Method for assembling a camshaft drive

Abstract

A method for assembling a camshaft drive unit for an internal combustion engine is disclosed, comprising the following steps: i. providing a camshaft drive unit with a transmission system pre-assembled on a base plate, the transmission system being form-fitted against a first camshaft drive wheel, a second camshaft drive wheel, and a crankshaft wheel, the base plate also having a tensioning device capable of being brought from an assembled position to a tensioned position, in which the tensioning device does not load the transmission system, and in the tensioned position, the tensioning device holds the transmission system under tension force; ii. locking the second camshaft drive wheel and the crankshaft wheel against torsion; iii. ... The first camshaft drive wheel rotates along a first rotational direction, during which the section of the transmission system between the first camshaft drive wheel and the second camshaft drive wheel is relaxed, and the transmission system is brought into contact with the tensioning device; iv. the tensioning device acting on the transmission system and disposed between the crankshaft wheel and the first camshaft drive wheel is released; v. the first camshaft drive wheel is rotated along the first rotational direction and the opposite second rotational direction, thereby tensioning the transmission system by the tensioning device; and vi. the first camshaft drive wheel is fixed to the first camshaft, the second camshaft drive wheel is fixed to the second camshaft, and the crankshaft wheel is fixed to the crankshaft.

Description

Technical Field

[0001] This disclosure relates to a method for assembling a camshaft drive, particularly a chain-driven camshaft drive, with a transmission system. The transmission system can in principle involve toothed belts or camshafts; however, the embodiments described below relate to camshaft drives with control chains. This disclosure particularly relates to a method for assembling a camshaft drive having an input camshaft and an output camshaft. In this camshaft drive, the control chain extends V-shaped from one crankshaft pulley to both camshaft drives. Background Technology

[0002] German patent document DE 36 36 918 A1 discloses a chain tensioning mechanism for an internal combustion engine. In this mechanism, a damping piston guided within a housing is axially loaded by a spring in the chain tensioning device. The damping piston can be locked by means of an assembly ring within the housing. To allow the damping piston to be brought into the locked position externally using a tool and to easily release the lock without a tool, the assembly ring engages with a groove on the damping piston that has a bevel and a locking surface. The assembly ring is brought to the locking surface by using a tool that can be inserted into the gap. Here, the assembly ring engages with the groove in the housing and locks the movement of the damping piston.

[0003] After assembly, the drivetrain is slack, the chain tensioner is not in contact with the tension rail, and the spring-loaded tensioning device acting on it is locked or locked. This can lead to a gap between the crankshaft pulley and the drivetrain, as the drivetrain sags downwards and cannot engage with the crankshaft pulley. The camshaft pulley cannot be secured because the drivetrain can move relative to the crankshaft pulley. This can cause control timing errors, and the crankshaft pulley may slip when bolted to the crankshaft, which often goes unnoticed during assembly and can cause engine damage when the internal combustion engine starts running. Summary of the Invention

[0004] One aspect of this disclosure provides a method for assembling a camshaft drive without the need for tools to unlock the tensioning device.

[0005] The technical solutions of the present invention address the aforementioned aspects. The technical solutions of the present invention can be combined with each other in a technically meaningful manner. This disclosure is characterized and further described in detail, particularly in conjunction with the accompanying drawings.

[0006] Therefore, a method for assembling a camshaft drive device for an internal combustion engine is disclosed, comprising the following steps:

[0007] i. A camshaft drive device with a transmission system pre-assembled on a base plate, the transmission system being form-fitted against a first camshaft drive wheel, a second camshaft drive wheel, and a crankshaft wheel. The base plate also has a tensioning device capable of being moved from an assembled position to a tensioned position, in which the tensioning device does not load the transmission system, and in the tensioned position, the tensioning device holds the transmission system under tension force.

[0008] ii. Torsionally lock the second camshaft drive wheel and crankshaft wheel.

[0009] iii. The first camshaft drive wheel is rotated along a first rotation direction, during which the section of the transmission system between the first and second camshaft drive wheels is relaxed, and the transmission system is brought into contact with the tensioning device.

