EP0915252A2 - Common rail fuel injection system - Google Patents

Abstract

The rail (12) has an accommodation aperture (44) for a plunger cylinder (46) of the high pressure pump (16) with a delivery chamber (56) and a through passage (62). The delivery chamber is connected with the pressure chamber (20) of the rail (12) via the through passage. The injectors (24) have inlet apertures (38) open to the pressure chamber of the rail.

Description

The invention relates to a common rail injection system for internal combustion engines.

Common rail injection systems are used in internal combustion engines, where the combustion medium is used to optimize the combustion performance in the combustion chambers of the individual cylinders should be atomized. For this, the combustion medium is in a High pressure pump compressed and on a rail on the injectors of the individual cylinder distributed. Finally, the electrical signal is transmitted Injection process of the combustion medium into the combustion chamber triggered, with the combustion medium under high pressure through the injectors of the injectors at high speed finely distributed in the combustion chambers of the engine.

An injection system of this type is, for example, in the older CH patent application No. 1997 1275/97. A pump housing High pressure pump is a flange on a motor housing Internal combustion engine attached. The high pressure pump works with one Plunger cylinder which, together with a plunger, creates a delivery chamber limited. The delivery chamber is with a line for the inflow of the pressure medium connected, which is regulated by a pressure-controlled inlet valve and the plunger cylinder has a passage for the outflow of the pressure medium, which is also controlled by a pressure-controlled valve is regulated on. The plunger cylinder is surrounded by a pressure body, whose flow channels follow the passage opening of the plunger cylinder connect outside. Via a high pressure hose between the pressure body and common rail or in that the common rail directly to the Pressure body is molded, the flow channels of the pressure body connected to the pressure chamber of the rail. The connection between the individual injectors and the rail is through high pressure hoses ensures that via appropriate connectors on the injectors or the rail are attached. With its separate pump housing and due to the various connectors and connections this shows Construction many different, partly quite expensive parts that are in complex assembly must be assembled.

JP-A-09 060562 discloses an internal combustion engine with direct injection, where a high pressure fuel pump with the cylinder head connected is. The cylinder head has a channel inside through which the fuel is pumped away from the high pressure fuel pump becomes. The common rail placed on the injection valves is included connected to the cylinder head and has a passage in its interior to distribute the fuel to the injectors.

In the construction known from US Pat. No. 5,603,303, a pump housing is created from a plunger cylinder and a piston guide formed for a high pressure pump. This from plunger cylinder and Existing pump housing engages in a suitable piston guide Opening a motor housing in the way that part of the pump housing protrudes from the motor housing and directly on this by means of bolts is attached. This construction is also in construction and assembly complex.

The present invention has set itself the task of a common rail To provide an improved injection system and before has a simpler structure.

This problem is solved by a common rail injection system with the Features according to claim 1.

The injection system is connected to a high pressure pump elongated rail, which has a pressure chamber along its longitudinal axis. Openings for direct reception penetrate the pressure chamber provided by injectors. The advantage of such a construction is that the injectors can be inserted directly into the rail, which makes assembly very easy. This brings a further simplification Insert a plunger cylinder in a designated opening of the rail. If the plunger cylinder has a press fit in the Fixing opening of the rail fixed, this affects in the same way and Way out as the encirclement by a pressure body, which in the older CH patent application No. 1997 1275/97. As stated there can by surrounding the plunger cylinder by a pressure body various advantages such as the load on the high pressure pump higher pressures can be achieved.

In a preferred embodiment, the injectors used have in the area that after insertion at the pressure chamber of the Rails lies on inlet openings through which the pressure medium enters the injectors flow and are sprayed from there into the combustion chambers can. The advantage is that the pressure medium from the pressure chamber of the rail can flow directly into the injectors. The assembly will thereby very simplified and by eliminating the connecting parts material costs can be saved.

