DE112008001286B4 - Clamping device with spring ring element as transport protection - Google Patents

Abstract

Clamping device (1) for a endless drive, such as a chain drive on an internal combustion engine, comprising a housing (2), a tensioning piston (3) displaceably guided in the housing (2), a spring element acting between the housing (2) and the tensioning piston (3) 4) and an adjusting device for the stepwise adjustment of the working range of the tensioning piston (3), wherein the adjusting device comprises a spring ring element (19) and an associated detent profiling, the spring ring element (19) of the adjusting device at least in a position of a transport securing position, in which the tensioning piston ( 3) relative to the housing (2) by means of the spring ring element (19) is locked, and a working position in which the clamping piston (3) relative to the housing (2) is slidably mounted, is designed to be movable, characterized in that the housing (2 ) has a locking projection (35) and the spring ring element (19) configured in such a way and about a longitudinal axis of the clamping piston (3) is rotatable, that it is blocked from the transport securing position, in which a portion of the spring ring element (19) of the locking projection (35), in the working position, in which the portion of the spring ring element (19) together with the clamping piston (3) of the locking projection (35) is released, is movable.

Description

The present invention relates to a tensioning device for a endless drive, such as chain drive on an internal combustion engine, according to the preamble of claim 1.

Such clamping devices are often used as chain tensioners in the automotive sector. In particular, in a timing chain drive on an internal combustion engine, it is of great importance that the chain is sufficiently tensioned during operation. For this purpose, a pivotally mounted on the engine block clamping rail is pressed by means of the chain tensioner against the chain. These are usually hydraulic chain tensioners that are connected to the engine oil hydraulics. Inside the tensioner is a compression spring which provides a certain basic tension at least in the switched-off state of the internal combustion engine. As soon as a sufficient operating pressure is available through the engine oil hydraulics, the tensioning takes place primarily by the hydraulic pressure acting on the tensioning piston. A leakage gap between the clamping piston and the housing ensures sufficient damping of the clamping system. Due to wear, the chain lengthens over time, which shifts the working range of the tensioning piston and this must be extended further and further. After the hydraulic pressure degrades again via the leakage gap when the internal combustion engine is switched off, in particular the starting process is critical. To allow even after some wear here not too large vibrations during startup, some clamping devices are provided with adjusting devices. It is known e.g. Ratchet mechanisms that allow adjustment in one direction and the opposite direction to bring about a blockage.

A generic clamping device is from the US 2003/0139235 A1 known. A clamping piston is inserted into a housing and biased by a spring. In a transport position, ie when retracted tensioning piston extension is prevented by a spring ring. The spring ring has two outwardly projecting gripping areas that can be actuated by a user. The spring ring is thereby extended, whereby the tensioning piston can extend out of the housing. Furthermore, the spring ring is used for a locking mechanism. For this purpose, a plurality of locking grooves are formed on the clamping piston into which the spring ring can engage.

Another tensioning device is eg from the DE 10 2006 026 702 A1 known. The tensioning piston is provided with a plurality of axially spaced-apart locking grooves. On the clamping piston an annular spring clip is pushed, which is initially engaged in the uppermost locking groove. For this annular spring clip, there is an upper stop surface and a lower stop surface on the housing. In between there is a sufficient distance so that the clamping piston can develop the damping effect in its working area. If, for example, the tensioning piston has to be extended further due to the lengthening of the chain, the annular spring clip strikes against the upper stop. If this happens with sufficient force, then the annular spring clip, after it has expanded radially, jumps into the next locking groove. The locking grooves are designed accordingly, so that this process is favored. On the other hand, if the annular spring clip strikes against the lower stop surface, the retraction movement of the tensioning piston is blocked. The locking grooves are shaped so that the annular spring clip can not jump out of the locking groove during the inward movement of the piston.

Such clamping devices have proven themselves very well in use. However, suitable provisions for the installation of the clamping device must be provided, since otherwise it must be worked against the spring force of the compression spring. Special tools for assembly or suitable transport safety pins can be used here. From the DE 103 43 508 A1 and the DE 103 43 507 A1 are each transport safety pins known to effect a simplified assembly. However, these are not clamping devices with adjusting devices.

It is therefore the object of the present invention to provide a clamping device of the type mentioned above, which provides an improved assembly and which represents an acceptable solution to the cost pressure in the automotive sector.

This object is achieved in that the housing has a locking projection and the spring ring element is configured and rotatable about a longitudinal axis of the clamping piston, that it is blocked by the transport securing position in which a portion of the spring ring element of the locking projection, in the working position, in the portion of the spring ring element is released together with the clamping piston of the locking projection, is movable.

