EP0686763A1 - Fuel injection valve for internal combustion engines - Google Patents

Abstract

The fuel injection valve has a control piston (50), the opening and closing movements of which are controlled by two control spaces (70,74). The volume and fuel control pressure of the second one can be altered by the movement of the piston. The opening motion is slowed down by the pressure in the second control space, at least at first. For the closing movement, the control piston is accelerated at a certain pressure in the second control space to cut off the injection aperture (21) more rapidly. Relief elements (77) equalise the pressure between the second control space and the high pressure region. <IMAGE>

Description

The invention relates to a fuel injection valve for intermittent fuel injection into the combustion chamber of an internal combustion engine according to the preamble of claim 1.

Injection valves of this type are known, for example, from the patents EP 0 228 578 or EP 0 426 205.

The invention, as characterized in the claims, solves the problem of creating a fuel injector which ensures improved operating behavior and is also extremely simple to manufacture and assemble.

The invention is described below with reference to the embodiments shown in the drawing.

Fig.1

eine erste Ausbildungsform eines Brennstoffeinspritzventils im Längsschnitt;

Fig.2

im vergrössertem Massstab und im Längsschnitt eine der Fig.1 entsprechende erste Ausführungsform einer Steuervorrichtung des Brennstoffeinspritzventils;

Fig.3

eine zweite Ausführungsform der Steuervorrichtung;

Fig.4

eine dritte Ausführungsform der Steuervorrichtung;

Fig.5

eine vierte Ausführungsform der Steuervorrichtung;

Fig.6

im partiellen Längsschnitt eine zweite Ausbildungsform des Brennstoffeinspritzventils mit einer fünften Ausführungsform der Steuervorrichtung;

Fig.7

in vergrössertem Massstab einen Teil der Steuervorrichtung gemäss Fig.6;

Fig.8

eine sechste Ausführungsform der Steuervorrichtung für das Brennstoffeinspritzventil nach Fig.6;

Fig.9

eine siebte Ausführungsform der Steuervorrichtung für das Brennstoffeinspritzventil nach Fig.1;

Fig.10

eine achte Ausführungsform der Steuervorrichtung für das Brennstoffeinspritzventil nach Fig.1;

Fig.11

eine neunte Ausführungsform der Steuervorrichtung für das Brennstoffeinspritzventil nach Fig.6;

Fig.12

eine zehnte Ausführungsform der Steuervorrichtung für das Brennstoffeinspritzventil nach Fig.6.

Show it:

Fig. 1

a first embodiment of a fuel injector in longitudinal section;

Fig. 2

on an enlarged scale and in longitudinal section, a first embodiment of a control device of the fuel injector corresponding to FIG. 1;

Fig. 3

a second embodiment of the control device;

Fig. 4

a third embodiment of the control device;

Fig. 5

a fourth embodiment of the control device;

Fig. 6

in partial longitudinal section, a second embodiment of the fuel injector with a fifth embodiment of the control device;

Fig. 7

on an enlarged scale, part of the control device according to Figure 6;

Fig. 8

a sixth embodiment of the control device for the fuel injector according to Figure 6;

Fig. 9

a seventh embodiment of the control device for the fuel injector of Figure 1;

Fig. 10

an eighth embodiment of the control device for the fuel injector according to Figure 1;

Fig. 11

a ninth embodiment of the control device for the fuel injector according to Figure 6;

Fig. 12

a tenth embodiment of the control device for the fuel injector according to Figure 6.

1 shows a fuel injection valve 1 in a position between two injection processes. The fuel injection valve 1 is connected via a high-pressure fuel connection 10 and via a fuel return connection 12 to a high-pressure delivery device for the fuel and via electrical connections 14 to an electronic control. The high-pressure conveyor and the electronic control are not shown in the drawing.

The housing of the fuel injector 1 is designated 15. At the lower end, the housing 15 is screwed down with a holding part 16 designed as a union nut, and at the upper end with a corresponding holding nut 17.

A nozzle body 18 is inserted in the holding part 16, the nozzle tip 19 of which protrudes from the holding part 16. The nozzle tip 19 is provided with a nozzle needle seat 20 and has a plurality of injection openings 21 in this area. In the nozzle body 18, an axially adjustable nozzle needle 24 forming an injection valve member is slidably guided in a needle guide bore 23. The injection openings 21 of the nozzle tip 19 can be closed by a lower end 25 of the nozzle needle 24.

The housing 15 is provided with a central guide bore 29 in which a control device 3 for controlling the adjustment movement of the injection valve member or the nozzle needle 24 is arranged. The control device 3 is described in detail below with reference to FIG. 2.

The fuel is conveyed by the high-pressure delivery device via the high-pressure fuel connection and a first short fuel feed bore 31 into two high-pressure feed lines 32, 33 arranged in the housing 15 parallel to the guide bore 29. The upper high-pressure supply line 33 leads to the control device 3. The lower high-pressure supply line 32 is connected via a connecting bore 35 arranged obliquely in an intermediate plate 36 to a nozzle body bore 26 which opens into an annular space 27 in the nozzle body 18. From the annular space 27, the fuel reaches the nozzle needle seat 20 or the injection openings 21 via passages (not shown in more detail). In the area of the annular space 27, the nozzle needle 24 is provided with a shoulder 28.

The intermediate plate 36 is positioned opposite the housing 15 via a pin 37 (it could also be two pins 37) and is arranged sealingly between the housing 15 and the nozzle body 18. An upper part 39 of the nozzle needle 24 projecting into a central bore 38 of the intermediate plate 36 is operatively connected to an intermediate needle element 40, which on the other hand is connected to a connecting rod 44 Control piston 50 of the control device 3 is connected. Between a spring washer 46 supported on a shoulder 45 of the housing 15 and the needle intermediate element 40, a nozzle needle spring 47 surrounding the connecting rod 44 is arranged pretensioned.

