EP1492943B1 - Device for modifying the timing of gas exchange valves of an internal combustion engine, in particular a device for hydraulically adjusting the rotational angle of a camshaft in relation to a crankshaft - Google Patents

Abstract

The invention relates to a device (1) for hydraulically adjusting the rotational angle of a camshaft in relation to a crankshaft of an internal combustion engine. Said device consists of a drive unit (4) that forms a driving connection to the crankshaft and an output unit (5) that is connected to the camshaft in a fixed manner. The drive unit (4) has a force transmission connection to the output unit (5) by means of at least two pressure chambers (6, 7) that are configured in the device (1), which, when subjected to pressure, cause a relative torsional stress or a hydraulic loading force on the output unit (5) in relation to the drive unit (4), whilst continually compensating external hydraulic fluid leakages. The device (1) also comprises a spiral spring (8), which is located outside the device (1) and is designed to equalize the adjusting speeds in both adjusting directions. According to the invention, the spiral spring (8) is positioned in an annular chamber, encapsulated by an additional housing (11). The annular chamber can be filled completely with the external hydraulic fluid leakages of the device (1), whereby said hydraulic fluid acts simultaneously as a damping medium for the resonant oscillations of the spring windings (13) of the spiral spring (8), resulting from vibrations of the internal combustion engine.

Description

Field of the invention

The invention relates to a device for changing the timing of Gas exchange valves of an internal combustion engine according to the preamble forming Features of claim 1, and it is particularly advantageous to a device to the hydraulic angle adjustment of a camshaft opposite a crankshaft feasible.

Background of the invention

From DE 100 07 200 A1 is a generic device for changing the timing of gas exchange valves of an internal combustion engine known the at the drive end of a cylinder head of the engine mounted camshaft and arranged as a function of different Operating parameters of the engine controllable hydraulic Actuator is formed. This device consists essentially of one in driving connection with the crankshaft and two axially Side covers limited drive unit and a rotatably with the Camshaft connected and used in the drive unit output unit, the alternately formed over at least two within the device or simultaneously acted upon by a hydraulic pressure medium Pressure chambers are in power transmission connection. The drive unit is in this device in concrete execution by a with an outer Tooth formed hollow cylindrical drive wheel formed in which through several radial partitions several hydraulic work spaces arise. As output unit is in this device accordingly an impeller provided with a plurality of radially from the Wheel hub is formed away extending wings, which occupy the work spaces the drive unit in each case two of said hydraulic pressure chambers divide. When pressurizing these pressure chambers is thus under permanent compensation of external pressure medium leakage a relative rotation or a hydraulic clamping of the output unit relative to the drive unit the device and thus the camshaft relative to the crankshaft the internal combustion engine. In addition, this device for alignment their adjustment speeds in both adjustment directions and to achieve a preferred for the start of the internal combustion engine position of the output unit to the drive unit on a spring means, which as outside the Device in front of one of the side cover of the drive unit arranged coil spring trained and with one end to the drive unit and with the other end is attached to the output unit.

In this known device, however, it has been found in practice that the coil spring used due to their free arrangement outside the Device by the vibrations emanating from the internal combustion engine is excited to resonant vibrations. Then swing the coil spring in their resonance frequencies, it comes in the worst case to such a large Vibration amplitudes that the occurring voltage overshoots lead to breakage of the coil spring. With a modified winding of the spiral spring can indeed by limiting the available path to the vibration of the Spring winding, the resonance frequency can be reduced, such measures However, have proved to be insufficient, the coil spring in any case safely designed against breakage.

Object of the invention

The invention is therefore based on the object, a device for changing the timing of gas exchange valves of an internal combustion engine, in particular device for hydraulic rotational angle adjustment of a camshaft over a crankshaft, to design, in the absence of any adverse effects the function of the device and without alterations of the Installation space of the device with simple means one of the vibrations of the Internal combustion engine excited swinging of the coil spring in their resonance frequencies and thus avoided a vibration breakage of the coil spring becomes.

