DE3247769A1 - Hydraulically controlled and cooled injection unit for internal combustion engines - Google Patents

Abstract

This relates to an injection unit (200) of the cam-driven type with open nozzle, which has a highly compact body (202) with a minimal number of internal flow passages and a two-part injection piston (222), so that there is a pressure-time calibration of fuel, a scavenging flow, a hydraulic control of the timing of the injection, a shut-off of the fuel flow and an abrupt shut-off of the fuel injection without high peak loads and wear compensation for retarded or advanced injection time. At the same time the injection body (202) has a form such that an admission passage (216) and a discharge passage (240) separate and sealed off from the former, are formed between the outer surface of the body (202) and the inner surface of a recess (203) for accommodation of the injection unit (200). This design allows a very simple pattern of passages to be provided in the body (202), that is mainly radial passages. <IMAGE>

Description

"Hydraulically controlled and cooled injection unit

for internal combustion engines " The invention relates to an injection unit, especially for internal combustion engines.

Internal combustion engine designers have increasingly recognized that significantly improved fuel supply systems are needed in order to increase To reach stages in exhaust gas cleaning and to reduce fuel consumption. Direct fuel injection appears among the known possibilities as one of the best candidates to achieve better function, however, have so far the high initial equipment costs prevent their general use. the previously explained situation is exacerbated by the fact that only higher developed and therefore normally more expensive direct injection systems are capable of the to satisfy the increasingly higher functional goals of the engine manufacturers.

So far, attempts have tended to provide one with a low one Cost-related injection system to rely on injection systems of the distribution type focus on having a single central high pressure pump and distribution valve for metering and timing the flow of fuel from the pump to each has a plurality of injection nozzles (cf.

U.S. Patent 3,557,765). Although these systems are simple in structure they generally suffer from problems related to the separation of the injectors from are peculiar to the central pump. In contrast, avoid systems with injection units the problems peculiar to distribution-type systems by removing each individual cylinder of an internal combustion engine is provided with its own cam driven pump (See U.S. Patent 3,544,008). Nevertheless have the functional advantages Injection unit systems generally do not suffer from the disadvantages of higher costs predominated, apart from heavy-duty engines with compression ignition.

Although injection units are not usually available in with low cost associated fuel systems have been many over the years Improvements have been proposed with the aim of keeping costs at bay lower the peculiar advantages. For example, the applicant has a. Injection unit developed with an open nozzle (cf.

U.S. Patents 3,351,288 and 3,544,008), which is characterized by that only a single feed line (collecting line) for the supply of all injection units with fuel is needed. Since the fuel is fed into each injection unit through a separate feed opening is measured, one can see from the opening time of the feed opening and run out of pressure in the manifold to be injected during each To control injection stroke metered amount of fuel. Further savings will be made achieved in that an open nozzle injection unit does not have a pressure relief valve needed at the injection port.

Even if injection systems with open nozzles are cost-effective are effective, various precautionary measures are to be taken with these Pressure / time systems ensure that the combustion gases and pressure peaks are not can get into the fuel supply system.

These precautions can include the use of a check valve upstream of the feed opening of the injection unit so as to include combustion gases to prevent entry into the fuel supply system (so-called backflow; It is also sometimes common to have a purge flow of fuel through the injection unit to be provided so that gases that could have got into the fuel supply line, be removed again. Such a flushing flow also serves the purpose that To cool the injection unit and would therefore be useful, even if it is not necessary would be to remove backflow gases. Ultimately, then, it is an economically acceptable one Injection unit even if it complies with all principles of simplification the Structure is designed, usually an axial labyrinth and radial holes. As far as the term “axially” is used in this application it means the longitudinal axis of the injection unit, while "radial" means the direction called perpendicular to the longitudinal axis of the injection unit. Otherwise is the body the lens injection unit, the injection body, usually from a plurality of Manufactured individual parts that require very tight manufacturing tolerances.

The problem of ever more complicated construction is still to come enlarged, if desired, a cam driven injection unit with the Ability to understand fuel injection during each injection cycle to bring it forward or to delay it (see U.S. Patents 4,249,499 and 3,951,117). The known examples of pressure / time injection units discussed above work depending on a hydraulic, variable pressure signal for the control the course of the injection over time. In both cases there are injection units known in which a hydraulic link of variable length in the mechanical actuation linkage between the engine camshaft and the injection piston, which moves back and forth to inject fuel through the injector, is used. In one case (see FIGS. 16 and 17 of US Pat. No. 3,951,117) a cam driven, open nozzle injection unit of the pressure / time type is known, in which the injection piston is divided into two areas, one in between to form lying time control chamber. During the calibration time of each injection cycle fuel is metered into the timing chamber in an amount appropriate to the pressure of the fuel supplied. A variety of other examples of cam driven Injection units with hydraulically variable injection times are known (cf. GB-PS 1,080,311, US-PS 2,863,438, 3,847,510, 3,859,973). A hydraulic control the injection time is also known in other types of injection systems (see US Pat 3 083 912), in which a reciprocating piston with a hydraulic pressure is applied against the bias of a helical spring, so as to reduce the injection time respectively.

to control the timing of the injection. In addition to the pure hydraulic controls are also mechanical controls and mechanical / hydraulic hybrid controls for cam-driven injection units has been used to implement various timing controls (U.S. Patents 2,313 264, 2 997 994). Mechanical systems, however, have the disadvantage that they have the The overall size and cost of the injection system increase, from the possibility of mechanical Not to mention malfunctions. If other properties at an injection are required, such as the ability to fully control the flow of fuel turn off, then the structure of the corresponding injection unit or the like. usually even more complicated.

In a very simple cam-driven injection unit (cf. AU-PS 202 734) axial holes in the body have been eliminated by the fact that between the exterior of the body and the interior of the recess in which the body is located a flow path is formed. With this construction, an easily manufacturable radial bore can be provided in the body to serve as the feed line from the feed path around the body in the injection chamber of the injection unit. As soon as the Injection unit is able to allow a fuel flush flow (cf. US-PS 3,351,288) increases the number of necessary flow passages and the The overall size of the injection unit must increase in order to be able to accommodate the passages. Multi-function injection units of this type usually require at least one one or more axial passages.

Such passages are and are more difficult and expensive to manufacture not even to be avoided with such injection units where the inlet and the drain lines to and from the injection unit completely within the Cylinder head are arranged (see. US Pat. No. 3,351,288).

In summary, it should be noted that injection units that Being able to adhere to rigorous functional specifications, which has so far inevitably been highly complex and expensive in manufacture and / or relatively large.

The invention is based on the prior art explained above now the task is based, while avoiding the disadvantages of the previously explained Stand to specify an injection unit of a considerably simplified design for the technology, which can nonetheless perform a variety of functions, including one Time control of the injection, which was previously only possible with more complex designs was.

The injection unit according to the invention, in which the previously shown The problem is solved, is characterized by an injection body with a central Bore and an injection opening connected to the central bore, an injection plunger in the central bore between an innermost position with closed injection opening and an outermost position with in the centric Bore between the inner end of the injection piston and the injection port formed injection chamber is movable back and forth, the injection piston a having inner piston part and an outer piston part in the central Bore can be moved back and forth independently of one another, thereby creating a timing chamber is formed with variable size between the piston parts, also by a Inlet connection to form an inlet path for pressurized liquid from a source into the injection chamber, further through a timing connection to form an inlet path for pressurized liquid from a source for timing fluid into the timing chamber to optionally form a hydraulic connection between said piston parts and by a biasing element to bias the inner and outer piston parts towards each other, this Biasing element at least one between the inner and outer piston parts extending spring for applying a moving the two piston parts towards each other Strength as 5 points.

Further advantageous embodiments of the teaching of the invention result from the subordinate claims.

The advantage achieved with the injection unit according to the invention is first of all to see that a highly compact injection unit is given, the consists of multi-function components including an injector body with a minimum number of liquid passages and including one two-part injection plunger that forms a timing chamber between two Parts or areas of the injection piston is designed, -a particular advantage of the invention is that the injection unit is simplified in construction has a hydraulic timing chamber, which by an uncomplicated distribution of flow passages and a timing port through the injection plunger is opened and closed, is supplied with a timing fluid. the Timing chamber is formed by the inner and outer piston parts, which by means of a spring arranged between them are biased towards one another. Will the A timing fluid is supplied to the timer chamber at a pressure sufficient to to overcome the spring force, the piston parts are removed from each other, so that a hydraulic connection is established between the parts and the injection time is brought forward.

Another advantage of the injection unit according to the invention lies in avoiding the disadvantages of the prior art, as explained above have been, in that a compact injection unit with variable Hydraulic timing is created in which the flow path over the liquid (Fuel) the timing chamber runs in or out of this, at the same time is used as a flow path for a cooling flow through the injection unit.

Furthermore, it is advantageous that the compact injection unit according to the invention comprises a two-part injection piston having a hydraulic timing chamber more variable Forms length between the piston parts and has an injection body, the flow passages in a simplified arrangement including a single flow path for the timing fluid and the cooling fluid.

It is particularly useful that in the invention a two-part, reciprocating injection plunger is provided to form a timing chamber variable length formed between the inner and the outer piston part is and in which one of the piston parts has a passage for the inflow of liquid has in the timing chamber and a check valve. This check valve is in this case arranged in the passage to firstly allow the inflow of timing fluid to allow into the timing chamber once the piston is in its extreme position has arrived to, secondly, the timing fluid during the injection phase to include in the timing chamber and, thirdly, cooling liquid through the Timing chamber to flow once the piston is in its innermost position stands.

