A belt-tensioning device, in particular for an internal combustion engine, the belt-tensioning device including a bearing housing having a latching recess, a tensioning roller, a pivoting arm and a locking device. The pivoting arm is mounted on the bearing housing, the pivoting arm being under a torsion spring load. The tensioning roller being coupled to the pivoting arm. The locking device having a first latching device and a second latching device. The first latching device and the second latching device being coupled with the pivoting arm. The latching recess interacts with at least one of the first latching device and the second latching device wherein the locking device is configured in such a way that the pivoting arm can be locked by the locking device in different predefined latching positions and the pivoting arm can be pivoted with predefined freedom in an operating position.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a belt-tensioning device for an internal combustion engine.

2. Description of the Related Art

Belt-tensioning devices are known from the prior art, e.g. from document US 2015/0031484 A1. Such belt-tensioning devices, in particular for an internal combustion engine, e.g. a fan belt drive of such an engine, generally have a tension spring, by means of which a pivoting arm having a contact pressure roller is subjected to a spring force and is pushed against a belt to permanently tension the latter. Owing to the high forces emanating from the belt and the tension spring, especially when used on large engines, safety is of great importance both during assembly and in the event of failure, e.g. if the belt tears during operation or if the spring breaks.

What is needed in the art is a belt-tensioning device which is suitable for ensuring safety during operation and assembly in an advantageously reliable manner, and in a structurally simple way.

SUMMARY OF THE INVENTION

The present invention is directed to a belt-tensioning device which can be provided particularly for a fan belt drive of an internal combustion engine and also more generally for other belt drives, especially those for use with an internal combustion engine, preferably a large engine. A large engine of this kind can be provided, for example, for a motor vehicle such as a ship, a locomotive or a commercial or special vehicle or, for example, for a stationary installation such as a combined heat and power plant or an (emergency) generating set, including those for industrial applications.

The belt-tensioning device has a pivoting arm, which is preferably formed with a shaft section or a shaft and a lever section, in particular a (tensioning) lever. In this case, the lever section is, in particular, angled, e.g. by 90°, relative to the shaft section. In general, the pivoting arm can be formed in one piece or preferably in several pieces, and, in preferred embodiments of the present invention, the tensioning lever is screwed to the shaft, for example (at the end; on a free shaft end).

Within the scope of the present invention, the pivoting arm is mounted on a bearing housing of the belt-tensioning device under torsion spring load. In this case, the bearing housing can have a mounting or bearing pedestal, in general a base on which a mounting of the bearing housing for mounting the pivoting arm is provided, in particular so as to extend away therefrom. In this case, the mounting, which is, in particular, formed integrally with the base, can be in the form of a tube section or a hollow cylinder and thus, as it were, a bearing bush. The shaft section of the pivoting arm is, in particular, mounted under a torsion spring load in the mounting, and is in particular rotatably or pivotably mounted.

To subject the pivoting arm to torsion spring loading, a tension or torsion spring is held captive between the bearing housing, in particular the bearing pedestal, and the pivoting arm. This arrangement subjects these to a load relative to one another, and can be fixed or held captive on the pivoting arm by way of a stop or contact element, for example. Design developments are, in particular, to the effect that the torsion spring is arranged around the mounting of the bearing pedestal, i.e. on the outer circumference. The torsion spring serves to enable the pivoting arm to be pressed by way of a tensioning roller in an envisaged pivoting direction against a belt (of a belt drive), i.e. in order to tension the belt. In particular at the end (at the free end thereof), the pivoting arm or the lever section thereof preferably has a tensioning roller. The shape of the pivoting arm together with the tensioning roller is thus preferably that of a crank.

The belt-tensioning device furthermore includes a locking means, which is formed by a first and a second latching device on the pivoting arm and by way of a latching recess (latching socket) on the bearing housing, which latching recess interacts with the latching devices. The latching devices are seated, for example, in a holder on the pivoting arm, in particular on the shaft section, in particular in a manner which allows detachment in each case from the pivoting arm, such as being screwed thereto. The holder for the latching devices is formed on the free end of the shaft section, i.e. on or in front of a region of connection to the lever section or behind the torsion spring in the direction from the supported end to the free end.

