Tensioner with single safety ring

Abstract

The invention relates to a tensioning device for a chain drive of an internal combustion engine, in particular a chain tensioner which is operated hydraulically, having a tensioner housing, a tensioning piston with a piston skirt which is guided in a movable manner in a piston bore of the tensioner housing, a transmission securing mechanism for securing the tensioning piston in the tensioner housing, an adjustment mechanism for stepwise readjustment and limitation of the working range of the tensioning piston, and a final position securing mechanism for the loss-proof arrangement of the tensioning piston in the piston bore. Here, the transmission securing mechanism, the adjustment mechanism and the final position securing mechanism together have a single securing ring for securing the tensioning piston in the tensioner housing, for stepwise readjustment and limitation of the working range of the tensioning piston and for the loss-proof arrangement of the tensioning piston in the piston bore. Furthermore, the invention relates to a chain drive of an internal combustion engine, in particular a control chain drive, having such a tensioning device.

Description

Technical Field

[0001] This invention relates to a tensioning device for a chain drive in an internal combustion engine, particularly a hydraulically operated chain tensioner, comprising a tensioner housing, a tensioning piston with a piston skirt guided movably in a piston bore of the tensioner housing, a transmission safety mechanism for securing the tensioning piston in the tensioner housing, a readjustment mechanism for progressively readjusting and limiting the working area of ​​the tensioning piston, and a final position safety mechanism for preventing the tensioning piston from being lost in the piston bore. Furthermore, this invention relates to a chain drive in an internal combustion engine having such a tensioning device, particularly a control chain drive. Background Technology

[0002] Hydraulically operated tensioning devices are widely used and employed in various applications, such as in the control chain drive systems of internal combustion engines. Such tensioning devices typically include a housing with a piston bore in which a tensioning piston, preloaded by a pressure spring, is arranged. The hollow cylindrical tensioning piston and the piston bore of the housing form a pressure chamber filled with hydraulic fluid to cushion the movement of the tensioning piston. This pressure chamber is connected to a hydraulic fluid supply mechanism, typically the engine oil circuit of the internal combustion engine, via a check valve to replace any hydraulic fluid that escapes from the pressure chamber during operation. In addition to a transmission safety mechanism and a final position safety mechanism for the tensioning piston, conventional tensioning devices often include a readjustment mechanism in the form of a locking mechanism. This readjustment mechanism defines the locking and sliding direction of the tensioning piston, thereby preventing the piston from moving too deeply into the piston bore by means of a stop, but allowing for readjustment of the working area of ​​the tensioning piston, for example, when the chain wears.

[0003] Conventional tensioning devices with readjustment mechanisms are known, for example, from DE 100 14 700 A1. For readjusting the working area, the piston skirt of the tensioning device has a serrated portion, into which a ratchet block engages through a window slot in the housing. The pre-tensioned ratchet block allows the tensioning piston to slide along the tension direction of the pressure spring while simultaneously preventing the tensioning piston from moving too far into the piston bore of the housing in the event of a fairly violent and powerful vibration impact. The free working area of ​​the tensioning piston is defined by the axial freedom of movement of the ratchet block within the window slot.

[0004] The tensioning device known from published document DE 196 80 418 C1, in addition to a readjustment mechanism for the working area of ​​the tensioning piston, also has a transfer safety mechanism. The readjustment mechanism includes multiple axially spaced, circumferential grooves into which calipers, inserted into the tensioning piston, engage. A stop ring on the tensioning side end of the piston bore allows the calipers, guided in two cutouts in the tensioner housing, to move across the grooves of the tensioning piston and simultaneously forms a final stop. The stop ring also serves to secure a transfer safety clamp, which, in the transfer position, engages in a safety groove formed on the tensioning end of the tensioning piston. The free working area of ​​the tensioning piston is limited between the stop ring and a lower stop slope formed in the piston bore of the housing.

[0005] Publication DE 36 36 918 A1 describes a tensioning device in which the expansion ring of a readjustment mechanism moves on a readjustment profile formed in the piston bore by a piston groove with a tooth profile formed on the tensioning piston, to induce readjustment of the tensioning piston. Here, the free working area of ​​the tensioning piston is defined by a tooth profile section of the piston groove. Another tooth profile section is used to lock the final position of the expansion ring in a safety groove in the piston bore. To secure the tensioning piston in the transfer position, a safety ring placed on the tensioning end of the tensioning stop is pushed into a safety groove through the gap between the housing and the tensioning piston, where the safety groove on the tensioning side end of the safety ring is supported. To release the transfer safety mechanism, the tensioning piston is pressed back into the piston bore, thereby causing the safety ring to jump back to its operating position on the tensioning end of the tensioning piston.

[0006] The type of tensioning device is known from DE 10 2011 101 865 A1, wherein the tensioning piston has multiple circumferential grooves spaced apart from each other in the axial direction. A retaining ring arranged on this readjustment profile of the tensioning piston is guided in a readjustment groove in the piston bore of the housing, wherein the readjustment groove defines the free working area of ​​the tensioning piston. To progressively readjust the working area of ​​the tensioning piston, the retaining ring is moved from the readjustment groove to the next groove of the readjustment profile. To secure the tensioning piston in the transfer position, a transfer safety clamp is positioned through an opening in the tensioner housing in a safety groove provided on the tensioning end of the tensioning piston.