[0010] iv. Loosen the tensioning device acting on the transmission system that is positioned between the crankshaft wheel and the first camshaft drive wheel.

[0011] v. Rotate the first camshaft drive wheel in a second rotation direction opposite to the first rotation direction, thereby tensioning the tensioning device's transmission system; and

[0012] vi. Fix the first camshaft drive wheel to the first camshaft, fix the second camshaft drive wheel to the second camshaft, and fix the crankshaft wheel to the crankshaft.

[0013] This type of transmission system, such as toothed belts and control chains, can be pre-assembled as a unit consisting of a camshaft drive wheel for the input camshaft and a camshaft drive wheel and crankshaft pulley for the output camshaft. This unit, consisting of the camshaft drive wheel for the input camshaft and the camshaft drive wheel and crankshaft pulley for the output camshaft, is pre-assembled on a base plate. The base plate facilitates the insertion of the unit into the corresponding position on the end side of the internal combustion engine.

[0014] A base plate with a tensioning device configured in this way can be fitted into an internal combustion engine, wherein the tensioning device is completely inaccessible after the base plate is fitted into the internal combustion engine. The tensioning device is activated or released by pressing it in a direction opposite to the subsequent tensioning direction until the unlocking device and locking hook or similar device are released. The tensioning device is, as described, inaccessible after the base plate is inserted into the internal combustion engine.

[0015] In one design, the unlocking device of the tensioning device is released only by applying a force opposite to the direction of subsequent action, wherein the torque that causes the first camshaft wheel to rotate in a first rotational direction is chosen to be so large that the tensioning device is correspondingly released by applying this force through the tensioning transmission system, wherein the tensioning device, in the released state, acts on the transmission system in the direction opposite to the direction of action of the force and thereby tensions the transmission system.

[0016] To implement the method, a base plate is provided, having a pre-assembled camshaft drive and transmission system. The transmission system is form-fitted against a first camshaft drive wheel, a second camshaft drive wheel, and a crankshaft wheel. The base plate also has a tensioning device that can be moved from an assembled position to a tensioned position, in which the tensioning device does not load the transmission system, and in which the tensioning device holds the transmission system under tension force. Here, the tensioning device is released (unlocked) only by applying a force opposite to the subsequent direction of action. For this purpose, a torque can be applied to the first camshaft drive wheel, which applies the force by tightening the transmission system to unlock the unlocking device that holds the tensioning device in the assembled position.

[0017] The assembly of the camshaft drive unit on the internal combustion engine is thus simplified, eliminating the possibility of errors. No tools are required for unlocking the tensioning device or unlocking mechanism; the unlocking can be performed externally.

[0018] The base plate with a pre-assembled camshaft drive unit can thus be used in an internal combustion engine having an assembly position in which the base plate can only be placed, when a tensioning device arranged on the base plate swings into and locks into the assembly position.

[0019] i. Wherein, the tensioning device does not apply tension force to the transmission system in the assembled position, wherein,

[0020] ii. In order to transition the tensioning device from the assembled position to the operational ready position, in the operational ready position, the unlocking device of the tensioning device is kept unlocked, and in the operational ready position, the tensioning device presses against the transmission system in the direction of action and thereby tensions the transmission system.

[0021] iii. Apply a force in the opposite direction to the subsequent action.

[0022] iv. Wherein, since the tensioning device is inaccessible at the assembly location, the force can also be applied through tensile stress in the transmission system caused by the torsion of the camshaft drive wheel relative to the crankshaft wheel. Attached Figure Description

[0023] The accompanying drawings are for illustrative purposes only and should not be construed as limiting the scope of this disclosure. In the drawings:

[0024] Figure 1A A camshaft drive with a V-shaped extension of the control transmission is schematically shown in the basic positional state.

[0025] Figure 1B The illustration shows the source Figure 1A A camshaft drive device having a transmission system located in a section between a first camshaft drive wheel and a second camshaft drive wheel, the section being drooping because the first camshaft drive wheel rotates clockwise;

[0026] Figure 1C It shows the source Figure 1A and 1B The camshaft drive device in the third position, in which the first camshaft drive wheel rotates counterclockwise, so that the section between the first and second camshaft drive wheels contacts the slide rail and the transmission system is tensioned; and

[0027] Figure 2 A method for assembling a camshaft drive for an internal combustion engine is illustrated in six steps. Detailed Implementation

[0028] The following description is purely illustrative. For the sake of brevity, the same reference numerals are used in the accompanying drawings to label similar elements.

