightness of the fuel present in the fuel range

  low pressure 17 at the upstream transfer pressure.

  The annular chamber 38 between the two radial seals 32, 33 serves to collect the leaks of these two fluids and to evacuate them by a fluid nozzle.

leak 39.

  The axial piston pump shown in Figure 2, includes a housing 1 'itself fixed with at least two and preferably three screws 2' (only one of these screws appears in the sectional view) against the wall 3 'of the breech. The

  pump includes 10 'pump elements distributed evenly

  about the axis X 'of the pump and extending in the di-

  axial rection; only one of these pump elements 10 'appears in the drawing; these pump elements are housed in a single fixing element 40. In this fixing element 40, there is also a low pressure inlet 20 'communicating with the low pressure supply range 17'

  of the pump as well as a 24 'high pressure connection, central

  tral, through which the 18 'high pressure transfer range as-

  associated with each 10 'pump element communicates by

through a channel 41.

  The construction of the pump element 10 'corresponds to

  pond to that of the pump element 10 of Figure 1 to

  with the exception of a sliding shoe or sliding shoe 42 mounted

  culé and whose structure is slightly different; this pa-

  tin is held by the spring 29 'in abutment against the

  frontal surface 43a of the free end 43 of a camshaft

  my 5 '; this frontal surface in the form of a nuta- surface

  tion, inclined (mirror) allows the control of the stroke of the piston 16 '. This free end 43 is in the form of a trunk of

  cone facilitating the mounting of two tight seals

  dials 44, 45 without mounting sleeve (intermediate ring); these joints are supported externally in the opening 3a 'of the wall 3' of the cylinder head. The radial seal 44 seals the conical surface of the truncated cone 43 for an annular leakage collecting chamber 46 formed between the two radial seals 44, 45, to protect it against the oil of lubrication of the cylinder head, the gasket

  radial seal 45 seals the bonding chamber

  leak reader 46 for beach fuel

  low pressure supply 17 'of the pump. An O-ring

  that 47 seals the low supply range

  pressure 17 'vis-à-vis the atmosphere. The collective bedroom

  trice 46 communicates with a connection for the leaking fluid 39 '

  As shown in the examples of realizations

  tion described above, the pump according to the invention does not

  does not have its own drive shaft; on the contrary, it is a set of pump without shaft which is

  mounted on the end of the camshaft of a

  internal bustion coming out of the breech; the stroke of the pump pistons is controlled by a surface of this end of the camshaft. This not only removes the pump shaft but also the bearings that would be required to

  this shaft as well as the coupling with the camshaft; this-

  reduces the number of components and the length of construction

  tion of the pump, gives a simpler mounting and a simpler possibility of replacing the pump as well as a more stable mounting of the drive shaft thanks to

  the significant distance of the camshaft bearings.

  It is clear that the invention is not limited to the embodiments shown and described. Thus, for example, the pump could have only one or two pistons in place of the three pistons. In the case of a radial piston pump, there could also be several piston devices one behind the

others in the axial direction.

  If taking distances it seems more integrated

  benefitting from using the camshaft as a shaft to drive the piston pump, in principle, it is also possible to use for this another shaft forming part of the internal combustion engine, which is driven and rotatably mounted

  in the engine such as the crankshaft.

  The cylindrical segment 6 shown in connection with the radial piston pump, segment which passes through the opening 3a of the wall 3 and serves as a circulation surface for the seals 32, 33 can also be used for the

axial piston pump.

  As well as the part in the form of a truncated cone of the shaft 5 'serving as a circulation surface for the seals 44, 45 and which passes through the opening 3a' of the wall 3 'as shown in connection with the axial piston pump, can also be used in the

  radial piston pump instead of cylindrical segment 6.

  The advantage of a cylindrical circulation surface

  that for seals is to only require one type of radial seals. However, the drawback is that the mounting of the seals is slightly more difficult since the seals have to be positioned more precisely with respect to the axis of the camshaft than in the case of a circulation surface. in the shape of a truncated cone

  for which the positioning of the seals of-

  requires less precision due to a certain self-centering effect. In the case of the truncated cone-shaped circulation surface, there is the drawback of requiring two different seals. In a practical case, knowing which of the two solutions is more advantageous ultimately depends on the manufacturing structure of the

  realization as well as a cost calculation.

  Finally, you can use the intermediate seal 37

  according to figure 1, regardless of whether the spray pump

  tones either a radial piston pump or an axial piston pump as well as independently of the fact that the part of the shaft 5 or 5 'passing through the opening 3a or 3a' is of

cylindrical or frustoconical shape.

Claims (7)

R E V E N D I C A T IONS   1) Piston pump driven by the shaft of a   internal bust for supplying high pressure fuel comprising: a housing which is mounted on a wall of the internal combustion engine and, - at least one pump piston sliding in the housing and defining an effective active chamber between a zone of low pressure supply and a high pressure transfer zone, - the active chamber being able to be connected alternately with the supply range or the transfer range in the sliding direction of the pump piston, characterized in that the piston pump is a assembly without shaft, which is mounted on one end (7; 43) of the shaft (5, 5 ') of the motor   internal combustion, leaving the engine and passing through one or   groove (3a; 3a ') of the wall (3) of the internal combustion engine   dull, and which controls a stroke of at least one piston of   pump (16; 16 ') by a surface (7a; 43a) of this extremi- tee (7; 43) of the shaft (5; 5 ').   2) Piston pump according to claim 1, characterized in that it is a radial piston pump and the end of the shaft (5) is in the form of an eccentric (7) whose surface   device (7a) controls the stroke of the pump piston (16).   3) Piston pump according to claim 2, characterized in that   the eccentric (7) is close to a range of shafts (6), cylin-   drique, centered on the axis of rotation (Y) of the shaft (5) and which serves as a circulation surface for two seals (32, 33) distant from each other, and which press against an intermediate ring (37) placed in the opening (3a) of the wall (3).   4) Pump according to claim 3, It characterized in that the intermediate ring (37) is sealingly separated by seals (34, 35) on the one hand relative to the internal combustion engine and on the other part with respect to the low pressure supply range (17). ) Piston pump according to claim 1, characterized in that it is an axial piston pump and the front surface (43a) of the end (43) of the shaft (5 ') is in the form of a nutation surface , tilted, controlling the piston stroke pump (16 ').   6) Piston pump according to claim 5, characterized in that the end (43) of the shaft (5 ') is in the form of a truncated cone serving as a circulation surface for two seals (44, 45 ) distant from each other and leaning   in the opening (3a ') of the wall (3').   7) Piston pump according to claim 3 or 6, characterized by an annular gap (38, 46) between the two seals   sealing (32, 33; 44, 45), communicating by a branch-   leakage ment (39, 39 ') with the evacuation of the leakage liquid.   8) Piston pump according to one of claims 1 to 7,   characterized in that the shaft (5, 5 ') is a camshaft of the internal combustion engine.