A particularly simple embodiment is described in claim 3. The openings for the injectors in the rail are with their opening axes aligned parallel to each other and are preferably in one plane. This will make the openings for the injectors both in the Rail as well as in the cylinder head housing and inserting the injectors in the openings simplified. This is especially for series production in the Industry of great importance.

The parallel axis guidance of the receiving opening for the plunger cylinder and the openings for the injectors in turn simplify insertion of the openings and assembly of the entire system. Also made possible this is a straightforward design of the rail.

The injection system can be further simplified if the rail connects one Forms part of the pump housing, especially if it integrally with the Pump housing or the housing cover is molded.

In addition to a very simple assembly and a simple structure by integrating the pump housing of the high pressure pump into one Engine housing, preferably in a cylinder head housing of an internal combustion engine, a weight saving can be achieved.

A further simplification of the injection system and thus also its Assembly can be carried out by preferred embodiments, as described in the further dependent claims are defined.

Fig. 1

im Längsschnitt einen Teil eines erfindungsgemässen Common-Rail Einspritzsystems;

Fig. 2

in einem Schnitt entlang der Linie II-II der Fig. 1, das dort gezeigte Einspritzsystem; und

Fig. 3

in einem Schnitt entlang der Linie III-III der Fig. 1, das dort gezeigte Einspritzsystem mit einem teilweise geschnitten dargestellten Verbrennungsmotor.

The common rail injection system according to the invention will now be described in more detail using an exemplary embodiment which combines several of the different simplification options. It shows purely schematically:

Fig. 1

in longitudinal section a part of a common rail injection system according to the invention;

Fig. 2

in a section along the line II-II of Figure 1, the injection system shown there. and

Fig. 3

in a section along the line III-III of Fig. 1, the injection system shown there with a partially cut internal combustion engine.

The part of the common rail injection system according to the invention shown in FIG. 1 8 one also indicated in FIGS. 2 and 3 Internal combustion engine 10 shows an elongated, straight rail 12, the parallel to a cylinder head housing belonging to the internal combustion engine 10 14 is arranged, and a high pressure pump 16 thereof Drive in a known, later described manner from Internal combustion engine 10 takes place.

The rail has a pressure chamber 20 and along its longitudinal axis 18 perpendicular to it, piercing the rail 12 in the area of the pressure chamber 20, Openings 22 for receiving injectors 24. The Openings 22 are parallel to one another with their opening axes 26 arranged and lie in one plane. In their extension, the Opening axes 26 also the axes of injector openings 28 of the Cylinder head housing 14. Finally, the injectors 24, when they pass through the openings 22 of the rail 12 into the injector openings 28 of the cylinder head housing 14 are used with their injector axes 26a parallel to one another and in one plane.

As shown in FIGS. 1 and 2, the injectors 24 essentially have are rotationally symmetrical, at one end injection nozzles 30 on. The injectors 24 are shaped such that the injection nozzles 30 after installation in a combustion chamber 32 shown in FIG. 2 of the internal combustion engine 10 protrude. One of the injector 30 opposite injector head 34 protrudes beyond the rail 12. How Fig. 1 shows, the injectors 24 in the section after the Insert the injectors 24 at the level of the pressure chamber 20 of the rail 12 lies, a circumferential groove 36 through which it is ensured that the Injectors 24 flow around the pressure medium located in the pressure chamber 20 can be. This section of the injectors 24 are also located Inlet openings 38 through which the pressure medium enters the injectors 24 can flow in. With the help of a fastener 40, for example a screw connection, in the area of the protruding beyond the rail 12 Injector head 34 and an attachment 42 on the opposite The outer wall of the rail 12, the injectors 24 are fixed in the rail 12.

On the side of the high pressure pump 16, the rail 12 has two receiving openings 44 for receiving plunger cylinders 46 and one Channel 20a on. The channel 20a goes in the dashed line 48 in the Pressure chamber 20 of the rail 12 and connects the receiving openings 44 with the pressure chamber 20 of the rail 12. So that the pressure medium used Plunger cylinders 46 can flow around the channel 20a circumferential grooves embedded in the plunger cylinder 46, which at used plunger cylinders 46 an annular channel 50 (indicated by dashed lines) form around the plunger cylinders 46. The plunger cylinders 46 are over a press fit in the rail 12 fixes what the same effect as that Enclose the plunger cylinder with a pressure body, as in the older one CH Patent Application No. 1997 1275/97.

