The invention relates to a device for changing control times for gas-exchange valves in an internal combustion engine according to features recited in the preamble of claim 1, which can be realized especially advantageously on a rotary piston adjustment device for angular adjustment of a camshaft relative to a crankshaft.
From DE 101 50 856 A1, a class-defining device for changing control times of gas-exchange valves in an internal combustion engine is known, which is mounted on the drive end of a camshaft supported in the cylinder head of an internal combustion engine and which, in principle, is embodied as a hydraulic actuator that can be controlled as a function of various operating parameters of the internal combustion engine. This device essentially consists of a drive wheel, in driven connection with the crankshaft of the internal combustion engine, and of a vane rotor, which is locked in rotation with the camshaft of the internal combustion engine. The drive wheel and vane rotor are in force-transmitting connection with each other and transmit the torque of the crankshaft to the camshaft of the internal combustion engine. The drive wheel has a hollow space, which is formed by a hollow cylindrical peripheral wall and two lateral walls and in which five hydraulic work chambers are formed by five radial limit walls which extend towards the longitudinal center axis of the device. Correspondingly, on the periphery of its rotor hub, the vane rotor has five vanes, which extend radially into the work chambers and which sub-divide the work chambers into an A pressure chamber and a B pressure chamber, which can be used to cause a pivoting motion or to fix the vane rotor relative to the drive wheel and thus the camshaft relative to the crankshaft through selective or simultaneous pressurization with a hydraulic pressure medium. In addition, the vane rotor can be mechanically coupled to the drive wheel by a separate locking element in a preferred base position within its adjustment region when the pressure medium pressure falls below a pressure necessary for adjustment, such as, for example, when the internal combustion engine is turned off, in order to prevent rattling of the vane rotor striking the limit walls of the drive wheel due to the changing torque of the camshaft, especially when the internal combustion engine is restarted and until the necessary pressure medium pressure has been established. This locking element, embodied as a sleeve-like cylinder pin, is arranged in a continuous axial bore hole in the rotor hub of the vane rotor and can move into a locked position within a receptacle in the lateral wall of the drive wheel facing away from the camshaft by a spring element, which is provided as a compression coil spring and which is supported on one side on the rear side of the locking element and on the other side on a holder similarly inserted into the axial bore hole. The receptacle of the locking element is connected to one of the A pressure chambers of the device via a pressure medium supply groove machined into the inner surface of the lateral wall facing away from the camshaft, so that when the A pressure chambers have been pressurized, the locking element can move hydraulically into an unlocked position within the axial bore hole in the rotor hub of the vane rotor.
However, a disadvantage in this known device is that the locking element is in constant pressure medium connection with the corresponding A pressure chamber of the device for mechanical coupling of the vane rotor with the drive wheel in its unlocked position also outside of the base position of the vane rotor via the pressure medium supply groove to its receptacle in the lateral wall of the drive wheel, so that when the A pressure chambers are pressurized, the applied pressure medium pressure and also the resulting pressure peaks of the pressure medium also act permanently on the locking element or on the entire locking mechanism. Because the pressurized locking element is supported on its holder arranged in the axial bore hole of the rotor hub and the usually plastic holder is supported on its side on the lateral wall of the drive wheel facing the camshaft and closing the axial bore hole, the pressure medium pressure permanently acting on the locking element leads to increased wear on the holder and on the lateral wall of the drive wheel due to the constant relative rotation between the vane rotor and the drive wheel. However, this wear negatively affects the function of the locking mechanism in a disadvantageous way and can lead to a loss of function over the service life of the device.
Therefore, the invention is based on the objective of designing a device for changing the control times of gas-exchange valves in an internal combustion engine, especially a rotary piston adjustment device for angular adjustment of a camshaft relative to a crankshaft, in which these disadvantageous effects on the entire locking mechanism resulting from the constant pressure medium connection of the locking element to one of the pressure chambers of the device or from the permanent pressurization of the locking element can be prevented in a simple way.
According to the invention, this objective is met for a device according to the preamble of claim 1, in that within the pressure medium supply groove machined into the inner surface of the appropriate lateral wall of the drive wheel, there is a local stop, by means of which the supply of pressure medium to the receptacle for the locking element is constantly interrupted when the vane rotor has pivoted out of the base position. However, in order to further enable a hydraulic unlocking of the locking element, in the side surface of the vane rotor hub opposite the pressure medium supply groove there is also a bypass, such that the local stop can be bypassed and a supply of pressure medium to the receptacle for the locking element is possible only when the vane rotor is pivoted into the base position.
Here, the locking element is provided as a sleeve-like cylinder pin, which is arranged in a though extending axial bore hole in the rotor hub of the vane rotor and which can move into its locked position in the receptacle in one of the lateral walls of the drive wheel via a spring element, which is provided as a compression coil spring and which is supported on one side on the rear side of the locking element and on the other side on a holder also inserted into the axial bore hole.