[0007] Traditional tensioning devices with transfer safety mechanisms, readjustment mechanisms, and / or final position safety mechanisms are widely used in the technology and have been well-proven in use in various designs and implementations. However, the corresponding solutions for common transfer safety mechanisms, readjustment mechanisms, and final position safety mechanisms are quite complex, requiring precise design and coordination of the necessary components with their respective functions, and demanding expensive machining of the tensioning device's components to ensure safe operation.

[0008] Many tensioning devices known in the prior art can be selected for specific applications and implementation methods. However, advancements in technology also create continuous pressure for innovation to improve existing designs, even for products already well-established in the technology. Therefore, the rising cost pressures in the automotive industry, combined with high component counts, create a constant need for optimization and a desire to reduce costs through synergistic effects. Summary of the Invention

[0009] In view of the disadvantages of tensioning devices known in the prior art that have a transmission safety mechanism, a readjustment mechanism and a final position safety mechanism, the object of the present invention is to provide a tensioning device that is designed to be manufactured at a low cost through the simplest possible structure and simplest operation while maintaining reliable function.

[0010] This task is solved according to the invention by having the transfer safety mechanism, readjustment mechanism, and final position safety mechanism together have a single safety ring. This safety ring serves to secure the tensioning piston in the tensioner housing, to provide incremental readjustment, to limit the working area of ​​the tensioning piston, and to securely position the tensioning piston in the piston bore to prevent loss. This multi-functional safety ring reduces the necessary components of the tensioning device, thereby lowering product costs and preventing malfunctions when the transfer safety mechanism, readjustment mechanism, and final position safety mechanism interact. Here, the multi-functional safety ring is substantially located inside the piston bore and is accessible only through a normally possible cutout or window in the tensioner housing. Advantageously, the tensioning device is a screw-in tensioner, wherein the unlocking of the transfer safety mechanism and the transfer of the single safety ring relative to the readjustment mechanism are accomplished by means of the tensioning piston moving into the piston bore against the preload of the pressure spring. In order to utilize a single safety ring for the transfer safety mechanism, readjustment mechanism, and final position safety mechanism, these functions of the tensioning device are correspondingly matched with the single safety ring, and the necessary grooves and teeth are correspondingly positioned in the piston bore and on the piston skirt of the tensioning piston. Apart from the single safety ring, the transfer safety mechanism, readjustment mechanism, and final position safety mechanism of the tensioning device according to the invention have no other components capable of moving relative to the piston bore of the tensioning piston and the tensioner housing.

[0011] An advantageous construction scheme specifies that the readjustment mechanism has a readjustment tooth profile with multiple grooves formed on the piston skirt of the tensioning piston. The safety ring is arranged in the grooves during operation in the working area for readjusting the tensioning piston. The readjustment mechanism also has a readjustment groove formed in the piston bore, wherein the readjustment tooth profile is arranged on the distal end of the tensioning piston. The readjustment tooth profile on the distal end of the tensioning piston typically has multiple grooves, which facilitates the use and reliable function of individual safety rings for the transmission safety mechanism, readjustment mechanism, and final position safety mechanism of the tensioning device. Here, the readjustment tooth profile is mainly arranged on the distal end of the piston skirt, that is, on the half of the piston skirt opposite to the tensioning side of the tensioning piston. This, during the operation of the tensioning device, protects the readjustment tooth profile formed on the piston skirt through the piston bore of the tensioning housing for the maximum extent of operation and achieves smooth, low-friction guidance of the piston skirt on the tensioning side portion in the piston bore. Significantly, the transfer safety tooth profile is constructed on the piston skirt of the tensioning piston in proximity to the proximal end of the readjustment tooth profile, enabling easy and rapid relocation to the operating position after the transfer safety mechanism is unlocked. For ease of manufacture and reliable function, the readjustment groove formed in the piston bore is constructed with a straight bottom extending parallel to the piston bore, a radially vertical readjustment side edge on the tensioning side, and an inclined stop side edge at the distal end.

[0012] Furthermore, the piston skirt can be configured as a smooth, toothless guide region on the tensioning side end of the tensioning piston, wherein the toothless guide region extends from the proximal end of the tensioning side of the tensioning piston, that is, from the pressure head within a range of at least 35%, preferably at least 40%, and especially at least 45% of the axial length of the tensioning piston. In rare cases, the toothless guide region can extend from the proximal end of the tensioning side of the tensioning piston within a range of at least 20% of the axial length of the tensioning piston. This smooth, toothless cylinder liner achieves low-wear guidance of the tensioning piston within the cylinder bore of the tensioner housing. Furthermore, the tooth-shaped portion of the tensioner housing, located at the distal end of the tensioning piston and used for the transfer safety mechanism, readjustment mechanism, and final position safety mechanism, is protected by the piston bore of the tensioner housing for most of the operating range. This is because, according to the arrangement of the transfer safety groove and the readjustment tooth on the distal end or distal half of the tensioning piston, the tooth-shaped area only protrudes from the piston bore when the tensioning piston is in its most distant position. Thus, the tooth-shaped area of ​​the piston skirt is protected by the tensioner housing for the maximum extent of the operating range.

