FR3084702A1 - METHOD OF ASSEMBLING A HYDRAULIC VALVE - Google Patents

Abstract

Method of assembling the hydraulic valve (112), the hydraulic valve (112) comprising: a body (126) extending along a longitudinal axis (X) in which a tubular sleeve (136) is clamped, the body (126) is provided with a bore (132) and a return channel (125) having an outlet orifice (OS), the tubular sleeve (134) comprising a wall (137) arranged between a first surface and a second surface, and being provided with at least two radial holes (142, 144), the step of assembling the hydraulic valve (112) is as follows: - insert the sleeve (136) by force into the bore of the body (126) so that the circumferential distance (DC142) between the outlet (OS) and the first hole (142) of the sleeve (136) is equal to the circumferential distance (DC144) between the outlet ( OS) and the second hole (144).

Description

Method of assembling a hydraulic valve

TECHNICAL AREA

The present invention relates to a hydraulic valve and more particularly to the valve of a diesel fuel injector.

TECHNOLOGICAL BACKGROUND OF THE INVENTION

According to Figure 1 is shown an injector 10 of diesel fuel, the injections are controlled by a solenoid valve 12 which opens or closes a leakage channel 25 thus making it possible to control the pressure in a control chamber. The solenoid valve 12 is provided with a bore 32 and comprises a sleeve 36. According to FIG. 1, said solenoid valve 12 comprises a rod 46 sliding in the sleeve 36 mounted tightly in the bore 32 provided in the body 26 of the solenoid valve , a magnetic frame 48 being fixed to one end of the rod 46. The sleeve 36 includes through holes in the extension of the leakage channel 25. When the solenoid valve opens, the rod 46 is subjected to a radial force coming from the leakage channel 25 via through holes 42, 44 arranged in the same plane as the leakage channel 25.

Said leakage channel 25 opens into an annular groove surrounding the sleeve 36 limiting the tightening thereof to the end zones of the bore located on either side of the annular groove. In addition, the sleeve 36 is radially drilled so that a hole allows pressurized fuel to pass from the groove inside the sleeve. The passage of fuel, for example through two through holes 42, 44 of the sleeve 36 are arranged at two different distances from the leakage channel 25 and thus creates stresses on the sleeve 36.

In the sleeve 36, the rod 46 is guided along a guide zone 40 extending between said radial hole 42 and the end of the sleeve 36 opposite the magnetic frame 48. Despite the limited functional clearance between the rod 46 and the sleeve 36, in use the pressurized fuel deforms the sleeve 36 and moves it radially so that the sleeve 36 approaches the rod 46 to limit leaks along the guidance area.

In this context, the object of the invention is to solve the problems mentioned above.

SUMMARY OF THE INVENTION

The present invention aims to remedy the drawbacks mentioned above by proposing a method of assembling a hydraulic valve for controlling a fuel injector. The hydraulic valve includes:

a body d extending along a longitudinal axis in which a sleeve is clamped (tubular, the body is provided with a bore and a return channel having an outlet orifice, the tubular sleeve comprising a wall arranged between a first surface and a second surface, and being provided with at least two radial holes passing through the wall of the sleeve and the first hole and the second hole being symmetrical with respect to the longitudinal axis. hydraulic valve are as follows:

- provide the body and the sleeve,

- locate and align the outlet orifice along an axis perpendicular to the longitudinal axis and align the holes of the sleeve along an axis perpendicular to the plane comprising the two axes perpendicular to the longitudinal axis,

- insert the sleeve by force into the bore of the body so that the circumferential distance between the outlet and the first hole of the sleeve is equal to the circumferential distance between the outlet and the second hole. In addition, in an alternative to the embodiment, the sleeve only comprises two holes. In addition, the method of assembling the hydraulic control valve in which the sleeve has the two holes symmetrical with respect to the longitudinal axis. The method of assembly including the following step:

- forcefully insert the sleeve into the bore of the body so as to have an angle of 90 degrees between the outlet orifice of the body and each of the two holes of the sleeve in the plane perpendicular to the longitudinal axis so as to that the two holes are equidistant from the outlet. In addition, the hydraulic valve comprises a body and a sleeve according to the production methods described above. In addition, a fuel injector comprises a hydraulic valve arranged between an actuator holder and an injection nozzle, said hydraulic valve being assembled according to the assembly methods described above.

BRIEF DESCRIPTION OF THE DRAWINGS

Other characteristics, objects and advantages of the invention will appear on reading the detailed description which follows and with reference to the appended drawings given by way of nonlimiting example.