Of course, by a person skilled in the art clamping devices with adjusting devices readily with suitable locking pins as they are well known in the art, are equipped. However, since the adjusting device is an important feature of the operation of the clamping device, it is such a functionally important device with a Double function to occupy. The present invention is characterized in that a component of the adjuster complies with its usual task in the operating position, but at the same time provides for transport an additional locking function in exactly the direction that normally represents the release position of the clamping device. The variety of parts is reduced by this measure and there is no waste piece that is no longer needed after assembly. Due to the previously existing fixed function assignment, the provision of a dual function was not obvious.

According to a further embodiment, it is provided that the housing has a locking projection and the spring ring element is configured and rotatable about a longitudinal axis of the clamping piston, that it from the transport securing position, in which the portion of the spring ring element is blocked by the locking projection, in the working position, in the portion of the spring ring element is released together with the clamping piston of the locking projection, is movable. A rotational movement of the spring ring element can make do with a smaller space, as a sliding version.

Conveniently, the spring ring element two spaced apart spring leg and the housing have two spaced juxtaposed insertion slots, wherein in each case a spring leg is inserted into one of the insertion slots. As a result, the spring legs are securely received in the slots and protected from external influences, in particular further bending etc. Also, the area where the plug-in extension engages in the plug-in opening can be arranged within the insertion slot. Such a slot may be in its width direction, i. parallel to the longitudinal axis of the clamping piston have a width that defines the working stroke of the clamping piston during operation. The two side walls of the insertion slot then form the upper and lower stop for the spring ring element. Due to the use of two and not a continuous slot, it is possible to perform the housing more stable at this point, in particular to place intervening webs.

In a further variant it is provided that the housing is designed as a flange housing with at least one laterally projecting Anbringflansch, the spring ring element has a laterally projecting handle and projecting the Anbringflansch and the handle in the same direction. This guarantees that the clamping device with flange housing builds as flat as possible and does not additionally have a projection due to the handle. In the cramped installation conditions of an internal combustion engine this is of great importance.

A structurally simple to produce variant provides that the spring ring element has a laterally projecting handle, which is formed by the connection region of the two spring legs. The spring ring element is thus formed by a kind of annular retaining clip, wherein the spring tension depends significantly on the configuration of the connection region.

Preferably, the housing may have a stop surface, the spring ring element may be provided with a stop projection and abut the stop projection in the working position on the stop surface, whereby further rotation of the spring ring element about the longitudinal axis of the clamping piston is prevented. This defines exactly how far the spring-ring element has to be turned for transferring from the transport securing position to the working position. A further rotation is also prevented, so that it can not lead to functional loss.

Furthermore, it can be provided that the spring ring element has a latching device, the housing has a complementary latching device and the two latching devices are locked in the working position, whereby an unintentional turning back into the transport securing position is prevented. The locking must only be such that for most applications, an unintentional turning back is prevented during operation. A user-desired turning back could be released if necessary. This additional measure ensures that the spring ring element does not unintentionally turn back into the transport securing position, which could lead to functional failure. Locking devices usually require overcoming a spring force to transfer from the unlatched to the locked position. As a rule, such a spring force can not be overcome by the usual vibrations, so that in this way a secure locking in the working position is provided. Conveniently, the latching device may be formed on the housing by a locking lug protruding between the two insertion slots and the latching device may be formed on the spring ring element by the connecting region of the two latching limbs. Here, the detent function is achieved by pure shaping of the housing and the spring ring element. After the spring ring element is designed as a resilient element, and the corresponding connection region can be configured such that a certain spring effect is achieved to support the locking function.

• 1 eine perspektivische Draufsicht eines nicht zur Erfindung gehörenden Kettenspanners,
• 2 den Kettenspanner aus 1 im Vollschnitt,
• 3 den Kettenspanner aus 2 entlang der Linie III-III geschnitten,
• 4 eine Ansicht ähnlich der 3, wobei das Federringelement in der Transportsicherungsstellung dargestellt ist,
• 5 eine perspektivische Draufsicht eines zweiten, nicht zur Erfindung gehörenden Kettenspanners,
• 6 der Kettenspanner aus 5 im Vollschnitt,
• 7 der Kettenspanner aus 6 entlang der Linie VII-VII geschnitten,
• 8 eine Ansicht ähnlich der 7, wobei das Federringelement in einer Transportsicherungsstellung dargestellt ist,
• 9 eine perspektivische Draufsicht eines erfindungsgemäßen Ausführungsbeispiels eines Kettenspanners,
• 10 den Kettenspanner aus 9 im Vollschnitt,
• 11 eine Schnittdarstellung, wobei das Federringelement in der Transportsicherungsstellung dargestellt ist,
• 12 eine Schnittdarstellung ähnlich der 11, wobei das Federringelement in der Arbeitsstellung dargestellt ist,
• 13 den Ausschnitt XIII aus 10 in vergrößerter Darstellung.
• 14 den Ausschnitt ähnlich 13, wobei das Federringelement in einer Blockierstellung dargestellt ist und
• 15 den Ausschnitt ähnlich 13, wobei das Federringelement in einer vorderen Anschlagstellung dargestellt ist.