[0013] A simple construction scheme specifies that the readjusting tooth profile has multiple grooves arranged side-by-side in the axial direction, surrounding the piston skirt of the tensioning piston. Thus, the readjusting tooth profile at the distal end of the piston skirt can be advantageously manufactured and constructed quite easily according to the function of the readjusting mechanism for progressively readjusting the working area of ​​the tensioning piston. Preferably, the axially arranged grooves are constructed with a surrounding, preferably rounded, serrated profile to ensure reliable locking of the tensioning piston, in addition to easy movement to the next locking position, if the tensioning piston moves too deeply into the piston bore. The straight surfaces between the serrations are respectively used for specific working areas between locking positions predetermined by the serrated profile.

[0014] Preferably, the distance between the tensioning side opening of the piston bore in the tensioner housing and the readjustment groove formed in the piston bore is at least 25%, preferably at least 30%, of the axial length of the tensioning piston. The tensioning side opening is, in this case, an open end of the piston bore without radial restriction of the tensioning piston by the housing, wherein windows or cutouts in the tensioner housing or protrusions of the tensioner housing are disregarded without contact with the tensioning piston. This large distance between the tensioning side opening of the piston bore and the readjustment groove allows for reliable guidance of the tensioning piston, particularly the proximal end of the toothless portion of the tensioning piston, within the piston bore of the tensioner housing.

[0015] In a preferred embodiment, the transfer safety mechanism has a transfer safety tooth pattern formed on the piston skirt of the tensioning piston and a transfer safety groove at the tensioning side end of the piston bore, wherein the safety ring is arranged in the transfer safety mechanism in the transfer safety position. The transfer safety tooth pattern and transfer safety groove, together with the multi-functional safety ring, enable the tensioning piston to be secured in the tensioner housing in the transfer safety position and enable the transfer safety mechanism to be easily unlocked by pressing the tensioning piston into the piston bore. To activate the transfer safety mechanism, the opening of the piston bore at the tensioning side end of the tensioner housing is provided with an inlet bevel. This inlet bevel or bevel at the transition from the piston bore to the end side facilitates the positioning and reception of the safety ring into the transfer safety tooth pattern on the piston skirt of the tensioning piston for activation of the transfer safety mechanism when the tensioning piston is pressed in.

[0016] An advantageous design specifies that the final position safety mechanism has a final position safety groove formed on the piston skirt of the tensioning piston, in which the safety ring is arranged in the final position. Here, the final position safety groove is typically constructed on the piston skirt in a manner that is distal to, and particularly adjacent to, the readjustment profile. The use of the single safety ring in the final position safety groove prevents functional collisions with the transfer safety mechanism and with the gradual readjustment of the working area. Compared to the final position safety mechanism of a conventional tensioning device, the vertical readjustment side edge of the readjustment groove formed in the piston bore here can serve as a stop for the safety ring to prevent the tensioning piston from being lost.

[0017] A meaningful modification specifies that the safety ring is constructed as a safety clamping ring, wherein the safety clamping ring is arranged on the tensioning piston in a pre-tightened manner relative to the piston skirt. Such a safety clamping ring can be constructed in a simple form as an open, radially elastic ring with, for example, a gap between the two ring ends. This safety clamping ring provides reliable functionality for the readjustment mechanism, but also for the transfer safety mechanism and the final position safety mechanism. The safety clamping ring is pre-tightened relative to the undisturbed outer periphery of the piston skirt approximately according to the diameter of the piston bore and also achieves reliable placement on the bottom of the groove of the transfer safety tooth profile, where only minimal clamping action or even no clamping action is required.

[0018] One variation specifies that the safety ring is constructed as an open spring ring having two opposing end faces at its ends. These two end faces are axially opposite each other, that is, opposite each other along the longitudinal axis of the spring ring's curvature. An open spring ring with two opposing end faces at its ends can be manufactured very easily and inexpensively, and this open spring ring can be made not only as a safety clamping ring but also as an expansion ring. The open spring ring, typically a circular ring with a slit and a circular annular cross-section, can be manufactured very easily and inexpensively, and still achieves the reliable function of the readjustment mechanism, the transfer safety mechanism, and the final position safety mechanism.

[0019] Another construction scheme specifies that the two end faces of the open spring ring are inclined relative to a straight line at the center point. This straight line extends from the center of the end face through the center point of the safety ring. Compared to the straight end facing the straight line at the center point, the inclined end faces achieve better alignment of the ring ends and thus ensure reliable interaction of the teeth and grooves of the readjustment mechanisms in the piston bore and on the piston skirt of the tensioning piston, as well as the transmission safety mechanism and the final position safety mechanism. Furthermore, this reduces the risk of burrs protruding from the end faces and corresponding damage to the surfaces of the piston skirt and piston bore. This combination of design features can also be protected and pursued independently without depending on any of the aforementioned design schemes.

[0020] Preferably, the angle of the inclined end faces of the open spring rings relative to the center point is between 20° and 60°, preferably between 30° and 40°, and particularly preferably 45°. When the safety ring is mounted on the tensioning piston and the transmission safety mechanism is activated, the inclined end faces can easily slide against each other by means of the corresponding angle relative to the center point. This reduces the risk of the safety ring jamming during the installation and operation of the tensioning device, wherein the sliding of the inclined end faces against each other is possible not only axially but also radially. Axial sliding against each other is preferred. This allows the distance between the ends of the open spring rings to be kept small. It is meaningful that the two inclined end faces of the open spring rings are arranged parallel to each other.