Summary of the invention

This object is achieved in a device according to the preamble of the claim 1 according to the invention solved such that the outside of the device arranged coil spring by encapsulation by means of an additional housing in one together with the adjacent side cover of the drive unit formed, closed annular space is arranged, which in the Cooperation with those occurring during operation of the internal combustion engine Centrifugal forces completely with the external pressure medium leaks of the device fillable and from the hydraulic pressure medium as leakage again can be discharged, with completely filled annular space, the hydraulic Pressure medium at the same time as a damping agent against the vibrations of the Internal combustion engine resulting resonance frequencies of the spring coils the spiral spring is formed.

In an expedient development of the inventively designed device the additional housing is preferably made of a cup-shaped Housing cover, incorporated in the bottom of a coaxial circuit breaker is and which forms the outer boundary walls of the annulus, as well from a sleeve-shaped housing hub, which in the circular opening in Housing cover is inserted and the inner boundary wall of the annulus forms. The two-part design of the additional housing has become doing particularly advantageous in terms of cost-effective production of Housing parts as punched drawing parts and with regard to the attachment of the ends the coil spring on the one hand on the drive unit and on the other hand on the output unit proved. It is also conceivable, however, a more than two-part training of the housing and its production in non-cutting or spannierender Production.

As an advantageous embodiment of the cup-shaped housing cover of the invention In addition, it is proposed that to form this with a peripheral wall, which is approximately the Outer diameter of the adjacent side cover of the drive unit corresponding Inner diameter and has an extended edge portion, with which the housing cover on the side cover of the drive unit can be locked. The peripheral wall is preferably perpendicular to the bottom of the housing cover Angled and has by the extended edge portion a height, over the width of the arranged in the annular space of the housing coil spring goes slightly beyond.

For locking the housing cover on the side cover of the drive unit the housing cover in a further embodiment of the invention has a circumferential Stage in its peripheral wall, the front side of the side cover of the Drive unit is applied and thus on the one hand an axial stop for the housing cover to avoid axial jamming of the housing arranged spiral spring forms and on the other hand, the housing cover to Side cover of the drive unit centered. By several in the extended one Edge part of the peripheral wall of the housing cover evenly distributed circumferentially arranged locking lugs, which engage behind the side cover of the drive unit, The housing cover is then form-fitting on the side cover of the drive unit secured and axially secured against unintentional loosening. Of the necessary space for the locking lugs can either by a circumferential Grooving in the adjacent edge part of the lateral surface of the drive unit or by a slightly larger diameter than the drive unit trained side cover of the drive unit can be created. Alternatively, it is also possible in the edge part of the lateral surface To incorporate the drive unit only local recesses, in the same Distance as the locking lugs on the housing cover are arranged to each other and at least have their width, so that the housing cover in addition is also secured against rotation in the circumferential direction. To avoid pressure medium leaks In addition, at this juncture, it has proven to be advantageous proved, between the step in the peripheral wall of the housing cover and the side cover of the drive unit, a ring seal made of rubber or Insert plastic, which in the attachment of the housing cover over the Latches in its peripheral wall axially between the housing cover and the drive unit is clamped. It is also possible, however, the attachment of the housing cover on the side cover of the drive unit as a press fit interpreted and thus the junction between the housing and the Side cover without additional sealant radially against pressure medium leaks seal.

The sleeve-shaped housing hub of the device according to the invention On the other hand, in an advantageous embodiment has a cylinder wall an approximately the inner diameter of the circular breakthrough in the housing cover corresponding outer diameter, which is used to lock the housing hub on the output unit on its front side with an inwardly directed Bending is formed. This will be on the housing hub formed annular base through which inserted into the housing hub Central screw can be passed, with the housing hub bolted together with the output unit of the device to the camshaft becomes. In its axial length, the housing hub is designed such that that with their other front side slightly out of the circle breakthrough protruding in the housing cover and this by an outwardly directed Bending of its edge part closes. As the housing hub through their attachment to the output unit represents a camshaft-fixed component, This can be seen from the case cover outstanding edge part in particular Advantageously, in addition to attaching further, for the function the device necessary components are used, for example by Connection to a pulser of a device for detection the camshaft position relative to the crankshaft position od. Like ..