The latching recess on the bearing housing is preferably formed on the outer circumference of the mounting on the housing, in particular extending over a section in the circumferential direction of the mounting (around the pivoting axis), e.g. over about 45°. In this case, the holder of the latching devices and consequently also the latching devices (in the non-latching position) can furthermore also sweep the mounting at the outer circumference, in particular in all the pivoting positions of the pivoting arm, that is to say to this extent also the latching recess in accordance with the relative rotational position. The latching recess is preferably formed at a free end of the mounting, that is to say, therefore, likewise behind the torsion spring when considered in the direction from the base to the region of connection to the tensioning lever or the free end of the mounting (wherein the mounting preferably projects beyond the torsion spring for this purpose).

Within the scope of the present invention, it is furthermore envisaged that, for the intended interaction with the latching recess, the latching devices can enter the latching recess, by way of latching sections, in various (predefined) pivoting positions of the pivoting arm in order to latch thereon (latching in; particularly in latching stop contact against the latching recess). For latching in, a respective latching section can be shifted toward the mounting, or toward the pivoting axis of the pivoting arm, or can emerge from the holder. When it re-enters the holder, latching with the latching recess on the part of at least one of the latching devices can be released (unlatching). The first and the second latching device are preferably arranged adjacent to one another, in the circumferential direction (around the pivoting axis), in particular on the holder.

The first latching device is formed by a spring-loaded latching pin, which latching pin forms the latching section of the first latching device. The first latching device is preferably configured in such a way that it can be brought into a first position, in which the latching pin can emerge under a spring load on a latching side of the first latching device (a side facing the outer circumferential surface of the mounting), and furthermore in such a way that it can be brought into a second position, in which the latching pin cannot emerge on the latching side of the first latching device. Here, the latching device can preferably maintain a respective adopted first or second position, and can also do so automatically.

As a further preference, the second latching device is a screw element, in particular a blocking screw, wherein an end section of the blocking screw forms the latching section of the second latching device. However, it is also conceivable to provide a latching device which differs therefrom or to form the first latching device similarly or identically to the second latching device.

In the context of the belt-tensioning device proposed according to the invention, it is possible here for the locking device to be configured in such a way that the pivoting arm can be locked by means of the locking device in different predefined latching positions and can be pivoted with predefined freedom in an operating position, in particular an operating position subject to (belt) load, (wherein, in particular, one of the latching devices in each case enters into latching stop contact with the latching recess in the predefined latching positions). Configuration of the latching devices is thus preferably accomplished in each case by user intervention, i.e. to shift the respective latching section of one or both latching device into the latching recess or out of the latching recess.

By way of the belt-tensioning device of the present invention, it is made possible, in a simple way, to both automatically adjust the belt tension using the tensioning roller that is pushed against the belt, by virtue of the freedom allowed in operation, and to ensure safety in any operating position of a belt drive formed with the belt-tensioning device, i.e. by virtue of latching positions that must inevitably be adopted in the case of a fault.

Within the scope of the present invention, a belt drive having a belt-tensioning device as explained above is furthermore also proposed, in particular for a fan of an internal combustion engine. Wherein the belt drive has a belt, and wherein the tensioning roller is provided in such a way that it can be pushed against the belt, tensioning the latter, by way of the torsion-spring-loaded pivoting arm, in particular in the operating position of the arm.

In a belt drive of this kind formed with the belt-tensioning device, it is possible in preferred embodiments for the locking device to be configured to lock the pivoting arm in a predefined (first) latching or pivoting position. The locking takes place by way of one of the latching devices, in particular the first latching device (preferably by means of a latching pin thereof) and the latching recess, starting from the latching or pivoting position, when the locking is released by the latching device, the pivoting arm pushes the tensioning roller, under torsion-spring load, against the belt and thus into the envisaged operating position. The pivoting position, starting from which the operating position is adopted in this case is, in particular, a mounting position, in which belt mounting is made possible.

