The invention relates to a tensioning device for a endless drive, in particular
Chain drive, especially for
a final drive for
an internal combustion engine of a motor vehicle.
Endless drives, in particular chain drives, are used in many applications, in particular in applications in connection with the drive of camshafts and ancillaries of internal combustion engines of motor vehicles. In particular chain drives have proven to be low-maintenance and durable as control drives. For clamping such Endlostriebe sliding elements are usually used, which act on the Endlostrieb for clamping. Such sliding elements are, for example, arranged pivotably on a base body and subjected to a force by means of a hydraulic tensioning device, so that they exert a force on the endless drive and tension it. In particular, hydraulically actuated clamping devices are used in the Lostrum of chain drives for wear and thermal expansion compensation. It can come here at standstill of Endlostriebes due to the principle-related retractive torques, in particular of camshafts to emptying of the hydraulically effective high-pressure chamber of the hydraulic tensioning device. When restarting the internal combustion engine, the hydraulic tensioning device again requires a short time to fill the high-pressure chamber and the hydraulic tensioner to take effect, during which it can come to noise due to striking of the components by insufficient loading of the tensioning device and / or the sliding element and / or the Endlostriebes arises and which is perceived as unpleasant. From the prior art is for example from the DE 37 14 645
known that a freewheel or a detent position is provided for the damping element, so that the damping element can follow rapid oscillations of Endlostriebs. From the DE 40 01 304 C2
It is known to decouple a band rail noisily from the motor housing, that the damping properties are effected by an elastic ring which surrounds a mushroom-shaped pressure piece and, moreover, wherein the bearing bush of the pivotable mounting has an elastic layer for floating mounting. Next chain tensioner to avoid this problem have been formed with an oil reservoir upstream of the high-pressure chamber or with a mechanical locking system, which should avoid a complete return stroke of the tensioner and thus a striking. On tensioners with oil reservoir is disadvantageous that the oil reservoir while shortening the time of oil pressure build-up until the hydraulic tensioner is fully effective, a complete suppression of noise during the first idle strokes of the tensioner is not possible. Moreover, the construction with oil reservoir requires additional channels and / or bores in the hydraulic tensioning device and is much more space consuming, whereby the desired goal of the noise avoidance can not be completely achieved (a similar construction is in the DE 40 35 823 C1
suggested). In the known embodiment of clamping devices with locking system, the complete return stroke of the hydraulic tensioning device is prevented by a mechanical locking device. In this case, however, the hydraulic tensioning device and the housing (the main body) must be processed consuming, in order to ensure a reasonably satisfactory functioning of the locking functionality. The production is extremely expensive. Immediately after reaching a new detent position the necessary return stroke to control the dynamics is mechanically limited, which has an undesirable increase in average power of Endlostriebes result.
The invention is a tensioning device for a Endlodrieb with a
To provide hydraulic tensioning device, the said disadvantages
will be a jig for
a endless drive, in particular chain drive, in particular for a
Endless drive proposed an internal combustion engine of a vehicle,
with at least one sliding element acting on the endless drive for clamping,
the pivotally mounted on a base body and means
a hydraulic tensioning device is acted upon. It is intended
that parallel to the clamping device on an elastic clamping means
the sliding element opposite
the clamping device biasing acts. In all cases, in
which the clamping device due to not yet fully built up oil pressure
or due to other circumstances
no sufficient, an acoustic noise such as by striking
of the sliding element on the base body
causes avoiding force, causes the parallel to
Clamping device acting elastic clamping means a bias
the sliding element opposite
the clamping device. A striking of the sliding element on the body finds
consequently, not or not in such a way,
that acoustically effective parts come into contact with each other, such as metal
In a preferred embodiment, it is provided that the tensioning means is an elastomeric body. Elastomeric bodies have the advantage that due to their material properties they have a definite, predetermined elasticity. On this way, it is very easy to select and use a clamping device with the desired specifications, these specifications being independent of the operating state of the endless drive, since they are based solely on the properties of the elastomer body. It is therefore (in contrast to the hydraulically acting clamping device) irrelevant whether the Endlostrieb is just put into operation or has been in operation for quite some time; The elastomer body always has the damping values predetermined by its material properties with a preload determined by its material properties.
a further preferred embodiment
consists of the elastomer body
made of plastic. Plastics can be targeted within wide limits
Manufacture to specific specifications are readily available and
a further embodiment
it is provided that the elastomeric body a locking member for releasable attachment
at the base body
or on the sliding element. The elastomeric body is thus carried out releasably, wherein
Attachment a locking member, for example in the form of a pin with
Undercut or in a similar
is available. If detected after a long period of operation
that should be the elastomeric body
no longer has the optimal specifications and damping characteristics,
This can be easily detached from its attachment and through
to be replaced by a new one. With a suitable attachment of the elastomeric body and / or
of the locking member is this not even more or less complete disassembly
the tensioning device required.
a preferred embodiment
has the sliding element or the base body to a contact surface to
Applying to the clamping device. The contact surface is used
in this case as a defined position in which the clamping means acts
becomes. This allows the desired within wide limits
Properties, especially with regard to damping and bias influence.
a preferred embodiment
is the contact surface
formed on a projection. This can be a substantially
line or punctiform,
but in any case exactly defined loading of the clamping device
through the contact surface
a particularly preferred embodiment
is the contact surface
a convex surface. hereby
effect a wide range of effective, but this clearly defined contact surface.
a further embodiment
the tensioning device is a hydraulic piston / cylinder unit.
Such piston / cylinder units are known in the art
known and readily available
and reasonably priced.
