EP1989406B1 - Cylinder head of an internal combustion engine having an electrohydraulic valve controller - Google Patents

Description

Field of the invention

• ■ zumindest eine von einer Nockenwelle angetriebene Gebereinheit,
• ■ zumindest eine ventilseitige Nehmereinheit,
• ■ zumindest ein elektrisch ansteuerbares Hydraulikventil,
• ■ zumindest einen Druckentlastungsraum
• ■ und zumindest einen volumenveränderlichen Druckraum, der im Übertragungssinn zwischen der zugehörigen Gebereinheit und der zugehörigen Nehmereinheit angeordnet und über das zugehörige Hydraulikventil mit dem zugehörigen Druckentlastungsraum verbindbar ist,

umfasst. Dabei gehören wenigstens die Gebereinheit, die Nehmereinheit, der Druckraum, das Hydraulikventil, der Druckentlastungsraum und zumindest ein Rückschlagventil im Verbund mit einem gemeinsamen Hydraulikgehäuse zu einer vormontierten und am Zylinderkopf befestigten Hydraulikeinheit, die über das in Richtung der Hydraulikeinheit öffnende Rückschlagventil an die Hydraulikmittelversorgung der Brennkraftmaschine angeschlossen ist.The invention relates to a cylinder head of an internal combustion engine with electro-hydraulic valve control, the

• At least one transmitter unit driven by a camshaft,
• At least one valve-side slave unit,
• At least one electrically controllable hydraulic valve,
• ■ at least one pressure relief room
• ■ and at least one volume-variable pressure chamber which is arranged in the transmission sense between the associated transmitter unit and the associated slave unit and is connectable via the associated hydraulic valve with the associated pressure relief space,

includes. At least the transmitter unit, the receiver unit, the pressure chamber, the hydraulic valve, the pressure relief chamber and at least one check valve in conjunction with a common hydraulic housing to a preassembled and attached to the cylinder head hydraulic unit, which opens the hydraulic unit of the internal combustion engine via the opening in the direction of the hydraulic unit check valve connected.

Background of the invention

Internal combustion engines with electrohydraulic valve control, in which the essential components required for the hydraulic transmission of cam lobes to the gas exchange valves are arranged in a preassembled hydraulic unit attached to the cylinder head, belong to the state of the art of the technique. So in the considered as generic EP 1 338 764 B1 , which is also to be considered as a reference for the present invention, discloses a cylinder head with a hydraulic unit attached thereto. This is formed in a first embodiment as independent of the bearing of the camshaft hydraulic housing with the therein arranged Gebereinheiten, Nehmereinheiten, hydraulic pressure accumulators and the connection and connection channels. In a second embodiment, moreover, the bearings and the lubricant supply for the camshaft are integrated into the hydraulic housing.

A prerequisite for the proper functioning of the electrohydraulic valve control is of course their adequate supply of ideally incompressible and practically largely gas bubble-free hydraulic fluid. Such supply can be ensured during operation of the internal combustion engine by the connection of the hydraulic unit to the hydraulic or lubricant supply of the internal combustion engine and, if necessary, by suitable devices for the separation of gas bubbles from the hydraulic unit. In the parked state of the internal combustion engine opening in the direction of the hydraulic unit check valve prevents backflow of hydraulic fluid in the hydraulic fluid supply and thus the formation of gas bubbles within the hydraulic unit. However, these funds proposed in the cited document do not take into account the situation of initial assembly of the hydraulic unit in the cylinder head or their reassembly in the maintenance or repair case of the internal combustion engine. In this situation, it may be provided that the hydraulic unit, although pre-assembled, but not or not completely filled in the cylinder head to assemble. A subsequent starting process of the internal combustion engine can then fail because the cam lobes are not transferred to the gas exchange valves due to the trapped between the transmitter units and the receiver units gas bubbles and thus remain closed. A successful restart or restart of the internal combustion engine would then possibly possible after a considerable and unacceptable delay time during which the engine is running at starter speed and a New or refilling the hydraulic unit of the already time-delayed and also then deficient pressure build-up in the hydraulic fluid supply is dependent.