Furthermore, provision is preferably made, in the belt drive formed with the belt-tensioning device, for the locking device to be configured to lock the pivoting arm in a predefined (second) latching position by way of one of the latching devices, in particular the second latching device (preferably in the form of a blocking screw), and the latching recess when the torsion spring load is removed, in particular starting from the operating position of the pivoting arm and furthermore also automatically. If the torsion spring breaks, for example, there is the risk that the tensioning roller will be catapulted away from the belt together with the pivoting arm, under pressure from the belt, during operation. However, with the embodiment according to the present invention, a predefined latching position is present, so that during such pivoting of the pivoting arm, to effect latching of the latching device on the latching recess (latching stop contact), to stop the movement of the pivoting arm.

Furthermore, the locking device of the belt drive formed with the belt-tensioning device can be configured, within the scope of the present invention, to lock the pivoting arm in a predefined (third) latching position by way of one of the latching devices. The locking of the pivot arm is effected by the second latching device, and the latching recess when the loading of the tension roller on the belt is removed, in particular starting from the operating position of the pivoting arm and furthermore the locking can occur automatically. If the belt tears, for example, there is the risk that the tensioning roller will move abruptly in the direction of the belt or cause abrupt movement of the belt pulley together with the pivoting arm due to the pressure from the belt during operation. Upon an initiation of such a movement the present invention stops the movement of the pivoting arm from pivoting due the latching action at the predefined latching position that takes place by the latching of the latching device on the latching recess (latching stop contact).

For implementation with a belt-tensioning device as discussed above, there is also a proposal for a method in which, in a first step, the pivoting arm is pivoted out of a rest position (referred to here as the 0° position), in which the torsion spring load is minimal, into a predefined pivoting position with an increase in the torsion spring load. At this pivoting position, the locking device is configured in such a way that both the first latching device and the second latching device latches on the latching recess, or the latching sections are moved into the latching recess with the ability to be latched thereon (and consequently the first latching position is adopted). Such a first latching position (in the present case a 110° position, for example) corresponds, in particular, to the above indicated mounting position for belt mounting.

As a development of the method, it is possible, in a second step, for the locking device to be configured in such a way that the first latching device is then unlatched from the latching recess. The result of the unlatching is that the operating position of the pivoting arm is adopted in the course of a pivoting movement in the direction of the belt (owing to the torsion spring load), in particular in such a way that neither the first nor the second latching device lock on the latching recess. Such an operating position, in which the pivoting arm is pushed against the belt and in which the second latching device is preferably lowered centrally into the latching recess, in particular without latching thereon or entering into latching stop contact (the pivoting arm thus having freedom of movement in the positive and negative pivoting directions), corresponds to a 98° position, for example.

Within the scope of the method, provision is furthermore made, in the second step, after unlatching, for the first latching device to be brought into a blocking position, in which automatic entry into the latching recess or latching on the latching recess is rendered impossible, irrespective of a pivoting position of the pivoting arm. Thus, starting from the operating position, only the second latching device then continues to act for the adoption, should it become necessary, of respective latching positions, as explained above, in the event of faults, that is to say if the belt tears or the spring load is removed.

The invention also proposes an internal combustion engine which has a belt-tensioning device of the kind explained above or a belt drive of the kind explained above, in particular also one which is configured for carrying out the proposed method.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the drawings, and more particularly toFIG. 1there is shown a belt-tensioning device1, in particular of a belt drive3(seeFIGS. 4 to 8), furthermore, in particular, for a fan belt drive, preferably of a large engine.

Belt-tensioning device1has a bearing housing5, which is formed with a bearing pedestal or base7, wherein base7is provided for affixing on an engine block, such as a trunnion holder, by way of a number of fastening points, formed by means of screw sockets9on bearing pedestal7, which may have three screw sockets.

Furthermore, a mounting11extends away from base7. Mounting11is substantially hollow-cylindrical or in the form of a tube section and, in the present case, is also formed integrally with base7(seeFIG. 2for supplementary information).

In addition to a shaft section15, a pivoting arm13of belt-tensioning device1includes a tensioning lever17, which, in the present case, is mounted on shaft section15of pivoting arm13, at an angle to the latter of preferably 90°, by a number of fastening elements19, which are in particular screws19. Thus, in the present case, pivoting arm13is formed of several parts. A tensioning roller21is arranged in a rotatable manner on a free end of tensioning lever17.

