The invention relates to an adjusting device for adjusting valve clearance for a charge-cycle valve of an internal combustion machine with a pivoted rocker lever, at the one end of which an actuation element is positioned that can be used to transfer a force to the charge-cycle valve. Furthermore, the invention relates to a method for adjusting valve clearance of a charge-cycle valve of an internal combustion machine using an adjusting device including a pivoted rocker lever, to the one end of which an actuation element is attached that can be used to transfer an actuation force to the charge-cycle valve.
For example, such an adjusting device for a charge-cycle valve is already described in DE 10 2009 018 963 A1 and thus is already known. The adjusting device described therein is designed as a valve clearance adjusting element and is positioned at a valve drive device for actuating at least one axially movable charge-cycle valve with an actuation unit that can be tilted by an actuation axis. The actuation unit includes a valve actuation element for coupling with the charge-cycle valve, as well as the valve clearance adjusting element for axial adjustment of the valve actuation element, and a ball joint positioned between the valve actuation element and the valve clearance adjusting element. The ball joint positioned there is oriented in a defined manner using a reset device once the ball joint has adopted a non-actuated operating condition. The reset element positioned there includes a spring element at least partially positioned within the ball joint. The spring element positioned there is designed as a so-called bending pin and is subject to particularly frequent alternating loads during motor operation, i.e., when actuating the valve for charge changing of a combustion chamber of the internal combustion machine. Therefore, there is the risk of a fatigue fracture or a misalignment of the valve clearance due to the frequently alternating loads of the reset device.
In order to adjust the valve clearance regarding rocker lever valve drives (without hydraulic clearance balancing elements such as hydraulic plungers), an adjusting screw or adjusting nut is used in most cases, with this screw or nut being equipped with a locking element in order to hold its position (for instance, nut or setscrew). These adjusting screws and nuts, respectively, of the locking element are usually tightened applying a high torque upon successful adjustment and fine adjustment, respectively, with this tightening occasionally mostly resulting in the previously set clearance value being misaligned. Furthermore, at least two tools are necessary requiring a corresponding clearance at the valve drive and simultaneous meshing. The locking torque introduced with the help of the tools is absorbed via the respective component bearing points and must be taken into account when designing the clearance value, i.e., the bearing clearance, due to possible component deformations caused by introducing the torque.
The purpose of the present invention is to create an adjusting device as well as a method for adjusting a valve clearance of a charge-cycle valve of an internal combustion machine using an adjusting device of the above-mentioned type that can be used to particularly accurately adjust a valve clearance with little effort and to simultaneously permanently eliminate deviations from the preset valve clearance during motor operation.
In order to create an adjusting device of the above-mentioned type, which can be used to permanently and accurately adjust a valve clearance using simple means, it is provided according to the invention that a transmission element is attached to the actuation element, at the end opposite of the charge-cycle valve of which a sleeve area is positioned supporting the transmission element regarding the actuation element. Due to the transmission element being supported regarding the actuation element by means of its sleeve area, it is possible to efficiently prevent any tilting of the transmission element in relation to the actuation element and to thus comply with more accurate position tolerances the longer the sleeve area. In this, the transmission element serves as a clearance balancing element and automatically maintains a preset position, with the transmission element not requiring any additional attachment and locking, respectively, within the framework of an additional installation step. As a consequence, the valve clearance adjustment of the charge-cycle valve can be performed particularly easily and quickly by the technician. In so doing, particularly misalignments and damages to the individual components of the adjusting device are avoided and possible maintenance times are shortened. Furthermore, the installation space and free tool access, respectively, required for installation is reduced.
In an advantageous embodiment of the invention, the transmission element has an internal area and an external area. For example, the internal area and the external area may have a cylindrical contour each and be thus positioned concentrically to one another. By positioning the internal area, in relation to the external area, in a concentric manner, it is, for instance, possible to initially create the internal area, for example in the form of a drilled hole, with this drilled hole then serving as the bearing point when creating and processing, respectively, the external area. As a consequence, the internal area and the external area can be aligned in relation to one another with a particular level of accuracy and using particularly simple means and thus the transmission element can be designed particularly accurately with particularly low manufacturing effort.
It has further been shown to be advantageous if the internal area has a female thread and the external area has a male thread for supporting the transmission element regarding the actuation element. The female thread and the male thread can be aligned particularly accurately to one another in the case of a respective concentric position to one another. Furthermore, the two threads can each be characterized by a particularly low pitch, inhibiting any misalignment of the valve clearance during the alternating load caused by operating the charge-cycle valve (self-inhibition), since it is possible to particularly efficiently prevent a relative rotation between the transmission element and the actuation element in the event of a low pitch of the respective threads.
Furthermore, it is particularly advantageous if the transmission element is supported at the actuation element via its female thread using a pre-stressed bolt. In so doing, the pre-stressed bolt is screwed into the transmission element and is supported using a contact face of the pre-stressed bolt's head at the actuation element. As a consequence, an internal force fit between the pre-stressed bolt, the transmission element and the actuation element is provided for, locally limiting possible component warpage due to the mutual bracing to a special degree, which is accordingly low.
In a preferred embodiment, the transmission element is supported at a thread of the actuation element using its external thread. As a matter of principle, threads are characterized by a certain clearance, which, as a consequence of the mutual bracing, is minimized particularly by the fact that both the internal thread and the external thread are loaded. Hence, the transmission element is not only screwed to the actuation element via its external thread, but is also screwed to the pre-stressed bolt via its internal thread, and accordingly both threads, i.e., both the internal and the external thread of the transmission element, are meshed with a load and braced in relation to one another under opposite-directional force effect. As a consequence, the transmission element is fixed in a particularly stationary manner, it being understood that a torque required for rotating the transmission element, with the torque being applied by using a tool, for example, is higher the higher the clamping force between the internal thread and the external thread, since an increased clamping force also entails an increased friction torque between the respective turns to be applied during rotation.
Ultimately, it has proved advantageous when the internal thread and the external thread of the transmission element are characterized by the same pitch. If the pitches of the internal thread and the external thread are identical, each of the load-bearing thread flanks is loaded particularly uniformly, allowing for the implementation of all the more high tightening torques. The application of high tightening torques guarantees a particularly high level of safety regarding any misalignment of the transmission element during alternating loads due to valve actuation during motor operation.
Within the framework of the method for adjusting a valve clearance of a charge-cycle valve of an internal combustion machine according to the invention, a transmission element is attached to the actuation element by compensating an external area of the transmission element, a clamping element is attached to an internal area of the transmission element, the transmission element is braced with the actuation element by applying a torque to the clamping element, as well as the clamping element is connected to the actuation element by means of a firm bond.
If, advantageously, a so-called pre-stressed bolt is used as the clamping element, the valve clearance can be secured against misalignment particularly permanently. By firmly bonding, i.e., through gluing, soldering, or welding, for example, the clamping element to the actuation element, the safety regarding a misalignment of the valve clearance is further increased.
The advantages and embodiments described for the adjusting device according to the invention are also applicable to the method according to the invention and vice versa.
The features and combinations of features mentioned within the framework of the above description, as well as the features and combinations of features mentioned in the below description of the figures and/or illustrated alone in the figures may not only be used within the framework of the combination specified in each case, but also within the framework of other combinations or alone, without exceeding the scope of the invention in so doing.
Further advantages, features, and details of the invention can be derived from the following description of preferred embodiments, as well as based on the drawings.
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