Object of the invention

The object of the invention is therefore to provide a cylinder head of the aforementioned type, in which the cited disadvantage is eliminated. Accordingly, the hydraulic unit should be filled with hydraulic fluid not only during operation of the internal combustion engine and the intervening shutdown phases but also immediately after assembly of the hydraulic unit in the cylinder head both during initial assembly and in repair or maintenance of the engine.

Summary of the invention

According to the invention this object is achieved directly by the characterizing features of claim 1, wherein in addition to the check valve at least one of the hydraulic fluid supply independent and trained on the hydraulic housing filling device is provided with a closure means for the first filling of the pressure relief chamber and / or the pressure chamber. The object is achieved indirectly by the features specified in the independent claim 12 for the hydraulic unit features. Thus, the above-described disadvantage is eliminated by simple means, since the hydraulic unit by means of the filling now independent of the hydraulic fluid supply to the engine and easily accessible with hydraulic fluid can be filled and is already operational before the starting process of the internal combustion engine in the hydraulic sense. In this case, the term of the first filling is understood as meaning both a first-time filling of the hydraulic unit before, during or in particular after its initial assembly to the cylinder head and also refilling of the hydraulic unit in the event of maintenance or repair of the internal combustion engine. Furthermore, in this context, the use of a normally open hydraulic valve a common filling of the pressure relief and the pressure chamber, since the hydraulic fluid can get into the then without further action interconnected spaces simultaneously.

In development of the invention, the hydraulic housing should have at least one communicating with the pressure relief space vent hole. This allows for a fast venting of the hydraulic unit during the initial filling and on the other hand a targeted separation of gas bubbles from the pressure relief chamber during operation of the internal combustion engine.

It is further provided that the pressure relief space is limited by a spring-loaded piston of a pressure accumulator arranged in the hydraulic housing. In connection with the filling device, a defined hydraulic fluid pressure within the pressure relief chamber can thereby be adjusted by filling and biasing the pressure accumulator independently of the hydraulic fluid supply and thus already before the starting process of the internal combustion engine.

In a particularly advantageous embodiment of the invention exactly one filling device is provided, which is accessible by their immediate arrangement maintaining a Hydraulikmitteleinfüllstutzens mounted on the cylinder head cylinder head cover. As a result, on the one hand, the number of components required for the first filling is reduced to a minimum, on the other hand allows this arrangement of the filling a Erstbefüllung the hydraulic unit after the internal combustion engine is already fully assembled and optionally installed in a vehicle.

While in the simplest case, a screw plug or a plug can be used as closure means, this should be formed in a preferred embodiment of the invention as also in the direction of the hydraulic unit opening, another check valve. This is particularly counter to a time-saving filling of the hydraulic unit during the initial assembly of the internal combustion engine, since no additional effort for disassembly and Reinstallation of the closure means is required.

It may further be provided that the hydraulic housing comprises a lower housing part and a final upper housing part, wherein the transmitter unit, the receiver unit, the pressure chamber, the hydraulic valve, the pressure relief chamber and the check valve in the housing lower part and the further check valve in the housing upper part are arranged. Such a split and structured with said arrangement of the components hydraulic housing is manufacturing technology particularly favorable to produce, if it is a pressure-tight forging with the necessary tool access to cavities in the interior of the hydraulic housing.

In order to prevent an unintentional hydraulic fluid outlet from the hydraulic housing, a seal may be provided between the upper housing part and the lower housing part, which is preferably printed or sprayed onto the upper housing part and consists of elastomer material.

