Patent Grant
7934478
The invention relates to a camshaft adjuster for an internal combustion engine, in which lubrication is performed by a lubricant flow.
Camshaft adjusters can be roughly classified as follows:
A. Phase adjusters with a control element, that is, a functional unit, which joins in the mass flow or energy flow formed, for example, hydraulically, electrically, or mechanically and rotates with gear elements of the camshaft adjuster.
B. Phase adjusters with a separate setting element, that is, a functional unit, in which the control parameter required for the control method of the control element is formed from the controller output parameter, and a separate control element. Here, there are the following structural forms:
a. Phase adjusters with a co-rotating actuator and a co-rotating control element, for example, a step-up ratio gear, whose adjustment shaft can be advanced by a co-rotating hydraulic motor or centrifugal force motor and can be reset by a spring.
b. Phase adjusters with a co-rotating control element and a stationary, engine-fixed actuator, for example, an electric motor or an electrical or mechanical brake, see also DE 100 38 354 A1, DE 102 05 034 A1, EP 1 043 482 B1.
c. Phase adjusters with a direction-dependent combination of solutions according to a. and b., for example, an engine-fixed brake, in which part of the brake power is used for adjustments toward an advanced position, in order to tension a spring, which allows resetting after the brake is deactivated, see also DE 102 24 446 A1, WO 03-098010, US 2003 0226534, DE 103 17 607 A1.
In systems according to B.a. to B.c., actuators and control elements are connected to each other by an adjustment shaft. The connection can be switchable or non-switchable, detachable or non-detachable, lash-free or with lash, and flexible or stiff. Independent of the structural form, the adjustment energy can be realized in the form of supply through a drive output and/or brake output, as well as with the use of leakage power of the shaft system (e.g., friction) and/or inertia and/or centrifugal force. Braking, advantageously in the adjustment direction of “retarded” can also be realized under the full use or shared use of the friction power of the camshaft. A camshaft adjuster can be equipped with or without mechanical limiting of the adjustment range. As a gear in a camshaft adjuster, one-stage or multiple-stage triple-shaft gears and/or multiple links or coupling gears are used, for example, in structural form as a wobble-plate gear, eccentric gear, planetary gear, undulating gear, cam-plate gear, multiple-link or linked gear, or combinations of the individual structural forms in a multiple-stage construction.
For operation of the camshaft adjuster, a lubricant must be fed to lubricating positions, especially bearing positions and/or rolling toothed sections, wherein the lubricant is used for lubricating and/or cooling components of the camshaft adjuster that can move relative to each other. For this purpose, the camshaft adjuster has a lubricant circuit, which can be coupled, for example, with the lubricant circuit of the internal combustion engine.
From DE 102 48 355 A1, it is known to feed lubricant to a camshaft via a camshaft bearing. For this purpose, the cylinder head or the camshaft bearing has a supply channel oriented in the radial direction to the camshaft. A receiving channel (here also oriented in the radial direction) is arranged aligned with the supply channel in the camshaft and moves relative to the supply channel. In the region of the receiving channel, the camshaft has a peripheral groove in the circumferential direction, which guarantees that the transfer of lubricant from the supply channel to the receiving channel is continuous and is possible for every angle position of the camshaft, wherein the lubricant is led from the supply channel via the groove to the receiving channel.
The present invention is based on the objective of enabling
an improved supply of lubricant to the camshaft adjuster and/or
an improved installation space construction of a supply region for the lubricant.
This objective is met according to the invention.
The invention first does away with the preconception that a supply of lubricant is necessary for each angular position of the camshaft and thus a continuous lubricant supply is required. Instead, the invention uses discontinuous lubricant supply.
Such a discontinuous lubricant supply can be created in a simply way according to the invention, under some circumstances, without requiring an especially complex control or regulation unit, an actuator, or a valve. According to the invention, the lubricant supply is enabled or shut off in a motion-controlled way by the relative motion of the components of the camshaft adjuster, which include the supply channel and the receiving channel.