Another advantage is a previously explained two-part Injection piston in a preloading element, with the help of which the piston parts move towards one another be pressed, with a force that depends on the distance between the piston parts is stepped, so that fluid of the chamber of variable length can be supplied or drained from this. This will produce the following results Achieved: time control, wear compensation, abrupt interruption of the fuel injection and completely interrupting the flow of fuel during an engine braking phase. These functions are achieved by the axial position of the piston parts and by the The pressure of the liquid supplied to the piston is controlled, the liquid being the Piston through a passage and a check valve in one of the two injection pistons is fed.

Further disadvantages of the prior art discussed above become avoided by the fact that the two-part, reciprocating injection piston in a delay function, an advance function and a fuel cut-off function can be moved simply by changing the pressure of the liquid that the is fed to the chamber formed between the two piston parts.

Further advantages are achieved within the scope of the invention in that an injection unit is given, the flow passages arranged in a simplified manner has, through which a hydraulic timing, a purge flow and a full Shutting off the fuel flow is achieved. These functions are related achieved with a two-part, reciprocating piston, in which the piston parts are biased towards one another by at least one tension spring, the tension spring is attached to one of the piston parts by a lost motion connection. Such Backlash connection allows a given free travel (backlash) between the piston parts, before the tension spring comes into operation and pulls the piston parts towards one another.

The invention also realizes a highly compact injection unit, with the measuring, flushing and time control functions by means of an extremely simple Injection body can be realized, which is designed so that from each other isolated inlet, outlet and flow paths for the timing fluid between its outer surface and the inner surface of a recess for receiving the Injection unit are formed. This injection unit comprises a two-part Injection piston, the parts of which are oppositely wound by means of a pair Spring elements are biased towards one another. This creates a timing chamber created with changeable size. The biasing elements comprise a first spring, the ends of which are integrated into the piston parts, as well as a second, stronger one Spring that is directly integrated with one piston part and that is attached to the other piston part is connected by means of a lost motion connection. This can be the most effective The length of the injection piston is adjusted by the pressure of the timing fluid in order to advance or delay the injection from cycle to cycle or to keep the inner piston part in its innermost position in order to do so to cause complete shutdown of the fuel flow from the injector.

Another advantage of the invention is the fact that a very compact injection unit is formed, the one between an inner and a outer piston part formed hydraulic timing chamber has in communication with a pair of tension springs, the first spring being connected to one of the piston parts by means of a first lost motion is connected and the second spring by means of a second, in turn connected to the first lost motion connection associated with it. In this way, there is one through the first lost motion connection minimum hydraulic connection is always given, at the end of each injection cycle of the injection piston collapses. There is also a hydraulic connection greater length, which is formed by the second lost motion connection, wherein through this when the pressure in the timing fluid that the injection unit increases is supplied, the injection time is brought forward, and by the one still further increasing the pressure in the timing fluid of the inner piston part can be held in its innermost position during several of one another subsequent injection cycles in order to shut off the fuel flow completely.

In the following, the invention is illustrated by means of only exemplary embodiments Drawing explained in more detail, with further advantages and features of the invention Injection unit by itself.

It shows Fig. 1 in a cross section, partially broken away Embodiment of the invention, in which the injection unit has both a variable Time control as well as a sudden shutdown of the fuel flow at the end allows any injection activity, Fig. 2a cross-sectional views of the injection unit according to Fig. 1 in to 2f different working phases, Fig. 3 in cross section another Embodiment of the invention in which a wear compensation and a abrupt termination of the injection during a mode of operation with timed Delay in the construction of the injection unit according to FIG. 1 has been added are, Fig. 3a is a diagram showing how the embodiment according to Fig. 3 is able to achieve a more sudden end of the injection, Fig. 4 shows a further embodiment of the invention, in which both a variable Time control as well as switching off the fuel is possible, whereby the time control and drainage passages axially interchanged compared to the constructions according to FIGS. 1 and 3, FIG. 5 shows a further exemplary embodiment in a split cross-sectional illustration an injection unit according to the invention, in which the injection piston parts by a pair of compression springs are biased towards one another, Fig. 6a is a split cross-sectional view the injection unit according to FIG. 5, in which the injection piston under two different Conditions is shown, Fig. 6b is a split cross-sectional view of a further embodiment of an injection unit according to the invention, in which the injection piston parts are biased towards one another by a pair of compression springs 6c is a split cross-sectional view of the injection unit according to FIG. 6b, in which the injection piston is shown under two different conditions is, Fig. 7 in a cross-sectional view of a further embodiment of the Invention, similar to the embodiments of FIGS. 5 and 6, in which a tension spring instead of the compression spring is used and a single lost motion connection between the inner piston part and the tension spring is provided, and Fig. 8 a graphical representation of the size of the piston distance (connection) as a function the pressure of the timing fluid.

In the context of this application, the terms "inwardly and "outward" the directions toward and away from the point of the fuel actually injected into the combustion chamber of an engine by the injection unit will. To further facilitate understanding of the invention, see the end of this particular part of the description is a list of the elements identified by reference numerals are indicated in the figures.

1 shows a pressure / time injection unit with an open nozzle according to FIG the invention. In particular, FIG. 1 shows an injection unit 200 with an injection body 202, which is in a recess 203 in the only partially shown head 205 of a Internal combustion engine is used. The body 202 is actually made up of two sections composed, namely an outer region or shaft 202a and an inner Area or socket 202b that are seamlessly connected to one another. How yourself from Fig. 1, the body 202 is in the recess 203 by means of mutually corresponding Thread 202c is held and can be inserted into its seat by a tool is inserted into the hexagonal socket 203a at the top of the body 202. Of the The fuel supply and the fuel drain for the injection unit 200 take place through Channels that are completely arranged in the head 205. In detail it is is an inlet channel 10 (sometimes also referred to as a collecting line), which is designed so that fuel can flow to the inlet unit 200, and around an outlet channel 2 (which is designed in such a way that the injection unit 200 released fuel is fed back into the fuel supply system. Both channels 204 and 206 can be designed so that they each with a A plurality of injection units in the head 205 cooperate, so that all external Flow channels to and from the injection units can be dispensed with. Additionally to the inlet channel 204 and the outlet channel 206, which via the inlet opening 208 and the drain opening 210 are in communication with the recess 203 is an additional one Timing channel 212 formed in head 205, between the inlet and drain channels 204, 206 and over which a timing fluid each of the injection units can be fed into the head 205. This timing channel 212 is in communication with the recess 203 via a timing opening 214.

The outer surface of the body 202 is shaped so that three annular Screwing laps 236, 234 and 238 are provided, which are in such an axial Distance from each other so that they are connected to the channels 204, 212 and

206 via the inlet opening 208, time control opening 214, or drain opening 210 related. In this way, between the inlet opening 208 and an inlet path 216 is formed on the outer surface of the body 202 that forms the recess 236. Similarly, a drain path 240 is also formed between the drain opening 210 and the outer surface of the body 202 forming the second recess 238. A The flow path of the timing fluid 232 is formed by the recess 234, which is arranged between the inlet path 216 and the outlet path 240. Around the inflow path Isolating 216 from the timing fluid flow path 232 is circumferential Seal 241 is arranged between the body 202 and the inner surface of the recess 203. From Fig. 1 it is evident that the circumferential seal 241 within a first small annular groove 241a between the two indentations 234, 236 is. A similar circumferential seal 243 is in a second small annular groove 243a arranged, which is arranged between the recesses 234 and 238, so as to Loss of fuel from the timing fluid flow path 232 to the drain path 240 to prevent. The inner end of the inlet path 216- is by means of a washer-like Seal 245 sealed between a radially inwardly directed lip 247 in the recess 203 and a radially outwardly directed outer surface 249 is held on the body 202 compressible. An outer circumferential seal 253 is in a small annular groove 253a on the body 202 (as shown in Fig. 1) held above the recess 238 and serves as a seal for the drainage path 240 against fuel losses to the outside. Preferably the drainage channel should be outside the inlet and the time control channel be arranged so as to prevent that under Pressurized fuel from the recess receiving the injection unit 200 203 exits.

The body 202 has a central bore 228 which is coaxial is arranged to the longitudinal axis of the body 202. At the inner (lower) end of the body 202 one or more small injection openings 251 are provided so that a connection path between the central bore 228 and a combustion chamber results. Fuel is fed into the combustion chamber via the injection openings 251 in controlled synchronism supplied with the action of the corresponding piston (not shown). In an injection piston 222 is arranged in the central bore 228 and is designed in such a way that that it can be moved back and forth as a function of a cam drive 270. The cam drive 270 has a specially profiled cam disk 271, which with the usual, Not shown here is connected to the engine camshaft. The cam drive 270 further comprises a plunger 272, a rocker arm 273 and a connection 274. Da the cam disk 271 in a very specific relationship to the reciprocating movement of the piston rotates in the cylinder, the precise shaping of the profile of the Cam 271 the movement of the injection piston 222 in relation to the movement of the piston can be controlled very precisely. The cam drive 270 can be a stepped Have cam profile, so that the injection piston during an uninterrupted Part of each injection cycle just prior to injection in an inboard position is held in which the feed opening of the injection unit is closed, in order to prevent the backflow of combustion gases. A cam driven one Mechanism of this type is described here in a corresponding parallel application Applicant entitled "Injection system with a backflow of combustion gases preventive cam drive ". The full disclosure of this The application becomes the subject matter of the disclosure content of the present application made.