The receiving openings 44 made in the rail 12 for the plunger cylinders 46 have axes 52 lying parallel to one another, which in one Plane with and parallel to the opening axes 26 of the openings 22 in the Rail 12 or the injector axes 26a of the injectors 24 are arranged. This leads to the fact that the plunger cylinders 46 after their insertion in the receiving openings 44 with their plunger axes 52a parallel and in lie on a plane to the opening axes 26 and the injector axes 26a.

Each plunger cylinder 46 defines together with a plunger 54 a delivery space 56. This delivery space 56 is in the plunger cylinder 46 let inlet channel 58 and a feed line 58a with a reservoir for the pressure medium, not shown. Of the The pressure medium is fed in through a pressure-controlled inlet valve 60 regulated. Via a passage 62, which is incorporated into the plunger cylinder 46 and connects the delivery chamber 56 to the ring channel 50, can the pressure medium, regulated by an also pressure controlled Exhaust valve 64, again flow out of the delivery chamber 56.

The high pressure pump 16 has a pump housing 66, to which below another includes a housing element 68 with a side wall 68a in which Housing openings 70 are excluded. The plunger cylinders 46 protrude now with the side in which the plungers 54 in the plunger cylinders 46 are guided into these housing openings 70 of the side wall 68a of the housing element 68 in. The housing openings 70 are so designed that between the plunger cylinders 46 and the Housing element 68 remains a small gap 72, so that the plunger cylinders 46 can be inserted into the housing element 68 with some play. The housing element 68 is above the side wall 68a via the columns 72 open to the outside. Through the rail 12, which on the side wall 68a of the Housing element 68 is arranged close to the housing element 68 as if closed by a lid.

In a wall 74 of the wall lying perpendicular to this side wall 68a Housing element 68 is formed on the inside as a bearing Recess 76 incorporated in which the drive shaft 78 with the Power transmission opposite end region 78a is mounted. On the on the other side, the wall 74 at the dashed dividing line 74a goes into the integrally molded cylinder head housing 14 on. Opposite the wall 74 of the housing element 68 closes a side plate 80 which also belongs to the pump housing 66, a further opening of the housing element 68. In a bearing opening 82 of this side plate 80 is the Drive shaft 78 on its side facing the power transmission stored. In the case of repairs, access is also via this side plate 80 allows the inside of the pump housing 66.

The plunger cylinders 46 with the plungers 54 and the drive shaft 78 the high pressure pump 16 are arranged at right angles to each other. For the Stroke movement of - by means of compression springs 83 in the direction against Drive shaft 78 pushed - plunger 54 in the plunger cylinders 46 of the high pressure pump 16 are on the drive shaft 78 of the high pressure pump 16 eccentric 84 attached. Between the eccentrics 84 and the plunger 54 are rolling rings 86 in a known manner attached, which can rotate freely on the eccentric 84. For the The high-pressure pump 16 is driven in the embodiment shown here the drive shaft 78 via a spur gear mechanism indicated in FIGS. 1 and 3 88 with a camshaft which is also only shown in a hint 90 of the internal combustion engine 10 coupled.

2 shows the common rail injection system 8 according to the invention Fig. 1 along the section axis II-II. The injector 24 is over the fastener 40 and the attachment 42 fixed in the rail 12 and in the Injector opening 28 of the cylinder head housing 14 inserted. The one in 3 only schematically indicated internal combustion engine 10 with a Engine housing 92 is only partially shown as a reciprocating piston engine formed in the piston 94, the combustion chamber 32 incorporated is. The injection nozzle 30 of the injector 24 projects into this combustion chamber 32 in. The piston 94 is via a crank mechanism 96 connected to a crankshaft 98, which is only hinted at is.