In a further embodiment of the invention, the further non-return valve in favor of low manufacturing and assembly costs to be formed as arranged in a bore of the upper housing unit, the minimum circumference of a bore mounted in the valve carrier, a cooperating with a valve carrier extending sealing seat ball, the ball in the direction of the sealing seat loading valve spring and a snapped in a radially circumferential undercut of the valve carrier valve cap for holding the valve spring and the ball. In this case, the assembly may additionally include a support ring with a disk-like base body and an inside collar with regard to a pressure-resistant and captive attachment to the upper housing part. The collar is for valve-side fixation of the support ring, axially supporting the valve cap, snapped in the undercut, and the body extends beyond the housing radially fixing the support ring at least partially radially and engages in a running between the upper housing part and the lower housing recess.

Furthermore, it is provided that the filling device comprises a dirt filter arranged in the filling direction in front of the further non-return valve. This serves to protect the dirt-sensitive components of the electro-hydraulic valve control, since the dirt filter can effectively prevent the ingress of dirt particles with mission critical size especially in repair or maintenance, but also during initial assembly of the engine. The dirt filter is in a preferred development as attached to an annular filter housing strainer, preferably in the filter housing spherically protruding, be formed, wherein the filter housing produced in a plastic injection molding is preferably secured by pressing or screwing into the bore on the housing top. Such a dirt filter is on the one hand inexpensive to produce and in the case that the sieve filter protrudes into the filter housing spherical, largely protected from damage by mechanical action.

Brief description of the drawings

Figur 1

einen Abschnitt eines Zylinderkopfs in perspektivischer Darstellung;

Figur 2

eine Hydraulikeinheit in perspektivischer Gesamtdarstellung;

Figur 3

einen Querschnitt durch eine Gebereinheit;

Figur 4

einen Querschnitt durch eine Nehmereinheit;

Figur 5

einen Querschnitt entlang eines Hydraulikventils;

Figur 6

einen Querschnitt durch eine Befüllvorrichtung,

Figur 7

die Befüllvorrichtung gemäß Figur 6 in vergrößerter Darstellung und

Figur 8

einen Abschnitt eines Gehäuseoberteil in perspektivischer Untersicht auf die Befüllvorrichtung.
Ausführliche Beschreibung der Zeichnungen

Further features of the invention will become apparent from the following description and from the drawings, in which an embodiment of the invention is shown. Show it:

FIG. 1

a section of a cylinder head in perspective view;

FIG. 2

a hydraulic unit in an overall perspective view;

FIG. 3

a cross section through a transmitter unit;

FIG. 4

a cross section through a receiving unit;

FIG. 5

a cross section along a hydraulic valve;

FIG. 6

a cross section through a filling device,

FIG. 7

the filling device according to FIG. 6 in an enlarged view and

FIG. 8

a section of an upper housing part in a perspective bottom view of the filling device.
Detailed description of the drawings

In FIG. 1 is a portion of a cylinder head 1 of an internal combustion engine with electro-hydraulic valve control disclosed. Below a cylinder head cover 2 a screwed to the cylinder head 1 hydraulic unit 3 with electrically controllable and externally contactable hydraulic valves 4 can be seen. Immediately below a Hydraulikmitteleinfüllstutzens 5 of the cylinder head cover 2, a filling device 6 is arranged for initial filling of the hydraulic unit 3 with hydraulic means. As drive the in FIG. 2 shown hydraulic unit 3 is a known and visible only as a shaft end camshaft. 7

FIG. 2 shows an overall view of the outside of the cylinder head 1 preassembled hydraulic unit 3, here for an internal combustion engine in four-cylinder in-line construction. In a hydraulic housing 8, which is composed of a housing lower part 9 and a housing upper part 10 by means of screw connections 11, gear units 12 driven by the camshaft 7 are accommodated. On the transmitter units 12 opposite side of the hydraulic housing 8, the hydraulic valves 4 and on the upper housing part 10, the filling device 6 can be seen.