The solutions known from the state of the art require a ring groove in the casing surface of the camshaft or in the cylinder head or the camshaft bearing, wherein, due to the groove, a width of the camshaft bearing or a counter surface of the cylinder head requires an enlarged construction. Such additional installation-space conditions can be avoided according to the invention.
According to the invention, lubricant is transmitted only when the supply channel and receiving channel are approximately aligned with each other. In addition, leakage with reduced transport volume can lead to transmission. In addition, in the scope of the invention, a groove not completely encircling the peripheral surface can be provided in the region of the supply channel and/or receiving channel, by which the period of lubricant transmission is lengthened. In the course of the relative motion between the supply channel and receiving channel, a transfer cross section that increases with time can be formed, which falls to zero again after reaching a maximum (aligned boreholes), by which the time period of the transfer volume flow can be set. Optionally, the width of a groove that is not completely encircling in the circumferential direction can be constructed suitably for influencing the time period of the transfer volume flow.
Due to the measures according to the invention, the transport quantity of the lubricant can be reduced relative to a continuous lubricant supply. Furthermore, pulses of the lubricant flow are generated in the camshaft adjuster, which can lead to improved lubrication and improved distribution of the lubricant.
The construction according to the invention is not limited to embodiments according to the state of the art named above, in which the supply is realized via a camshaft bearing. Instead, for creating a discontinuous lubricant flow, the supply channel and receiving channel can be arranged in any components, which are moved relative to each other in the course of the rotation of the camshaft and/or the camshaft adjuster.
For the case that the transfer of lubricant through a single supply channel and receiving channel is not sufficient, several supply channels and/or receiving channels could be distributed uniformly or non-uniformly around the periphery.
If undesired pulse oscillations are produced in the lubricant circuit, at least one non-return valve could be arranged in the lubricant circuit, in particular, in the region of the camshaft adjuster, the camshaft, the camshaft bearing, or the cylinder head.
According to another construction of the invention, the pulses of the lubricant are used in such a way that downstream of the receiving channel there is a lubricant injection nozzle, from which, with increasing pressure for the opened transfer cross section, the lubricant can be discharged with increasing velocity.
Advantageous improvements of the invention emerge from the claims, the description, and the drawings. The advantages named in the introduction of the description for features and combinations of several features are merely exemplary, without these having to be necessarily realized by embodiments according to the invention. Additional features are to be taken from the drawings—in particular, the illustrated geometries and the relative dimensions of several components to each other, as well as their relative arrangement and effective connection. The combination of features of different embodiments of the invention or of features of different claims is similarly possible deviating from the selected associations of the claims and is suggested with this reference. This also relates to features that are shown in separate drawings or are noted in the associated description. These features can also be combined with features of different claims. Likewise, features listed in the claims can be left out for other embodiments of the invention.
Additional features of the invention emerge from the following description and the associated drawings, in which embodiments of the invention are shown schematically. Shown are:
In the figures, components that correspond with respect to form and/or function are to some extent provided with the same reference symbols.
The adjustment shaft 4 is driven by an electric motor 7 or is in active connection with a brake. The electric motor 7 is supported relative to the surroundings, for example, the cylinder head 8 or another engine-fixed part.
For the embodiment shown in
Here, a continuous, cyclical, pulsing, or intermittent feed and/or forwarding of a lubricant via the lubricant channels is realized. Using a feed recess 25 of the cylinder head 8, the lubricant is fed to a flow channel 26 of the camshaft 6, which communicates with a flow channel 27, which is formed with a hollow cylindrical shape between an inner casing surface 28 of the hollow shaft 16 and an outer casing surface 29 of the central screw 22. Through the use of radial boreholes 30 of the hollow shaft 16, the lubricant can emerge from the flow channel 27 outwardly in the radial direction and can be fed to the lubricating positions.