- Figure 1 is a sectional view of the sleeve and the body according to the prior art,

- Figure 2 is a sectional view of a fuel injector according to the invention,

- Figure 3 is an enlarged sectional view of the hydraulic valve according to the invention,

FIG. 4 is a sectional view of the sleeve and of the body according to the invention,

- Figure 5 is a top view of the sleeve and the body according to the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The invention is now described with reference to the attached figures. To facilitate and clarify the following description, the orientation from top to bottom is chosen arbitrarily and the words and expressions such as above, below, above, below ... can be used without any intention of limiting the invention .

According to Figure 2 is shown a fuel injector 110 forming part of the injection system of an internal combustion engine in axial section along a longitudinal axis X. The injector 110 comprises a hydraulic control valve 112 held tight by a nut injector 114 between an actuator holder 116 and an injection nozzle 118.

The fuel injector 110 comprises a high pressure circuit 120 and a return circuit 122. The high pressure circuit 120 is also called the HP circuit 120.

The HP circuit 120 has a main channel traversing the injector 110 from an inlet mouth to injection holes and, a branch branch allowing the supply of a control chamber 124. In said main channel is arranged a first NPO passage restriction, known by its English acronym NPO meaning "Nozzle Path Orifice" which means nozzle, creating a pressure drop between upstream and downstream, the branch branch extending from upstream from the first NPO restriction to the control chamber 124.

The return circuit 122 departs from said control chamber 124 to extend to an outlet. In this return circuit 122 are arranged a second restriction SPO, also known by the acronym SPO meaning "Spill Orifice" which means depressurization orifice, and the control valve 112 which opens or closes said circuit. When the latter is closed, the pressure in the control chamber 124 increases pushing a needle 127 into a position preventing fuel injection and, when the valve 112 opens the return circuit 122 the pressurized fuel can escape from the control chamber in which the pressure drops allowing the needle 127 to move towards a fuel injection position.

In an embodiment which is described more precisely in FIGS. 3, the control valve 112 comprises a cylindrical body 126 extending along the longitudinal axis X between a first transverse face 128, or upper face, arranged against the injector holder and, a second transverse face 130, or lower face, arranged against the injection nozzle, the HP circuit 120 extending in an eccentric zone of the body 126 and comprising the first NPO restriction arranged in the vicinity of the lower face 130.

The return circuit 122 includes a hydraulic bore 132 extending along the longitudinal axis X from a blind bottom 134, close to the underside 130, to an opening located in the center of the bottom of a recess opening more widely in the upper face 128.

According to Figures 2 and 3, in the underside 130 of the body 126 opens a hollow hemisphere in direct connection with the control chamber 124 and from which a restricted channel forms the second restriction SPO which joins a return channel 125 of leakage of fuel extending obliquely into the body 126 from a lower end to an outlet orifice OS opening into the bore 132.

According to Figure 4 is described the bore 132 where the sleeve 136 is inserted having a cylindrical tubular wall 137 kept clamped in two clamping zones 138,140.

According to Figures 4 and 5, the sleeve 136 extends into the bore 132 from a first end flush with the bottom of the recess to a second end located at the lower limit of the second clamping zone. In addition, the sleeve 136 is provided with at least two holes 142,144 passing through the wall 137 and creating a permanent fluid connection between the outlet port OS and the interior of the sleeve 136.

The valve 112 further comprises a rod-armature assembly comprising a generally cylindrical rod 146 inserted and crimped in the center of a disk-shaped magnetic armature 148. The rod 146 is slidably mounted in the sleeve 136 and extends from a first end emerging in the recess and to which the magnetic armature 148 is fixed until a second end flush with the second end of the sleeve 136.

According to Figures 4 and 5, the rod 146 is guided against the inner face of the sleeve 136 along a guide zone located towards the bottom of the bore 32 between the opening of the through holes 142, 144 and the second end of the sleeve. At the opening in the recess, the rod 146 and the sleeve 136 cooperate to define a hydraulic seat 150 and, between the seat 150 and the guide zone, in the part facing the through holes 142,144, the rod 146 is thinned.

According to Figure 5 is described an alternative to the embodiment described above where the sleeve 136 comprises only two holes 142, 144 arranged symmetrically with respect to the longitudinal axis X. the hole 142 is called the first hole 142 and the hole 144 is called the second hole 144. The return channel 125 has an outlet port OS whose distance DOS is the width of the outlet port OS. The midpoint of the DOS distance is called the MOS point. The two holes 142, 144 defined in the sleeve 136 are equidistant from the outlet port OS described in the following relation. The point M142 is the midpoint of the width L142 of the hole 142 and the point M144 is the midpoint of the width L144 of the hole 144. The invention is characterized by the following relation:

DC142 = DC144 with the circumferential distance DC142 between the point

M142 and the MOS point and the circumferential distance DC144 é between the point Ml44 and the MOS point.