Another feature of the sleeve-shaped housing hub of the invention trained device is that the cylinder wall partially as a hollow square is formed, on which the complementarily formed inner End of the coil spring is positively secured. This concerns in particular the disposed within the annular space of the housing part of the cylinder wall the housing hub and means that the inner end of the coil spring is preferred is formed so that it is at least three sides of the Hohlvierkantes the Housing hub encloses and thus the coil spring by positive locking rotation on the housing hub and on this in turn to the output unit of the Locked device. The diameter of the hollow cylindrical part of the housing hub and the side length of the Hohlvierkantes the housing hub are here preferably formed identically and correspond approximately to the diameter of the Screw head of the central screw, with the housing hub and the output unit are bolted to the camshaft. However, there is also the Possibility of the diameter of the housing hub and the side length of the Hohlvierkantes form with different dimensions or the housing hub to be provided with another polygonal hollow profile cross section at the inner end of the coil spring then for positive fastening is complementarily adapted on the housing hub. It is the same also possible, the housing hub over its entire length hollow cylindrical form and trained in this case without additional deformations inner end of the coil spring by a rivet or screw od. Like. Non-positively fastened to the housing hub.

The outer end of the coil spring, however, in a further embodiment of the Inventively designed device preferably bent hook-shaped trained and at an axially projecting suspension point on the Drive unit of the device positively secured. As a particularly advantageous It has been proven this suspension point for the outer end of the Spiral spring by an already arranged on the drive unit of the device Component, such as in Rotationskolbenverstellern by a extended fixing screw to form the side cover of the drive unit However, also provided specifically for the spring attachment suspension points can be arranged on the drive unit. Likewise is It is possible here that the outer end of the coil spring without additional deformations form and od by a rivet or screw. Like. non-positively attached to the drive unit of the device.

Finally, it is designed as a further feature of the invention Device still proposed that the external pressure medium leaks the Device via gap seals between the drive unit and the output unit targeted to a coaxial breakthrough in the housing adjacent Side cover of the drive unit discharged and from there by a Annular gap between the opening in the side cover and the outside of the Housing hub are introduced into the annular space of the housing. These external Pressure medium leaks occur by design in all known hydraulic Devices for adjusting the angle of rotation of a camshaft, the associated volume and pressure loss in the hydraulic Pressure chambers of the device permanently via a corresponding control the device is compensated. This results in the operation of the internal combustion engine a constant leakage flow, at least in the case of chain or gear-driven Devices usually directly into the cylinder head of the Internal combustion engine derived in the inventively designed device However, initially collected in the additional housing. The trapped pressure medium leaks are completely depressurized and flow on the described way as long as in the housing until the formed in this Annulus completely filled and the spring coils of the coil spring on all sides are enclosed by the pressure medium. That between the spring coils located pressure medium must thus permanently when swinging the spring be displaced and caused by its viscosity damping the spring vibrations. Through a further annular gap between the housing cover and the housing hub, the pressure medium leaks are then in known manner again from the housing in the cylinder head of the engine derived, where it is alternatively possible, the feeder and / or the discharge of pressure medium leaks in and out of the housing to be realized via dedicated inflows and / or outflows.

The inventively designed device for changing the timing of gas exchange valves of an internal combustion engine, in particular device to the hydraulic angle adjustment of a camshaft opposite a crankshaft, thus facing those known from the prior art Devices have the advantage of being outside the device one of the side cover arranged on the drive unit coil spring Encapsulation by means of an additional housing, which with the already existing Pressure medium leaks of the device can be filled, not now more freely arranged but on all sides of the hydraulic pressure medium of the Device is enclosed and thus in their vibration of the internal combustion engine excited resonant vibrations hydraulic damped becomes. As a result, the vibration amplitudes are reliably kept so low that no voltage peaks in the spring coils more occur and avoided in any case a vibration fracture of the coil spring becomes. In addition, such damping has proven to be durable and additionally has the advantage that the function of the device is not affected and that the additional housing no changes requires the existing space for the device.

Brief description of the drawings

Figur 1

eine Sprengdarstellung der erfindungsgemäß ausgebildeten Vorrichtung;

Figur 2

einen Längsschnitt durch eine erfindungsgemäß ausgebildete Vorrichtung;

Figur 3

eine vergrößerte Darstellung der Einzelheit X nach Figur 2.