[0021] One particular design specifies that the tensioner housing has a fitting opening in the area of ​​the readjustment slot to facilitate the reset of the readjustment mechanism. This fitting opening allows the readjustment ring to return via the readjustment teeth as the tensioning piston retracts into the piston bore by preventing the readjustment ring from abutting against the inclined stop edge of the readjustment slot, for example, by locking the readjustment ring with a suitable tool. This allows the tensioning device to be placed in an operating position compatible with the chain drive after disassembly. This combination of design features can also be protected and pursued independently without depending on any of the aforementioned design options.

[0022] Advantageously, the fitting openings in the tensioner housing can be constructed as drilled holes, preferably as drilled holes passing through the tensioner housing. Such drilled holes can be made very easily and cost-effectively during the manufacture of the tensioner housing, wherein, instead of drilled holes passing through the tensioner housing, two fitting openings can also be simultaneously created on the opposite side of the readjustment slot. Here, the diameter of the drilled holes used to construct the fitting openings in the tensioner housing can correspond to the diameter of the hydraulic medium inlet hole leading to the pressure chamber of the tensioning device, and is preferably located at the same radial position on the tensioner housing. The use of the same diameter for different drilled holes and the creation of drilled holes at the same radial position on the tensioner housing reduce the number of steps in the manufacture of the tensioner housing and thus also reduce production costs.

[0023] One modification specifies that the tensioning device is configured as a screw-in tensioner. The screw-in tensioner allows for easy and reliable installation of the tensioning device in the engine mount of the internal combustion engine.

[0024] Here, the thread profile on the tensioner housing preferably extends on both axial sides of the fitting opening on the tensioner housing. Besides facilitating easy installation of the screw-in tensioner into the motor housing, the thread profile extending on both sides of the fitting opening for screwing the tensioning device into the motor housing provides additional sealing against the open motor chamber for the fitting opening that is connected to the pressure chamber of the tensioning device through the leakage gap between the tensioning piston and the piston bore.

[0025] Furthermore, the present invention relates to a chain drive device for internal combustion engines, and more particularly to a control chain drive device, comprising a drive sprocket, at least one driven sprocket, a drive chain connecting the drive sprocket and at least one driven sprocket to each other, and a tensioning device for tensioning the drive chain according to one of the embodiments described above. Through a special design of the tensioning device, this chain drive device, despite its simple and low-cost structure, achieves reliable pre-tensioning of the drive chain with a reliable readjustment function, as well as reliable transmission safety mechanisms and final position safety mechanisms, wherein the readjustment function is used to progressively readjust the tensioning piston and to limit the infeed movement. Such a chain drive device, in addition to its simple installation and operation, can correspondingly prevent drive chain skipping. Attached Figure Description

[0026] The embodiments of the present invention will now be explained in detail with reference to the accompanying drawings. Wherein:

[0027] Figure 1 A chain drive device for an internal combustion engine according to the present invention is shown;

[0028] Figure 2It shows Figure 1 An enlarged cross-sectional view of the tensioning device according to the invention in the operating position;

[0029] Figure 3 It shows Figure 2 An enlarged partial view of the tensioning device in its first readjustment position;

[0030] Figure 4 It shows Figure 1 An enlarged cross-sectional view of the tensioning device according to the invention in the conveying position;

[0031] Figure 5 It shows Figure 4 An enlarged schematic diagram of the components of the insurance company's transmission system;

[0032] Figure 6 It shows Figure 4 A schematic diagram of the tensioning device when it is transitioning from the transmission safety device to the operating position;

[0033] Figure 7 It shows Figure 2 A schematic diagram of the tensioning device in its moved-out operating position;

[0034] Figure 8 It shows Figure 1 An enlarged cross-sectional view of the tensioning device in its final, secure position;

[0035] Figure 9 It shows Figure 8 An enlarged schematic diagram of the components of the final location insurance institution;

[0036] Figure 10 It shows the use of Figure 1 An enlarged cross-sectional view of the tensioning device of the chain drive according to the invention in another embodiment;

[0037] Figure 11 It shows the use of Figure 1 An enlarged cross-sectional view of the tensioning device of the chain drive according to the invention in another embodiment;

[0038] Figure 12 It shows Figure 11 A schematic diagram of the tensioner housing of the tensioning device in the second embodiment; and

[0039] Figure 13 A schematic diagram of the safety clamping ring is shown. Detailed Implementation

[0040] According to the present invention, the tensioning device 1 according to the present invention is as follows: Figure 1The chain drive 2 shown is installed in an internal combustion engine. This chain drive 2 is a control chain drive, having a lower crankshaft-drive sprocket 3 and two upper, side-by-side camshaft-driven sprockets 4, along with a drive chain 5. The drive chain 5 is continuously laid around the drive sprockets 3 and driven sprockets 5 and connects them to each other. A guide rail 6 is provided in the drive section of the chain drive 2, along which the drive chain 5 slides. On the opposite return section of the chain drive 2, there is a tension rail 7 rotatably supported near the drive sprocket 3, which can be pressed onto the drive chain 5 by means of a tensioning device 1 to pre-tension the return section of the chain drive 2. The tensioning device 1... Figure 1 In the current embodiment of the chain drive 2, the tensioner 1 is configured as a screw-in tensioner, which is screwed into a corresponding opening in the motor base 8 for pressing its tensioning piston 9 against the pressing area 10 of the tensioning rail 7, which is thus pressed onto the drive chain 5 with a predetermined force. Alternatively, the tensioning device 1 can also be configured as a flange tensioner, which is connected to the motor base 8 by a flange with suitable fasteners.