In particular, lets
the clamping device according to the invention by
Easily modify such known devices,
by the clamping device according to the invention
a particularly preferred embodiment
the biasing force of the clamping device is so large that
At reduced clamping force of the clamping device, a touch of the
Sliding element with the clamping device and / or with the main body in
Substantially or completely
is avoided. That way
be sure to avoid it due to undamped striking of example
metallic parts of the tensioning device and the sliding element or
of the main body and
of the sliding element to a noise
("Rattle") comes. The only
takes place between the clamping device and the contact surface. At the same time
a still effective bias and thus voltage of Endlostriebs
causes, but the working damping but
takes place through the clamping device.
emerge from the dependent claims
and combinations thereof.
Invention will be described below with reference to embodiments and drawings
closer to it
1 a schematic representation of a Endlostriebs with a clamping device and
2 a clamping device with clamping device and clamping device.
1 shows a schematic representation of a Endlostriebes 1 namely a chain drive 2 , an internal combustion engine 3 , The chain drive 2 is from a crankshaft wheel 4 the internal combustion engine 3 drives and drives ancillaries 5 as well as camshafts 6 , Inside of the chain drive 2 is a tensioning device to ensure sufficient chain tension 7 arranged, which is a basic body 8th that is due to the internal combustion engine 3 is arranged, and one to the main body 8th via a pivot axis 9 pivotally mounted sliding element 10 having. Between the main body 8th and the slider 10 is a clamping device to form a clamping action 11 arranged, namely a hydraulic piston / cylinder unit 12 , The hydraulic piston / cylinder unit 12 causes a between the main body 8th and the slider 10 on the inside, acting outward force application of these two components, so that these apart and on the inside of the chain drive 2 pressed, causing the chain drive 2 is tense. In particular, also the main body 8th in turn, at least in sections in the form of a shoe 13 be formed, so that the chain drive 2 is subjected to internal load both on Lostrum and on the load side, in order to tension it. The exact arrangement and design of the clamping device 7 is of course dependent on the design of the endless drive 1 in view of the structural requirements of the internal combustion engine 3 and the number and arrangement of the ancillary units to be driven 5 and / or camshafts 6 , The illustration shown here is exemplary and only to clarify the principal mode of action.
2 shows the tensioning device 7 , The main body 8th is as a holding device 14 for one at the base body 8th arranged sliding block 13 educated. The main body 8th points to the slide shoe 13 essentially opposite side a holding fork 15 for receiving the pivot axis 9 on top of that, the sliding shoe 13 essentially opposite, the sliding element 10 is arranged pivotably, namely with its one, upper side 16 over the pivot axis 9 hinged on one side, with its other, lower end 17 essentially free-moving. The main body 8th points essentially transversely to the sliding element 10 a recording 18 on, in which the clamping device 11 , namely, the hydraulic piston / cylinder unit, is introduced. This applied with a stamp 19 one on the slider 10 trained, the stamp 19 facing (and thus a sliding surface 20 substantially opposite) pressure acting surface 21 , Spaced to the clamping device 11 towards the pivot axis 9 is at the body 8th a contact surface 33 in the form of a projection 22 formed, with the projection 22 a substantially convex surface 23 is. The convex surface 23 forms a substantially parallel to the pivot axis 9 running, half-barreled training 24 , This is located on a printing surface 25 one on the slider 10 the contact surface 33 opposite clamping device 26 at. The clamping device 26 is as an elastomeric body 27 formed, preferably made of plastic 28 consists. For holding the clamping device 26 has the base body facing side of the sliding element 10 a recess 29 on, for example, as an undercut hole 30 can be trained. The clamping device 26 has one of the recess 29 form-fitting locking element 31 on, which is for example mushroom-shaped. By means of the locking member 31 can the clamping device 26 detachable in the recess 29 on the slider 10 Fasten.
In installation position, so with the arrangement of the clamping device 7 within the envisaged endless drive 1 , the clamping device acts 26 through its support on the contact surface 33 of the basic body 8th biasing, parallel to the clamping device 11 , By suitable choice of the clamping device 26 Especially with regard to its spatial dimension and its material properties (in particular damping), the degree of bias can be set within wide limits. In principle, it is achieved by the selected arrangement shown here that already a certain deflection of the sliding element 10 around the pivot axis 9 relative to the main body 8th and the shoe arranged thereon 13 is effected, even if the clamping device 11 not yet their full effectiveness, in particular has not yet reached their full work damping, as for example when cold starting the engine or after another stoppage of the engine by previous oil pressure loss within the hydraulic piston / cylinder unit 12 the case may be. The chosen arrangement can further be a metallic striking of the sliding element 10 on the body 8th or on the stamp 19 the clamping device 11 avoid, so that no unwanted noise in the start-up phase and at the beginning of operation of the clamping device occur. It is hereby in addition to the bias parallel to the chuck a targeted stop 32 of the sliding element 10 in the area of the printing area 25 opposite the contact surface 33 causes a mechanical interference of metallic components is avoided. In this way, can be an undesirable noise in an operating condition in which the hydraulic piston / cylinder unit 12 has not yet reached its full effectiveness, avoid. The working damping is still of the, compared to elastomers considered more efficient clamping device 11 namely, the hydraulic piston / cylinder unit 12 , causes. The preload acting parallel to this by the clamping means 26 serves only the purposeful bias and to avoid acoustic abnormalities. Of course, it can be parallel to the clamping device 11 acting bias within wide limits by suitable choice of the clamping device 10 and its configuration vary and adjust, so that the requirements of various constructive embodiments of the clamping device 7 , depending on their arrangement on various engine devices, can be accommodated within wide limits.
- endless drive
- chain drive
- Internal combustion engine
- crankshaft gear
- swivel axis
- tensioning device
Piston / cylinder unit
- holding fork
- sliding surface
- Pressure acting area
- head Start
- half-barreled training
- print area
- clamping means
- elastomer body
- locking member
- contact surface