JPH04311669A - Time-limit changeover valve for pressure medium system - Google Patents

Abstract

PURPOSE: To provide a time limit selector valve having selective times by the unit of millisecond which is capable of assuring correct reproducibility. CONSTITUTION: A valve member 3 has a prescribed mass, a spring 38 to act on the valve member 30 has a prescribed force-distance characteristic line, and the valve member 30 is moved from one selective position to the other selective position at a constant passage time after release control of adjusting pressure based on mutually harmonized mass and force under actin of the spring 38 based on laws of damping harmonic wave vibration.

Description

[Detailed description of the invention]

0001

FIELD OF INDUSTRIAL APPLICATION The invention relates to a timed switching valve for pressure medium systems, the valve being shiftable in a casing with a connection for a pressure source and a connection for a consumer. A member is provided, the valve member being shiftable by a fluid regulating pressure to a first switching position and by a spring to a second switching position spaced a predetermined distance from the first switching position. Concerning forms that are shiftable.

0002

BACKGROUND OF THE INVENTION A timed switching valve with a piston spool is used for controlling the opening or closing of a hydraulic or pneumatic valve after a predetermined time has elapsed after the occurrence of a positive or negative pressure signal. It is known that control pressure chambers are arranged on one control side and on the other control side of this piston spool, in which control pressure chambers the piston can be moved from one switching position to the other switching position. To shift the spool, fluid is supplied or withdrawn from this control pressure chamber. In order to implement a certain degree of delay during the inflow or outflow of the fluid, a restriction is arranged in the supply or discharge conduit, which, in cooperation with the force of the return spring, meters the fluid to the control chamber. Let it flow out. As a result, a certain amount of time elapses between the opening control operation of the control pressure chamber in which the control spool occupies one switching position and the entry operation of the control spool in the other switching position. Switching times, which are times in seconds, are significantly affected by fluid viscosity changes during temperature fluctuations.

0003

SUMMARY OF THE INVENTION It is therefore an object of the invention to improve a timed switching valve of the type mentioned at the outset, which has a switching time in particular in the millisecond range and which guarantees precise reproducibility. It is an object of the present invention to provide a timed switching valve that can

0004

[Means for Solving the Problem] In order to solve this problem, in the configuration of the present invention, the valve member has a specified mass, and the spring acting on the valve member has a specified force-distance characteristic line. In this case, the valve member is moved into one switching position after a certain elapsed time, based on the law of damped harmonic oscillations, after the opening of the regulating pressure on the basis of the mutually harmonized masses and the force under the action of the spring. from one switching position to the other switching position.

[0005]

A time-limited switching valve constructed as in the present invention has the following advantages. That is, in the timed switching valve according to the present invention, the elapsed time from the start of the switching timing to the achievement of the switching timing is always constant based on the principle, and in this case, it is not influenced by the regulated pressure, temperature, and viscosity of the regulated fluid. . Therefore, the timed switching valve according to the invention can be used in a diesel fuel injection system, i.e. for the purpose of preconditioning the combustion chamber for combustion, by injecting a small pre-injection quantity at a time lag before injecting the main injection quantity. It can be used particularly advantageously in a diesel fuel injection device designed to inject into a room. By carrying out such preconditioning, combustion noise can be reduced without deteriorating the emissions of HC, NOx, smoke and the like and the inherent fuel consumption.

[0006]

Embodiments Next, embodiments of the present invention will be described with reference to the drawings.

The injection device shown in FIGS. 1 and 2 mainly includes an injection nozzle 1 having a front injection device 2, and a timer member 3.
, a tension member 4 , a control valve device 5 and a pressure valve 6 . In connection with the control valve device 5, the timing element 3 controls the injection nozzle 1 with the pre-injection device 2 as follows:
Control is performed so that a predetermined period of time elapses from the start of pre-injection to the start of main injection each time. The individual parts are constructed as modules 7, 8 and together with the injection nozzle 1 form a unit.

[0008] The injection nozzle 1 has a general-purpose structure.
a shiftable and closing spring 1 within the nozzle body 12;
Valve needle 1 pressed towards valve seat 13 by 4
1. The nozzle body 12 is fastened by means of a cap nut 15 via an intermediate disk 16 to a nozzle holder 17, which accommodates a closing spring 14 in its chamber. In the area of the pressure shoulder 18 of the valve needle 11,
The nozzle body 12 has a pressure chamber 19.