3 is the injection system 8 from FIG. 1 along the section III-III shown. The dashed circular lines 100 and the arrows 102 indicate the power transmission from the camshaft 90 via the spur gear 88 to the drive shaft 78 of the high pressure pump 16. Right angled to the drive shaft 78 is the plunger cylinder enclosed by the rail 12 46 arranged and with the supply line 58a for the inflow of the pressure medium Mistake. The internal combustion engine 10 is with its motor housing 92, piston 94, crank gear 96 and crankshaft 98 also only hinted at here.

However, it is advantageous for the functioning of the injection system 8 necessary that the rotational movement of the drive shaft 78 and that of the Camshaft 90 of the internal combustion engine 10 is operated in angular synchronism become. The drive shaft 78 is then preferably driven, for example, via the spur gear 88, in a known manner from the camshaft 90, as indicated in FIGS. 1 and 3. Due to the rotational movement of the drive shaft 78, mediated by the Eccentric 84, the plungers 54 perform stroke movements. At a Suction stroke of the plunger 54 opens the inlet valve under pressure control 60 and the pressure medium flows from the reservoir over the Supply line 58a and the inflow channel 58 into the delivery chamber 56 The compression stroke of the plunger 54 closes the inlet valve 60 and the outlet valve 64 opens under pressure control and gives the passage 62 free. The pressure medium can thus through the passage 62 from the Delivery chamber 56 into the ring channel 50 and further into the channel 20a of the rail 12 stream. From there it flows further into the pressure space 20 of the rail 12 and through the inlet openings 38 into the interior of the injectors 24. Via The indicated injection process 104 becomes an electrical signal triggered and the print medium at high speed and high Pressure finely distributed into the combustion chamber 32.

Different drive options than the one described above by the Camshaft 90 to the drive shaft 78 via a spur gear 88 naturally also possible. So instead of a spur gear 88, e.g. also the power transmission by means of a belt drive is conceivable, or a drive instead of from the camshaft 90 directly from the crankshaft 98.

In a different embodiment, a is used instead of the rail 12 Housing cover 106 close to the side wall 68a of the Housing elements 68 arranged and that over the columns 72 between the used plunger cylinders 46 and the housing element 68 open Housing element 68 closed in this way. To do this, the Housing cover 106 analogous to the rail 12 receiving openings 44 for the Receiving the plunger cylinder 46 and have a channel 20a. As in the rail 12 are also in the housing cover 106, which have a Press fit plunger 46 used so that everyone Delivery chamber 56 through the passage 62 and the through the annular groove Plunger cylinder 46 shaped ring channel 50 with the channel 20a of the Housing cover 106 is connected. That containing the plunger cylinders 46 Component, which in FIG. 1 closely adjoins the housing element 68 is arranged, can also be the housing cover 106 to which the Rail 12 is integrally formed on the dashed line 48. Just like that but it would also be conceivable that the rail 12 in a different way, e.g. about a high pressure hose with the channel 20a of the housing cover 106 would be connected.

The housing element 68 itself can also have receiving openings 44 for the accommodation of the plunger cylinders 46 and a channel 20a may be provided, such that the plunger cylinders 46 directly into the housing element 68 a press fit can be used. They are here too Plunger cylinder 46 configured so that the delivery chamber 56 over the Passage 62 and the ring channel 50 is connected to the channel 20a. The In this case, rail 12 only has openings 22 for receiving the Injectors 24 but not the receiving openings 44 for the plunger cylinders 46 on. The pressure chamber 20 of the rail 12 can then either over High pressure hoses with the channel 20a of the housing element 68 be connected or in that the rail 12 directly to the Housing element 68 is integrally formed.