It is of particular importance that the injection piston 222 between an innermost position in which the injection openings 251 by means of the front End 223 of the injection plunger 222 are closed, and an extreme position, in which an injection chamber in the central bore 228 between the front End 223 of the injection piston 222 and the injection openings 251 is formed, towards and is movable forward. Since this invention relates to injection units with refers to open nozzles, the injection openings 351 then remain opposite the Combustion chamber open when injection piston 222 moves from its innermost position is moved outside. Injection units of this type have their own cost advantage compared to more complex injection units with closed nozzles, where a Pressure-dependent triggered needle valve is provided, with the help of which the injection opening is kept closed outside of the pure injection process. The injection piston 222 is continuously spring-loaded in the direction of its outermost position, namely through a feedback element 275 with a collar-like coupling part 276, which is attached to his lower end 277 is connected to the upper end of the injection piston 222. Next the uppermost part of the coupling part 276 is a radially outwardly directed Flange 278 is provided. A pretty hard compression spring 279 is between the upper one End of the body 202 and the flange 278 arranged so as to the injection plunger 222 to be constantly burdened to the outside.

To control the movement of the The injection unit 200 has the amount of fuel injected in the injection piston 222 the ability to inject fuel according to a "pressure / time function" during which fuel into the injection chamber before each injection cycle through a filling and feed opening 219 is measured. This feed opening 219 is very precisely dimensioned to such a change in the amount of fuel injected during a given Time by changing the pressure in the supply line (collecting line) enable. As a result, the actually measured amount of fuel is a function the supply pressure and the total measuring time during which fuel is through the feed opening 219 flows. This principle applies to the injection unit in question 200 realized in that an inlet connection 217 for specifying a flow path for fuel under pressure from the feed path 216 in the area of the central bore 228, which represents the injection chamber, is given. The inlet connection 217 comprises an inlet 218 extending from the outer surface of the body 202 to the inner surface of the central bore 228 along a radial straight line perpendicular to the Longitudinal axis of the body 202 extends.

A drawn-in point of the inlet passage 218 forms the feed opening 21 has the precisely adjusted hydraulic properties in order to achieve the desired To achieve pressure / time calibration characteristics that-has been addressed previously.

The length of time that the injection plunger 222 is in either the innermost or in the outermost position depends partly on the profile the cam disk 271. As can be seen from Fig. 1, a preferred embodiment includes of the cam disk 271 a region 280 over more than 1800 of the complete circumference. This area 280 causes the injection piston 222 to assume its innermost position. A second area 281 of nearly 900 of the full circumference causes this Injection piston 222 to assume its extreme position.

The first area 280 and the second area 281 are of one third area 282, the task of which is to move the injection plunger 222 into to move a position in which this blocks the inlet passage 218, in so that the injection piston 222 is moved sufficiently far inward to the To close feed opening 219 without the injection piston 222 about far enough would be moved to actually commence fuel injection. The third Area 282 is shaped so that the feed opening 219 closes during the time in which the internal cylinder pressure rises to such a high value that a significant Backflow of combustion gases into the fuel supply line is fundamental is possible. A fourth, particularly narrow area 283 of the cam disk 271 represents approximately that part of the cam disk 271, with the help of which the actual injection is carried out. The exact point of the start of injection is only approximately determined, as it depends in part on the amount of fuel that is in the injection chamber during is measured in every measure.

The first area 280 comes at the lower end of the plunger 272 at one Point to the facility, which is immediately before the start of the work cycle of the engine piston lies. This system on the tappet 272 remains during the exhaust stroke and during the period one Get part of the intake stroke. The second area 281 approximately encompasses the plunger 272 halfway through the intake stroke of the piston and ends this influencing approximately halfway through the compression stroke. The second area 281 defines the time during which is metered into the injection chamber in each injection stroke. Of the third area 282 causes the injection piston 222 to move so far in the direction of it to move innermost position that the feed opening 219 is closed, however injection does not start yet. This third area 282 is arranged so that it detects the plunger 272 about halfway through the compression stroke and this Effect is maintained until the start of the injection. The fourth, small area 283 is the area of the cam disk 271 through which the injection piston 222 extends its outermost position is moved to its innermost position, so that the in The amount of fuel metered into the injection chamber through the injection openings 251 is injected into the combustion chamber of the engine.

A slight increase 284 (exaggerated in Fig. 1) is provided on the cam disk. 271 near the end of the fourth area 283, in order to load the injection piston 222 abruptly at the end of the injection process, so that the injection plunger 222 is pressed firmly against the injection socket 202b. This ability makes the injection plunger 222 very tightly attached to the injection socket 202b to be pressed ensures that the injection openings 251 closed suddenly and remain closed at the end of each injection period, including during the function of the illustrated embodiment according to FIG. 1 with a delayed Injection. A very important characteristic of the injection unit according to Fig. 1 is that the actual injection event versus motion the associated engine piston can be moved forward, only by the measure, to vary the pressure of a timing fluid passing through the timing channel 212 is supplied. Because all injection units have one and the same timing control channel can be a very simple control to change the injection time all injection units can be realized.

In order to ensure the previously explained adjustability in terms of time, the injection plunger 222 of each injection unit is divided into two parts, viz a inner piston part 224 and an outer piston part 226. The two parts are independent arranged from each other in the central bore 228 of the body 202, so one Form timing chamber 230 with variable size (volume). (The timing chamber 230 is shown in its fully collapsed position.) Timing fluid becomes the timing chamber 230 via the timing fluid flow path 232 fed.

Timing fluid flows through timing connection 242 in FIG the central bore 228, the timing connection 242 being a flow path for fuel from the timing fluid flow path 232 to the central Bore 228 forms. The timing connection 242 includes a timing passage 244, which extends from the outer surface of the body 202 to the inner surface of the centric Bore 228 along a straight radially extending path perpendicular to the longitudinal axis of the body 202 extends. The outer surface of the inner piston part 224 is shaped to that a flow controller 246 for controlling the flow of fuel and the flow the timing fluid in the injection unit is given. Includes in detail the flow control 246 has an annular groove 248, which is arranged in the axial direction is that it is in communication with timing passage 244 at all times. The flow control 246 also includes a transverse passage 250 in the interior the annular groove 248, which at its ends with the through the annular groove 248 in the central Hole 226 partitioned space is connected.

The outer end of the inner piston part 224 has a recess 252, at the bottom of which a ball check valve 254 is arranged, the one One-way flow from the transverse passage 250 into the recess 252 allows. From Fig. 1 it results that the recess 252 directly with the timing chamber 230 in connection stands and a flow of timing fluid through timing passage 244, the annular groove 248, the transverse passage 250, the check valve 254 and the recess 252 allowed. The flow control 246 on the inner piston portion 224 also includes one cylindrical widening 248a formed on the inner surface of the central bore 228 comes to abut in a sealing manner, around the of the annular groove 248 within the central Defined bore 228 Space from the injection chamber of the injection unit to separate. In Fig. 1 it is shown that the cylindrical widening 248a axially is arranged so that the feed opening 290 opens in the manner previously explained and can be closed.

For permanent pre-tensioning of the inner and outer piston parts 224, Pretensioning elements 256 are provided towards one another 226. The biasing element 256 comprises a first coil spring 258 which at each of its ends is integral with a the piston parts is connected, so that at all times at least a first predetermined Force is applied to bring the piston parts 224, 226 toward one another. One second coil spring 260 is arranged coaxially within first coil spring 258 and connected at one end to the inner piston part 224. At the other end is this second helical tension spring via a lost motion connection 262 with the outer piston part 226 connected.

In this way, a second one is predetermined by the second tension spring 258 Force applied to move the piston parts 224, 226 towards each other once the piston parts 224, 226 more than one predetermined by the lost motion connection 262 Spaced apart. As can be seen from Fig. 1, the lost motion connection is 262 in an inwardly opening recess 226a in the outer piston part 226 arranged. The lost motion connection 262 includes a pin 262a which extends transversely in the recess 226a approximately perpendicular to the longitudinal axis of the outer piston part 226 extends. The ends of the pin 262a are similarly on the corresponding one Area of the outer piston part 226 attached, for example by a press fit. An anchoring element is formed within the recess 226a by the pin 262a 262b held, which has an elongated opening 262c for receiving the pin 262a having. Obviously, the axial length of the opening 262c (elongated hole) defines the relative movability between the outer piston part 226 and the anchoring element 262b, as soon as the piston parts 224, 226 move from the position shown in FIG a position are moved in which the second coil spring 260 begins, a To exert force on the piston parts 224, 226 aimed at these piston parts 224, 226 towards each other. The axial length of the opening 262c thus defines the backlash that exists between the piston parts 224, 226, before the coil spring 260 comes into effect. The ends of coil spring 258 (tension spring) are connected to the inner and outer by means of helical threads 258a and 258b Piston part 224 or 226 'connected. The ends of the coil spring are similar 260 by means of threads 260a and 260b to the inner piston part 224 and the anchoring element, respectively 262b connected.