The control device 3 has a control body 52 which is inserted into the guide bore 29 in a stationary manner. The control piston 50 is provided with an upper piston part 51 of reduced diameter. As can be seen particularly from FIG. 2, the upper piston part 51 projects into a sleeve 64 which is axially displaceable and closely sliding in the guide bore 29. Close sliding fits are also provided between the piston part 51 and the inner diameter of the sleeve 64. A spring 63 is arranged between a lower end face 65 of the sleeve 64 and a piston shoulder surface 53. The sleeve 64 is supported with a narrow annular sealing surface 66 on a lower end face 55 of the control body 52, which on the other hand is axially fixed in the guide bore 29 by a lock nut 54 screwed to the housing 15.

In the lower region of the control body 52 there is an annular space 69 in the housing 15, which is connected to the upper high-pressure supply line 33 via a transverse bore 68. The control body 52 has a circumferential annular groove 67 corresponding to the annular space 69. Furthermore, the control body 52 is provided with a connecting bore 60 opening into a first control space 70, which is connected via an inlet throttle bore 58 to the circumferential annular groove 67 or to the annular space 69 and thus also to the high-pressure supply line 33. At the top, the connection bore 60 narrows into an outlet opening 59.

The first control chamber 70 is radial through the inner surface of the sleeve 64, axially through the lower end surface 55 of the Control body 52 and an upper end face 56 of the piston part 51 limited.

Between the piston part 51 and the guide bore 29 there is an annular, second control chamber 74 below the sleeve 64, in which the spring 63 is also arranged and which is connected to the high-pressure supply line 33 via a connecting bore 75. An aperture 76 with a throttle 77 is inserted into the connecting bore 75.

The control body 52 is installed in the guide bore 29 of the housing 15 in such a way that no significant leakage can take place. This will e.g. achieved with a press fit or a narrow sliding fit, but could also be realized by other fuel-tight connections, for example using suitable sealing rings.

The control device 3 also has an electromagnetically actuated pilot valve 80, of which only one armature 82, which is firmly connected to a pilot valve stem 81, can be seen in FIG. In the position shown in FIG. 2, the outlet throttle bore 59 is held in the closed position via a flat valve seat 85. As can be seen from FIG. 1, in the de-energized state of an electromagnet 86, the pilot valve stem 81 is pressed downward into the position closing the valve flat seat 85 by the force of a compression spring 87. This force can be adjusted in size by means of an adjusting screw 88. To actuate the pilot valve 80 or to raise the pilot valve stem 81 from the flat valve seat 85, an excitation coil 83 of the electromagnet 86 assigned to the armature 82 receives control pulses from the electronic control via the electrical connections 14.

The fuel emerging from the outlet opening 59 when the pilot valve stem 81 is raised is collected in a drainage chamber 89 according to FIG. 1 and fed via a drain hole 90 to the fuel return connection 12, which is installed in the holding nut 17 together with the electromagnet 86. The fuel accumulated by leaks in a space 91 below the control piston 50 also flows into the discharge space 89 via a relief bore 92. Part of the fuel is thus returned to the high-pressure delivery device practically without pressure. The space 91, the relief bore 92, the drain space 89 and the drain bore 90 form a so-called low-pressure part of the fuel injection valve 1.

The following mode of operation of fuel injector 1 results from the structure described:

Before the injection process, the high-pressure part of the fuel injection valve 1, i.e. in the fuel supply bore 31, in both high pressure supply lines 32, 33, in the annular spaces 27, 69 and in both control spaces 70, 74 the same high pressure or injection pressure, which can be up to over 1000 bar.

As soon as a pulse of selected duration is given to the electromagnet 86 via the electronic control, the armature 82 is attracted against the force of the spring 87, whereby the pilot valve 80 is opened. The outlet opening 59 of the control body 52 is thus opened. The pressure in the first control chamber 70 drops. The nozzle needle 24 is raised from the nozzle needle seat 20 by the fuel pressure prevailing in the annular space 27 and acting on the shoulder 28. The injection openings 21 are opened and the fuel is injected into the combustion chamber of the internal combustion engine in a manner known per se.

When the nozzle needle 24 is raised, the control piston 50 is also moved upward via the intermediate needle element 40 and the connecting rod 44. The volume of the second control chamber 74 becomes smaller, the pressure in the control chamber 74 increases under this pumping action. The sleeve 64 is pressed even more strongly into the sealing position with respect to the control body 52. The pressure in the second control chamber 74, which counteracts the opening movement of the injection valve member or the nozzle needle 24, is defined in a desired, controlled manner via the connection bore 75 and the throttle 77, which lead to the high-pressure supply line 33. A desired, controlled opening of the injection valve is thereby achieved.

As is known, the end of the injection process should take place as quickly as possible. Again, electronically controlled, the pilot valve 80 is brought into its closed position via the electromagnet 86. Since the outlet opening 59 is now closed again, the pressure increases in the first control chamber 70 and the control piston 50 is moved downward by the force acting on the upper end face 56 of the piston part 51. The volume of the second control chamber 74 is increased, the fuel pressure in the second control chamber 74 drops. The sleeve 64 initially remains pressed onto the control body 52. When the fuel pressure in the second control chamber 74 drops, the sleeve 64 follows the piston movement; it should be mentioned that the spring 63 is biased relatively weakly, so that the pressure effect of the spring 63 is negligible compared to the fuel pressure forces. As soon as the sleeve 64 with the sealing surface 66 lifts off from the control body 52, fuel suddenly arrives via this new connection from the annular space 69 or from the high-pressure supply line 33 into the first control space 70. The control piston 50 and also the sleeve 64 are accelerated downward; The nozzle needle 24 is inserted into the injection openings 21 via the connecting rod 44 and the intermediate needle element 40 closing position pressed. In this way, a rapid injection closing process is implemented in the fuel injection valve 1 according to the invention.

As soon as the pressure in the second control chamber 74 is again adjusted to the high system fuel pressure via the throttle 77 and the connecting bore 75, the spring 63 presses the sleeve 64 with the sealing surface 66 into the position radially delimiting the first control chamber 70.