In the embodiment shown in FIG. 1, the housing element 68 Integrated part of the cylinder head housing 14 and thus the Motor housing 92. Other embodiments in which other parts of the pump housing 66 is an integral part of the motor housing 92 preferably the cylinder head housing 14 of the internal combustion engine 10 are, but are also conceivable. Here, e.g. the rail 12 on the one hand the cylinder head housing 14 and on the other hand to the housing cover 106 or the housing element 68 can be integrally formed so that these elements over the rail 12 in the engine housing 92 or the cylinder head housing 14 to get integrated. Housing cover 106 or side plate 80 can also be in the engine housing 92 or the cylinder head housing 14 may be integrated or combinations of these parts.

To flow around the injectors 24 and the plunger cylinder 46 through the Ensuring print media can use other options than that Circumferential grooves 36 on the injectors 24 and the annular channel 50 shaping circumferential ring grooves on the plunger cylinders 46 be provided. For example, annular grooves on the Inside of the openings 26 for the injectors 24 or in the Receiving openings 44 for the plunger cylinders 46. It would also be conceivable that the injectors 24 instead of a fastening element 40 and an attachment 42 in a different way with the rail 12 be connected, for example by a shrink fit. As well can also the plunger cylinder 46 in a different way than via a Press fit to be fixed in the receiving openings 44. For the In principle, it is also not of crucial importance whether the plunger cylinder 46 from the receiving the plunger cylinder 46 Component protrudes, just closes with it or covers it is bordered. This also applies to the injectors 24 in the rail 12 Alignment of the axes 52 of the receiving openings 44 for the Plunger cylinder 46 and the opening axes 26 of the openings 22 for the Injectors 24 do not necessarily have to be parallel and in one plane be arranged. Other orientations are also conceivable.

Claims (9)

Common rail injection system (8) for internal combustion engines (10) a rail (12) connected to a high pressure pump (16), the a pressure chamber (20) and connected to this pressure chamber (20) Has openings (22) for receiving injectors (24), characterized in that the rail (12) has a receiving opening (44) for receiving a one conveying space (56) and one Passage (62) having plunger cylinder (46) of the High pressure pump (16), the delivery chamber (56) via the Passage (62) is connected to the pressure chamber (20) of the rail (12). Injection system (8) according to claim 1, characterized in that the injectors (24) inserted into the openings (22) of the rail (12) Have inlet openings (38) against the pressure chamber (20) of the Rails (12) are open. Injection system (8) according to claim 1 or 2, characterized in that that the openings (22) of the rail (12) opening axes (26) have, which are arranged parallel to each other and preferably lie in one plane so that the injectors (24), in turn Have injector axes (26a) when inserted into the openings (22) of the rail (12) with their injector axes (26a) also in parallel lie to each other and are preferably in one plane. Injection system (8) according to claim 3, characterized in that the receiving opening (44) for receiving the plunger cylinder (46) has an axis (52) which is parallel to the opening axes (26) of the Openings (22) in the rail (12) or to the injector axes (26a) of the used injectors (24) run and preferably with these in lie on one level so that the plunger cylinder (46), which in turn has a plunger axis (52a) with this plunger axis (52a) also parallel and preferably in one plane to the Opening axes (26) or the injector axes (26a). Injection system (8) according to one of claims 1 to 4, characterized characterized in that the high pressure pump (16) is a pump housing (66) and the rail (12) a part of the pump housing (66) forms. Injection system (8) according to claim 5, characterized in that the rail (12) a housing cover (106) of the pump housing (66) forms. Injection system (8) according to claim 5, characterized in that the rail (12) is integrally formed on the pump housing (66). Injection system (8) according to one of claims 5 to 7, characterized characterized in that the pump housing (66) of the high pressure pump (16) and in particular the rail (12) integrated components of a Engine housing (92), preferably a cylinder head housing (14), the internal combustion engine (10). Common rail injection system (8) with a pump housing (66) high pressure pump (16) with housing cover (106), characterized in that the pump housing (66) integrated Part of a motor housing (92), preferably one Cylinder head housing (14) of the internal combustion engine (10).

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