To prevent the piston parts 224, 226 from rotating relative to one another, the coil springs 258 and 260 are coiled in opposite directions Injection unit shown in Fig. 1 includes a drain connection 264 for formation a flow path for fuel from the central bore 228 to the drain path 240 and a leakage connection 265 to form a flow path for fuel, leaked out of the timing chamber 230 to the drain path 240. The leakage connection 265 includes an annular cavity 267 extending from the central bore 228 extends radially outward and a leak passage 269 extending from the annular Cavity 267 extends to drain path 240. The drain connection 264 includes the rest a drain passage 266, which is obliquely away from the central bore 228 and toward the outer surface of the annular recess 238. The connection point between the drain passage 266 and the central bore 228 occurs in the axial Direction at a point through the contact point between the piston parts 224, 226 with the inner piston part 224 in the innermost position, as shown in FIG. 1 shown, is defined. The innermost end of the outer piston part 226 faces radial passages 268 (grooves; shown in dashed lines). These passages 268 are arranged to provide a communication path for timing fluid, so that it can exit the timing chamber 230 as soon as the inner piston part 224 is in its innermost position. The drain passage 266 includes a restriction 266a, which is used to control the flow rate, with the liquid from the timing chamber 230 flows off. This is explained in more detail below.

The mode of operation of the injection unit according to FIG. 1 will now be based on 2a to 2f explained in more detail. In Fig. 2a has the not shown Cam drive moves the injection plunger 222 to its innermost position, in which each fuel gauge has been turned off, but the timing fluid through the injection unit flows to carry out one of the normal flushing functions. In the illustrated embodiment the flushing flow serves in particular to cool the injection unit. These Function occurs as soon as timing fluid, which can also be fuel, enters the timing passage 244, the annular groove 248, the transverse passage 250, the Check valve 254, recess 252 (not shown) and the radial passages 268 flows through and exits through the drain passage 266. Since the cam drive the keeps the outer piston part 226 in its innermost position, the timing chamber can 230 do not expand from their fully collapsed position. By arrows 270a, the flushing flow path (cooling path) is indicated.

Fig. 2b shows a phase of the operation of the injection unit, at which the injection piston 222 has been moved to its outermost position to the To open inlet passage 218 and to close the outlet passage 266 so that the Trapping of timing fluid in timing chamber 230 can begin. In 2b, both the timing and the calibration have just started. Accordingly very little fuel is measured into the injection chamber in this position been. As has been explained above, the calibration is carried out according to a pressure / time principle.

In the phase shown in Fig. 2c, timing fluid flows into the timing chamber 230 only when the timing fluid pressure is high enough, namely sufficient to overcome the preload that acts on the piston parts 224, 226 is exerted by the tension coil spring 258. Fig. 2c shows the effect of a such sufficiently high pressure of the timing fluid applied at the moment in which the injection plunger 222 makes its inward movement begins. At this moment the check valve 254 acts as a trap for the timing fluid in the timing chamber 230 so that a hydraulic connection between the inner and the outer piston part 224, 226 is realized. Unless the timing pressure has not been high enough, there is no enlargement of the timing chamber 230 takes place, as Fig. 2d shows. From this explanation results It is easy to know the instant of injection by enlarging the timing chamber 230 can be brought forward in cycles. As long as the pressure of the timing fluid in the timing chamber 230, the combined spring forces of the first and second Coil tension springs does not exceed 258 and 260, is the maximum value of the expansion the timing chamber 230 is limited by the backlash of the backlash connection 262. Although not intended for the preferred embodiments of the invention is, the advance of the injection time could be designed to be infinitely variable by applying the pressure / time principle to the time control as well. For example, the opening of the check valve 254 could be precisely dimensioned to the amount of liquid entering the timing chamber 230 as a function the pressure of the timing fluid and the dwell time of the injection unit to limit with respect to the phase shown in Fig. 2c. Alternatively it would be possible advancing the injection time from the exact pressure of the timing fluid alone and make it independent of the timing period.

FIG. 2e shows the injection unit with the injection piston 222 in FIG his innermost position. In order to change from the conditions according to FIG. 2c to the conditions To get to Fig. 2e, all fuel metered into the injection chamber will be pushed out through the injection ports 251, as shown by the arrows 272e is. All timing fluid that has been metered into timing chamber 230 is pushed out through the drain passage 266, like that by the arrows 274e is indicated. To this extent, the drainage passage 266 also forms a relief means for the timing fluid through which a timing fluid flow path is given from the timing chamber 230 to the drain path 240. In a corresponding way The drain passage-266 also acts as a relief passage for the timing fluid.

Under certain engine operating conditions, for example at Use of the engine brake, in which the engine is supposed to have a braking function, is often a complete shutdown of the fuel injection is desired. These functionality can be realized by drastically increasing the pressure of the timing fluid be an increase in pressure to a level at which the pressure in the timing chamber 230 exceeds the biasing force of the first and second tension coil springs 258 and 260, so that the inner piston part 224 remains in its innermost position while the outer piston part 226 reciprocates under the influence of the cam drive. Under these circumstances, timing fluid flows into the timing chamber 230 on as the inner piston portion 224 travels upward and becomes through the drain passage 266 as the injection plunger 222 moves downward.

As can now be summarized, the embodiment is one Injection unit, which is shown in Figs. 1 and 2, capable of a variety of injection functions that previously had a significantly larger number of Components of the injection unit required. In particular, this embodiment allows a pressure / time fuel metering function and a timing function as well as a cooling flow function using the timing liquid as the cooling liquid. The injection unit according to FIG. 1 can also be operated so that the injection in spite of further engine operation and going back and forth of the cam drive completely is switched off.

In Fig. 3 a further embodiment of the invention is shown, where wear compensation and the ability to end the more abruptly Injection (even if the injection time is not advanced) in addition to the construction the injection unit according to FIGS. 1 and 2a to 2f is given by the inclusion of another lost motion connection. FIG. 3 shows a detailed illustration Injection unit 300 with an injection body 302 ,.

which is formed in a manner similar to the injection body 202 of FIG is. The inlet passage 304 and the timing passage 306 are formed so that that they work like the corresponding passages in the embodiment according to Fig. 1. The lengths of the inner piston part 308 and the outer piston part 310 have been adapted to the axial position of the timing chamber with variable Size 307 axially outwards (upwards) embarrassed so that a Drainage and relief passage is formed with a dual function in the body 302, directed radially, perpendicular to the longitudinal act of the body 302.

A significant difference between the embodiments of Fig. 3 and 1 consists in the inclusion of a further lost motion connection 316 on the outer (upper) end of the first tension spring 318. In this way, the piston parts reach 308, 310 a predetermined distance from one another during each injection cycle, so as to realize the minimum override distance "at" caused by the lost motion connection 316, which can be viewed as the first lost motion connection, is specified. First after the piston parts 308, 310 move the override distance "a" from each other are removed, the first tension spring 318 begins to exert its preload in order to achieve the Pull piston parts 308, 310 towards one another. Similar to the mode of operation of the exemplary embodiment According to FIG. 1, the second lost motion connection 320 prevents the second tension spring 322 exerts some additional biasing force on the piston parts 308, 310 before these piston parts 308, 310 by an additional "advance" distance "b" from one another which are determined by the characteristic of the second lost motion connection 320 is.

The first lost motion connection 316 has a pin 316a and an anchoring element 316b, which is similar to the pin and the anchoring element according to FIG. Different compared to Fig. 1 is that the anchoring element 316b via a thread directly with connected to the outer end of the first tension spring 318, rather than the second Tension spring 322. The second lost motion link 320 also includes a pin 320a as well a second anchoring element 3 in a downwardly open recess 316c are arranged in the anchoring element 316b. The pin 320a is on the anchoring element 320b and its outer ends are in lengthwise slots 320 held in the anchoring element 316b. This determines the axial length of the slots 320c the dead passage between the anchoring elements 316b and 320b can occur before the second tension spring 322 begins to apply its tension, which tries to pull the piston parts 308, 310 towards each other.

The functional advantages resulting from the second lost motion connection 320 result can best be seen in FIG. 3a. This figure shows the Movement sequence of the outer (upper) piston part 310 as a function of the angular position the cam disk when the injection unit is operated with injection delay, d. H. when the pressure of the timing fluid is insufficient to bias to overcome the tension spring 318, so that the piston parts 308, 310 only by the of the lost motion connection 316 are separated from one another by a defined distance "a". the Piston parts 308, 310 are thereby already moved apart by the distance "a", that a given minimum pressure is always given by the timing fluid is. Because of this minimal pressure, the pressure between the piston parts increases 308 and 310 formed timing chamber 307 in each case as soon as the outer piston part 310 migrates to the outside. This minimum pressure of the timing fluid can, however not to overcome the bias of the tension spring 318. If the piston parts 308, 310 by a cam drive (a profiled cam disk, e.g. like the cam disk 1) moved inwards, the inner piston part 308 reaches the injection socket 324 of the body 302 rather than the outer piston part 310 its innermost Position reached. This is shown by the point i1 in Fig. 3a, where from This illustration shows that the outer piston part 310 is still moving inward although the inner piston part 308 has already reached the injection socket 324 and the injection opening closes. At this moment the timing fluid, which was previously included in the enlarged timing chamber 307 by the Drain passage 312 ejected at very high pressure, so that the inner piston part 308 remains in its innermost position. This functionality contrasts with the delay mode (operation without bringing the injection time forward) of the Embodiment according to FIG. 1, in which the timing chamber 230 is completely is pushed together before the front piston part 244 the injection socket has reached. This is represented by point i2 in Fig. 3a.