In a first alternative variant of the control device 3 according to FIG. 2, not shown in the drawing, a constriction designed as a throttle is attached either in the transverse bore 68 or in the upper high-pressure supply line 33, which causes a slight throttling and thereby accelerates the closing process Control piston 50 dampens slightly. This reduces the impact of the nozzle needle 24 on the nozzle needle seat 20 at the end of the closing process. If the mentioned constriction is provided in the upper high-pressure supply line 33, this can be located either in the area below the throttle 77 or above it. This first variant of the control device 3 is particularly preferred if (for design reasons) there is a risk that the nozzle needle seat 20 could be damaged by an excessive impact of the nozzle needle 24.

In a second alternative variant of the control device 3, which is also not shown in the drawing, the throttle 77 is made large, or the throttle 77 is dispensed with entirely, so that the connecting bore 75 is connected directly to the upper high-pressure supply line 33. Thus, in this variant, the system fuel high pressure always prevails in the second control chamber 74, which increases practically or not at all due to the pumping action of the control piston 50 during the opening movement of the nozzle needle 24; the pressure in the second control room drops during the closing process 74 either. In this case, the sleeve 64 does not lose contact with the lower end face 55 of the control body 52 during the closing movement of the nozzle needle 24, which is ensured by suitable dimensioning of the spring 63. The advantage of this variant lies in a control surface which is reduced compared to known solutions and which has to be controlled by the two throttle bores 59 and 58. The movement of the substantially larger control piston 50 is controlled via the control surface corresponding to the end face 56 of the upper piston part 51.

FIGS. 3, 4 and 5 show further embodiments of the control device for the fuel injector and are described in more detail below. The parts known from FIGS. 1 and 2 and having the same effect are also identified by the same reference numerals.

In the embodiment of a control device 4 shown in FIG. 3, the sleeve 64 known from FIGS. 1 and 2 is replaced by a sleeve 94. The sleeve 94 has a plurality of ribs 95 arranged axially one behind the other on the circumference, the outer diameter of which forms a precisely defined radial annular gap 93 with respect to the guide bore 29. The annular groove 67 in the control body 52 and the annular space 69 in the housing 15 are eliminated. Above the uppermost rib 95, the transverse bore 68 feeding the high-pressure fuel opens into the guide bore 29. On the upper end face, the sleeve 94 is provided with a narrow, annular sealing surface 96. The sealing surface 96 has a plurality of circumferentially distributed radial depressions 97 of shallow depth (approx. 0.02-0.03 mm), through which the throttled fuel passes from the guide bore 29 and consequently from the transverse bore 68 to the first control chamber 70 and which Replace the inlet throttle bore 58 of the control device 3 known from FIG. 2. The ribs 95, on the other hand, replace the throttle 77 known from FIG. 2 and installed between the second control chamber 74 and the high-pressure supply line 33. The ribs 95 have sharp edges to achieve a turbulent flow regardless of the viscosity of the fuel. By arranging several ribs 95 one behind the other, the fuel pressure is gradually reduced or the flow rate is reduced. As a result, the annular gap can be dimensioned more generously.

The position of the sealing surface 96 in relation to the outer or inner diameter of the sleeve 94 can be selected depending on the necessary contact pressure. The same sealing surface 96 and / or the radial depressions 97 could also be used in the sleeve 64 of FIG.

This embodiment of the control device 4 is simpler in terms of production technology than the embodiment shown in FIGS. 1 and 2. Otherwise the mode of operation is the same as already described.

Similar to the control device 3 according to FIG. 2, the control device 4 according to FIG. 3 can also be designed in accordance with the described first and also the second alternative variant. In order to implement the second variant, in which the second control chamber 74 is in direct connection with the high-pressure zone, a wide annular gap 93 can be provided between the sleeve 94 and the guide bore 29, or the ribs 95 can be omitted entirely.

4 shows a further embodiment of the control device and is designated by 5.

In a part 99 of the guide bore 29 which is enlarged in diameter, a sleeve 98 is guided in a closely sliding manner and, like the sleeve 94 known from FIG. 3, is equipped with the narrow sealing surface 96 provided with depressions 97. The spring 63 is biased between the lower end face 65 of the sleeve 98 and a housing shoulder 100.

Parallel to the guide bore 29, a housing bore 102 is made in the housing 15, in which a ball check valve 103 is installed. A lower valve seat element 104 of the ball check valve 103 has a bore 105 which is connected to the second control chamber 74 via bores 106, 107. A ball 108 assigned to the valve seat element 104 is pressed against the valve seat element 104 via a second valve element 109 by the force of a spring 110. The ball check valve 103 is axially fixed in the housing bore 102 by means of a locking pin 111, via which the spring preload can also be selected. The connection of the second control chamber 74 to the high pressure zone is thus established via the ball check valve 103.

If the fuel pressure in the second control chamber 74 increases as the nozzle needle 24 and the control piston 50 move upward as a result of the pumping action of the control piston 50, the ball 108 of the ball check valve 103 is raised and the pressure suddenly adapts to the high system pressure, thereby counteracting the opening movement the nozzle needle 24 is suddenly lifted (the throttle 77 according to FIG. 2 has brought about a continuous pressure adjustment.). By means of the control device 5, the opening movement of the nozzle needle 24 is divided into a phase with a lower opening speed (before the ball check valve 103 opens) and a phase with a large opening speed. Such a course of the opening movement of the nozzle needle 24 causes a favorable engine combustion.

A rapid closing movement is achieved in the same way as in the control device 3, in which the sleeve 98 releases the connection of the high pressure system to the first control chamber 70 when the control piston 50 moves downward and the fuel pressure in the second control chamber 74 drops below a certain size.