In the following, embodiments of the present invention will be explained in more detail with reference to a drawing. Show it:

• 1 a top perspective view of a not belonging to the invention chain tensioner,
• 2 the chain tensioner off 1 in full section,
• 3 the chain tensioner off 2 cut along the line III-III,
• 4 a view similar to the one 3 , wherein the spring ring element is shown in the transport securing position,
• 5 a perspective top view of a second, not part of the invention chain tensioner,
• 6 the chain tensioner off 5 in full section,
• 7 the chain tensioner off 6 cut along the line VII-VII,
• 8th a view similar to the one 7 wherein the spring ring element is shown in a transport securing position,
• 9 a perspective top view of an embodiment of a chain tensioner according to the invention,
• 10 the chain tensioner off 9 in full section,
• 11 a sectional view, wherein the spring ring element is shown in the transport securing position,
• 12 a sectional view similar to the 11 , wherein the spring ring element is shown in the working position,
• 13 the section XIII 10 in an enlarged view.
• 14 similar to the clipping 13 , wherein the spring ring element is shown in a blocking position and
• 15 similar to the clipping 13 wherein the spring ring element is shown in a front stop position.

Based on 1 to 4 For explanation purposes, a first non-inventive chain tensioner will now be described 1 explained in more detail. The chain tensioner 1 has a flange housing 2 , one in the flange housing 2 slidably guided tensioning piston 3 , one between the flange housing 2 and the tensioning piston 3 acting compression spring 4 , one between the compression spring 4 and the tensioning piston 3 arranged packing 5 and an adjusting device to be described in more detail.

The flange housing 2 has a central main body 6 and two laterally projecting mounting flanges 7,8. Each of these Anbringflansche 7,8 is provided with a fastening eye 9,10. In the main body 6 is an oil collection chamber 11 provided when flanging the chain tensioner 1 to an engine block (not shown) communicating with an outlet of the engine oil hydraulics. From the oil collection chamber 11 goes a radially extending inlet channel 12 away, in an axial inlet channel 13 empties. In the axial inlet channel 13 is a check valve 14 arranged, via the hydraulic fluid in the pressure chamber 15 can flow into it.

The clamping piston is in a corresponding receiving bore 16 in the main body 6 guided axially displaceable. The mostly made of plastic filler 5 with mushroom-shaped head mainly serves the volume reduction, so that the pressure chamber 15 not too big. Furthermore, the filler pushes 5 with his mushroom head on a vent 17 at the pushing of the tensioning piston 3 so that only a metered escape through this vent 17 can be done. Between the trained as a hollow body clamping piston 3 and the receiving bore 16 a leakage gap is formed, by means of which the damping of the chain tensioner 1 provided.

The adjusting device is characterized by a plurality of saw teeth in cross-section (or a correspondingly shaped geometry) annular grooves 18 in the tensioning piston 3 and through one in these annular grooves 18 engaging spring ring element 19 educated.

In this chain tensioner 1 has the spring ring element 19 approximately the shape of an eight, wherein the interrupted area represents the actual latching area and is formed by the two spring legs 20,21, and the closed area the two spring legs 20,21 connecting handle 22 represents. For receiving the spring ring element 19 has the flange housing 2 at its front portion two juxtaposed insertion slots 23,24, in the front and rear area by means of the web 25 are separated from each other, but otherwise from the receiving bore 16 are permeated. The width of the slot B _s is dimensioned so that when snapped spring ring element 19 still a certain work area for the tensioning piston is available. In the in the 2 and 3 shown position of the spring ring element 19 this is in the topmost detent groove 18 on the tensioning piston 3 engaged. At the end of the spring legs 20,21 each plug-in extension 26,27 is provided, each having a stop step 29 having.

The flange housing 2 has a laterally projecting portion 30 in which two Plug openings 31,32 are arranged for receiving the plug-in extensions 26,27. Laterally next to the flange housing 2 a stop surface 33 and a stop surface 34 on, each with the stop steps 28 and 29 can come to the plant.