Because the point i1 is in an area of higher speed in the course of movement is, the inner piston member 308 comes to the injection socket 324 with a higher Speed to abut than the piston inner part 224 in Fig. 1, so that a more abrupt end to fuel flow occurs during injection. In addition, there is no longer a need for a rise 284 on the cam profile, since the timing fluid in the timing chamber ensures that the inner Piston part 308 is firmly pressed against the injection socket 324 while the Inward movement of the outer piston member 310 nears its end. Fig. 3a shows a minimal overdrive d of 0.018 inches (0.0457 cm) after the two made contact Piston parts 308, 310, but before reaching the innermost position of the outer piston part 310. This construction allows the elevation 284 on the cam profile according to FIG Fig. 1 to eliminate in a further override of the outer piston part 310 would have been precipitated (see the dashed line in Fig. 3a). Of course, the service life of the cam disc is increased if the increase 284 created sudden load can be switched off. Another advantage the embodiment of FIG. 3 is that all wear, the occurs in the actuation linkage of the injection unit, automatically compensated is by making a minimum hydraulic connection during deceleration operation the injection is created.

Another embodiment of the invention in question is shown in FIG. The injection unit 400 shown here has an injection body 402 with three axially offset recesses 404, 406 and 408 which are arranged on the outside at an axial distance from each other. The innermost Recess 404 is used in conjunction with the recess into which the injection unit is used to form the feed path. The middle recess 406 is like this designed that a drain path for fuel is formed, which is not with one is in connection with the drain opening shown, which opens into a recess, in which the injection unit can be used. The outer recess 408 forms finally, a flow path for the timing fluid that does not illustrated timing opening is in connection, which is also in the recess is open, in which the injection unit 400 is to be inserted. This explanation makes it clear that in connection with the use of the exemplary embodiment according to FIG. 4, the time control channel and the inlet channel in relation to the positions according to FIG FIGS. 1 and 3 are interchanged.

The injection piston 412 is divided into two parts including one inner piston part 414 and an outer piston part 416 which form a timing chamber 426 variable size include between them. The piston parts 414, 416 are biased towards each other by biasing means which are first and second coaxial to each other arranged tension spring and a lost motion include, which correspond to the embodiment of FIG.

An annular groove 418 is located on the outside of the inner piston part 414 formed, which is in communication with an inlet passage 420, once the inner Piston part 414 reaches its innermost position, which is shown in FIG. A drain passage 422 is arranged to communicate with that of the recess 406 formed drainage path is in connection. Both inlet passage 420 and the drain passage 422 are arranged perpendicular to the longitudinal axis of the injection unit and therefore very easy to manufacture.

As realized in the construction shown in Fig. 4, works the injection unit 400 with regard to the metering of fuel and the injection identical to the exemplary embodiment according to FIG. 1. Taking into account the forward shift the injection time, however, the timing control connection 424 is designed so that there is a flow path for timing fluid through the recess 408 and from which the timing fluid enters the timing chamber 426 formed between the inner and outer piston parts 414 and 416 is.

The timing connection 424 includes a timing port 425, which extends from the outer surface of the body 402 to the inner surface of the centric Bore along a radial, perpendicular to the longitudinal axis of the body 402 directed straight lines. This arrangement is also minimal Manufacturing expense associated with the formation of timing passage 425.

Rinsing takes place as soon as the injection piston 412 is in its innermost position Position according to FIG. 4 is so that fuel through the inlet passage 420, the Annular groove 418 and the drain passage 422 can flow. The rinsing takes place in the same way as that previously with respect to the copending patent application thereof Applicant has been explained.

From Fig. 4 it is readily apparent that the timing chamber 426 variable size is completely pushed together. Nonetheless, the timing chamber is coming 426 in communication with the timing passage 425 as soon as the injection plunger 412 reached its extreme position. During the time the inner piston part 416 is in its extreme position, timing fluid can enter the timing chamber 426 enter. In the embodiment shown in Fig. 4, the amount of liquid which enters the timing chamber 426, solely a function of the dead gear, which is predetermined by the lost motion connection 440, which in the same way as the Lost motion connection 262 according to FIG. 1 operates. Once the inner piston portion 414 is in is moved to its innermost position, the timing chamber 426 is in communication with a timing relief 428 to provide a flow path for the timing fluid to flow out of the timing control chamber 426 into that formed by the recess 406 Drain path is given. In this way, the timing chamber 426 is closed during each Injection unit cycle fully collapsed. The time tax relief 428 includes a relief passage 429 which, like the drain passage 312 in Fig. 3 is shaped. In the embodiment according to FIG. 4, the function requires which is realized by the drain connection 264 according to FIG. 1, both a relief passage 429 and a drain passage 422 (i.e., the functions of draining the timing fluid and relieving the fuel purge flow).

The body 402 of the injection unit 400 also has the braking function with fuel cut-off, which in connection with the embodiment according to FIG. 1 has been explained. For this purpose, the body 402 has a shut-off passage 430, which extends obliquely from the outer surface of the body 402 by the recess 408, extends to the central bore of the body.

This shut-off passage 430 is arranged axially at a point which allows timing fluid to flow into timing chamber 426, as soon as the inner piston part 414 has reached its innermost position. By a sufficiently large increase in the pressure of the timing fluid that results in the forces in the timing chamber 426 represent the combined forces of the pair of extension springs exceed that form the aforementioned pretensioning device, the inner one remains Piston part 414 in its innermost position, while the outer piston part 416 is, driven by the cam drive, not shown, moved back and forth. A check valve 432 is located in shutdown passage 430 so that the timing fluid only flow in one direction through shutoff passage 430 into timing chamber 426 can. The check valve 432 ensures that the hydraulic connection between the piston members 414 and 416 at all times during the inward movement of the injection piston 412 is given until the inner piston part 414 reaches its innermost position.

To possibly between the injection piston 412 and the central Bore of body 402 to catch upward leakage of fuel is one Leak connection provided for the discharge of leaked fuel into the formed by the recess 406. Drainage serves.

This leakage connection 434 has an annular cavity 436, which extends outward from the central bore at a point that is above the highest attainable point of the timing chamber 426 is. Also has the leakage connection 434 still has a leakage passage 438, which extends from the annular Cavity 436 extends to the drainage path formed by the recess 406.

From the above explanations it follows that the embodiment 4 works in a manner similar to that of the exemplary embodiment according to FIG. 1, at least with regard to the metering of fuel and the timing chamber, except that timing fluid is supplied to timing chamber 426 only becomes when the outer piston part 416 the axial position of the passage 425, while in the embodiment of FIG. 1 timing fluid is fed to the timing chamber at all times.

Still another embodiment of the invention will now be described explained, which is shown in Figs. Fig. 5 shows an injection unit 500 with a body 502 similar to the body 402 according to FIG. 4.

In particular, timing gate 507 operates in the same manner like the timing gate 425. The main difference here is that the Shutdown passage has been eliminated and that the drain passage 503 on the opposite Timing relief passage 505 and timing passage 507 side is arranged. However, the drain passage 503 can be in any radial Be arranged position.

As in the embodiment according to FIG. 4, the passages form 503 and 505 a drain connection for removing fuel from the central Bore of the injection body 502 The biasing means in the embodiment 5 and 6 have a single compression spring 504 instead of the two tension springs of the exemplary embodiments according to FIGS. 1 and 3. In detail is the outer Piston part 506 designed as a hollow collar, which has a radially inwardly directed Lip 508 next to the inner piston part 510. In addition to the compression spring 504, the biasing means comprises a connecting pin 512 with a shank portion 514, which is connected at one end to the inner piston part 510 and extends into the collar-like area of the outer piston part 506. The connecting pin 512 also includes an enlarged head 516 on that of the inner piston portion 510 far end. The compression spring 504 is between the lip 508 and the head 516 arranged. In this embodiment, the connecting pin 512 provides a Part of the inner piston part 510, so that the compression spring 504 are viewed as such may appear to extend between the inner and outer piston parts 510 and 506.

The operation of the injection unit 500 shown in FIGS. 5 and 6a is explained, results from the drawings and from the preceding explanation the mode of operation of the injection unit according to FIG. 4. In detail, FIG. 5 'shows the left side of the center line the position of the inner and outer piston parts 510 and 506 with the timing chamber fully pushed together and in its innermost Position of the injection piston. To the right of the center line in Fig. 5 are the piston parts 506, 510 shown at the time the injection has just ended and the timing chamber is still expanded. Fig. 6a shows the corresponding areas of the piston parts 506, 510 with the injection piston in its outermost position.

On the left is the position of the piston parts when they are fully pushed together Time control chamber shown. On the right is the position of the piston parts shown with the timing chamber expanded.

Yet another embodiment of the invention will be based on the Figs. 6b and 6c will be explained. The injection unit 500a shown in FIG. 6b has a body 502a similar to the injection body 502 according to FIGS. 5 and 6a. A major difference is that the pretensioning device according to the Figures 6b and 6c have a pair of compression springs 504a and 504b in place of the tension springs in the exemplary embodiments of FIGS. 1 and 3.