A further alternative embodiment of the control device is shown in FIG. 5 and is designated by 6. Instead of the ball check valve 103 known from FIG. 4, a cone seat valve 113 is installed in the housing bore 102. The conical seat between a valve body 114 and the housing 15 is designated 115. The valve body 114 is provided with a transverse bore 116 and a throttle bore 117 arranged perpendicular to the transverse bore 116. The second control chamber 74 is connected to the high-pressure region via the bores 107, 106, the throttle bore 117 and the transverse bore 116.

In this variant, the fuel pressure in the second control chamber 74 can be compensated gradually via the throttle bore 117 when the control piston 50 moves upward, with the cone seat valve 113 closed, and can also be abruptly adjusted to the system pressure by lifting the valve body 114 from the cone seat 115 in the event of a large overpressure. At a low system pressure, the poppet valve 113 does not respond.

6 shows in partial section an alternative embodiment of the fuel injection valve, which is designated by 2 and is equipped with a further control device 7. The identical and identically acting parts already known from FIGS. 1 to 5 are again identified by the same reference numerals. A part of the control device 7 is shown enlarged in FIG. 7 for better understanding.

According to FIG. 6, the fuel injection valve 2 has a housing 120 which is provided with a central guide bore 121 for the control device 7. In the guide bore 121, a control piston 122 is arranged so as to be axially displaceable in a closely sliding manner. At the top, the control piston 122 has a piston part 123 of reduced diameter. The corresponding sales area is designated 126. At the bottom, the control piston 122 merges into a connecting rod 124, via which it engages non-positively with the one not shown in FIG Injection valve member (nozzle needle) is connected. If necessary, the connecting rod 124 could even be formed in one piece with the injection valve member. A piston shoulder 129 is formed at the transition to the connecting rod 124.

The relatively short, first fuel supply bore 31 from the high-pressure fuel connection 10 opens directly into a space 125 between the connecting rod 124 and the guide bore 121. The housing 120 itself no longer has any further high-pressure supply lines, which in the embodiment shown in FIG were designated; there are also no further annular spaces or transverse bores in the housing 120, as a result of which an extremely simple and technically advantageous housing 120 is realized.

The upper piston part 123 is provided on its upper end face with a recess 128 into which a central connecting bore 130 made in the control piston 122 opens. The connecting bore 130 is connected to the space 125 filled with high-pressure fuel via a transverse bore 131 made in the control piston 122.

A control body 135 is inserted into the guide bore 121 in a fixed position (for example pressed in) and is axially fixed by the already known locking nut 54. The control body 135 is provided on its lower end face with a recess 136 into which the upper piston part 123 projects in a closely sliding manner. In a part 137 of the recess 136 with a diameter, a spring 138 is arranged, by means of which a valve seat disk 140 is pressed against the upper, annular end face of the upper piston part 123, designated 127. The valve seat disk 140 has a central disk hole 141.

In the recess 128 of the control piston 122, a disk hole 141 is effective in the position shown a spring 144 arranged to close a throttle bore 142 valve body 143.

The valve seat disk 140 and the valve body 143 closing the disk hole 141 form a first valve flat seat 151. The end face 127 of the piston part 123 and the valve seat disk 140 form a second valve flat seat 152 (see FIG. 7).

A first control chamber 155 is present between an annular, lower end face 139 of the control body 135 and the shoulder surface 126 of the control piston 122, which is delimited radially by the upper piston part 123 on the one hand and the guide bore 121 on the other hand. On the circumference of the upper piston part 123, an inlet throttle 133 is made, which opens radially into the connecting bore 130 and forms a connection between the first control chamber 155 and the high-pressure fuel zone.

At least one connecting groove 157 is made on the circumference of the control body 135 and connects the first control chamber 155 with a transverse bore 158 in the control body 135. An outlet opening 159 of the control body 135 opening into the transverse bore 158 is kept closed in the position shown by the pilot valve stem 81, as a result of which the first control chamber 155 is separated from the low-pressure part of the fuel injection valve 2.

A second control chamber 156 is formed in the recess 136 of the control body 135 above the piston part 123 and is kept separate from the system or high-pressure fuel zone in the illustrated starting position between two injection processes by the two valve flat seats 151, 152.

The mode of operation of the fuel injection valve 2 or of the control device 7 is as follows:
When the pilot valve stem 81 is raised and electronically controlled in the same way as described above, the outlet opening 159 is opened. The fuel pressure in the first control room 155 drops. The control piston 122 is moved upward by the high fuel pressure acting on the piston shoulder 129 and prevailing in the space 125. In this way, the injection valve member opens the injection openings to the combustion chamber of the internal combustion engine in the manner already described. When the control piston 122 together with the valve seat disk 140 is raised, the volume of the second control chamber 156 is reduced, the pressure increases with this pumping action and counteracts the opening movement in the desired manner. This results in a slow opening process. As soon as the pressure in the second control chamber 156 reaches a certain level, the valve body 143 is pressed down against the system pressure in the recess 128 and the force of the spring 144 via the disk hole 141 and the first valve flat seat 151 is opened, as a result of which the opening process of the control piston 122 and consequently the injection valve member is accelerated.

If the outlet opening 159 is closed again by the pilot valve stem, the pressure in the first control chamber 155 rises again. The pressure in the second control chamber 156 is again adjusted to the high system pressure. The spring 144 presses the valve body 143 against the valve seat disk 140, which on the other hand is loaded by the force of the spring 138. The first flat valve seat 151 is closed. The control piston 122 is moved downward over the shoulder surface 126. The volume of the second control chamber 156 is increased, the pressure drops. As soon as the pressure in the second control chamber 156 falls below a certain value at which a sufficient contact pressure is not exerted on the valve seat disk 140 from above, the second flat valve seat 152 is opened. At this moment, a connection between the second control chamber 156 and the high-pressure fuel supply is established produced, the fuel accelerating the control piston 122 downward via the end face 127. In this way, the injection valve member is closed quickly.

The fuel injector 2 according to the invention has the advantage, in addition to the simplification of construction and assembly technology, that minimal leaks take place. The fuel emerging from the outlet throttle bore 159 is in turn fed to the fuel return connection via the drain bore 90.