[0029] exist Figures 1A to 1C The transmission system 41 is schematically shown. Transmission system 41 is part of the camshaft drive unit 40. Transmission system 41 is configured to transmit rotational motion at a constant gear ratio between crankshaft pulley 30 and first camshaft drive pulley 10 and second camshaft drive pulley 20. The gear ratio here is 1:2, meaning that a full 360° rotation of crankshaft pulley 30 causes a half 180° rotation of camshaft drive pulleys 10 and 20. Slippage should be minimized, hence the use of a form-fitting toothed belt and chain drive. In the illustrated design, transmission system 41 is a control chain held under tension by a tension rail 44. Transmission system 41 operates the camshafts 11 and 12 of the internal combustion engine 60, which are only schematically shown.

[0030] The compact internal combustion engine 60 has limited space. The camshaft drive unit 40 is mounted on the base plate 45, so that the entire unit, consisting of the first camshaft drive wheel 10, the second camshaft drive wheel 20, and the crankshaft wheel 30, along with the transmission system 41 and tension rail 44 V-shaped around the unit, can be positioned at a corresponding mounting position 61 on the internal combustion engine 60. However, this mounting is only successfully completed when the tensioning device 43 is in the mounting position 46 to pre-tension the transmission system 41. In the subsequent tensioning position 47, the tensioning device 43 is no longer accessible, or the transmission system 41 can no longer be locked by the wedge.

[0031] Figures 1A to 1C Three basic positions are shown, in which the camshaft drive 40 is assembled in the internal combustion engine 60. The base plate 45 has the pre-assembled camshaft drive 40 and transmission system 41, which form-fits against the first camshaft drive wheel 10, the second camshaft drive wheel 20, and the crankshaft wheel 30. The base plate 45 also has the aforementioned tensioning device 43, which can be moved from the assembled position 46 to the tensioned position 47, in which the tensioning device does not load the transmission system 41, and in the tensioned position, the tensioning device holds the transmission system 41 under tension force. Here, the tensioning device 43 is released only by applying a force F opposite to the subsequent direction of action 48 (the spring force of the tensioning device 43). For this purpose, a torque M51 can be applied to the first camshaft drive wheel 10 using a torque wrench (not shown), which applies force F by tightening the transmission system 41 to unlock the unlocking device 49 that holds the tensioning device 43 in the assembled position 46. exist Figure 1B The corresponding situation is shown in the figure. Section 42 of the transmission system 41 is shown as drooping, and the transmission system 41 is tensioned between the crankshaft wheel 30 and the first camshaft drive wheel 10.

[0032] In this configuration, the first camshaft drive wheel and the second camshaft drive wheels 10, 20 can typically be moved and fixed by bolts. The corresponding bolts (not shown) are still accessible to tools. Similarly, the following sections of the transmission system 41 are still accessible so that they can be held in place if necessary.

[0033] Figure 1A A base plate 45 on an internal combustion engine 60 with a pre-assembled camshaft drive 40 is shown. The internal combustion engine has an assembly position 61, in which the base plate 45 can only be placed when a tensioning device 43 arranged on the base plate 45 swings into and locks into the assembly position 46.

[0034] In the assembly position 46, the tensioning device 43 does not apply tension to the transmission system 41. To change the tensioning device 43 from the assembly position 46 to the operational ready position 47, the corresponding... Figure 1B A force F is applied to unlock the tensioning device 49 in the ready-to-operate position, and in this position, the tensioning device 43 is pressed against the transmission system 41 along the direction of action 48, thereby tensioning the transmission system. The force F is applied here in the opposite direction to the subsequent direction of action 48. Now, since the tensioning device 43 lacks accessibility in the mounting position 61, this force F can also be applied via tensile stress in the transmission system 41, caused by the torsion of the camshaft drive wheel 10 relative to the crankshaft wheel 30.