In particular, the outer piston part 506 is defined by a hollow collar 506a formed so that an inner cavity 506c results. The inner end of the Collar 506a includes an inwardly directed lip 508. In addition to the compression springs 504a and 504b, the biasing means includes a connecting pin 512 having a Shank area 514 which is connected at one end to the inner piston part 510 and extends into the inner cavity 506c in the outer piston portion 506. The connecting pin 512 further closes an enlarged head 516 on that of the end remote from the inner piston part 510. The inner compression spring 504b is between the lip 508 and the enlarged. Head 516 arranged. In this embodiment the connecting pin 512 forms a part of the inner piston part 510, so that the spring 504b can be viewed as extending between the interior and the piston outer part 510 and 506. The compression spring 504b works to at all times so that a force is generated, which the piston parts 506 and 510 towards each other wants to move. The compression spring 504a is arranged coaxially to the compression spring 504b and extends from lip 508 towards the lower edge of a male connector Part 506b. A ring 504c separates the outer end of the compression spring 504a from the inner one End of the plug-like part 506b. Since the ring 504c extends radially inward, the head 516 always comes to rest on the ring 504c when the inner and outer Piston parts 506, 510 are spaced apart by more than a predetermined distance. Only when the piston parts 506, 510 are at such a distance from one another, comes the compression spring 504a to act to make its biasing force the biasing force of the compression spring 504b for biasing the piston parts 506, 510 towards one another. Accordingly the two compression springs 504a and 504b operate in a similar manner to the two Tension springs and the lost motion connection in the exemplary embodiment according to FIG. 1.

The operation of the injection unit of FIGS. 6b and 6c should from the drawings and from the above explanation of the mode of operation the injection units shown in FIGS. 1 and 4 result. Fig. 6b shows in detail on the left side of the center line the positions of the piston parts when the timing control chamber is fully pushed together and in the innermost position inner piston portion 510. To the right of the centerline of Figure 6b are the Piston parts shown in their extreme positions, the timing function here just starting. However, timing fluid can only flow into the timing chamber when the pressure of the timing fluid is sufficient to bias the spring 504b to overcome. On the left side of Fig. 6c is the position of the piston parts shown with enlarged timing chamber. On the right side of this figure is seeing the result that the timing fluid pressure is sufficient, to overcome the bias of both compression springs 504a and 504b. Take the piston parts this position, the metering of fuel is aborted.

A final exemplary embodiment of the invention is finally shown in FIG. 7th

An injection unit 600 is shown here which operates in a similar manner like the injection units according to FIGS. 5 and 6. The decisive difference here is that the compression spring of the embodiment of FIGS 6 has been replaced by a tension spring 602. A lost motion connection 604 is here is provided between the lower end of the tension spring 602 and the inner piston part 606. The tension spring 602 is arranged so that a preload between the piston parts to overcome dynamic forces and to overcome friction. the The tension spring 602 is pretensioned enough to hold the piston parts during the deceleration function to hold together during operation, so when only a low pressure of the timing fluid through timing passage 608 is applied.

If the aim is to bring the injection time forward, then -The pressure of the timing fluid increases so that the timing chamber 610 between the piston parts 606 and 612 is fully enlarged. Unlike the previously explained Embodiments here are a rotation of the two piston parts 606, -612 prevented against each other by a massive pin 614, which is in an elongated Slot 616 in the inner piston part 606 extends. The ends of the tension spring 602 are fastened and stored in threads in the piston parts 606 and 610.

The graphical representation in FIG. 8 makes the functional differences between the embodiment of Figs. 1, 4, 6b and 6c with a single lost motion connection and two springs in comparison with the exemplary embodiment according to FIG. 3 with two lost motion connections and two feathers clearly.

In detail, Fig. 8 shows a graphic representation of the distance of the piston parts as a function of the timing pressure (pressure of the timing fluid). Line 11 represents the ratio of piston distance to timing pressure at Embodiment according to FIG. 3. Here the piston parts move during each Injection cycle away from each other as shown by line l. The one given here minimal distance ensures a hydraulically applied sudden load to produce a more abrupt end to each injection due to the override function of Piston. Line 12 shows the corresponding ratio for the other embodiments (Fig. 1, 4, 6b, 6c), which this override at the delay function does not show. This ratio is given by the line part 12 shown in FIG. Although in none of the exemplary embodiments explained above which is exactly described. it would be possible to have a single lost motion connection and a use a single spring element to generate a preload that the piston parts moved towards each other only after the piston parts have been moved by the lost motion connection predetermined path have been removed from each other. Such an arrangement could the override can also be implemented in an injection unit that does not have a corresponding Has fuel shutdown capability.

As is apparent from the above explanation, as the timing fluid motor fuel is usually used in all exemplary embodiments, as this eliminates any problems associated with mixing dissimilar liquids could result in the drainage duct of the engine.

LIST OF REFERENCE NUMERALS 200 injection unit 202 body 202a shaft od. outer area 202b socket or inner area 202c thread 203 recess 203a hexagonal socket 204 inlet channel 205 head 206 outlet channel 208 inlet opening 210 Drain opening 212 timing channel 214 timing opening 216 inlet path 217 Inlet connection 218 Inlet passage 219 Feed opening 222 Injection piston 223 front end 224 inner piston part 226 outer piston part 226a inwardly open Recess 228 central bore 230 timing chamber with variable size 232 Timing fluid flow path 234 rotation (timing) 236 rotation (Inlet) 238 recess (outlet) 240 outlet path 241 circumferential seal 241a small Annular groove 242 timing connection 243 circumferential seal 243a small annular groove 244 Timing passage 245 washer type seal 246 flow control 247 inwardly directed lip 248 annular groove 248a cylindrical expansion 249 outer surface 250 transverse passage 251- injection openings 252 recess 253 outer circumferential seal 253a small ring groove 254 ball check valve 256 preload element 258 first coil spring 258a thread 258b thread 260 second coil spring 260a Thread 260b thread 262 lost motion connection 262a pin 262b anchoring element 262c elongated opening 264 drainage connection 265 leakage connection 266 drainage passage 266a constriction 267 annular cavity 268 radial passage 269 leakage passage 270 cam drive 270a arrows 271 cam disk 272 tappet 272e arrows 273 rocker arm 274 connecting part 274e arrow 275 piston return element 276 collar-like coupling part 277 lower end 278 outwardly facing flange 279 compression spring 280 'first area 281 second area 282 third area 283 fourth area 284 Elevation 300 Injection Area 302 Body 304 Inlet Port 306 Timing Port 307 timing chamber 308 inner piston part 310 outer piston part 312 dual function Drain and relief passage 314, leakage passage 316, first lost motion connection 316a Pin 316b anchoring element 316c downwardly open recess 318 first train spring 320 second lost motion connection 320a pin 320b anchoring element 320c slots 322 second tension spring 324 injection socket 400 injection unit 402 body 404 innermost Recess 406 middle recess 408 outer recess 412 injection piston 414 inner piston part 416 outer piston part 418 annular groove 420 inlet passage 422 drain passage 424 timing connection 425 timing passage 426 timing chamber 428 Timing relief 429 Relief passage 430 Shut-off passage 432 Check valve 434 leakage connection 436 annular cavity 438 leakage passage 440 lost motion connection 500 injection unit 500a injection unit 502 body 502a body 503 drain passage 504 compression spring 504a compression spring 504b compression spring 504c ring 505 timing relief passage 506 outer piston part 506a hollow collar 506b plug-like part 506c inner Cavity 507 timing passage 508 inwardly facing LipPe 510 inner piston portion 512 connecting pins 514 shaft area 516 enlarged head 600 Injection unit 602 tension spring 604 lost motion connection 606 inner piston part 608 timing passage 610 timing chamber 612 outer piston part 614 solid pin 616 elongated Slot A miniaturized injection unit according to the invention can be used in a wide variety of internal combustion engines can be used. A particularly significant one Can be used for small compression igniter engines (diesel engines) for automobiles. Lighter truck engines and medium-power engines can also be used benefit from the injection construction according to the invention.

Claims (35)