A cross section through one of the transmitter units 12 is shown in FIG FIG. 3 shown. In this exemplary embodiment, the encoder unit 12 comprises a rocker arm 14 mounted in an articulated manner on a rigid support element 13 with a roller bearing roller 15 as cam cam surface and a spring-loaded pump piston 16 driven by rocker arm 14, which has a variable volume Pressure chamber 17 limited. In order to control the material occurring in the pressure chamber hydraulic fluid pressures in the range of 200 bar and more material, the lower housing part 9 is designed as a pressure-tight forging made of aluminum. When the hydraulic valve 4 is open, the pressure chamber 17 is connected to a pressure relief chamber 18, which in turn is delimited by a spring-loaded piston 19 of a pressure accumulator 20. A screwed into the lower housing part 9 sensor 21 is used to detect the hydraulic fluid temperature.

In FIG. 4 is one with the pump piston 16 of the encoder unit 12 via channels 22 according to FIG. 3 and 23 according to FIG. 4 in hydraulic operative connection standing and offset in the longitudinal direction of the hydraulic unit 3 to the transmitter unit 12 arranged receiving unit 24 for actuating one of the gas exchange valves of the internal combustion engine recognizable. The slave unit 24 comprises a slave housing 25 screwed into the lower housing part 9, a slave piston 26 mounted longitudinally movably and delimiting the pressure chamber 17, a hydraulic valve clearance compensation element 27 clamped between the slave piston 26 and the gas exchange valve and a hydraulic valve brake 28. This ensures a defined braking and gentle Closing the during the lifting phase of the associated cam lift hydraulically decoupled and acted upon by the valve spring in the closing direction gas exchange valve, while the hydraulic valve 4 is opened, a rapid outflow of hydraulic fluid from the pressure chamber 17 in the pressure relief chamber 18.

The separation of the pressure chamber 17 from the pressure relief chamber 18 through the hydraulic valve 4 goes out of the in FIG. 5 illustrated cross section along the hydraulic valve 4, which is also arranged offset to the associated transmitter unit 12 and slave unit 24 in the longitudinal direction of the hydraulic unit 3, out. The channels 22 ( FIG. 3 ) and 23 ( FIG. 4 ) are hydraulically connected to one another via an annular groove 29 running on the hydraulic valve 4, so that the annular groove 29 as well as the channels 22 and 23 are part of the pressure chamber 17. In the open state, the hydraulic valve 4 allows an overflow of Hydraulic fluid from the pressure chamber 17 in the pressure relief chamber 18 and back via a pressure relief chamber 18 with the annular groove 29 connecting bore 30 to.

The supply of hydraulic fluid required for the proper operation of the hydraulic unit 3 is shown in a further cross section through the hydraulic unit 3 in FIG FIG. 6 shown. To compensate for the loss of hydraulic fluid during operation of the internal combustion engine and the intermediate stoppage phases from the hydraulic unit 3 is arranged in the lower housing part 9 and opening in the direction of the hydraulic unit 3 check valve 31. This is about an obliquely extending in the housing part 9 tap hole 32 with mündungsseitigem filter element 33 at the hydraulic fluid supply of the internal combustion engine connected. In contrast, the filling device 6 serving for the initial filling of the hydraulic unit 3 comprises a closure means 35 which likewise opens in the direction of the hydraulic unit 3 and is designed as a further check valve 34, and a dirt filter 36 arranged in the filling direction.

An enlarged view of the filling device 6 shows FIG. 7 , The further check valve 34 is designed as arranged in a bore 37 of the upper housing part 38 unit 38, a pressed into the bore 37 cylindrical valve carrier 39 with a sealing seat 40, a cooperating with the sealing seat 40 ball 41, the ball 41 in the direction of the sealing seat 40 loading valve spring 42 and a snapped in a radially circumferential undercut 43 of the valve carrier 39 valve cap 44 for holding the valve spring 42 and the ball 41 has. For pressure-resistant and captive mounting of the other check valve 34 in the bore 37, the assembly 38 further includes a support ring 45 having a disk-like base body 46 and an inside collar 47. The collar 47 is snapped for valve-side fixation of the support ring 45 in the undercut 43 and simultaneously supports the Valve cap 44 axially from, while the base body 46 for housing-side fixing of the support ring 45, the bore 37 projects radially beyond and extending into a between the upper housing part 10 and the lower housing part 9 and engages recess formed in the lower housing part 9 9 here.