If the valve body 143 with the throttle bore 142 and the spring 144 were omitted in the control device 7 according to FIGS. 6 and 7 and the valve seat disk 140 was provided directly with a disk hole 141 designed as a throttle, the mode of operation of the control device 7 would be that of the control device 3 from Fig. 2 correspond. The disk hole 141 designed as a throttle would then correspond to the throttle 77 from FIG. 2, which connects the second control chamber 156 (control chamber 74 in FIG. 2) to the high-pressure zone.

If the valve seat disk 140 and the spring 138 were also omitted, the control device 7 would correspond to the second alternative variant to the control device 3 according to FIG. 2 (with a large or missing throttle 77), since in this case the second control chamber 156 would also be connected directly to the high-pressure zone .

8 shows a further alternative embodiment of a control device 8 which can be used for the fuel injection valve 2. The parts known from FIGS. 6 and 7 are again identified by the same reference numbers.

In this case, the control piston 122, which is displaceably arranged in the guide bore 121 of the housing 120, has no Diameter offset piston part, but it is closed with an upper end face 161. Between the control piston 122 and the control body 135, an intermediate piston 162 is arranged, which protrudes closely into the recess 136 of the control body 135. A first, annular control chamber 160 is delimited radially by the intermediate piston 162 and the guide bore 121, axially by the upper end face 161 of the control piston 122 and the lower end face 139 of the control body 135. A second control chamber 165 is located in the recess 136 above the intermediate piston 162 or above an upper end face 163 of the intermediate piston 162.

The intermediate piston 162 is provided with a shoulder 166. A spring 167 surrounding the intermediate piston 162 is supported on the shoulder 166 on the one hand and on the lower end face 139 of the control body 135 on the other hand. The intermediate piston 162 has a narrow, annular sealing surface 168 at the bottom, which is assigned to the upper end surface 161 of the control piston 122. The diameter of the sealing surface 168 is smaller than the diameter of the recess 136 or the diameter of the upper end surface 163 of the intermediate piston 162.

The intermediate piston 162 is provided with a central recess 170 from below. Between the recess 170 and the second control chamber 165, a connecting bore 174 is made in the intermediate piston, to which a ball valve 171 arranged in the recess is assigned. A valve spring 173 is prestressed in the recess 170 by means of a securing element 172 which is pressed or screwed into a bore 180 of the intermediate piston 162. The securing element 172 has a central connecting bore 182, via which the space of the recess 170 communicates with the connecting bore 130 arranged centrally in the control piston 122 and thus with the high-pressure fuel zone. The intermediate piston 162 is also with a Throttle bore 175 is provided, via which the second control chamber 165 is connected to the recess 170 and thus to the high-pressure fuel zone parallel to the connecting bore 174 which can be closed by means of the ball valve 171.

The intermediate piston 162 has an inlet throttle 184, which connects the first control chamber 160 to the bore 180 and thus to the high-pressure fuel zone.

Instead of the inlet throttle 184, it would be entirely possible to provide the sealing surface 168 of the intermediate piston 162 with a plurality of radial depressions distributed around the circumference - similar to the case with the sleeve 94 according to FIG. 3 (see depressions 97), for an inlet throttle connection of the first control room 160 with the high-pressure fuel zone.

The structure of the control device 8 has the following operation:
When the pilot valve stem 81 is raised, the pressure in the first control chamber 160 is reduced via the outlet opening 159, the transverse bore 158 and the connecting groove 157. The control piston 122 is moved upwards in the manner already described, the injection valve member opening the injection openings to the combustion chamber of the internal combustion engine. The intermediate piston 162 pressed against the end face 161 with the sealing surface 168 is also moved upward. Due to the pumping action of the intermediate piston 162, the pressure in the second control chamber 165 increases. At a certain excess pressure, the ball valve 171; thus the opening movement of the control piston 122 is accelerated.

If the outlet opening 159 is closed again by the pilot valve stem 81, the pressure in the first control chamber 160 rises. The pressure in the second control chamber 165 is at the System high pressure adjusted. The ball valve 171 closes. With the increasing pressure in the first control chamber 160, the control piston 122 and also the intermediate piston 162 are moved downward. The volume of the second control chamber 165 increases, the pressure drops. With a certain pressure drop, the contact force of the intermediate piston 162 against the end face 161 of the control piston 122 is no longer guaranteed. The intermediate piston 162 or its sealing surface 168 separates from the control piston 122, and the control piston 122 is additionally accelerated downward by the high fuel pressure acting on its end surface 161 (supplied via the connecting bore 130). The injection valve member is closed suddenly. In contrast to the control device 7 known from FIG. 7, the entire piston surface is acted on here, similar to the control device 3 in FIG.

The control device 8 means a significant design simplification. As is well known, the exact concentricity, i.e. precise processing important. In this embodiment, none of the parts has two such sliding surfaces to be coordinated. The control piston 122 has an extremely simple shape here. The assembly of individual parts of the control device 8 in the fuel injection valve 2 is easy. Furthermore, the essential control elements determining the function (the throttle bores 175 and 184 and the ball valve 171) are manufactured or installed in the intermediate piston 162. These throttle bores 175, 184 and the ball valve 171 can be checked for their correct function before the fuel injector 2 is assembled.

If one omitted the ball valve 171 with the valve spring 173 in this control device 8, the device would correspond to the control device 2 known from FIG. 2; here, too, the second control room 165 would only be via the Throttle 175 (corresponding to throttle 77 according to Figure 2) connected to the high pressure zone.

The control device 8 could, however, also be designed in accordance with the second alternative variant to the control device 2, which is not shown in the drawing, in that the second control chamber 165 does not have the throttle 175, which together with the securing element 172, the ball valve 171 and the valve spring 173 are eliminated would, but would be connected directly to the high pressure zone via a large through hole in the intermediate piston 162.