Arranged around mounting11is a torsion spring23, which is fixed at one end to bearing housing5, on the base side, by a mounting block25screwed thereto. The other end of torsion spring23, adjacent to tensioning lever17of belt-tensioning device1or pivoting arm13, is fixed to shaft section15on another mounting element27(formed integrally with shaft section15). Torsion spring23, which is held captive in this way, exerts a turning effect on pivoting arm13. The turning effect serves to enable pivoting arm13to be pressed against a belt29by way of tensioning roller21arranged on arm13in order to tension the belt (seeFIGS. 4 to 9), in particular with an automatic adjusting action.

Pivoting arm13is torsion-spring-loaded in this way, with belt-tensioning device1mounted on bearing housing5by mounting11, i.e. via shaft section15accommodated therein. Shaft section15and, therefore, pivoting arm13is fixed, in particular pivotably mounted, on bearing housing5, in particular base7thereof, by a screwed joint, i.e. is mounted so as to be pivotable about a rotational or pivoting axis A (further details of this arrangement will be explained below in the context ofFIG. 2).

Belt-tensioning device1furthermore has a locking device31. Locking device31is formed by a first33and a second35latching device on pivoting arm13and by a latching recess37, in particular in the form of an elongate hole37, on bearing housing5(not visible inFIG. 1). Latching recess37interacts with latching device33,35, wherein locking device31can be configured in such a way that pivoting arm13can be locked by locking device31in different predefined latching positions (corresponding to predefined pivoting positions) and can be pivoted with predefined freedom in an operating position subject to (belt) load. In the present case, belt-tensioning device1can be configured such that automatic locking, in particular starting from the operating position, in two latching positions is possible, as well as locking, in particular before the start of operation, in a further latching position, in particular by user intervention.

AsFIG. 1illustrates, first latching device33and second latching device35are accommodated next to one another in the circumferential direction of pivoting axis A in a holder39. Holder39is formed at the end, on a free end41of shaft section15or adjacent to tensioning lever17(facing in the direction of the torsion spring23), in particular integrally with shaft section15. In a rotational direction B of the torsion spring action, the first latching device33is here arranged ahead of second latching device35in holder39. In this arrangement, latching device33,35that are accommodated in holder39are screwed in a manner which allows release by user intervention, wherein it is also possible, by user intervention, for latching sections thereof to be moved toward or away from the rotational axis A of shaft section15, thus enabling different configurations of locking device31to be achieved.

First latching device33, seeFIGS. 3ato 3dfor supplementary information, is preferably formed by a spring-loaded latching pin43and, once again in the context of a user intervention, can be moved into a first and a second position. In the first position, latching pin43of first latching device33emerges, under spring load, from a housing45of latching device33, in particular for latching on latching recess37(latching stop contact), i.e. on a latching side thereof, and can also reenter the housing45when subjected to a force in the opposite direction. In the second position (illustrated inFIG. 3b), latching pin43is retracted into housing45of first latching device33and is also fixed (locked) in this position.

Second latching device35is preferably a blocking screw35, which can be screwed in or out by user intervention. A latching section for latching with latching recess37or for locking (latching stop contact) thereon is formed here by a thread-side end section of blocking screw35. In general, latching device33,35are thus capable of entering or emerging from latching recess37with latching sections.

First latching device33and second latching device35are each screwed into holder39, wherein first latching device33is screwed in by way of housing45, while blocking screw35is screwed in by its screw thread.

Now, additionally referring toFIG. 2there is shown a section view through belt-tensioning device1, wherein the section passes transversely through belt-tensioning device1and first latching device33. As can be seen, mounting11extends, over its length, through tensioning spring23, wherein a free end section47projects beyond the latter and is provided for the purpose of forming latching recess37on bearing housing5, that is to say, in the present case, on the (outer) circumferential wall of mounting11.