[0035] Therefore, the corresponding... Figure 2 The method, in a first step 101, provides a camshaft drive device 40 pre-assembled on a base plate 45. The camshaft drive device has a transmission system 41 that fits form-fittingly against a first camshaft drive wheel 10, a second camshaft drive wheel 20, and a crankshaft wheel 30. The base plate 45 also has a tensioning device 43, which can be moved from an assembled position 46 to a tensioned position 47, in which the tensioning device does not load the transmission system 41, and in which the tensioning device holds the transmission system 41 under tension force. The tensioning device 43 holds the transmission system under tension force by a spring (not shown). The force F must therefore overcome the tension force applied by the spring (along the direction of action 48, see...). Figure 1C ).

[0036] In the second step 103, the second camshaft drive wheel 10 and crankshaft wheel 30 are locked in a torsion-resistant manner. The locking is achieved by wedges or even simply by holding the wheels 10, 20, and 30 in place.

[0037] In the third step 103, the first camshaft drive wheel 10 is rotated along a first rotation direction 51, during which the section 42 of the transmission system 41 between the first camshaft drive wheel 10 and the second camshaft drive wheel 20 is relaxed, and the transmission system 41 is brought into contact with the tensioning device 43. The first rotation direction 51 is clockwise in the view shown. The section 42 then sags, and the remaining sections between the crankshaft wheel 30 and the first camshaft drive wheel 10, and between the crankshaft wheel 30 and the second camshaft drive wheel 20, are tensioned. The torque is applied by a tool, particularly a torque wrench.

[0038] In step 104, the tensioning device 43, which acts on the transmission system 41 and is located between the crankshaft wheel 30 and the first camshaft drive wheel 10, is released. This release is achieved by unlocking the unlocking device 49.

[0039] In step 105, the first camshaft drive wheel 10 is rotated along a second rotation direction 52, which is opposite to the first rotation direction 51, thereby tensioning the tensioning device 43 tensioning the transmission system 41. This is preferably done by a torque wrench.

[0040] In step 106, the first camshaft drive wheel 10 is fixed to the first camshaft 11, the second camshaft drive wheel 20 is fixed to the second camshaft 21, and the crankshaft wheel 30 is fixed to the crankshaft 31. The fixing is achieved by bolts (not shown) passing through wheels 10, 20, and 30 and frictionally holding the wheels on shafts 11, 21, and 31.

[0041] The unlocking device 49 is hereby released individually by applying a force F opposite to the subsequent direction of action 48, as described above. This causes the first camshaft wheel 10 to rotate along the first rotation direction 51 (see...). Figure 1B The torque M51 is chosen so large that the tensioning device 43 correspondingly applies a force F against the spring force of the tensioning device 43 through the tensioning transmission system 41 to unlock the unlocking device 49. In the released state, the tensioning device 43 acts on the transmission system 41 in the opposite direction 48 to the force F and thereby tensions the transmission system.

[0042] Although at least one embodiment has been shown in the foregoing description and accompanying drawings, it should be noted that numerous variations exist. Furthermore, it should be pointed out that this embodiment or these embodiments are merely examples and are not intended to limit the scope of protection, applicability, or specific design in any way or by any means. Rather, the description and accompanying drawings are intended to provide useful guidance to those skilled in the art for implementing at least one embodiment, and it should be indicated herein that different changes may be made to the described features and functions without departing from the scope of the claims and their equivalents.

[0043] List of reference numerals

[0044] 10 First Camshaft Drive Wheel

[0045] 11 Camshaft

[0046] 20 Second Camshaft Drive Wheel

[0047] 21 Camshaft

[0048] 30 Crankshaft Wheel

[0049] 31 Crankshaft

[0050] 40 Camshaft Drive Unit

[0051] 41 Transmission System

[0052] Section 42

[0053] 43 Tensioning device

[0054] 44 tension rails

[0055] 45 substrate

[0056] 46 Assembly Position

[0057] 47 Tensioned Positions

[0058] 48. Direction of action

[0059] 51 First rotation direction

[0060] 52 Second Rotation Direction

[0061] 60 internal combustion engine

[0062] 61 Assembly position

[0063] 101 steps

[0064] 102 steps

[0065] 103 steps

[0066] 104 steps

[0067] 105 steps

[0068] 106 steps

[0069] F force

[0070] M51 torque.