We will describe the method of assembling the hydraulic valve

112 control as described above for the invention, that is to say where the sleeve 136 comprises two holes 142,144. The assembly steps are as follows:

a / provide the body 126, the rod 46, a frame 148, the sleeve 136,

b) crimp the rod 146 on the frame 148,

c) locate and align the outlet port OS of the return channel 125 with the holes 142, 144 of the sleeve 136 along a Y axis perpendicular to the longitudinal X axis.

d) insert the sleeve 136 by force into the bore 132 of the body 126 so that the circumferential distance DC142 between the outlet port OS and the first hole 142 of the sleeve 36 is equal to the circumferential distance DC144 between the port of OS output and the second hole 144,

e) mount the rod 146 and the armature 148 crimped together in the sleeve 136, the rod 146 has one end flush with one end of the sleeve 136.

In the alternative where the sleeve 136 has only two holes 142,144, the step of assembling the hydraulic valve 112 includes the following step dl) dl) insert by orienting the sleeve 136 in force in the bore 132 of the body 126 in order to have a 90 degree angle between the outlet port OS of the body 126 and each of the two holes 142, 144 of the sleeve 136 so that the two holes 142,144 are equidistant from the outlet port OS .

The operation of the injector 110 is now summarized in two key stages:

Step 1: a coil arranged in the actuator holder 116 is not supplied and, a valve spring arranged at the heart of the coil pushes the rod 146 back to the closed position of the hydraulic seat 150 and closes the return circuit 125. The high fuel pressure enters the control chamber 124 where the pressure increases pushing the needle 127 to a position preventing fuel injection.

Step 2: The coil is energized and generates a magnetic field which attracts and moves the armature 148 and thereby opens the hydraulic seat 150. The fuel can then leave the control chamber 124 successively passing through the hollow hemisphere, the second SPO restriction, the return channel 125, the outlet port OS, the holes 142, 144 to exit through the hydraulic seat 150 in the recess before flowing in the return circuit as far as an outlet mouth .

REFERENCES injector solenoid valve leakage channel body bore sleeve hole hole rod armature

110 fuel injector

112 hydraulic valve

114 nut

116 actuator holder

118 injection nozzle

120 high pressure circuit

122 return circuit

124 control chamber

125 return channel

126 bodies

127 needle

128 first face 130 second side 132 bore 134 blind background 136 muff 137 wall 138 first clamping area 140 second clamping area 142 sleeve hole 144 sleeve hole 146 stem 148 armature 150 hydraulic seat X longitudinal axis Y axis Z axis NPO first restriction SPO second restriction BONE outlet port L142 hole width 142 L144 hole width 144 BACK OS outlet opening width D142 distance D144 distance MOS DOS midpoint M142 midpoint of the distance D142 M144 midpoint of the distance D144

Claims (5)

CLAIMS: 1. Method for assembling a hydraulic valve (112) for controlling a fuel injector (110), the hydraulic valve (112) comprising: a body (126) extending along a longitudinal axis (X) in which a tubular sleeve (136) is clamped, the body (126) is provided with a bore (132) and a return channel (125) having an outlet (OS), the tubular sleeve (136) comprising a wall (137) arranged between a first surface and a second surface, and being provided with at least two radial holes (142, 144) and passing through the wall (137) of the sleeve (136) and the first hole (142) and the second hole (144) being symmetrical with respect to the axis (X), the steps for assembling the hydraulic valve (112) are the following : - provide the body (126) and the sleeve (136), - locate and align the outlet (OS) along an axis (Y) perpendicular to the longitudinal axis (X) and align the holes (142,144) of the sleeve (136) along an axis (Z) perpendicular to the plane (X, Y ) - forcibly insert the sleeve (136) into the bore (132) of the body (126) so that the circumferential distance (DC142) between the outlet orifice (OS) and the first hole (142) of the sleeve (136 ) is equal to the circumferential distance (DC144) between the outlet (OS) and the second hole (144). 2. Method of assembling the hydraulic valve (112) for controlling a fuel injector (10) according to claim 1, in which the sleeve (136) comprises only two holes (142,144). 3. Method of assembling the hydraulic valve (112) for controlling a fuel injector (110) according to claim 2, in which the sleeve (136) has the two holes (142,144) symmetrical with respect to the longitudinal tax ( X), the assembly method comprising the following step: - insert by orienting the sleeve (136) in force in the bore (132) of the body (126) in order to have an angle of 90 degrees between the outlet (OS) of the body (126) and each of the two holes (142,144) of the sleeve (136) in the plane (Y, Z) perpendicular to the longitudinal axis (X) so that the two holes (142,144) are equidistant from the outlet (OS). 4. Hydraulic valve (112) comprising a body (126) and a sleeve 5 (136) according to claims 1 to 3. 5. Fuel injector (110) comprising a hydraulic valve (112) arranged between an actuator holder (116) and an injection nozzle (118), said hydraulic valve (112) being assembled according to claims 1 to 4.