FIG. 2furthermore shows, shaft section15of pivoting arm13forms holder39for first latching device33(and second latching device35), wherein holder39is arranged in such a way that free end section47, or latching recess37formed thereon, can be swept by holder39and consequently by latching device33,35, that is to say in the course of an overlapping of free end section47of mounting11and holder39(in a direction toward the shaft axis A). In this case, holder39is formed on a flange-shaped end section of shaft section15, which is also provided for fastening tensioning lever17by screw elements19.

Shaft section15is supported in mounting11with the aid of (dry) sliding bearing bushes49and thrust washers51as well as an axial washer53, which is supported against base7. A screw55is screwed to the shaft section passes through axial washer53and thus fixes shaft section15in a rotatably supported manner on mounting11by way of a corresponding threaded hole. In this arrangement, an end cap57forms a closure on base7. A hexagon profile59is formed on the end of shaft section15, in particular for simple rotation or rotatability of shaft section15(and for screwing to screw55).

Now, additionally referring toFIGS. 3ato 3dthere is illustrated a preferred embodiment of first latching device33, in greater detail. First latching device33includes a latching pin43or latching bolt43, on which a head61is formed on the user intervention side. First latching device33includes a housing45with a screw-in thread on the outer circumference and a hexagon, which is provided for screw fastening on holder39of shaft section15. Radial webs63are formed at the head end of latching pin43and can be introduced and latched into deeper first radial grooves65or shallower second radial grooves67on the head-side housing end, depending on the rotational position of latching pin43relative to housing45. It is thereby possible to define the first (unlocked) position or the second (locked) position of first latching device33, i.e. after axial retraction from the respective first radial grooves65or second radial grooves67by a rotation of latching pin43through 90°.

As is apparent, latching pin43is spring-loaded by a compression spring69, held captive between housing45and latching pin43. Spring69has the effect that, when radial webs63enter the deeper, first radial grooves65, latching pin43is pushed, under spring load, toward emerging on the latching side (first position of latching device33), i.e. for the purpose of latching in latching recess37of shaft section15. If, on the other hand, radial webs63have latched into the shallower second grooves67, latching pin43is prevented from emerging at the latching side (second position of latching device33,FIG. 3b).

Different configurations of locking device31, viewed together with the predefined adoptable latching positions or the predefined operating position of belt-tensioning device1or pivoting arm13thereof, are now explained in greater detail with reference toFIGS. 4 to 8, in particular in the context of a belt drive3formed with belt-tensioning device1. Here, each of the Figs. show, on the left-hand side, belt-tensioning device1in a sectional view of a section passed transversely through locking device31and, on the right, the corresponding position of belt-tensioning device1in the context of belt drive3.

It is also apparent, in particular, from these Figs. that the arc length of latching recess37corresponds, in particular, substantially to the dimension or length which defines the outer ends (in the circumferential direction) of the mutually adjacent latching sections of latching device33,35, wherein the width of a respective latching section corresponds approximately to one third or two fifths of the length of latching recess37, seeFIG. 5for example.

FIG. 4shows belt-tensioning device1in a pivoted position of shaft section15or of pivoting arm13under minimal torsion spring load, i.e. in a relaxed position. This pivoting position corresponds, for example, to a standby or preinstallation condition which, in the present case, is defined as the 0° position with respect to pivoting arm13, for example. In this pivoting position, the configuration of locking device31is such that neither first latching device33nor second latching device35can be inserted into latching recess37or, consequently, latched. Here, blocking screw35is unscrewed, and the latching bolt has been moved into the second, locked position.

In this pivoting position, an angular offset—in each case with reference to the center and viewed anticlockwise—between latching recess37and latching device33,35is about 110°. In this position, belt-tensioning device1can be mounted on the engine block, for example, preferably before the mounting of a fan-driving belt pulley71of belt drive3.

FIG. 5shows a latching position state of belt-tensioning device1in which locking device31is configured to lock pivoting arm13in a predefined first pivoting position or latching position by way of first latching device33and second latching device35(latching, in particular locking of first latching device33and of second latching device35on latching recess37). In the present case, this position is defined as the 110° position, for example, once again with reference to pivoting arm13.