FIG. 9 shows a further embodiment of a control device 9, which essentially corresponds in its design and mode of operation to the control device 8 from FIG. 8, but which is suitable, for example, for the fuel injection valve 1 according to FIG. 1, in which, in contrast to the fuel injection valve 2 according to FIG. 6, the high-pressure fuel supply to the control device takes place from above. Analogous to control device 8, control device 9 also has the above-mentioned advantages in terms of production and assembly.

In this variant, a control body 177 provided with a lower end face 178 is arranged in the guide bore 29 of the valve housing 15 in a stationary manner. The control piston 50, which is axially displaceable in the guide bore 29, is provided at the top with a central recess 176. An intermediate piston 179, which is supported on the end face 178 of the control body 177 via a narrow, annular sealing surface 187, projects closely into the recess 176 of the control piston 50. The intermediate piston 179 corresponds essentially to the intermediate piston 162 according to FIG. 8, but is arranged so that it is vertically reversed by 180 °. Since the internal configuration of the intermediate piston 179 corresponds to that of the intermediate piston 162, the parts having the same effect are identified with the same reference numbers (see recess 170, ball valve 171, securing element 172, connecting bores 174, 182, throttle 175, valve spring 170). A spring 183 surrounding the intermediate piston 179 is supported on the one hand on a shoulder 185 of the intermediate piston 179 and on the other hand on an upper end face 186 of the control piston 50. A first, annular control chamber 201 is delimited radially by the intermediate piston 179 and the guide bore 29, axially by the upper end face 186 of the control piston 50 and the lower end face 178 of the control body 177. The first control chamber 201 is connected to the control devices 7 and 8 according to FIGS. 7 and 8 via at least one connecting groove 157 made on the circumference of the control body 177 and via the transverse bore 158 with the outlet opening 159 which can be closed off by the pilot valve stem 81. The transverse bore 158 is connected via a throttle 198 and via a passage 199 to the transverse bore 68 leading to the upper high-pressure supply line 33 (see FIG. 1).

A second control chamber 202 is formed below the intermediate piston 179 in the recess 176 of the control piston 50. The second control chamber 202 is temporarily connected to the transverse bore 68 connected to the high pressure zone via the connecting bore 174 which can be closed by the ball valve 171 and continuously via the throttle 175 and via the connecting bore 182 in the securing element 172 and via a passage 200 made in the control body 177.

The mode of operation of the control device 9 corresponds to the mode of operation of the control device 8 according to FIG. 8 and is therefore not repeated. Analogously to the control device 8, this control device 9 could also be formed alternatively by omitting individual parts, in order then to correspond to the control device 2 according to FIG. 2 or the described second alternative variant of this control device 2.

10 shows a further embodiment of a control device 11, provided for the fuel injection valve 1 according to FIG. 1. This form of training is particularly suitable for small fuel injection valves, where there is no space for arranging valves and springs.

In the central guide bore 29 of the valve housing 15, a control body 205 is fixed in place (for example pressed in) and axially fixed by the lock nut 54, which is designed here as a union nut. The control body 205 has at the bottom a part 206 with a diameter, with which it projects into a central recess 207 of the control piston 50, which is axially displaceable in the guide bore 29. A first, annular control chamber 211 is delimited radially by the part 206 of the control body 205 and by the guide bore 29, axially by a shoulder surface 209 of the control body 205 and an upper end face 208 of the control piston 50. The first control chamber 211 is in turn connected in the same way as in control devices 7, 8 and 9 via at least one connecting groove 157 made on the circumference of the control body 205 and via the transverse bore 158 to the outlet opening 159 which can be closed off by the pilot valve stem 81. The transverse bore 158 is connected in the same way as in the control device 9 via the throttle 198 and via the passage 199 to the transverse bore 68 leading to the upper high-pressure supply line 33 (see FIG. 1), which is arranged obliquely here, and which has a radial recess 213 of the Control body 205 is assigned. The recess 213 is connected via a throttle 214 and a central bore 215 in the control body 205 to a second control chamber 212, which is located below the control body 205 in the central recess 207 of the control piston 50.

In this embodiment, the opening process takes place in a manner similar to that of the control device 2 according to FIG Step; the throttle 214 corresponds here to the throttle 77 from FIG. 2. However, in this variant, no additional acceleration takes place during the closing process, as was the case with the control device 2. The control device 11 is simple to manufacture and assemble and, as already mentioned, is particularly suitable for small fuel injection valves.

FIG. 11 shows a further embodiment of a control device 13 that can be used for the fuel injection valve 2 according to FIG. 6. The control piston 122 provided with the central connecting bore 130, which is connected to the high pressure zone, and axially displaceable in the guide bore 121 of the valve housing 120 has a central recess at the top 218 on. A first control body part 220 is arranged in the guide bore 121 in a fixed position (for example pressed in) and axially fixed by the lock nut 54. A second control body part 221 projects into the recess 218 and is pressed by a spring 222 arranged in the recess 218 at the top against a lower end face 223 of the first control body part 220.

The first control body part 220 is provided with a bore 260, which tapers into an outlet opening 259 which can be closed off by the pilot valve stem 81, and which is connected to a first control chamber 226 via at least one radial groove 224 made in the lower end face 223. The groove 224 could also be formed in the end face of the second control body part 221. The first, annular control chamber 226 is delimited radially by the guide bore 121 and the second control body part 221, axially by the lower end face 223 of the first control body part 220 and an upper end face 225 of the control piston 122. A second control chamber 227, which is connected directly to the high-pressure zone via the connection bore 130, is located in the recess 218 below the second control body part 221.

The second control body part 221 is provided with a central bore 257 which tapers into an inlet throttle bore 258 at the top. The first control chamber 226 is connected to the high-pressure zone via the inlet throttle bore 258 (similar to the inlet throttle bore 58 according to FIG. 2). The spring 222 can possibly be omitted, since the system high pressure prevailing in the second control chamber 227 ensures that the second control body part 221 is constantly pressed against the first control body part 220.