In contrast to the embodiment according to
The filter element 35 can be constructed, e.g., as
According to
For the embodiment shown in
Dead spaces according to the dead space 37 can be arranged at any position in the gear drive, as well as in the region of the camshaft, by which it can be achieved that important functional surfaces, for example, in the direct neighborhood of the dead spaces, are not “silted up” due to centrifuged contaminants in the gear. The centrifugal effect is amplified by an increase in the distance of the dead spaces from the longitudinal axis 21-21.
According to a first construction, the dead space has no additional outflow, so that centrifuged contaminant particles are deposited permanently in the dead space 37. According to the preferred construction shown in
For an alternative construction, contaminants are separated in such a way that the lubricant is guided in a flow channel with a labyrinth-like or zigzag-shape construction. Contaminant separation through such a labyrinth-like contaminant separator touches upon the different inertia of the lubricant and interfering particles in the lubricant. In particular, for high flow rates, a strong deflection of the lubricant flow can lead to the result that the particles are not deflected, but instead are deposited at the borders of the labyrinth. For the case that individual channels of the labyrinth are oriented in the radial direction, deposition in the labyrinth on surfaces on the outside in the radial direction can take place in such channels, as well as similarly in axial channels, due to the centrifugal force described above. An alternative or additional separating effect can be produced when the lubricant is decelerated and accelerated, wherein the lighter lubricant can be accelerated more easily, while contaminant particles remain behind.
In additional to generating the centrifugal effect due to rotation of the housing 9 or other parts of the camshaft adjuster 1, the centrifugal effect can be generated at least partially in such a way that the flow channels guiding the lubricant are oriented in a circular or spiral construction, so that a deposit can form on the outer boundaries of the flow channels just due to the movement of the lubricant through the curved flow channels.
Deviating from the embodiments shown in
Through the use of the diaphragms 41, 43 and throttles 42, 44, the volume flow to the camshaft adjuster is throttled. Additional throttling can be produced through the use of the filter element 35. Advantageously, the filter element is arranged in the flow direction upstream of the flow elements, so that the flow elements do not become blocked by particles or clogged over the course of time.
In addition to the use of flow elements with constant flow characteristics, a flow element that is continuous or that can be changed in steps can be used. The use of a flow element, whose flow effect is variable
The flow element is changed in such a way that, for example, the volume flow of the lubricant is held at a constant value independent of the temperature of the lubricant. It is also possible that the volume flow is increased or decreased due to an effect of the flow element in operating regions, in which there are higher or lower lubricant or cooling requirements.
For the construction of the flow elements in the form of throttles 42, 44 and diaphragms 41, 43, under some circumstances, embodiments are to be used, in which ring gaps or annular cross sections are used instead of boreholes with, for example, a circular cross sectional surface, because, under some circumstances, a borehole can be more easily blocked than a ring gap.
For the embodiment shown in
One part of the lubricant fed to the groove 48 via the receiving channel 45 and borehole 46 is led via an axial borehole 49 of the camshaft 6, which opens into the groove 48, and an axial borehole 50 of the housing 9 with a certain amount of overlap, but offset in the radial direction, in the inner space of the gear 2 to the lubricating positions, for example, to the bearing element 17, the bearing element 14, the rolling toothed connections of the wobble plate 15, and/or the bearing 19.
The other part of the lubricant fed to the groove 48 is led via a flow channel 51 with a circular ring-shaped cross section and formed between the inner casing surface of the hollow shaft 16 and the outer casing surface of the central screw 22 to at least one radial borehole 52 to a lubricating position, for example, the bearing position 17 or in the inner space of the gear 2. The groove 48 is constructed with a radial projection, which extends over the borehole 49, so that a peripheral, ring-shaped dead space 37 is formed on the outside in the radial direction. Between the boreholes 49, 50, a transfer region 53 can be formed in the shape of a recess, a radial groove, or the like, in order to allow transfer between the boreholes 49, 50 that are offset relative to each other in the radial direction. In the form of the boreholes 49, 50 that are not aligned with each other, for a partial overlap of the boreholes, a kind of diaphragm can be formed with a small transfer cross section or diaphragm cross section, although the boreholes 49, 50 can be produced with relatively large diameters and thus with rough tools.