This latching position adopted by the pivoting of pivoting arm13(clockwise), starting from the 0° position, corresponds, in particular, to a position in which belt mounting on belt drive3is envisaged. To adopt this position, first latching device33is first of all moved into the first position, and then shaft section15is then turned clockwise (counter to the direction of rotation of the spring action), that is to say by means of hexagon59, until latching pin43automatically latches in the latching recess37. While maintaining this position, blocking screw35is then screwed in, wherein this too latches in on latching recess37. Owing to the identical arc dimensions of latching recess37and of the locking outer ends of the latching sections of latching device33,35, seeFIG. 5, this latching position is thus secured against any twisting. In this position, belt29can now be mounted around belt pulleys71,73.

In this latching position, first latching device33has thus been moved into the first position thereof and, as a consequence, latching pin43has entered latching recess37directly adjacent to a first end face75(in the lead in the spring-load-determined direction of rotation B). Second latching device35, in the form of blocking screw35, has furthermore also entered, i.e. has been screwed into, latching recess37, and is in stop contact with the trailing end face77. Although not shown, provision can be made, for the sake of even simpler belt mounting, to release tensioning lever17from shaft section15to such an extent, for example by unscrewing a number of fastening elements19, that it can be moved even further away from belt29, separately from the shaft section15, to furthermore pivot tensioning lever17back again after belt mounting and to screw it to shaft section15again.

Starting from this first latching position, the pivoting arm13can now furthermore be moved into the envisaged operating position together with the tensioning roller21, with the release of the locking by first latching device33(of latching pin43of first latching device33) and the belt load acting during this process on tensioning roller21. For this purpose, first latching device33is merely pulled out and moved into the second position. Subsequently, pivoting arm13pivots under torsion spring and belt load into the operating position illustrated inFIG. 6, in which tensioning roller21is thus pushed against belt29of belt drive3under torsion spring load.

FIG. 6illustrates the abovementioned operating position, which is defined with reference to pivoting arm13, in the present case as the 98° position, for example. As is evident, latching pin43of the first latching device33is retracted into housing45, and the latching section of second latching device35is plunged into the latching recess37, in the center thereof, thus allowing pivoting arm13a predefined freedom when pivoting for the purpose of automatic adjustment, but also in a direction counter thereto. The freedom can be a pivoting angle of ±5°, for example.

In the operating position, an angular offset, in each case with reference to the center and viewed anticlockwise, between latching device33,35and latching recess37is about 12°, for example.

FIG. 7shows belt drive3in a second predefined latching position of pivoting arm13of belt-tensioning device1. This position corresponds, for example, to the case of a fault corresponding to removal of the torsion spring load, in particular in the event of a breakage of torsion spring23during operation. Here, the configuration of locking device31corresponds to that of the operating position, only the second latching device35has entered latching recess37, although now, however, second latching device35also enters into latching stop contact. against end face77of latching recess37(which is the trailing end face in the spring-load-determined direction of rotation). The result of this position illustrates that the uncontrolled movement of pivoting arm13, owing to the catapulting away on the part of the belt load, in the opposite direction to belt29is stopped, and this latching position is maintained. In the present case, this position is defined as the 112° position, for example, with reference to pivoting arm13.

FIG. 8shows belt drive3in a third predefined latching position of pivoting arm13of belt-tensioning device1, which corresponds, for example, to the case of a fault corresponding to removal of the loading of tensioning roller21on the part of belt29, such as when belt29tears during operation. Here, the configuration of locking device31once again corresponds to that of the operating position, i.e. only second latching device35has entered latching recess37, wherein second latching device35also, in turn, enters into latching stop contact, in this case, however, against end face75of latching recess37(which is the leading end face in the spring-load-determined direction of rotation). The result is that the uncontrolled movement of the pivoting arm13, owing to the tearing of the belt, in the direction of the29is stopped, and this latching position is maintained. In the present case, this position is defined as the 84° position, for example, with reference to pivoting arm13.

FIG. 9furthermore illustrates belt-tensioning device1in accordance with another possible embodiment of the invention, wherein an optional tension arm79is connected to tensioning lever17, which can be fixed at the other end to the engine block. If torsion spring23breaks, tension arm79can continue to push tensioning roller21against belt29, i.e. as a fallback solution.