The preinjection device 2 is arranged in the nozzle body 12 axially parallel to the valve needle 11, as is known, for example, from German Patent No. 1252002. The pre-injection device has a pre-injection piston 21 which can be shifted in a cylinder bore 22 against the action of a return spring 24, which pre-injection piston is shifted by a defined stroke when the pressure increases and is then A predetermined, respectively constant quantity of fuel, the so-called preinjection quantity, is pumped through the channel 23 into the pressure chamber 19 of the injection nozzle 1, from which the preinjection quantity is injected into the combustion chamber.

The main injection quantity is supplied to the injection nozzle 1 via a tensioning element 4 and a timing element 3, the timing element 3 defining the temporal interval between the pre-injection and the main injection; It is itself triggered by the control valve arrangement 5. The timing member 3 is a spring-mass system and has a mass in the form of a piston spool 30 with an active piston part 31 and a valve-spool part 32, which piston spool has a control groove 33 and a valve-spool part 32. Control edges 34, 35 are used to control inlet 36 and outlet 37. piston spool 30
is loaded on the side facing the pressure surface of the piston part 31 by a spring 38, which is preferably a helical compression spring. In the unpressurized state, the piston spool 30 occupies a defined position in which the control groove 33 creates a connection between the inlet 36 and the outlet 37. And this connection is the piston part 3
1, the piston part 31 of the piston spool 30 moves against the force of the spring 38 against the stop 39
is interrupted when shifted towards. The mass of the piston spool 30 and the force of the spring 38 are such that, after the respective actuation of the timing member 3 due to the pressure drop in the piston part 31, the control edges 34, 35 of the spool part 32 connect to the inlet 36. Arrangements are made such that a preselected period of time elapses before a connection with outlet 37 occurs. The interval from the start of pre-injection to the start of main injection is defined by this constant time lapse or oscillation lapse.

[0011] At the beginning of the delivery of the injection quantity by the injection pump and when the pressure builds up, the tensioning piston 40 of the tensioning member 4 is shifted, which tensioning piston then forces the fuel through the channel 42 into the piston part 31 of the piston spool 30. As a result, the timing member 3 or its piston spool 30 is tensioned or brought into its starting position, so that the spool part 32 interrupts the connection from the inlet 36 to the outlet 37. Spring 43 in no pressure state
When the tensioning piston 40 is shifted from the starting position brought about by the pressure applied by the tensioning piston 40 , the tensioning piston 40 with the control edge 44 creates a connection from the supply channel 45 to a channel 46 leading to the inlet 36 of the timing member 3 . The supply passage 45 is connected to a conveying or pressure conduit 47;
This pressure conduit extends from a high pressure and injection pump, not shown.

The control valve device 5 for controlling the start of the pre-injection and the activation of the piston spool 30 of the timing member 3 has a control or valve spool 50 which is connected to a first control of the annular groove 52. An edge 51 controls the connection between a passage 53 connected to the pressure conduit 47 and a passage 54 leading to the pre-injection device 2, and a second control edge 55 controls the connection between the piston part 31 of the piston spool 30 and the pressure-free connection. The connection passage 56 connecting the oil leakage passage 65 is controlled. In its closed position, the valve spool 50 is loaded by a return spring 57 which is supported on the housing and rests with its control edge 55 on a stop shoulder 49 fixed to the housing. The valve spool 50 advantageously has the same diameter as the tensioning piston 40 , is arranged coaxially with respect to this tensioning piston 40 , and has an extension 58 projecting towards the tensioning piston 40 . There is. This additional part is the tension piston 4
0 and the pressure-free starting position of the valve spool 50 has a defined spacing towards the tensioning piston 40 . The chamber 59 accommodating the return spring 57 is relieved of pressure via an outflow or pressure valve 64, which is adjusted to an opening pressure of approximately 20 bar, and an oil leakage channel 66. The chamber 59 is furthermore connected by a passage 63 to the pressure valve 6, which has a differential piston 60 loaded by the pump pressure, which differential piston with a control lip 61 is connected to the control valve device. The connection between the chamber 59 of No. 5 and the passage 62 communicating with the passage 53 is controlled. The pressure valve 6 creates a pressure difference in the tensioning piston 40 and the valve spool 50 and ensures the return of these parts when pressure is built up. The pressure-free chambers associated with the control piston 50, the differential piston 60 and the piston spool 30 are
Via oil leakage passages 65 to 69, it is connected to a collective oil leakage passage (not shown), through which the leakage oil is also discharged from the chamber accommodating the closing spring 14 of the injection nozzle 1. Ru.