The invention will be explained in more detail below with reference to an embodiment and is shown schematically in the accompanying drawings. Showing:

FIG. 1

an exploded view of the device according to the invention;

FIG. 2

a longitudinal section through an inventively designed device;

FIG. 3

an enlarged view of the detail X of Figure 2.

Detailed description of the drawings

From Figures 1 and 2 is clearly a device 1 for changing the Control times of gas exchange valves of an internal combustion engine forth, the exemplified as a vane-adjusting device for hydraulic rotation angle adjustment a camshaft relative to a crankshaft and formed in Dependence of various operating parameters of the internal combustion engine controllable is. This device 1 is at the drive-side end of a cylinder head the internal combustion engine mounted, not shown in the drawings Camshaft attached and essentially consists of one with a also not shown crankshaft in drive connection standing drive unit 4 and from a non-rotatably connected to the camshaft output unit 5th

In particular, by the exploded view of the device shown in Figure 1 1, it can be seen that the drive unit 4 by one of two side covers 2, 3 axially limited and formed with an external toothing Drive wheel is formed, in which by unspecified several Partitions several hydraulic work spaces arise. The output unit 5 of the device 1, however, clearly visible by a in the drive unit 4 usable impeller formed, which with several radially extending from the wheel hub, also unspecified Wings is formed. These wings divide the working spaces in the Drive unit 4 in two oppositely acting hydraulic pressure chambers 6, 7, via which the drive unit 4 and the output unit 5 of the Device 1 by alternating or simultaneous pressurization with a hydraulic pressure medium together in power transmission connection stand. The pressurization of the pressure chambers 6, 7 thus causes a Relative rotation or hydraulic clamping of the output unit. 5 relative to the drive unit 4 or the camshaft with respect to the crankshaft, wherein between the drive unit 4 and the output unit 5 design-related Pressure medium leaks arise from the device. 1 be removed and constantly balanced.

In addition, the device 1 for the adjustment of their adjustment speeds in both Verstellrichtungen and to reach one for the start of Internal combustion engine prefer position of the output unit 5 against on the camshaft alternating moments acting spring means, which in Figure 1 clearly visible as outside the device 1 in front of the side cover 2 of the drive unit 4 arranged and with one end 9 on the drive unit 4 and attached to the other end 10 of the output unit 5 Spiral spring 8 is formed.

Since arranged outside the device 1 coil spring 8 by the Internal combustion engine excited vibrations to resonant vibrations is caused by further swing until the breakage of the coil spring. 8 can lead, this, as can be seen in Figures 2 and 3, according to the invention a closed annular space 12 arranged by encapsulation the coil spring 8 by means of a particularly clearly shown in Figure 1 additional housing 11 together with the adjacent side cover 2 the drive unit 4 is created. In this closed annulus 12 are the external pressure medium leaks of the device 1 initially collected as long as until the hydraulic pressure medium in cooperation with the in operation the internal combustion engine acting centrifugal forces the annular space 12 in Housing 11 completely filled from radially outside to radially inside and then as pressure medium leakage is removed from this again. At complete filled annulus 12 thus become the spring coils 13 of the coil spring 8 enclosed on all sides with the hydraulic pressure medium, so that the Any existing pressure medium leaks of the device 1 as a damping means against the resulting from vibrations of the internal combustion engine resonant vibrations the coil spring 8 act.

In concrete execution, therefore, the additional housing 11, as in Figure 1 shown, from a cup-shaped housing cover 14 with a in the bottom 15 incorporated coaxial circular aperture 16 and from a in this circular opening 16 plug-in housing hub 17th

The cup-shaped housing cover 14 in this case has one in Figure 2 with the reference numeral 18 numbered peripheral wall at right angles to the bottom 15 is angled and approximately the outer diameter of the adjacent Side cover 2 of the drive unit 4 corresponding inner diameter having. Over an extended edge portion 19 of this peripheral wall 18 is the housing cover 14 can then be locked on the side cover 2 of the drive unit 4, by having a diameter-reduced circumferential step 20 in FIG its peripheral wall 18 centered on the side cover 2 and by several in the Edge portion 19 of the peripheral wall 18 evenly circumferentially distributed and the Side cover 2 engaging behind latching lugs 21 attached to this form-fitting becomes. The necessary space for the locking lugs 21 is thereby by a circumferential recess 31 in the adjacent edge part of the lateral surface the drive unit 4 created.