In the 3 is the operating position of the chain tensioner 1 shown, whereas in the 4 the transport securing position is shown. In the transport locking position is the spring ring element 19 radially spread and the plug-in extensions 26 and 27 are in the associated locking holes 31 and 32 plugged in. Here are the stop stages 28 and 29 with the stop surfaces 33 and 34 to the plant, so that a further radial expansion is no longer possible. Furthermore, from the 4 to see that in this position, the transition region between the spring legs 20,21 and the handle 22 still in an annular groove 18 engages, causing the tensioning piston 3 locked in this position. In this locked position, the chain tensioner 1 delivered for assembly. After the chain tensioner 1 was bolted to the engine block and the chain drive including the clamping rail are attached to the handle 22 drawn. This unlocks the tensioning piston 3 and the spring ring element 19 takes the in 3 shown operating position, so is in this process radially to the axis of the clamping piston 3 postponed. The tensioning piston 3 can now extend so far until the spring ring element 19 abuts the stop surface of the insertion slots 23,24 or until the clamping rail sufficient force on the clamping piston 3 exercises. Optionally, the spring ring element jumps 19 an annular groove 18 further. This process is repeated in operation over time several times due to elongation of the chain, so that an automatic readjustment is given. Due to the contour of the annular grooves 18 Although the clamping piston 3 further out of the flange housing 2 drive out; However, further retraction is prevented by striking the opposite surface of the insertion slots 23,24.

By the difference of the 3 and 4 It can be seen that in the transport securing position the plug-in extensions 26, 27 are aligned axially parallel to the locking openings 31, 32, whereas in the operating position (FIG. 3 ) have the plug extensions 26,27 facing each other.

The following is based on the 5 to 7 for explanatory purposes, a further non-inventive chain tensioner explained in more detail. In the following, only the essential differences to the preceding exemplary embodiment will be discussed. Therefore, reference is made to the above description with the aid of the same reference numerals for components of identical construction and the same effect.

This second embodiment of the chain tensioner 1 has a slightly larger oil collection chamber compared to the first embodiment 11 on. Furthermore, the spring ring element 19 differently designed. While in the first embodiment, a flat wire or a punching out of a sheet leads to the desired shape, in the second Ausführungsbeiform a brought into the appropriate shape round wire is used. The area of the handle 22 forms, has a simple U-shape. The plug extensions 26,27 are aligned in the operating position substantially parallel to each other, whereas they are in the in 8th shown transport securing position slightly away from each other and something is wedged in the locking holes 31,32, whereby the necessary unlocking force increases slightly. Furthermore, the design of pronounced stop steps and stop surfaces is dispensed with.

Operation and operation of this second embodiment are otherwise substantially identical to the first embodiment.

Based on 9 to 15 Now, an inventive chain tensioner will be described in detail. In the following, only the essential differences from the previous embodiments will be discussed. Therefore, reference is made to the above description with the aid of the same reference numerals for components of identical construction and the same effect.

Instead of a transverse to a longitudinal axis A of the clamping piston 3 displaceable spring ring element 19 , In the present embodiment, the spring ring element 19 designed to be rotatable about the longitudinal axis A. Except for further to be described formations on the housing 2 are both the case 2 as well as the tensioning piston 3 as well as between tensioning pistons 3 and flange housing 2 Existing elements identical executed to the same elements of the preceding embodiments.

From the 11 and 12 it can be seen that the case 2 a locking projection 35 whose radial distance to the bottom of an annular groove 18 smaller than the diameter of the formed from round wire spring ring element 19 , As a result, the locking projection 35 with appropriately positioned spring ring element 19 capable of the axial movement of the tensioning piston 3 to block. The 11 shows the corresponding associated transport safety position in which this is the case. The upper spring leg 20 lies exactly in the ring groove 18 and extends to the mid-plane of the tensioning piston 3 , The locking projection 35 opposite is on the flange housing 2 a locking projection 36 arranged in the area between the two spring legs 20 and 21 protrudes. The end face of the locking projection 36 is to the vertical ( 11 ) obliquely, so that an undercut is formed. The handle 22 of the spring ring element 19 is now designed so that it is a Rasteinbuchtung 37 having. This ramp dent 37 is seen in the radial direction slightly closer to the axis A than the largest radial distance of the locking projection 36 ,

Will now be the spring ring element 19 from the in 11 shown transport securing position in the in 12 pivoted working position (rotated about the longitudinal axis A), so the handle must 22 by means of elastic deformation the locking projection 36 overcome. That means the ridge dent 37 then in the area of the locking projection 36 formed undercut and thus a locking in the working position takes place and turning back into the transport locking position is prevented. The locking projection 35 is with a down facing stop surface 38 (please refer 11 and 12 ) and the lower spring leg 21 has a stop projection 39 on, in the transport locking position with the stop surface 38 comes to rest and thus limits the rotation about the longitudinal axis A clockwise. The interaction of stop surface 38 and stop projection 39 as well as locking projection 36 and latch dent 37 give a secure positioning of the spring ring element 19 in the working position ( 12 ). Very good is based on the 12 to see that the upper spring leg 20 no longer through the locking projection 35 is blocked.