The injection device whose structure is schematically shown in FIG.
In FIG. 2, a simplified embodiment is shown. In this case, an injection nozzle 1 of general construction type with a pre-injection device 2 includes a module 7 with a control valve device 5 and a module 8 with a timing element 3, a tensioning element 4 and a pressure valve 6. , distribution head 9 are assigned. The housings of the modules 7, 8 have approximately the same cross section as the injection nozzle 1 and are clamped coaxially and one behind the other. The above-mentioned connecting channels are configured as longitudinal holes and transverse holes in the housing, with the channels 53, 63 extending in a plane that is offset relative to the cross-section in FIG. . Similarly, the differential piston 60 of the pressure valve 6 is arranged angularly offset relative to the tensioning piston 40 in the housing of the upper module 8 . The piston spool 30 of the timing element 3, the tensioning piston 40 of the tensioning element 4, the differential piston 60 of the pressure valve 6 and the valve spool 50 of the control valve arrangement 5 are arranged in corresponding cylinder bores of the housings 7, 8. It is possible to shift.

A passage 25 extending from the outlet 37 of the timing member 3 and communicating with the pressure chamber 19 in the nozzle body 12 connects the two casings 7, 8, the nozzle holder 17 and the intermediate disk 1.
6 and the nozzle body 12. Passage 53, 63
similarly penetrates through the casings 7 and 8. A passage 54 extending from the valve control device 5 and communicating with the pre-injection device 2
passes through the casing 7, the nozzle holder 17, the intermediate disk 16, and the nozzle body 12. The channels extending parallel to the axis are designed as through holes or blind holes. The transverse holes are drilled radially from the outside and are closed in a highly consolidated manner. An arcuate groove 91 in the distribution head 9 connects the passages 45 , 46 , 53 with the pressure conduit 47 .

The working type of the above-mentioned injection device will be explained using the functional diagram shown in FIG. In this diagram, curve p shows the pressure in the supply or pressure conduit 47 with respect to time t taken on the horizontal axis, and curve a
curve b shows the movement course of the tensioning piston 40, curve b shows the movement course of the piston spool 30, curve c shows the movement course of the valve spool 50, and curve h shows the stroke of the valve needle 11.

During the discharge stroke of the injection pump, the pressure conduit 47
The pressure p at increases. As a result, the differential piston 60 of the pressure valve 6 and the tensioning piston 40 of the tensioning element 4 are shifted against the action of their return springs 60', 43, first of all the control edge 61 of the differential piston 60 being shifted. but,
The connection between the chamber 59 of the control valve device 5 and the pressure channel 62 is interrupted, and also the connections 71, 42 from the pressure channel 62 to the timing element 3 via the control device 5 are cut off. Control valve device 5
When a predetermined pressure height defined by the spring 43 of the timing element 3 and the spring 38 of the timing element 3 is exceeded, the tensioning piston 40 is shifted, with the tensioning piston reaching the first position of its movement course.
At part a' of the timing member 3, the fuel is passed through the passage 42.
as a result of which the piston spool 30 is shifted against the force of the spring 38 towards the stop 39, with the spring 38 being compressed (movement sequence b'). In the next part a'' of the movement sequence, the tensioning piston 40 engages the extension 5 of the valve spool 50.
8, the outflow valve 64 and the tensioning piston 40 shift the valve spool 50, so that this valve spool with its control edge 55 releases pressure-free air from the pressure chamber of the piston part 31 of the timing member 3. connection to the oil leakage passage 65;
A connection is established from the pressure line 47 to the pre-injection piston 21 via channels 53, 54. Due to this opening control, the pre-injection piston 21 pumps the pre-injection amount into the pressure chamber 19 under increased pressure, so that the valve needle 11 is lifted from the seat 13 (motion course h'), and at this time the pre-injection quantity is injected from the nozzle body 12 and, at the same time, due to the relief of the piston part 31 of the piston spool 30, the spring 38 moves the piston spool 30 into its starting position, i.e. the piston spool 30 interrupts the connection between the pressure conduit 47 and the injection nozzle 1. From the starting position where the
). The pre-injection amount, which is set small by the pressing surface and stroke of the pre-injection piston 21, is pumped and injected within an extremely short period of time. During the elapse of this time and during the subsequent predetermined time, the elapsed time ΔSB of the timer 3
elapses, and this elapsed time depends on the mass of the piston spool 30 and the spring 3 that loads the piston spool 30.
8 and the piston spool movement distance up to the opening control of the inlet 36 and outlet 37 by the control edges 34, 35. After this time lapse ΔSB, which is completely independent of the delivery pressure of the injection pump and the state of the internal combustion engine, the main injection starts when the timing element 3 is opened. The duration of this main injection is determined by the injection quantity pumped by the injection pump. In this case, the valve needle 11 performs a movement course h''. When the output pressure p falls to the specified pressure again at the end of discharge of the injection pump, after the pressure valve 6 is opened by the return spring 60', the springs 43, 57, 24 move the differential piston 60, the valve spool 50, and the tension piston 40. and the pre-injection piston 21 are returned to the starting position shown in FIG. 1, with pressure compensation taking place. In order to fill the chamber in front of the tensioning piston 40 and to tension the timer member 3 and to quickly unload the piston member and return it, FIG.
As shown in FIG.
1 is placed. This connecting channel can be omitted if the pressure pump delivering the injection quantity has a pressure relief capacity. Such a pressure relief capacity can be obtained by connecting a constant volume relief valve, which is known per se, to the outlet of the high-pressure injection pump, ie pressure line 47.
This is done by placing it at the entrance of the The tension element 4 can also be omitted if, instead of such a constant volume relief valve, a constant pressure valve, also known per se, is arranged, which maintains a defined level pressure in the pressure line 47 after the pressure step. The function of the tensioning piston 40 is produced by level pressure.