Claims

1. A method for assembling a camshaft drive device (40) for an internal combustion engine, comprising the following steps: vii. A camshaft drive (40) with a transmission system (41) is provided pre-assembled on a base plate (45), the transmission system being form-fitted against a first camshaft drive wheel (10), a second camshaft drive wheel (20), and a crankshaft wheel (30). The base plate (45) also has a tensioning device (43) that can be moved from an assembled position (46) to a tensioned position (47), in which the tensioning device does not load the transmission system (41), and in the tensioned position, the tensioning device holds the transmission system (41) under tension. viii. Torsionally lock the second camshaft drive wheel (10) and the crankshaft wheel (30), ix. The first camshaft drive wheel (10) is rotated along a first rotation direction (51), during which the section (42) of the transmission system (41) between the first camshaft drive wheel (10) and the second camshaft drive wheel (20) is relaxed, and the remaining sections between the crankshaft wheel (30) and the first camshaft drive wheel (10) and between the crankshaft wheel (30) and the second camshaft drive wheel (20) are tensioned, and the transmission system (41) is brought into contact with the tensioning device (43). x. Release the tensioning device (43) acting on the transmission system (41) that is located between the crankshaft wheel (30) and the first camshaft drive wheel (10). xi. Rotate the first camshaft drive wheel (10) along a second rotation direction (52) opposite to the first rotation direction (51), thereby tensioning the tensioning device (43) tensioning the transmission system (41); and xii. Fix the first camshaft drive wheel (10) to the first camshaft (11), fix the second camshaft drive wheel (20) to the second camshaft (21), and fix the crankshaft wheel (30) to the crankshaft (31).

2. The method according to claim 1, wherein, The unlocking device (49) holding the tensioning device (43) is released only by applying a force (F) opposite to the subsequent direction of action (48), wherein the torque (M51) that causes the first camshaft wheel (10) to rotate in the first direction of rotation (51) is selected so large that the tensioning device (43) is correspondingly released by applying the force (F) to the transmission system (41), wherein the tensioning device (43) in the released state acts on the transmission system (41) in the direction of action (48) opposite to the force (F) and thereby tensions the transmission system.

3. A substrate (45) having a pre-assembled camshaft drive (40) and transmission system (41) using the method according to claim 1 or 2, the transmission system being form-fitted against a first camshaft drive wheel (10), a second camshaft drive wheel (20), and a crankshaft wheel (30), the substrate (45) further having a tensioning device (43) capable of being moved from an assembled position (46) to a tensioned position (47), in which the tensioning device does not load the transmission system (41), and in the tensioned position, the tensioning device holds the transmission system (41) under tension force, wherein, The tensioning device (43) can be released by applying a force (F) opposite to the subsequent direction of action (48), wherein a torque (M51) can be applied to the first camshaft drive wheel (10), the torque being applied by the tensioning transmission system (41) to unlock the unlocking device (49) that holds the tensioning device (43) in the assembled position (46).

4. Application of a base plate (45) having a pre-assembled camshaft drive (40) using the method according to claim 1 or 2 on an internal combustion engine (60), the internal combustion engine having an assembly position (61) in which the base plate (45) can only be positioned when a tensioning device (43) arranged on the base plate (45) swings into and locks into the assembly position (46). v. among which, The tensioning device (43) does not apply tension to the transmission system (41) in the assembled position (46), wherein, vi. In order to change the tensioning device (43) from the assembled position (46) to the operational ready position (47), in the operational ready position, the unlocking device (49) of the tensioning device (43) is kept unlocked, and in the operational ready position, the tensioning device (43) is pressed against the transmission system (41) along the direction of action (48) and thereby tensions the transmission system. vii. Apply a force (F) opposite to the direction of the subsequent action (48), viii. Since the tensioning device (43) is inaccessible at the mounting position (61), the force (F) can also be applied by tensile stress in the transmission system (41), which is caused by the torsion of the camshaft drive wheel (10) relative to the crankshaft wheel (30).

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