Claims: {Injection unit, especially for internal combustion engines, G e k e n n part i c h n e t d u r c h an injection body (202) with a central Bore (228) and one with the central bore (228) in connection Injection opening (251), an injection piston (222) in the central bore (228) between an innermost position with closed injection opening (251) and an outermost position with in the central bore (228) between the inner one End of the injection piston (222) and the injection opening (251) formed injection chamber is movable to and fro, wherein the injection piston (222) has an inner piston part (224) and an outer piston part (226) in the central bore (228) can be moved back and forth independently of one another, thereby creating a timing control chamber (230) is formed with a variable size between the piston parts (224, 226), furthermore by an inlet connection (217) to form an inlet path for under Pressurized liquid from a source into the injection chamber continues through a timing connection (242) for providing a pressurized feed path Fluid from a source of timing fluid into the timing chamber (230) for the optional formation of a hydraulic connection between the above Piston parts (224, 226) and by a biasing element (256) for biasing the inner and outer piston parts (224, 226) towards one another, this biasing element (256) at least one between the inner and outer piston parts (224, .226) extending spring (258, 260) for applying one of the two piston parts (224, 226) has force to be moved towards one another. 2. Injection unit for insertion into an injection unit that receives the injection unit Recess in an internal combustion engine for the periodic injection of a quantity of fuel in a combustion chamber of the internal combustion engine, in particular according to claim 1, characterized through an inlet opening (208) opened in the recess (203) for the supply of Fuel and an axially offset one that is also open into the recess (203) Drain opening (210), wherein supplied but not injected Fuel can be supplied to this drainage opening (210), furthermore through one into the recess (203) open timing opening (214) for supplying timing fluid with variable pressure, further through an injection body (202), this Injection body (202) is shaped so that it can be inserted into the recess (203) is possible and that thereby an inlet path (216) between the inlet opening (20 and the outer surface of the injection body (202) and a drain path (240) from the inlet path (216) separated, between the drain opening (210) and the outer surface of the injection body (202) and finally a timing fluid flow path (232), are separated from the inlet path (216) and the outlet path (240), between the timing opening (214) and the outer surface of the body (202) are formed, the body (202) a central bore (228) and one closest to the inner end of the central bore (228) arranged injection opening (251), moreover by an inlet connection (217) to form a feed path for pressurized fuel from the inlet path (216) into the central bore (228), further through an outlet connection (264) to form a drainage path for fuel from the central bore (228) in the drainage path (240), even further through an injection piston (222), which is in the central bore (228) between an innermost position with through the inner End of the injection piston (222) closed injection opening (251) and an outermost one Position with in the central bore (228) between the inner end of the injection piston (222) and the injection opening (251) formed injection chamber can be moved back and forth is, wherein the injection piston (222) has an inner piston portion (224) and an outer Has piston part (226) that are in the central bore (228) independently of one another can be moved back and forth, thereby creating a timing chamber (230) with a variable Size between the piston parts (224, 226) is formed, the injection piston (222) also a prestressing element ~ (256) for prestressing the inner and outer Having piston parts (224, 226) towards one another and wherein the injection piston (222) Finally, a flow control (246) for creating a flushing flow path for a purge flow of fuel through the body (202), the Purge flow always occurs when the injection plunger (222) less than a first predetermined axial distance from the innermost position is removed and wherein a metering of fuel into the injection chamber from the feed path (216) is made possible as soon as the injection piston (222) has more than a second one predetermined axial distance from the innermost position, eventually by a timing connection (242) to provide a fluid pathway from the flow path (232) into the central bore (228) for optional training a hydraulic connection between the piston parts (224, 226). 3. Injection unit according to claim 1 or 2, characterized in that that the drain connection (264) has a drain passage (266) for the timing fluid has, via which the timing fluid from the timing control chamber (230) during sufficient time during each reciprocation of the injection plunger (222) can flow to the outside of the body (202), so that a perfect collapse the timing chamber (230) ensures that the drain passage (266) a Has constriction (266), so that during the collapse of the timing chamber (230) maintain a sufficiently high pressure in the timing chamber (230) to hold the inner piston part (224) in its innermost position. 4. Injection unit according to one of claims 1 to 3, characterized in that that the drain connection communicates with a drain passage (422) in the body (402) with the flushing flow path, via the liquid flowing in the flushing flow path is drained into the drainage path and one in the body (402) separate from that Drain passage (422) arranged relief passage (429) for draining timing fluid having in the drainage path. 5. Injection unit according to one of claims 1 to 4, characterized in that that the outer piston part (506) has a hollow collar (506a) with a radially facing inwardly directed lip (508) at the end facing the inner piston part (510) comprises that the inner piston part (510) has a connecting pin (512) with a Comprises shaft region (514), wherein the shaft region (514) one end is connected to the remaining area of the inner piston part (510: and extends into the hollow collar (506a) so that the connecting pin (512) an enlarged head (516) on its from the remainder of the inner piston part (510) distal end and that the biasing element extends between the Has lip (508) and the head (516) extending spring (504b). 6. Injection unit according to one of claims 1 to 5, characterized in that that the relief passage (429) is axially level with the contact point of the two piston parts (414, 416) when the injection piston (412) is in the innermost position. 7. Injection unit according to claim 6, characterized in that the Relief passage (429) extends from the outer surface of the body (402) to the inner surface the central bore along a radially directed straight line perpendicular to the longitudinal axis of the body (402). 8. Injection unit according to claim 7, characterized in that the Drainage passage (422) extends from the outer surface of the body (402) to the inner surface the central bore along a radially directed straight line perpendicular to the longitudinal axis of the body (402). 9. Injection unit according to one of claims 1 to 8, characterized in that that the body (202) has three axially spaced apart grooves (234, 236, 238) on the outer surface, whereby the recess (234 236, 238) the flow path (232) of the timing fluid, the inlet path (216) or the drainage path (240) are formed that continue to form sealing elements to form circumferential Seals (241, 243) between the body (202) and the recess (203) for receiving of the body (202) are provided and that the seals (241, 243) are so arranged are that the flow paths (232, 216, 240) fluidly separated from each other are. 10. Injection unit according to one of claims 1 to 9, characterized in that that the inlet connection (217) has an inlet passage (218) that the inlet passage (218) extends from the central bore (228) to the corresponding one, the feed path (216) forming recess (236) extends that the drain connection (264) a Drainage passage (266) has that the drainage passage (266) is between the central Bore (228) and the recess (238) forming the drainage path (240) extends and that the timing connection (242) has a timing passage (244) and itself the timing passage (244) between the central bore (228) and the den Flow path (232) for the timing fluid forming recess (234) extends. 11. Injection unit according to claim 10, characterized in that the inlet passage (218) and the timing passage (244) along corresponding ones Straight lines are formed perpendicular to the longitudinal axis of the body (202). 12. Injection unit according to claim 11, characterized in that the drainage passage (266) along a perpendicular to the longitudinal axis of the body (202) directed straight line is formed. 13. Injection unit according to one of claims 1 to 12, characterized in that that the timing connection (242) extends from the outer surface of the body (202) timing passage (244) extending to the inner surface of the central bore (228) and that the timing passage (244) relative to the body (202) axially so is arranged that timing fluid in the timing chamber (230) is optional is able to occur during each reciprocation of the injection plunger (222), once the pressure in the timing fluid is high enough, the biasing force the prestressing elements (256) which prestress the piston parts (224, 226) towards one another to overcome. 14. Injection unit according to claim 13, characterized in that the inlet connection (217) has a straight inlet passage (218) in the body (202) and that the inlet passage (218) is arranged perpendicular to the longitudinal axis of the body (202) is. 15. Injection unit according to one of claims 1 to 14, characterized in that that the flow control (246) has an annular groove (248) on the outer surface of the inner Piston part (224) for forming a flushing flow path that the annular groove (248) extends axially from the inlet passage (218) to the outlet passage (266), as soon as the injection piston (222) is in its innermost position, that the flow control (246) further comprises a cylindrical widening (248a) and that via the cylindrical widening (248a) in communication with the inner surface the central bore (228) a seal between the flushing flow path and the injection chamber is given. 16. Injection unit according to one of claims 1 to 15, characterized in that that the timing passage extends in the body (202) along a radially extending Straight lines extending perpendicular to the longitudinal axis of the body (202). 17. Injection unit according to one of claims 1 to 16, wherein at an internal combustion engine, the timing fluid is identical to that of the injection unit supplied fuel, characterized in that a leakage connection (265) to form a flow path for fuel from the timing chamber (230) is leaked out, is provided in the drainage path (240) and that the leakage connection (265) has an annular shape extending outward from the central bore (228) Cavity (267) and one extending from the cavity (267) to the drainage path (240) Has leak passage (269). 18. Injection unit according to one of claims 1 to 17, characterized in that that the timing passage (244) during each reciprocating cycle of the injection piston (222) is opened and closed by means of the injection piston (222). 19. Injection unit according to claim 18, characterized in that the outer piston part (226) opens the timing passage (244) as soon as its outermost one Position is reached. 20. Injection unit according to one of claims 1 to 19, characterized in that that a piston return element (275) is provided and that the piston return element (275) is connected to the outer piston part (226), so that the outer piston part (226) normally towards the extreme position of the injection piston (222) is pressed, with a force that is greater than that at all times Force of the biasing element (256). 21. Injection unit according to one of claims 1 to 20, characterized through an injection body (202) with a central bore (228) and a the injection opening (251) connected to the central bore (228), an injection piston (222) in the central bore (228) between a innermost position with closed injection opening (251) and an outermost one Position with in the central bore (228) between the inner end of the injection piston (222) and the injection opening (251) formed injection chamber can be moved back and forth is, wherein the injection piston (222) has an inner piston portion (224) and an outer Piston part (226) -has in the central bore (228) independently of one another can be moved back and forth, thereby creating a timing chamber (230) with a variable Size between the piston parts (224, 226) is formed, further by an inlet connection (217) to form a feed path for pressurized liquid from a Source into the injection chamber, further through a timing connection (242) to the Formation of an inlet path for pressurized liquid from a source for timing fluid into the timing chamber (230) and through a biasing element (256) for prestressing the inner and outer piston parts (224, 226) towards one another and finally by a prestressing element (256) for prestressing the two piston parts (224> 226) against each other with a force that is gradual from the distance of the two piston parts (224, 226) are dependent on one another. 