[0041] Figure 2 An enlarged cross-sectional view of the tensioning device 1 according to the invention clearly shows the tensioner housing 11, which is configured as a screw-in tensioner, and the tensioning piston 9. The tensioner housing 11 is machined and has a hexagonal screw head 12 with abutment flange 13, by means of which the tensioning device 1 is screwed into a corresponding opening in the motor housing 8. Below the abutment flange 13, an annular seal 14, rectangular in cross-section, is provided for sealing the tensioning device 1 screwed into the motor housing 8 relative to the environment. An inflow section 16 with a small outer diameter is provided between the annular seal 14 and the thread profile 15 on the tensioner housing 11, through which a hydraulic medium, i.e., engine oil, is supplied to the tensioning device 1. An inflow hole 17 extending radially to the housing axis connects the supply section 16 to a front chamber 18 inside the tensioner housing 11. At the bottom of the piston bore 20, there is a valve seat 21 for the check valve 22, through which oil from the front chamber 18 can flow into the pressure chamber 23 formed between the tensioning piston 9 and the tensioner housing 11.

[0042] The tensioning piston 9, constructed as a hollow cylindrical component, is received in the piston bore 20 of the tensioner housing 11 in a longitudinally movable manner. The tensioning piston 9 is pre-tensioned along the longitudinal direction of the tensioning device 1 by means of a helical pressure spring 26 arranged in the pressure chamber 23. The tensioning piston 9, as a hollow cylindrical component, has a clamping head 25 that is closed on the tensioning side except for the central vent 24. Furthermore, a filler 19 is provided in the hollow cylindrical tensioning piston 9, which reduces the volume of the pressure chamber 23 and seals the vent 24 on the opposite end of the pressure chamber 23 containing hydraulic medium. For this purpose, the head of the filler 19 is pressed by the clamping head 25 on the tensioning side end of the tensioning piston 9 by the pressure spring 26 supported towards the check valve 22, so that the vent 24 is connected to the pressure chamber 23 in a controlled fluid connection.

[0043] The tensioning piston 9 has a readjustment tooth 28 on its outer piston skirt 27 in the region opposite to the distal end of the pressure head 25, that is, at the rear end of the tensioning piston 9 along the tensioning direction. This readjustment tooth has multiple slots 29 arranged side-by-side along the longitudinal direction. Here, the profile of the readjustment tooth 28 is serrated, and the tips between the slots 29 are flattened. The outer diameter of the piston skirt 27 at the flattened tips of the readjustment tooth 28 has the same diameter as the toothless guide region 30 of the tensioning piston 9 at the front end along the tensioning direction. This achieves improved guidance of the tensioning piston 9 in the piston bore 20, especially in the region at the distal end of the piston skirt 27. The toothless guide region 30, with a constant maximum outer diameter of the tensioning piston 9, not only ensures reliable, low-friction guidance of the tensioning piston 9 within the piston bore 20 of the tensioner housing 11, but also supports the readjustment tooth 28 without tilting within the piston bore 20 for the maximum extent of the tensioning device 1's operating state, as the readjustment tooth 28 only protrudes from the piston bore 20 in the extremely far outward position of the tensioning piston 9. The readjustment tooth 28 on the piston skirt 27 of the tensioning piston 9, together with the readjustment groove 31 formed in the piston bore 20 and the safety ring 32 arranged in the readjustment groove 31, constitutes a readjustment mechanism for progressive readjustment and defining the working area of ​​the tensioning piston 9. The tensioning device 1, during operation, provides damping within the free working area of ​​the tensioning piston 9. This free working area is defined by the axial length of the readjustment groove 31, which extends radially perpendicularly to the straight bottom of the readjustment groove 31 between the readjustment side edge 33 on the tensioning side and the inclined distal stop side edge 34. When the retaining ring 32 abuts against the readjustment side edge 33 on the tensioning side, it is pressed into the next slot 29 of the readjustment tooth profile 28 as the tensioning piston 9 further moves out of the piston bore 20, for readjusting the working area of ​​the tensioning piston 9 in case of wear of the drive chain 5. The retaining ring 32... Figure 2 As shown, when pressed against the inclined stop edge 34, the safety ring 32 is pressed into the corresponding slot 29 and locked to prevent the tensioning piston from moving too deeply into the piston bore 20. Figure 2 The readjustment mechanism in Figure 3 The enlarged view shown clearly shows the situation where the safety ring 32 abuts against the first slot 29 of the readjustment tooth profile 28 after the tensioning device 1 is activated.

[0044] A transmission safety mechanism is provided in the opening of the piston hole 20 at the tensioning side end of the tensioner housing 11. For example, in... Figure 4As shown, the transmission safety mechanism includes a transmission safety tooth profile 35 formed on the piston skirt 27 of the tensioning piston 9, a transmission safety groove 36 formed on the tensioning side end of the piston bore 20, and a safety ring 32, which is also used for readjustment and limiting the working area of ​​the tensioning piston 9 during operation. The open end of the piston bore 20 on the tensioning side is slightly chamfered or beveled to facilitate activation of the transmission safety mechanism during assembly of the tensioning device 1. The transmission safety tooth profile 35 on the piston skirt 27 of the tensioning piston 9 is arranged between the guide area 30 and the readjustment tooth profile 28, directly adjacent to the readjustment tooth profile 28. See also Figure 5 When the transfer safety mechanism is activated, the safety ring 32 is almost completely compressed into the transfer safety tooth profile 35 through the beveled opening of the piston hole 20, so that as the tension piston 9 is further moved in, the safety ring 32 slides into the transfer safety groove 36 and expands slightly there. In the transfer position, the safety ring 32 is simultaneously engaged with the end of the tension side of the transfer safety groove 36 and the side edge of the beveled distal end of the transfer safety tooth profile 35.