In addition, the control valve device 5, the tension member 4, and the pressure valve 6 can be combined structurally, and in this case, the control spool 50, the tension piston 40, and the differential piston 60 are arranged as shown in FIG. and constructed as a unit, as in the embodiment shown in FIG. This figure 4
and in the embodiment shown in FIG. 5, the construction, mutual arrangement and function of the injection nozzle 1, the pre-injection device 2 and the timing member 3 are similar to the above-described embodiment shown in FIGS. 1 to 3. can be,
Therefore, in the following, the same reference numerals will be used for the same members. Instead of the pressure valve 6, the tensioning piston 4 and the control valve 5, a control valve arrangement 80 is arranged in the embodiment of FIGS. It has only one control spool 81 with a first annular groove 82 with two control edges 84 , 85 and a second annular groove 83 with a control edge 86 for controlling the pre-injector 2 . There is. One end face 87 of the piston-shaped control spool is loaded by the pump pressure or output pressure via the supply channel 45, and the other end face is loaded by a return spring 88 in a depressurized chamber 89.

During the pause phase between the two discharge phases, pressure conduit 47, pressure passage 53 and passage 46 are
A level pressure of approximately 15-20 bar is maintained by a constant pressure valve 91 arranged at the outlet of the injection pump 90. The constant pressure valve 91 has a check valve 92 and a return flow valve 93, which allow the level pressure in the pressure conduit 47 to be constant regardless of the load and rotation speed of the internal combustion engine being operated. will be maintained. In the rest phase, this level pressure is transferred via the control valve arrangement 80, which occupies one switching position.
Acting on the piston spool 30 of the timing member 3, the spool section 32 of the piston spool interrupts the connection from the inlet 36 to the outlet 37 (FIG. 4), and in this switching position the control spool 81 of the control valve arrangement 80 , the connection from the pressure passage 53 to the passage 54 leading to the pre-injection device 2 is cut off.

At the beginning of the discharge phase of the injection pump 90, when the pressure builds up in the pressure conduit 47, the pressure acting on the end face 87 causes the control spool 84 to be shifted into its other starting position. In this case, the control lip 81 first interrupts the connection from the pressure channel 53 via the channel 42 to the piston spool 30 of the timing element 3 . At the same time, the control edge 86 controls the opening of the connection from the pressure passage 53 to the pre-injection passage 54, and the control edge 85 controls the opening of the connection from the pressure passage 53 to the pre-injection passage 54.
The connection from the pressure chamber of the piston portion 31 to the pressureless oil leakage passage 65 is controlled to be opened. By this opening control, the pre-injection piston 21 pumps the pre-injection amount, and the piston portion 31
The release of pressure causes the spring 38 to shift the piston spool 30 from its starting position to the open control position. As a result, as described in the first embodiment, the main injection is delayed by a predetermined period of time after the pre-injection. At the end of delivery of the injection pump, when the pressure in the pressure conduit 47 drops, the return springs 24, 88 move the front injection piston 2
1 and the control spool 81 to their starting position, so that the piston spool 30 of the timing member is tensioned again by the control lip 84 which controls the opening by means of the level pressure.