22 Injection unit according to Claim 21, characterized in that the biasing element (256) has two oppositely wound, helical tension springs (258, 260) and that the piston parts (224, 226) with mutually complementary Threads (258a, 258b) for receiving the ends of the tension springs (258, 260) are provided. 23. Injection unit according to claim 22, characterized in that the biasing element (256) has a first helical tension spring (258) that the first Coiled tension spring (258) at each end integral with one of the two piston parts (224, 226) is connected, so that at all times a first predetermined force occurs the piston parts (224, 226) is applied, through which the piston parts (224, 226) are drawn towards each other that the biasing element (256) also has a second helical tension spring (260) comprises that the second tension coil spring (260) is integral with one of the piston parts (224) is connected that a lost motion connection (262) to connect the other The end of the second tension spring (260) is provided with the other piston part (226) and so that a second, additional, predetermined one by the second tension spring (260) Force can be exerted on the piston parts (224, 226) that these piston parts (224, 226) seeks to move towards one another as soon as the piston parts (224, 226) move are at a first predetermined distance from each other. 24. Injection unit according to one of claims 21 to 23, characterized in that that the biasing element (256) has a first tension spring (258), a second tension spring (260) and a lost motion connection (262) that the first tension spring (258) with both Piston parts (224, 226) is connected at the end that the second tension spring (260) at the end connected directly or via the lost motion connection (262) to the piston parts (224, 226) is, so that a backlash between the second tension spring (260) and one of the piston parts (224, 226) is given and the second tension spring (260) is given a second Can exert force on the piston parts (224, 226) as soon as these piston parts (224, 226) are separated from each other by more than a predetermined distance 25th Injection unit according to one of Claims 1 to 24, characterized in that a second backlash connection (320) for specifying a backlash between the End of the first tension spring (318) and the first lost motion connection (316) provided is, so that on the piston parts (308, 310) no pretensioning force is exerted as long these piston parts (308, 310) by less as a first given Are separated from each other by the first lost motion connection (316) is given, but when the piston parts (308, 310) by more than the first predetermined distance, but less than a second predetermined distance from each other are removed, only from the first tension spring (318) a force on the piston parts is exercised and finally when the two piston parts (308, 310) by more are apart from each other than the second predetermined distance, both tension springs (318, 322) act with their pretensioning forces on the piston parts (308, 310) and that the second predetermined distance is equal to the sum of the dead gears of the two backlash connections (316, 320) is. 26. Injection unit according to one of claims 1 to 25, characterized in that that a source of timing fluid is provided, the pressure of which between a Pressure to bring the injection time forward and a higher pressure to switch off fuel is variable, and that the spring rates of the first and second tension springs (258, 260) and the effective cross-sectional areas of the corresponding kib parts (224, 226) are chosen so that on the one hand the by supplying timing fluid with the previously first-mentioned pressure generated, the piston parts (224, 226) separating force in the area of the timing chamber (230) is greater than the first predetermined force, but smaller than the sum of the first and second predetermined forces and that on the other hand that by supplying timing fluid with the aforementioned second Pressure generated force in the area of the timing chamber (230) is greater than the sum of the first and second predetermined forces. 27. Injection unit according to one of claims 1 to 25, characterized in that that a source of timing fluid is provided, the pressure of which between a Residual pressure, a larger pressure to advance the injection timing and a even greater pressure is provided to shut off the fuel flow and that the spring rates of the first and second tension springs (258, 260 and 318, 322, respectively) and the corresponding cross-sections of the piston parts (224, 226 or 308, 310) are selected in this way are that on the one hand by supplying timing fluid force generated at the aforementioned pressure in the area of the timing chamber is less than the first predetermined force that on the other hand that by supply of timing fluid at the aforementioned second pressure in the area of the timing chamber generated force is greater than the first specified force, but smaller than the Sum of the first and second predetermined forces and that finally those by supply of timing fluid with the pressure in the area previously mentioned third The force generated by the timing chamber is greater than the sum of the first and second given forces. 28. Injection unit according to one of claims 1 to 27, characterized through an inlet opening (208) opened in the recess (203) for the supply of Propellant une an axially offset, also opened into the recess (203) Drain opening (210), with supplied but not injected fuel this The drain opening (210) can be fed in, furthermore through an opening into the recess (203) Timing opening (214) for supplying variable timing fluid Pressure, continued through an injection body (202), this injection body (202) is shaped so that it can be inserted into the recess (203) and that thereby an inlet path (216) between the inlet opening (208) and the outer surface the injection body (202) and a drain path (240), separated from the supply path (216), between the drain opening (210) and the outer surface of the injection body (202) and finally, a timing fluid flow path (232) separate from that Inlet path (216) and the outlet path (240), between the timing opening (214) and the outer surface of the body (202) are formed, the body (202) having a centric Bore (228) and one arranged next to the inner end of the central bore (228) Has injection opening (251), moreover through an inlet connection (217) to Forming a feed path for pressurized fuel from the feed path (216) into the central bore (228), further through a drain connection (264) to form a drainage path for fuel from the central bore (228) in the drain path (240), further through an injection piston (222), which in the central bore (228) between an innermost position with through the inner End of the injection piston (222) closed injection opening (251) and an outermost one Position with in the central bore (228) between the inner end of the injection piston (222) and the injection opening (251) formed injection chamber can be moved back and forth is, wherein the injection piston (222) has an inner piston portion (224) and an outer Has piston part (226) that are in the central bore (228) independently of one another movable to and fro, thereby creating a timing chamber (230) with a variable Size between the piston parts (224, 226) is formed with the injection barrel (222) furthermore a prestressing element (256) for prestressing the inner and their Having piston parts (224, 226) towards one another and finally by a timing connection (242) to form a pathway for liquid from the flow path (232) in the central bore (228) for the optional formation of a hydraulic connection between the piston parts (224, 226). 29. Injection unit according to one of claims 21 to 28, characterized in that that a drain connection (264) to form a drainage path for liquid to Drainage from the central bore (228) to the outside of the body (202) is provided is. 30. Injection unit according to claim 28 or 29, characterized in that that the drain connection (264) has a drain passage (266) for the timing fluid has over which the timing fluid from the timing chamber (230) during sufficient time during each reciprocation of the injection plunger (222) can flow to the outside of the body (202), so that a perfect collapse the timing chamber (230) is assured that the drain passage (266) is a dead end (266a), so that during the pushing together of the timing chamber (230) a sufficiently high pressure is maintained in the timing chamber (230), to hold the inner piston part (224) in its innermost position. 31. Injection unit according to one of claims 1 to 30, wherein periodically metered amounts of fuel from a fuel source into a combustion chamber of an internal combustion engine are injected and wherein a source of a pressure-variable timing fluid is provided, characterized by an injection body (202) with a central Bore (228), a feed opening (219), through which fuel from the fuel source can enter the central bore (228), and an injection opening (251), through the fuel measured in the central bore (228) into a combustion chamber can occur, furthermore through one arranged in the central bore (228) Injection piston (222), the injection piston (222) in the central bore (228) can be moved back and forth in a clocked manner and has a flow control (246) and wherein, by the flow controller (246), fuel is passed through the feed opening (219) can be measured in the central bore (228) during a calibration part of each cycle and during an injection part of each cycle the metered amount of fuel can be injected into the combustion chamber through the injection opening (251), finally due to pressure changes in the timing fluid during a timing part Timers responding to each cycle to control the timing of the injection part of each cycle and to control the timing fluid in the way that this during a different cooling part from the time control part each cycle flows through the body (202) so as to both the body (202) and to cool the injection piston (222). 32. Injection unit according to claim 31, characterized in that the injection piston (222) has an inner and an outer piston part (224 and 226, respectively) has that the piston parts (224, 226) can be moved back and forth in the central Bore (228) are arranged and so a timing chamber (230) with changeable Include size between them and that the timing devices on the one hand a biasing element (256) for biasing the piston parts (224, 226) towards one another and on the other hand a timing connection (242) and that via the biasing element (256) a step-like dependent on the distance between the two piston parts (224, 226) Force can be applied and through the timing connection (242) Flow path for fluid under pressure from a source of timing fluid is specified in the timing chamber (230). 33. Injection unit according to claim 31 or 32, characterized in that that the flow control (246) has an annular groove (248) on the outside of the inner Piston part (224) has that the inner piston part (224) on the one hand in the annular groove (248) and on the other hand in the timing chamber (230) opening piston passage and that the inner piston part (224) has a check valve (254), so that only one-way flow through the piston passage in the inner piston part (224) of liquid into the timing chamber (230) is possible. 34. Injection unit according to one of claims 31 to 33, characterized in that that the timing connection (242) comprises a timing passage (244) that the timing passage (244) extends from the outer surface of the body (202) to the inner surface the central bore (228) extends and that the timing passage (244) opposite the body (202) is axially arranged so that timing fluid enters the timing chamber (230) optionally to enter during each reciprocation of the injection plunger (222) can, as soon as the pressure in the timing fluid is high enough, the biasing force the prestressing elements (256) which prestress the piston parts (224, 226) towards one another to overcome. 35. Injection unit according to one of claims 31 to 34, characterized marked that a drain connection (264) is provided and that through the Drain connection (264) a flow path for fuel from the central bore (228) to the outside of the body (202) is formed and that the drain connection (264) has a drain passage (266) through which timing fluid from the Timing chamber (230) is able to flow to the outside of the body (202), namely during each to-and-fro movement of the injection plunger (222) for one sufficient long time to let the timing chamber (230) fully collapse that the Drainage passage (relief passage) (266) a constriction (266a) and that through the constriction (266a) during the pushing together of the timing chamber (230) maintain a sufficiently high fluid pressure in the timing chamber remains to hold the inner piston part (224) in its innermost position. The reference symbols used in the claims presented above do not represent any limitation to any of the preferred embodiments of the invention rather, the explanations in the claims presented above relate analogously to all illustrated embodiments.