By contrast, the sleeve-shaped housing hub 17 has, as also shown in FIG. 2 shows a cylinder wall 22 with an approximately the inner diameter the circular aperture 16 in the housing cover 14 corresponding outer diameter on, for locking the housing hub 17 on the output unit 5 at its one end face 24 with an inwardly directed bend 23 is formed. By the thus formed annular bottom is then passed through a central screw not shown in the drawings, with the housing hub 17 together with the output unit. 5 the device 1 is screwed to the camshaft. With her other End face 26 protrudes the housing hub 17 while slightly from the circuit breaker 16 in the housing cover 14 out and closes this by one after outwardly directed, unspecified bend their edge section.

In addition, FIGS. 1 and 2 show that the cylinder wall 22 of the housing hub 17 within the annular space 12 in the housing 11 as a hollow square 25 is formed, on which the complementarily formed inner End 10 of the coil spring 8 is positively secured. For that purpose that is inner end 10 of the coil spring 8 shaped such that, as shown in Figure 1, on all four sides of the Hohlvierkantes 25 of the housing hub 17 abuts and thus the coil spring 8 locked by positive engagement rotationally fixed to the housing hub 17. The diameter of the hollow cylindrical part of the housing hub 17 and the side length of the Hohlvierkantes 25 of the housing hub 17 is formed identical and corresponding approximately to the diameter of the screw head of the central screw, with the housing hub 17 and the output unit 5 on the camshaft are bolted. The outer end 9 of the coil spring 8 is against how also shown in Figure 1, shown in a hook shape and on an axial protruding suspension point on the drive unit 4, which in the pictured Device 1 by an extended fastening screw 27 for the side cover 2, 3 is formed, positively secured.

Due to the enlarged view of the detail X in Figure 3 is finally still clearly that the external pressure medium leaks of the device 1 on not closer designated gap seals between the drive unit 4 and the output unit 5 targeted to a coaxial opening 28 in the housing 11 adjacent Side cover 2 of the drive unit 4 are discharged, where they pass through an annular gap 29 between the opening 28 and the housing hub 17 in the annulus 12 of the housing 11 are introduced. If the annulus 12 is then complete with filled the pressure medium leaks and all spring coils 13 of the coil spring. 8 enclosed by the hydraulic pressure medium are caused by this occurring Resonant vibration of the coil spring 8 damped and the more trailing Pressure medium is through a further annular gap 30 between the housing cover 14 and the housing hub 17 removed from the annular space 12 as pressure medium leakage.

LIST OF REFERENCE NUMBERS

1

contraption

2

side cover

3

side cover

4

drive unit

5

driven unit

6

pressure chamber

7

pressure chamber

8th

spiral spring

9

the one end

10

the other end

11

casing

12

annulus

13

spring coils

14

housing cover

15

ground

16

Circular passageway

17

housing hub

18

peripheral wall

19

edge part

20

step

21

locking lugs

22

cylinder wall

23

angulation

24

the one end face

25

Hollow square

26

the other front side

27

fixing screw

28

breakthrough

29

annular gap

30

further annular gap

31

Started

Claims (8)

1. Device for modifying the control times of gas exchange valves of an internal combustion engine, in particular an apparatus for hydraulically adjusting the rotation angle of a camshaft in relation to a crank shaft, having the following features:

   the device (1) is arranged at the drive end of a camshaft mounted in the cylinder head of the internal combustion engine, and said device is embodied essentially as a hydraulic actuator drive which can be controlled as a function of various operating parameters of the internal combustion engine.