For a construction that otherwise corresponds to
For a construction that otherwise corresponds to the embodiments described above, the camshaft 6 according to
In a deviating construction, the flow element 59 can be tensioned outward, for example, in the radial direction against the borehole 46, wherein, in this case a ring gap 60 is formed between the inner surface of the flow element and the central screw. Also, a positive-fit holding of the flow element 59, for example, in a suitable groove of the camshaft or the central screw, is conceivable. An arbitrary construction of the contours of the flow element 59 in the region of the ring gap 60 is possible for influencing the flow ratios, for example, with stepped transitions or continuous transitions.
For the embodiment shown in
The camshaft 6 is supplied with a lubricant from a lubricant gallery of the cylinder head 8. The transition of the lubricant from the engine-fixed cylinder head 8 to the rotating camshaft 6 is realized usually by known rotation transmitters. This typically involves a ring groove 64 of the outer casing surface of the camshaft 6. The ring groove 64 is enclosed by a corresponding cylindrical casing surface 65 of the cylinder head 8, to which a pass borehole or supply channel 66 oriented in the axial direction toward the ring groove 64 leads out of the lubricant gallery. The supply channel 66 can pass through the casing surface 65, as shown in
A rotation transmitter can be arranged in a radial bearing for the camshaft 6 or on a separate shoulder. For the latter, however, due to the usually larger radial gap, often sealing rings 67, 68, for example, a steel sealing ring, cast-iron sealing ring, or plastic sealing ring, are required. In an arrangement of the rotation transmitter in a radial bearing of the camshaft 6 it is to be taken into account that the bearing width is reduced by the width of the ring groove.
In another embodiment, ring grooves can be constructed fixed to the cylinder head, for example, in the bearing, the bearing bridge, or an installed bearing bushing. In the camshaft, no ring grooves 64 are required.
The use of a rotation transmitter described above causes a continuous flow of lubricant from the cylinder head 8 into the camshaft 6 due to the peripheral ring groove and the radial boreholes or receiving channels 69, which connect the ring groove 64 to the borehole 46.
For a special construction, the supply channel 66 and the ring groove 64 are arranged offset relative to each other in the axial direction, by which, in the transfer of the lubricant from the supply channel 66 to the ring groove 64, a type of throttle is created, whose opening cross section becomes smaller the greater the offset in the axial direction between the supply channel 66 and ring groove 64. A throttle effect can also be achieved for a relatively large diameter of the supply channel 66 and a large width of the ring groove 64, so that no small boreholes or grooves, which are sensitive to contaminants and production, have to be created.
According to another special construction, lubricant is fed via a cyclical lubricant supply. In such a case, the ring groove 64 is left out, so that a lubricant connection between the supply channel 66 and the receiving channels 69 is given only for rotational positions of the camshaft 6, for which the channels 66, 69 align with each other or overlap. If increased transfer times are desired, then the transition region between the supply channel 66 and receiving channel 69 of the cylinder head 8 or the casing surface of the camshaft 6 can have a groove running through a partial extent, so that a transfer from the supply channel 66 to the receiving channel 69 is possible as long as these channels 66, 69 are connected to each other by the groove. In addition, through the construction of the width profile of the groove, there can be a variable transfer of the lubricant. Thus, a volume flow and mass flow of the lubricant can be given structurally and cyclically. Furthermore, a pulsing lubricant flow can be realized, which results in fluctuations in pressure that can be used, for example, for better mixing and wetting of the lubricating positions with the lubricant. Furthermore, through pulsing lubricant flows, the risk of blockages can be reduced, for example, for diaphragms or throttles. If such lubricant pulses lead to pulse oscillations in the lubricant cycle, then a non-return valve can be arranged in the lubricant circuit, in particular, in the region of the cylinder head 8, in the region of the camshaft, and/or in the gear drive.