The embodiment described above is illustrated in detail in FIG. 5, in which, as in the first embodiment, the injection nozzle part is omitted. Control valve device 80 and timing member 3
is mounted within module 95. Moreover, since this embodiment has the same structure as the first embodiment,
Identical parts are designated by the same reference numerals. The connection holes are shown partially in section in the drawing for clarity.

In the third embodiment (FIGS. 6 and 7), which has a simpler structure than the two embodiments described above, a pre-injection device 2 is further integrated into the control valve device 100. As a result, the injection nozzle 1' can be used particularly as shown in FIG.
An injection nozzle without a pre-injection device is used, as shown in . The injection nozzle 1' is otherwise constructed as shown in FIG. 2 and will not be described further here. Time limit member 3
are assigned in a similar manner to the injection nozzle 1' and the control valve arrangement 100 and have similar functions.

The control valve arrangement 100 has two valve cones 102, 103 located opposite each other in a casing 104.
The valve member 101 has a valve member 101 with a valve seat 105, 106 arranged in a casing 104, respectively.
Collaborate with. Valve cone 102 together with valve seat 105 forms an inlet valve, and valve cone 103 together with valve seat 106 forms an outlet valve. Valve cones 102, 103, which are rigidly connected to each other by a shaft 107, are connected to chambers 108, 109.
The shaft 107 is arranged in an intermediate chamber 110 which is separated from the chambers 108, 109 by valve seats 105, 106. valve cone 1
03 against the valve seat 106 is arranged and is depressurized via a passage 112.
On the side 09, an attachment part 121 for holding a front injection piston 120 is connected to the valve member 101. The front injection piston 120 has entered the cylinder 122,
This cylinder is connected via a channel 23 to a supply channel 25 leading to the pressure chamber 19 of the injection valve 1'. A channel 45 which is connected to a pressure line 47 opens into a chamber 108 which is located opposite the depressurized chamber 109 and which is arranged on the pump side. The intermediate chamber 110 is connected to the control pressure chamber of the timing member 3 via a passage 42 .

In the rest phase between the two delivery phases of an injection pump equipped with a constant pressure valve as in the second embodiment, a predetermined level pressure is maintained in the pressure line 47, so that the control valve arrangement 100 inlet valve 102,10
5, the piston spool 30 of the timing member 3 is kept in its starting position against the action of the spring 38 (FIG. 6).
. At this level pressure, the inlet valve 10 of the control valve arrangement 100
2,105 in the open state, and the outlet valve 103,10
6 in the closed state, the return spring 111 loads the valve member 101 in such a way that the force of this return spring is
is dimensioned to overcome the opposing forces produced by the level pressure on the pressure acting surface of the pressure. In this case, the pre-injection piston 120 also occupies its starting position.

When the pressure in the pressure conduit 47 increases at the beginning of the discharge phase of the injection pump, the force exerted by the pressure on the valve member 101 is reduced by the return spring 111.
, which causes the valve member 101 to shift, with the inlet valves 102, 105 closing and the outlet valves 103, 106 opening. As a result, the timer member 3
The piston spool 30 is depressurized and at the same time the pre-injection quantity is pumped and injected through the injection nozzle 1'. After the vibration time has elapsed, the timing member 3 controls the opening of the main injection as in the above embodiment.

In the embodiment shown in principle in FIG. 6 and in detail in FIG. , the connecting holes are arranged in different planes in this module, and in this case the passage connecting the control chamber of the piston spool 30 with the intermediate chamber 110 of the control valve arrangement 100 is Indicated by a dashed line. Base module 1
A bushing 115 for guiding the piston spool 30 and a bushing 116 with valve seats 102, 103 for the valve member 101 are inserted into the bore of the casing 14. Valve member 101 consists of multiple parts.

In the injection device according to the invention, which injects a pre-injection amount for a specified time before injecting the main injection amount, the hydraulically controlled timing member is of great significance. This timer is simple in its construction and has a constant elapsed time related to the mass of its piston spool and the force of the spring. The control of this timing element is then possible by means of various control valve arrangements which also control the pre-injection.