The operation of the control device 13 corresponds to that of the second alternative variant to the control device 2 according to FIG. 2, which is not shown in the drawing. In this variant, too, the system fuel high pressure prevails in the second control chamber 227, which remains practically unaffected by the pumping action of the control piston 122. The opening and closing movement of the control piston 122 and thus also the nozzle needle 24 is controlled via the annular upper end face 225 of the control piston 122 by the control pressure prevailing in the first control chamber 226, this control pressure being determined by the design and spatial arrangement of the inlet throttle bore 258 and the outlet opening 259 is dependent.

The division of a single control body into two control body parts 220, 221 results in particularly simple manufacture and assembly of the control device 13.

A further embodiment of a control device 22 for the fuel injection valve 2 according to FIG. 6 is shown in FIG. 12 and described below. The same reference numerals are used for the already known parts.

This form of training is similar to the control device 11 according to FIG. 10, especially for small ones Fuel injectors suitable for which there is no space for arranging valves and springs.

The first control chamber 155 of the control device 22, like the control device 7 according to FIGS. 6 and 7, is delimited radially by the guide bore 121 and the piston part 123 with a reduced diameter, axially by a piston shoulder 126 and the lower end face 139 of the control body 135. The piston part 123 is here also provided with an additional offset part 190. A second control chamber 195 is formed above the piston part 123 in the recess 136 of the control body 135. A throttle 191 made radially in the offset part 190 connects the second control chamber 195 to the connecting bore 130 and thus to the high-pressure fuel zone. The throttle 191 could also be mounted on the longitudinal axis of the control piston 122 or the fuel injector 2 (similar to the throttle bores 197 and 159). In the control body 135 there is a central bore 196 which opens into the second control chamber 195 and is connected to the transverse bore 158 via a throttle 197. In contrast to the control device 7 according to FIG. 7, the first control chamber 155 is not connected to the high-pressure system (see throttle bore 133 in FIG. 7), but instead receives pressure from the second via the throttle 197, the transverse bore 158 and the connecting groove 157 Control room 195. The pressure in the two control rooms 155, 195 or the pumping action of the control piston 122 depends on the design of the throttles 191, 197 both when opening and when closing. The throttle 191 replaces the first valve flat seat 151 or the throttle bore 142 according to FIG. 7. In this embodiment, no additional acceleration takes place during the closing process. The form of training as well as assembly is extremely simple.

Claims (25)