[0045] For example, it can be in the tensioning device 1 Figure 4 As clearly seen at the transmission position shown, the tensioning piston 9 extends far from the piston bore 20 through the guide area 30 when the transmission safety mechanism is activated, such that the pressure spring is only slightly pre-tensioned. This not only reduces the risk of unintentional unlocking of the transmission safety mechanism but also reduces the risk of injury should the transmission safety mechanism be unintentionally unlocked. To unlock the transmission safety mechanism and according to the activation of the tensioning device 1, the tensioning piston 9 is pushed from its position relative to the piston bore 20 by overcoming the pre-tension force of the pressure spring 26. Figure 4 The tension piston 9 is pressed into the piston bore 20 in either the transfer or locking position shown. Because the tension piston 9 extends relatively far from the piston bore 20 in the locking position, only a relatively small pressure must be applied to unlock it. When the tension piston 9 is pressed into the piston bore 20, the safety ring 32 is first pressed into the transfer safety tooth 35 from the flattened distal end of the transfer safety groove 36 and then driven by the transfer safety tooth 35 until the safety ring 32 extends back into the readjustment groove 31, see also Figure 6 As the tensioning piston 9 moves out of the piston bore 20, the safety ring 32 is then pushed from the readjustment side edge 33 of the readjustment groove 31 onto the first slot 29 of the readjustment tooth profile 28, see [link to relevant documentation]. Figure 3 As the tensioning piston 9 further moves out of the piston bore 20, the safety ring 32 is always further pushed along the readjustment profile 28 into the next slot 29 until the clamping head 25 abuts against the tensioning rail 7 or compensates for the elongation of the drive chain 5 caused by wear. See [link to relevant documentation]. Figure 7The guide area 30 of the tensioning piston 9 is also... Figure 7 In the operating position shown, the piston has not yet fully exited the piston bore 20, thus both the transmission safety tooth 35 and the readjustment tooth 28 are protected in the piston bore 20 from external influences, and the tensioning piston 9 is reliably guided in the piston bore 20 of the tensioner housing 11.

[0046] exist Figure 8 and 9 The structure and function of the final position safety mechanism of the tensioning piston 9 in the piston bore 20 are explained in detail below. Figure 8 In the final position shown, the tensioning piston 9, pre-tensioned by the pressure spring 26 along the tensioning direction, extends to its maximum extent from the piston bore 20, wherein, in addition to the guide region 30, a portion of the transfer safety tooth 35 disposed in the middle of the tensioning piston 9 and the distal readjustment tooth 28 on the piston skirt 27 also extend from the piston bore 20. The safety ring 32 used together is positioned here in the final position safety groove 37 formed on the distal end of the piston skirt 27. The portion of the safety ring 32 extending relative to the piston skirt 27 abuts against the straight readjustment side edge 33 of the readjustment groove 31 in the piston bore 20 and prevents the tensioning piston 9 from moving further out of its final position in the piston bore 20. At the end of the normal operating time of the chain drive 2, when the drive chain 5 is overstretched, the safety ring 32 is pushed from the rearrangement side edge 33 of the last distal end of the rearrangement tooth profile 28 into the final position safety groove 37 as the tension piston 9 moves further out of the piston hole 20. In the subsequent single movement caused by the operation of the tension piston 9, the safety ring 32 in the final position safety groove 37 is able to move within the normal operating range of the tension piston 9 along the axial length of the rearrangement groove 31 up to the inclined stop side edge 34. According to the final position safety groove 37, in Figure 9 The design shown has a vertically extending radial side edge. The safety ring 32, upon contact with the vertical readjustment side edge 33, also remains in the final position safety groove 37 and prevents the tensioning piston 9 from further retracting into the piston bore 20. When the tensioning device 1 is removed from the motor base 8 for replacement or repair of the chain drive 2, the safety ring 32, positioned in the final position safety groove 37, prevents the tensioning piston 9 from falling out or jumping out of the piston bore 20. In the tensioning device 1... Figure 8 In the illustrated embodiment, the safety ring 32, positioned in the final position safety groove 37, also prevents the tensioning piston 9 from resetting to the running or conveying position. The tensioning device 1 must also be replaced accordingly when servicing or replacing the chain drive 2.