The dirt filter 36 consists of an annular, produced in a plastic injection molding and in the bore 37 also pressed filter housing 49 and a fixed to the filter housing 49 sieve filter 50 which protrudes to protect against damage due to mechanical action in the filter housing 49 spherically. The first filling of the hydraulic unit 3 is preferably carried out as a pressure filling by means of a filter housing 49 surrounding but not shown filling tool. The pressure filling serves to overcome the resulting pressure drop at the other check valve 34 and to ensure rapid filling of the hydraulic unit 3 within the available cycle time during the initial assembly of the internal combustion engine and possibly also to allow a filling of the spring-loaded pressure accumulator 20. Of course, integrated inserts, in which the filter housing and the valve carrier are integrally formed, for example as plastic injection molded parts, also belong to alternative embodiments of the filling device 6. Also, both such inserts as well as the valve carrier as a single part instead of pressing by expert joining techniques, such as screwing, caulking, gluing, etc. are secured in the bore 37. Finally, it is also conceivable to carry out the upper housing part as a moderate hydraulic fluid pressure exposed plastic part, in which the stationary relative to the upper housing part components of the filling device are already integrated.

The ventilation of the hydraulic unit 3 required during the filling process takes place via vent holes 51 which are in FIG. 1 and in the greatly enlarged bottom view of the upper housing part 10 according to FIG. 8 are shown. The vent holes 51 are calibrated holes made, for example, by laser drilling or punching, the diameter of which in this embodiment is about 0.4 mm. In FIG. 8 is also an inserted between the upper housing part 10 and the lower housing part 9 seal 52 recognizable, which is formed here as sprayed onto the upper housing part 10 profile made of elastomeric material.

LIST OF REFERENCE NUMBERS

1

cylinder head

2

Cylinder head cover

3

hydraulic unit

4

hydraulic valve

5

Hydraulikmitteleinfüllstutzen

6

filling

7

camshaft

8th

hydraulic housing

9

Housing bottom

10

Housing top

11

screw

12

transmitter unit

13

supporting

14

cam follower

15

role

16

pump pistons

17

pressure chamber

18

Pressure relief chamber

19

piston

20

accumulator

21

sensor

22

channel

23

channel

24

receiver unit

25

takers housing

26

slave piston

27

hydraulic valve clearance compensation element

28

valve brake

29

ring groove

30

drilling

31

check valve

32

branch bore

33

filter element

34

another check valve

35

closure means

36

strainer

37

drilling

38

unit

39

valve

40

sealing seat

41

Bullet

42

valve spring

43

undercut

44

valve cap

45

support ring

46

body

47

collar

48

recess

49

filter housing

50

strainer

51

vent hole

52

poetry

Claims (13)

1. Hydraulic unit for a cylinder head (1) of an internal combustion engine having an electrohydraulic valve controller, which hydraulic unit comprises

   ■ at least one master unit (12) which is driven by a camshaft (7),

   ■ at least one valve-side slave unit (24),

   ■ at least one electrically actuable hydraulic valve (4),

   ■ at least one pressure relief space (18)