Fuel injection valve for intermittent fuel injection into the combustion chamber of an internal combustion engine, with a housing (15; 120), with a valve seat element (19) provided with injection openings (21), with an injection valve member, which is built into the housing (15; 120) and is adjustable in length, for closing or opening the Injection openings (21), with a control device (3; 4; 5; 6; 7; 8; 9; 11; 13; 22) for controlling the adjustment movement of the injection valve member, the control device (3; 4; 5; 6; 7; 8; 9; 11; 13; 22)) has a control piston (50; 122) which is arranged in a longitudinally displaceable manner in a guide bore (29; 121) and which is operatively connected to the injection valve member and which on the one hand and through the fuel system pressure from a high pressure supply line (32; 31) the fuel control pressure in a first control chamber (70; 155; 160; 201; 211; 226) is acted on the other hand, the first control chamber (70; 155; 160; 201; 211; 226) via at least one inlet throttle (58; 97 ; 133; 1 84; 197; 198; 258) is connected to the high pressure supply line (31), and the control pressure in the first control chamber (70; 155; 160; 201; 211; 226) by opening or closing at least one outlet opening (59; 159) is controllable, for which purpose the control device (3; 4; 5; 6; 7; 8; 9; 11; 13; 22) is provided with a controllable pilot valve (80), characterized in that the control device (3; 4; 5; 6; 7; 8; 9; 11; 13; 22) has a second control chamber (74; 156; 165; 195; 202; 212; 227) permanently or temporarily connected to the high-pressure supply line (31), the volume of which is caused by the adjustment movement of the control piston (50; 122) can be changed, the pressure in the second control chamber (74; 156; 165; 195; 202; 212; 227) Counteracts opening movement of the injection valve member or the control piston (50; 122). Fuel injection valve according to Claim 1, characterized in that the pressure in the second control chamber (74; 156; 165; 202; 227) is practically achieved by a direct connection of the second control chamber (74; 156; 165; 202; 227) to the high-pressure supply line (31) is kept constant. Fuel injection valve according to claim 1, characterized in that in the second control chamber (74; 156; 165; 195; 212) during the opening movement of the injection valve member or the control piston (50; 122) a pressure increase counteracting this opening movement is generated, the control device (3 ; 4; 5; 6; 7; 8; 9; 11; 22) has relief elements (75.77; 95; 103; 113.117; 142.151; 171.175; 191; 214) for connecting the second control chamber (74; 156; 165; 195) with the high pressure supply line (31). Fuel injection valve according to Claim 3, characterized in that means (64; 94; 98; 152; 162) are provided, by means of which the closing movement of the injection valve member or of the control piston (50; 122) can take place quickly. Fuel injection valve according to Claim 4, characterized in that a direct connection from the high-pressure line (33, 31) to one is provided by the means (64; 94; 98; 152; 162) when the fuel pressure in the second control chamber (74; 156; 165) drops of the two control spaces (70; 156; 160) is released in order to bring about an additional acceleration of the control piston (50; 122). Fuel injection valve according to one of claims 3 to 5, wherein the first control chamber (70,) between a upper end face (56) of the control piston (50) and a fixed control body (52) provided with the outlet opening (59), characterized in that the control piston (50) has a piston part (51) of reduced diameter and a corresponding piston shoulder surface ( 53), that on the piston part (51) on the one hand and in the guide bore (29) on the other hand, a displaceable sleeve (64; 94; 98) is arranged so that it slides, that the second, annular control chamber (74) radially through the piston part (51) and the guide bore (29) is axially limited at least by the piston shoulder surface (53) and a lower end face (65) of the sleeve (64; 94; 98), and that at the same pressure in both control chambers (70; 74) and at the opening movement of the control piston (50) with a sealing surface (66; 96) on the control body (52) abutting sleeve (64; 94; 98) during the closing movement of the control piston (50) when the pressure in the second control chamber (74) drops significantly Releases connection between the high pressure supply line (33) and the first control chamber (70). Fuel injection valve according to one of Claims 3 to 6, characterized in that the relief elements are formed by a connecting bore (75) which connects the second control chamber (74) to the high-pressure supply line (33) and is provided with a throttle (77). Fuel injection valve according to one of claims 3 to 6, characterized in that the relief elements are formed by a ball check valve (103). Fuel injection valve according to one of Claims 3 to 6, characterized in that the relief elements are formed by a valve (113), the valve body (114) of which connects the second control chamber (74) to the high-pressure supply line (33) when the seat (115) is closed Throttle bore (117) is provided. Fuel injection valve according to claim 6, characterized in that the sleeve (94) on the circumference has a plurality of ribs (95) arranged axially one behind the other, through which an annular gap (93) is formed in relation to the guide bore (29), and which the relief elements in the Form the connection between the second control chamber (74) and the high-pressure supply line (33) opening into the guide bore (29) above the uppermost rib (95). Fuel injection valve according to Claim 6, characterized in that the sealing surface (66; 96) of the sleeve (64; 94; 98) is provided with a plurality of depressions (97) which connect the inlet throttle connection between the high pressure supply line (33) and the first control chamber (70) form. Fuel injection valve according to one of Claims 1 to 3, with a stationary control body (135) provided with the outlet opening (159), characterized in that the control body (135) is provided with a recess (136) into which a diameter-offset, upper piston part (123) slidably protrudes, and that the first annular control chamber (155) radially through the piston part (123) and through the guide bore (121), axially through a piston shoulder (126) and a lower end face (139) of the Control body (135) is limited. Fuel injection valve according to one of Claims 1 to 3, with a stationary control body (135) provided with the outlet opening (159), characterized in that the control body (135) is provided with a recess (136) into which an intermediate piston (162) protrudes closely slidingly, which is operatively connected via a sealing surface (168) to an upper end surface (161) of the control piston (122), and that the first, annular Control chamber (160) is delimited radially by the intermediate piston (162) and the guide bore (121), axially by the upper end face (161) of the control piston (122) and a lower end face (139) of the control body (135). Fuel injection valve according to Claim 12, characterized in that the second control chamber (156; 195) is formed in the recess (136) above a piston end face (127) and via a throttle (142; 191) with a connecting bore (centrally arranged in the control piston (122)) 130) is connected to the high pressure supply line (31). Fuel injection valve according to Claim 13, characterized in that the second control chamber (165) is formed in the recess (136) above an end face (163) of the intermediate piston (162) and via a throttle (175) with a connecting bore arranged centrally in the control piston (122) (130) to the high pressure supply line (31) is connected. Fuel injection valve according to Claim 5, Claim 12 and Claim 14, characterized in that the upper piston end face (127) is assigned a valve seat disc (140) which separates the second control chamber (156) from the connecting bore (130) and is provided with the throttle (141), which forms a flat valve seat (152) with the piston end face (127), which releases the direct connection of the second control chamber (156) to the connecting bore (130) during the certain lowering of the pressure in the second control chamber (156) and thus releases one direct piston loading through high fuel pressure enabled. Fuel injection valve according to claim 16, characterized in that the piston part (123) is provided with a recess (128) in which one with the Throttle (142) provided valve body (143) is axially adjustable, that the valve seat disc (140) has a disc hole (141) which can be closed by the valve body (143) down to the throttle (142), and that the valve seat disc (140 ) forms a further valve flat seat (151) with the valve body (143) to relieve the pressure on the second control chamber (156) during a certain pressure increase during the opening movement of the control piston (122). Fuel injection valve according to Claim 5, Claim 13 and Claim 15, characterized in that the intermediate piston (162) which bears at the same pressure in both control spaces (160, 165) with the sealing surface (168) on the end face (161) of the control piston (122) during the closing movement of the control piston (122) releases the connection between the connecting bore (130) or the high-pressure supply line (31) and the first control chamber (160) when the pressure in the second control chamber (165) drops. Fuel injection valve according to claim 3 and claim 15, characterized in that the intermediate piston (162) is provided with a recess (170) connected to the connecting bore (130), in which a connecting bore (174) between the recess (170) and the second Control chamber (165) closing valve (171) is arranged to relieve the second control chamber (165) at a certain pressure increase during the opening movement of the control piston (122). Fuel injection valve according to claim 15 and claim 19, characterized in that the throttle (175) is made parallel to the connecting bore (174) in the intermediate piston (162) and opens into the recess (170). Fuel injection valve according to Claim 3 and according to one of Claims 12 or 13, characterized in that the first control chamber (155; 160) via a connecting groove (157) on the circumference of the control body (135) and via a transverse bore (158) in the control body (135) is connected to the outlet opening (159). Fuel injection valve according to claim 3 and claim 12, characterized in that the first control chamber (155) via an inlet throttle (133) made in the piston part (123) and opening radially into a central connecting bore (130) of the control piston (122) with the high-pressure supply line (31 ) connected is. Fuel injection valve according to claim 3 and claim 13, characterized in that the first control chamber (160) via an inlet throttle (184) made in the intermediate piston (162) and opening radially into a central bore (180) of the intermediate piston (162) with the high-pressure supply line (31 ) is connected. Fuel injection valve according to Claim 3 and Claim 13, characterized in that the sealing surface (168) of the intermediate piston (162) is provided with a plurality of depressions which form the inlet throttle connection between the high-pressure supply line (31) and the first control chamber (160). Fuel injection valve according to Claim 12, Claim 14 and Claim 21, characterized in that the second control chamber (195) is connected to the transverse bore (158) via a bore (196) made in the control body (135) and provided with a throttle (197) and thus in connection with the first control room (155).

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