[0047] Figure 10 An enlarged cross-sectional view shows another embodiment of the tensioning device 1 according to the invention for the chain drive 2. Relative to the tensioning device 1 in... Figure 2 In the embodiment shown, a fitting opening 38, in the form of a drilled hole passing through the tensioner housing 11, is provided in the region of the readjustment slot 31. This fitting opening 38 allows access to the tensioner housing 11 from the outside to the tensioner piston 9 in its final position, that is, when the safety ring 32 abuts against the final position safety slot 37, for example after the tensioning device 1 has been removed from the motor housing 8. This not only allows the tensioning device to be disassembled into its individual components when needed (by prying the safety ring 32 out of the final position safety slot 37 and moving it toward the distal end of the tensioner piston 9) but also allows the tensioner piston 9 to be reset to the operating position or the transfer safety position. For this purpose, the safety ring 32 can be pried out of the final position safety groove 37 and separated from the inclined stop edge 34 of the readjustment groove 31 by one or two fitting openings 38 on the opposite side of the tensioner housing 11 using a simple tool, such as a screwdriver. This allows the safety ring 32 to move across the slot 29 of the readjustment profile 28 to the transfer safety profile 35 in the piston skirt 27 of the tensioning piston 9 when the tensioning piston 9 is pressed into the piston bore 20. In the position of the safety ring 32 in the transfer safety profile 35, the corresponding pressure applied to the safety ring 32 can guide it to the transfer safety groove 36 on the tensioning side end of the piston bore 20, where the safety ring 32 then holds the tensioning piston 9 in the transfer position.

[0048] exist Figure 11 Another embodiment of the tensioning device 1 with a fitting opening 38 is shown. Threaded sections 15 on the outer periphery of the tensioning housing 11 extend on both sides of the fitting opening 38, such that the area between the readjustment groove 31 and the fitting opening 38, which is filled with hydraulic medium during operation of the tensioning device, is sealed from the motor housing 8 relative to the environment and the internal space of the internal combustion engine. This area filled with hydraulic medium can therefore be used during operation as a container 40 for hydraulic medium or engine oil, from which hydraulic medium can return to the pressure chamber 23 via the inlet 17 and check valve 22 when the hydraulic medium supply is restricted or interrupted.

[0049] Figure 12 The following is shown: for tensioning device 1 having a fitting opening 38, in Figure 10The embodiment shown is an alternative form of the tensioner housing 11. The inlet hole 17 for supplying hydraulic medium to the pressure chamber 23 has the same diameter in this tensioner housing 11 as the fitting opening 38, which is formed as a drilled hole leading to the readjustment groove 31. Furthermore, the drilled holes for the inlet hole 17 and the fitting opening 38 are constructed at the same radial position on the tensioner housing 11, so that the inlet hole 17 and the fitting opening 38 can be manufactured using not only the same tools but also without changing the radial position of the tensioner housing 11 relative to the tools.

[0050] Figure 13 A schematic diagram of one embodiment of a single safety ring 32 is shown, which is configured to not only secure the tensioning piston 9 in the tensioner housing 11 with a transmission safety mechanism, progressively readjust it by means of a readjustment mechanism, and limit the working area of ​​the tensioning piston 9, but also to secure the tensioning piston 9 in the piston bore in a way that prevents it from being lost by means of a final position safety groove. Compared to a conventional simply cut ring, this safety ring 32 has two end faces 39 facing each other at the open end of the safety ring 32, which are inclined relative to a straight line from the center of the end face 39 to the center point of the safety ring 32. These inclined end faces 39 allow the tips of the inclined end faces 39 to slide on each other during the installation of the tensioning piston 9 and during the progressive adjustment of the working area of ​​the tensioning piston 9, and correspondingly allow for a small gap between the end faces 39, without adversely affecting the function and operation of the safety ring 32.

[0051] List of reference numerals in the attached diagram:

[0052] 1. Tensioning device

[0053] 2. Chain drive device

[0054] 3. Drive sprocket

[0055] 4 Driven sprocket

[0056] 5. Drive chain

[0057] 6 guide rails

[0058] 7 tension rails

[0059] 8 Motor base

[0060] 9 tensioning pistons

[0061] 10 Compacting Area

[0062] 11 Tensioner Housing

[0063] 12 Spiral Head

[0064] 13. Flange

[0065] 14. Annular seal

[0066] 15. Thread profile

[0067] 16 Supply Sections

[0068] 17 Inlet Hole

[0069] 18 front room

[0070] 19. Filler

[0071] 20 Piston bore

[0072] 21 Valve seat

[0073] 22 Check valve

[0074] 23 Pressure Chamber

[0075] 24 Exhaust ports

[0076] 25. Pressure head

[0077] 26. Compression Spring

[0078] 27 Piston Skirt

[0079] 28. Readjust tooth shape

[0080] 29 Card Slots

[0081] 30 Guiding Area

[0082] 31. Readjustment slot

[0083] 32 Safety Ring

[0084] 33. Adjust the side edges again.

[0085] 34. Stop side edge

[0086] 35. Transmitter safety tooth type

[0087] 36 Conveyor Safety Slot

[0088] 37 Final position safety slot

[0089] 38 Fitting opening

[0090] 39 End side

[0091] 40 containers.