For the embodiment shown in
In addition to the structural measures for constructing the flow cross sections in the cylinder head and also in the camshaft, the flow ratios in the lubricant circuit in the gear can be influenced. Here, the supply borehole can be throttled through the use of a throttle or diaphragm. Alternatively or additionally, the throttling of the discharge through a rear-side closing of the gear, for example, with a sheet-metal cover, is possible, which forms, together with the adjustment shaft, a ring-shaped gap, in particular, with a gap height in the range from 0.1 to 2 mm.
In addition, it is possible to use bearings in the gear drive, which are equipped with sealing elements. According to
According to another construction of a camshaft adjuster 1, the outer casing surface of the housing 9 has recesses or windows 77, which can be distributed uniformly or non-uniformly in the peripheral direction, cf.
In addition, through the arrangement of the openings 77, 78 of the gear housing, the lubricant can be sprayed directly onto a toothed section or other lubricating positions. It is also conceivable that the spraying with lubricant is combined with the lubricant supply of other engine components, for example, a chain or a tensioner. It is also conceivable that a point or a surface outside of the gear drive 2 is sprayed with the lubricant. Lubrication is then guaranteed through the rebounding or deflected lubricant or a lubricant mist generated in this manner.
According to an alternative construction, a lubricant supply can be realized by the lubricant mist, which is already present in a timing case and which can penetrate into the camshaft adjuster through the openings 77, 78.
In another construction of a lubricant supply according to
To reliably guarantee functioning for lubrication with a lubricant mist, mist lubricant droplets, or with a lubricant stream, even at low temperatures of the lubricant or for a cold start, the lubricating positions, for example, slide bearings and/or toothed sections, are to be equipped with emergency-running properties. Such emergency-running properties can be guaranteed, for example
In particular, the lubricant reservoirs are provided by microscopically or macroscopically small pockets of the lubricating positions, in which lubricant can be stored for a cold start or for low lubricant temperatures. Better emergency-running properties can also be provided, advantageously, when roller bearings are provided at the bearing positions as much as possible.
Furthermore, for lubrication, oil dripping from an oiled traction element (timing chain) can also be used, which passed through an opening of the housing. Under some circumstances, the traction element is lubricated by wobble or spray oiling or by stripping oil from oiled chain tensioners or deflection rails. A part of the oil supplied by the chain can drop above the drive wheel (chain wheel) of the gear drive and can thus be led into openings of the gear drive lying underneath. In addition, it is possible to feed oil through the capillary effect to the gear drive or to drip positions lying above the gear drive. It is also possible that oil is “blown,” for all practical purposes, to the lubricating position, by air currents resulting, e.g., from the drive movement of the control drive or adjustment parts.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2005 059 840 | Dec 2005 | DE | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP2006/068804 | 11/23/2006 | WO | 00 | 7/2/2008 |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO2007/071518 | 6/28/2007 | WO | A |
| Number | Name | Date | Kind |
|---|---|---|---|
| 20020017257 | Axmacher et al. | Feb 2002 | A1 |
| 20030226534 | Watanabe et al. | Dec 2003 | A1 |
| 20040094113 | Honda et al. | May 2004 | A1 |
| Number | Date | Country |
|---|---|---|
| 19745234 | Apr 1998 | DE |
| 10038354 | Feb 2002 | DE |
| 10205034 | Aug 2003 | DE |
| 10317607 | Nov 2003 | DE |
| 10224446 | Dec 2003 | DE |
| 10248355 | Apr 2004 | DE |
| 0821139 | Jan 1998 | EP |
| 1043482 | Oct 2003 | EP |
| 11153014 | Jun 1999 | JP |
| 2001107709 | Apr 2001 | JP |
| 03098010 | Nov 2003 | WO |
| Number | Date | Country | |
|---|---|---|---|
| 20080308054 A1 | Dec 2008 | US |