Based on 13 to 15 Now, the operation of the spring ring element 19 explained in detail in the working position. In 13 is the pitch T of the annular grooves 18 located. The spring ring element 19 is in contact with the straight side of the ring groove 18 as well as with the front wall of the insertion slots 23 and 24 , Now moves the tensioning piston 3 starting from the 13 in the flange housing 2 into it, so also moves the spring ring element 19 until it abuts the other wall of the insertion slots 23 and 24 comes. In the in 14 shown position is another retraction of the clamping piston 3 blocked.

Now moves the tensioning piston 3 due to gradually adjusting wear of the chain ever further outward, so shifts the spring ring element 19 gradually in the ring groove 18 until it attaches to the ramp 18.1 the ring groove 18 comes. Starting from this in 15 shown position causes a further extension of the clamping piston 3 in that the spring ring element 19 elastically expands and it snaps into the next ring groove 18 comes. These processes can then gradually repeat as a function of the elongation of the chain and the wear, until the last locking groove 18 is reached. The same operation also applies to the first and second embodiments.

Between the in 14 shown blocking position and the in 15 Beginning skipping shown is a free travel of the tensioning piston 3 of about 0.5 x the pitch T exist.

In addition, it should be mentioned that other wire cross sections for the design of the spring ring element 19 can be used.

Claims (7)

Clamping device (1) for a endless drive, such as a chain drive on an internal combustion engine, comprising a housing (2), a tensioning piston (3) displaceably guided in the housing (2), a spring element acting between the housing (2) and the tensioning piston (3) 4) and an adjusting device for the stepwise adjustment of the working range of the tensioning piston (3), wherein the adjusting device comprises a spring ring element (19) and an associated detent profiling, the spring ring element (19) of the adjusting device at least in a position of a transport securing position, in which the tensioning piston ( 3) relative to the housing (2) by means of the spring ring element (19) is locked, and a working position in which the clamping piston (3) relative to the housing (2) is slidably mounted, is designed to be movable, characterized in that the housing (2 ) has a locking projection (35) and the spring ring element (19) configured in such a manner and about a longitudinal axis of the clamping piston (3 ) is rotatable so that it is blocked from the transport securing position, in which a portion of the spring ring element (19) of the locking projection (35) in the working position in which the portion of the spring ring element (19) together with the clamping piston (3) of the Arresting projection (35) is released, is movable. Clamping device (1) after Claim 1 , characterized in that the spring ring element (19) has two spaced spring legs (20,21) and the housing (2) has two spaced juxtaposed insertion slots (23,24), wherein in each case a spring leg (20,21) in one of the insertion slots (23,24) is inserted. Clamping device (1) according to one of the preceding claims, characterized in that the housing (2) is designed as a flange housing with at least one laterally projecting Anbringflansch (7,8), the spring ring element (19) has a laterally projecting handle (22). and the Anbringflansch (8) and the handle (22) protrude in the same direction. Clamping device (1) after Claim 2 or 3 , characterized in that the spring ring element (19) has a laterally projecting handle (22) which is formed by the connecting region of the two spring legs (20,21). Clamping device (1) according to one of the preceding claims, characterized in that the housing (2) has a stop surface (38), the spring ring element (19) is provided with a stop projection (39) and the stop projection (39) in the working position on the Stop surface (38) is applied, whereby further rotation of the spring ring element (19) about the longitudinal axis of the clamping piston (3) is prevented. Clamping device (1) according to one of the preceding claims, characterized in that the spring ring element (19) has a latching device (37), the housing (2) has a complementary latching device (36) and the two latching devices (36,37) in the working position latched, whereby an accidental turning back into the transport locking position is prevented. Clamping device (1) after Claim 6 , characterized in that the latching device (36) on the housing (2) by a between the two insertion slots (23,24) protruding latching projection (36) is formed and the latching device (37) on the spring ring element (19) of the connection region (22) the two spring legs (20,21) is formed.

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