[0027] From the trigger of the time switch or time member to the opening control of the through hole of its valve body, for example in one of the embodiments described above, from the start of pre-injection to the start of main injection, it takes 0.8 ms. In the example in which time has elapsed and the switching distance of the piston spool is 3.6 mm, the spring constant c = 2.6 N/mm, based on the law of damped harmonic oscillations.
and the residual preload of the spring in the open control position is 2.5, the piston spool 30
The mass of m is 1.8 g, taking into account the buffering that occurs in this case.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the principle of a first embodiment of a fuel injection device according to the present invention.

FIG. 2 is a vertical sectional view specifically showing a first embodiment of the fuel injection device according to the present invention.

FIG. 3 is a diagram showing a functional diagram of a first embodiment of the fuel injection device according to the present invention.

FIG. 4 is a diagram showing the principle of a second embodiment of the fuel injection device according to the present invention.

FIG. 5 is a longitudinal sectional view specifically showing a second embodiment of the fuel injection device according to the present invention.

FIG. 6 is a diagram showing the principle of a third embodiment of the fuel injection device according to the present invention.

FIG. 7 is a vertical sectional view specifically showing a third embodiment of the fuel injection device according to the present invention.

[Explanation of symbols]

1 injection nozzle, 2 front injection device, 3
time member, 4 tension member, 5 control valve device,
6 pressure valve, 7,8 module, 9
distribution head, 11 valve needle, 12
Nozzle body, 13 valve seat, 14 closing spring, 15 cap nut, 16 intermediate disk,
17 nozzle holder, 18 pressure shoulder, 19 pressure chamber, 21 front injection piston, 22 cylinder hole, 23 passage, 24 return spring, 3
0, piston spool, 31 piston part, 32 valve/spool part, 33 control groove,
34, 35 control edge, 36 inlet, 37
outlet, 38 spring, 39 stopper,
40 tension piston, 42 passage, 43 spring, 44 control edge, 45 supply passage,
46 passageway, 47 pressure conduit, 50 valve spool, 51 control lip, 52 annular groove,
53, 54 passage, 55 control edge, 5
6 connection passage, 57 return spring, 58
Additional part, 59 chamber, 60 differential piston,
61 control edge, 61' return spring, 62
passage, 63 passage, 64 pressure valve;
65, 66, 67, 68, 69 oil leakage passage, 80
Control valve device, 81 Control spool, 82, 83
Annular groove, 84, 85, 86 Control edge, 87
end face, 88 return spring, 89 chamber, 91
groove, 95 module, 100 control valve device, 101 valve member, 102,103
Valve cone, 104 Casing, 105, 106
Valve seat, 107 Shaft, 108,109
chamber, 111 return spring, 114 module, 115, 116 bush, 120 front injection piston

Claims (5)

[Claims] 1. A timed switching valve for a pressure medium system, in which a valve member is provided which is shiftable in a casing with a connection for a pressure source and a connection for a consumer. , of the type in which the valve member is shiftable by a fluid regulating pressure into a first switching position and by a spring into a second switching position spaced a predetermined distance from the first switching position. in which the valve member (30) has a defined mass and the spring (38) acting on the valve member has a defined force-distance characteristic line, and the valve member has masses and masses that are matched to each other. After the release control of the regulating pressure based on the force under the action of the spring, the switching position is moved from one switching position to the other after a certain elapsed time based on the law of damped harmonic oscillations. A timed switching valve for a pressure medium system, characterized in that: 2. The valve member (30) is connected to the control device (5; 80
2. The timed switching valve according to claim 1, wherein the valve is operable by a sudden release of the regulating pressure by means of a spring (38). 3. The valve member (30) blocks the through hole in the first switching position, in which the valve member is held against the action of the spring (38) by the regulating pressure, and the valve member is free of pressure. 3. A timed switching valve as claimed in claim 1, characterized in that the opening of the through-bore is controlled in the second switching position, which is maintained by the preload of the spring (38). Claim 4: The valve member is a piston spool (30).
4. The timed switching valve according to claim 1, further comprising: a control lip (34, 35); and a defined mass. 5. A fuel injection device equipped with a fuel injection pump that performs timing-controlled discharge in order to perform control such as injecting a main injection amount after a predetermined time after injecting a pre-injection amount into a combustion chamber. Claims 1 to 4 used in
The time-limited switching valve described in any one of the following items.