Claims

1. A tensioning device (1) for a chain drive (2) of an internal combustion engine, the tensioning device having a tensioner housing (11), a tensioning piston (9) with a piston skirt (27) guided in a movable manner in a piston bore (20) of the tensioner housing (11), a transmission safety mechanism for fixing the tensioning piston (9) in the tensioner housing (11), a readjustment mechanism for progressively readjusting and limiting the working area of ​​the tensioning piston (9), and a final position safety mechanism for preventing the tensioning piston (9) from being lost in the piston bore (20). in, The transfer safety mechanism, readjustment mechanism, and final position safety mechanism together have a single safety ring (32) for securing the tensioning piston (9) in the tensioner housing (11), for progressive readjustment and limiting the working area of ​​the tensioning piston (9), and for preventing the tensioning piston (9) from being lost in the piston bore (20). The readjustment mechanism has a readjustment tooth profile (28) formed on the piston skirt (27) of the tensioning piston (9) and having multiple slots (29). The safety ring (32) is arranged on the readjustment tooth profile during operation in the working area for readjusting the tensioning piston (9). The readjustment mechanism also has a readjustment groove (31) formed in the piston bore (20). The readjustment tooth profile (28) is arranged on the distal end of the tensioning piston (9). The transmission safety mechanism has a transmission safety tooth profile (35) formed on the piston skirt (27) of the tensioning piston (9) and a transmission safety groove (36) formed in the piston hole (20), and the safety ring (32) is arranged in the transmission safety mechanism in the transmission safety position. The characteristic feature is that the piston skirt (27) is configured as a smooth, toothless guide region (30) on the tensioning side end of the tensioning piston (9), wherein the smooth, toothless guide region (30) extends within a range of at least 35% of the axial length of the tensioning piston (9) between the tensioning side end of the tensioning piston (9) and the readjustment tooth profile (28) formed on the piston skirt (27), and The piston hole (20) is configured as a smooth, toothless hole region on the tensioning side end of the tensioner housing (11), wherein the smooth, toothless hole region extends between the opening of the piston hole (20) on the tensioning side and the readjustment groove (31), and the distance between the opening of the piston hole (20) on the tensioning side and the readjustment groove (31) is at least 25% of the axial length of the tensioning piston (9), and wherein the smooth, toothless guide region (30) of the tensioning piston (9) is guided in the smooth, toothless hole region of the tensioner housing (11).

2. The tensioning device (1) according to claim 1. Its features are, The smooth, toothless guide region (30) extends over a range of at least 40% of the axial length of the tensioning piston (9).

3. The tensioning device (1) according to claim 1 or 2. Its features are, The readjustment tooth profile (28) has a plurality of slots (29) arranged side by side around the piston skirt (27) of the tensioning piston (9).

4. The tensioning device (1) according to claim 1 or 2. Its features are, The distance between the opening on the tensioning side of the piston hole (20) in the tensioner housing (11) and the readjustment groove (31) formed in the piston hole (20) is at least 25% of the axial length of the tensioning piston (9).

5. The tensioning device (1) according to claim 1 or 2. Its features are, The transmission safety groove (36) is formed on the end of the piston hole (20) on the tension side.

6. The tensioning device (1) according to claim 1 or 2. Its features are, The final position safety mechanism has a final position safety groove (37) formed on the piston skirt (27) of the tensioning piston (9), and the safety ring (32) is arranged in the final position safety groove (37) in the final position.

7. The tensioning device (1) according to claim 1 or 2. Its features are, The safety ring (32) is configured as a safety clamping ring, wherein the safety clamping ring is arranged on the tensioning piston (9) in a manner that is pre-tightened relative to the piston skirt (27).

8. The tensioning device (1) according to claim 1 or 2. Its features are, The safety ring (32) is configured as an open spring ring having two end sides (39) facing each other at the end of the open spring ring.

9. The tensioning device (1) according to claim 8. Its features are, The two end sides (39) of the open spring ring are inclined relative to the center point in a straight line.

10. The tensioning device (1) according to claim 1 or 2. Its features are, The tensioner housing (11) has a fitting opening (38) in the region of the readjustment groove (31) for resetting the readjustment mechanism.

11. The tensioning device (1) according to claim 10. Its features are, The fitting opening (38) in the tensioner housing (11) is configured as a drilled hole.

12. The tensioning device (1) according to claim 11. Its features are, The diameter of the borehole in the tensioner housing (11) corresponds to the diameter of the inlet (17) of the hydraulic medium leading to the pressure chamber (23) of the tensioning device (1).

13. The tensioning device (1) according to claim 1 or 2. Its features are, The tensioning device (1) is configured as a screw-in tensioner.

14. The tensioning device (1) according to claim 1. Its features are, The tensioning device (1) is a chain tensioner operated by hydraulic means.

15. The tensioning device (1) according to claim 4. Its features are, The distance between the opening on the tensioning side of the piston hole (20) in the tensioner housing (11) and the readjustment groove (31) formed in the piston hole (20) is at least 30% of the axial length of the tensioning piston (9).

16. The tensioning device (1) according to claim 9. Its features are, The angle of the inclined end side (39) of the open spring ring relative to the center point is between 20° and 60°.

17. The tensioning device (1) according to claim 9. Its features are, The angle of the inclined end side (39) of the open spring ring relative to the center point is between 30° and 40°.

18. The tensioning device (1) according to claim 11. Its features are, The fitting opening (38) in the tensioner housing (11) is configured as a drill hole passing through the tensioner housing (11).

19. The tensioning device (1) according to claim 13. Its features are, The thread profile (15) on the tensioner housing (11) extends on both sides of the fitting opening (38).

20. A chain drive device (2) for an internal combustion engine, comprising a drive sprocket (3), at least one driven sprocket (4), a drive chain (5) connecting the drive sprocket (3) and at least one driven sprocket (4) to each other, and a tensioning device (1) for tensioning the drive chain (5) according to any one of claims 1 to 19.

21. The chain drive device (2) according to claim 20. Its features are, The chain drive device is a control chain drive device.

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