   the device (1) is composed of a drive unit (4) which has a drive connection to a crank shaft and is bounded axially by two lateral covers (2, 3), and of an output unit (5) which is connected fixed in terms of rotation to the camshaft and is inserted into the drive unit (4),

   the drive unit (4) of the device (1) has a force-transmitting connection to the output unit (5) of the device (1) via at least two pressure chambers (6, 7) which are formed inside the device (1) and to which a hydraulic pressure medium can be applied alternately or simultaneously,

   pressure is applied to the pressure chambers (6, 7) with continuous compensation of outer pressure medium leakages and brings about a relative rotation or a hydraulic clamping of the output unit (5) with respect to the drive unit (4) of the device (1),

   the device (1) has a spring means for approximating the adjustment speeds of the device (1) in both adjustment directions and for bringing about a position of the output unit (5) with respect to the drive unit (4) which is preferred to start the internal combustion engine,

   the spring means is configured as a helical spring (8) which is arranged outside the device (1) in front of one of the lateral covers (2 or 3) of the drive unit (4), said helical spring (8) being attached by one end (9) to the drive unit (4) and by the other end (10) to the output unit (5),

      characterized in that

   the helical spring (8) which is arranged outside the device (1) is arranged, by encapsulation by means of an additional housing (11), in a common enclosed annular space (12) which is formed with the adjoining lateral cover (2) of the drive unit (4),

   which annular space (12) can be filled completely, in conjunction with the centrifugal forces occurring during the operation of the internal combustion engine, with the outer pressure medium leakages of the device (1) and out of which the hydraulic pressure medium can be conducted away again as leakage,

   in which case, when the annular space (12) is completely filled, the hydraulic pressure medium is configured at the same time as a damping means for damping the resonant frequencies of the spring turns (13) of the helical spring (8) which result from vibrations of the internal combustion engine.
2. Device according to Claim 1, characterized in that

   the additional housing (11) is preferably composed of a cup-shaped housing lid (14) with a co-axial circular breakthrough (16) formed in its base (15), and of a sleeve-shaped housing hub (17) which can be plugged into this circular breakthrough (16).
3. Device according to Claim 2, characterized in that

   the cup-shaped housing lid (14) preferably has a circumferential wall (18) with an inner diameter which corresponds approximately to the outer diameter of the adjacent lateral cover (2) of the drive unit (4), and can be locked to this lateral cover (2) by means of an extended edge part (19) of the circumferential wall (18).
4. Device according to Claim 3, characterized in that

   the housing lid (14) is centred with a peripheral step (20), with reduced diameter, in its circumferential wall (18) on the lateral cover (2) of the drive unit (4) and is attached in a positively locking fashion to said cover (2) by a plurality of latching projections (21) which are distributed along the circumference of the edge part (19) of the circumferential wall (18) and engage behind the lateral cover (2).
5. Device according to Claim 2, characterized in that

   the sleeve-shaped housing hub (17) preferably has a cylinder wall (22) with an outer diameter which corresponds approximately to the inner diameter of the circular breakthrough (16) in the housing lid (14) and can be locked with a radially inwardly directed angled portion (23) on one (24) of its end sides to the output unit (5).
6. Device according to Claim 5, characterized in that

   by means of its end-side angled portion (23), the housing hub (17) is screwed, together with the output unit (5), to the camshaft by means of a central screw and its cylinder wall (22) is configured partially as a hollow square (25) to which the inner end (10) of the helical spring (8) which is of complementary design is attached in a positively locking fashion.
7. Device according to Claim 1, characterized in that

   the outer end (9) of the helical spring (8) is preferably bent in a hook shape and is attached in a positively locking fashion to a suspension point on the drive unit (4) which protrudes away axially, preferably to an extended attachment screw (27) for the lateral covers (2, 3) of the drive unit (4) or the like.
8. Device according to Claim 1, characterized in that

   the outer pressure medium leakages of the device (1) can be conducted away in a selective fashion to a co-axial breakthrough (28) in the lateral cover (2), adjacent to the housing (11), of the drive unit (4) via gap seals between the drive unit (4) and the output unit (5),

   and can be introduced into the annular space (12) of the housing (11) through an annular gap (29) between the breakthrough (28) and the housing hub (17), and can be discharged from said annular space (12) again through a further annular gap (30) between the housing lid (14) and the housing hub (17).

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