   ■ and at least one variable-volume pressure space (17) which is arranged in the transfer direction between the associated master unit (12) and the associated slave unit (24) and can be connected via the associated hydraulic valve (4) to the associated pressure relief space (18),

   at least the master unit (12), the slave unit (24), the pressure space (17), the hydraulic valve (4), the pressure relief space (18) and at least one non-return valve (31) belonging in one assembly with a common hydraulic housing (8) to the pre-assembled hydraulic unit (3) which is fastened to the cylinder head and is connected to the hydraulic-medium supply of the internal combustion engine via the non-return valve (31) which opens in the direction of the hydraulic unit (3), characterized in that at least one filling apparatus (6) which is independent of the hydraulic-medium supply, is configured on the hydraulic housing (8) and has a closure means (35) is provided in addition to the non-return valve (31) for the initial filling of the pressure relief space (18) and/or the pressure space (17) with hydraulic medium.
2. Hydraulic unit according to Claim 1, characterized in that the closure means (35) is configured as a further non-return valve (34) which opens in the direction of the hydraulic unit (3) and upstream of which in the filling direction a sieve filter (50) which is fastened in a filter housing (49) is connected.
3. Cylinder head of an internal combustion engine having an electrohydraulic valve controller, the cylinder head comprising a hydraulic unit according to Claim 1.
4. Cylinder head according to Claim 3, characterized in that the hydraulic housing (8) has at least one ventilation hole (51) which communicates with the pressure relief space (18).
5. Cylinder head according to Claim 3, characterized in that the pressure relief space (18) is delimited by a piston (19), loaded with spring force, of a pressure accumulator (20) which is arranged in the hydraulic housing (8).
6. Cylinder head according to Claim 3, characterized in that precisely one filling apparatus (6) is provided which is accessible as a result of its direct arrangement below a hydraulic-medium filler neck (5) of a cylinder-head cover (2) which is mounted on the cylinder head (1).
7. Cylinder head according to Claim 3, characterized in that the closure means (35) is configured as a further non-return valve (34) which opens in the direction of the hydraulic unit (3).
8. Cylinder head according to Claim 7, characterized in that the hydraulic housing (8) comprises a housing lower part (9) and a housing upper part (10) which closes the former, the master unit (12), the slave unit (24), the pressure space (17), the hydraulic valve (4), the pressure relief space (18) and the non-return valve (31) being arranged in the housing lower part (9) and the further non-return valve (34) being arranged in the housing upper part (10).
9. Cylinder head according to Claim 8, characterized in that a seal (52) is provided between the housing upper part (10) and the housing lower part (9), which seal (52) is preferably pressed or injection-moulded onto the housing upper part (10) and is composed of elastomer material.
10. Cylinder head according to Claim 8, characterized in that the further non-return valve (34) is configured as a structural unit (38) which is arranged in a hole (37) of the housing upper part (10) and has, as minimum extent, a valve support (39) which is fastened in the hole (37), a ball (41) which interacts with a sealing seat (40) which runs on the valve support (39), a valve spring (42) which loads the ball (41) in the direction of the sealing seat (40), and a valve cap (44) which is snapped into a radially circumferential undercut (43) of the valve support (39) in order to secure the valve spring (42) and the ball (41).
11. Cylinder head according to Claim 10, characterized in that the structural unit (38) additionally comprises a supporting ring (45) with a disc-like main body (46) and an inner-side collar (47), which collar (47) is snapped into the undercut (43) in order to fix the supporting ring (45) on the valve side, so as to support the valve cap (44) axially, and which main body (46), in order to fix the supporting ring (45) on the housing side, protrudes radially beyond the hole (37) at least in sections and engages into a recess (48) which runs between the housing upper part (10) and the housing lower part (9).
12. Cylinder head according to Claim 7, characterized in that the filling apparatus (6) comprises a dirt filter (36) which is arranged upstream of the further non-return valve (34).
13. Cylinder head according to Claims 10 and 12, characterized in that the dirt filter (36) is configured as a sieve filter (50) which is fastened to an annular filter housing (49), so as to preferably protrude spherically into the filter housing (49), the filter housing (49) which is produced in a plastic injection-moulding process preferably being fastened to the housing upper part (10) by being pressed or screwed into the hole (37).

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