Correspondingly, the receptacle for the locking element is provided in a similarly known manner as a local recess in the inner surface of the lateral wall opposite the locking element. This lateral wall has a preferably rectangular outline, which is larger by a defined amount of play than the cross-sectional surface of the locking element. The pressure medium supply groove with a preferably arc-shaped profile opens into this lateral wall.
In a useful improvement of the device according to the invention, the receptacle for the locking element formed in this way and its pressure medium supply groove are preferably arranged in the inner surface of the lateral wall facing away from the camshaft and created in this lateral wall without cutting by stamping, wherein the local stop in the pressure medium supply groove is preferably provided as a material crossbar remaining after the stamping. However, for a correspondingly opposed arrangement of the locking element in the axial bore hole in the rotor hub of the vane rotor, it is also possible to arrange the receptacle for the locking element and its pressure medium supply groove in the lateral wall of the drive wheel facing the camshaft. As an alternative to stamping, it is also possible to produce the receptacle for the locking element and its pressure medium supply groove by milling in the corresponding lateral wall of the drive wheel and here to provide the local stop in the pressure medium supply groove also as a material crossbar that is left behind. In addition, for retrofitting it can be advantageous, especially for devices not constructed according to the invention, to form the local stops through later insertion of a corresponding straight pin into a bore hole within the typically continuous pressure medium supply groove.
Finally, according to the preferred arrangement of the receptacle for the locking element in the lateral wall of the drive wheel facing away from the camshaft, it is also proposed as another useful improvement of the device according to the invention to arrange the bypass for the local stop in the pressure medium supply groove also in the lateral wall of the side surface of the vane rotor hub facing away from the camshaft and to provide this bypass as an elongated hole-like recess. It has proven to be effective in an especially advantageous way to form this elongated hole-like recess along with the typically powder-metallurgical production of the vane rotor hub without further tools in the corresponding side surface of the rotor hub, that is, to form the stamping mold for the vane rotor hub such that absolutely no finishing work on the recess forming the bypass is necessary anymore. Here, it is also possible, naturally especially for the use of other suitable materials for the vane rotor hub or also for the retrofitting of devices not embodied according to the invention, to machine the elongated hole-like recess forming the bypass into the corresponding side surface of the vane rotor hub at a later time by cutting processes, such as, for example, milling. To prevent additional throttling positions for the pressure medium, it is also advantageous to dimension the bypass at least twice as long as the width of the material crossbar forming the local stop in the pressure medium supply groove, while its width and depth have approximately the same width and depth as the pressure medium supply groove in the lateral wall of the drive wheel.
Thus, it is possible with a bypass provided in this way in the side surface of the vane rotor hub to bypass the local stop in the pressure medium supply groove to the receptacle for the locking element in the lateral wall of the drive wheel when the vane rotor of the device has been pivoted into its base position, like, for example when the internal combustion engine is turned off, and when the locking element of the device has been pushed into this position in its receptacle in the lateral wall of the drive wheel. When the pressure chambers of the device, of which one is also connected to the pressure medium supply groove to the receptacle for the locking element, are pressurized, such as, for example, when the internal combustion engine is restarted, the hydraulic pressure medium first reaches the local stop in the pressure medium supply groove and then flows within the bypass into the vane rotor hub past the local stop into the receptacle for the locking element, and then moves the locking element into its unlocked position within the axial bore hole in the vane rotor hub. The vane rotor, which is now unlocked, then pivots out of its base position due to the further pressurization of the pressure chambers, so that the bypass in its rotor hub also moves out of its bypass position for the local stop in the pressure medium supply groove and the continued supply of pressure medium to the receptacle for the locking element is interrupted by the smooth side surface of the vane rotor hub now contacting the local stop.
The device according to the invention for changing the control times of gas-exchange valves in an internal combustion engine, especially a rotary piston adjustment device for angular adjustment of a camshaft relative to a crankshaft, thus features the advantage, in comparison with the devices known from the state of the art, that the locking element for mechanical coupling of the vane rotor with the drive wheel is no longer in pressure medium connection with the correspondingly pressurized pressure chamber of the device outside of the base position of the vane rotor due to the arrangement of a simple local stop in the pressure medium supply groove to its receptacle in the lateral wall of the drive wheel. Through such a local stop, it is thus ruled out in each position of the vane rotor outside of its base position that when the pressure chamber connected to the pressure medium supply groove is pressurized, neither the normally applied pressure of the hydraulic pressure medium nor its pressure peaks exert a negative effect on the locking mechanism. In particular, the holder of the locking element and the lateral wall of the drive wheel supporting the holder no longer experience increased wear, so that their function is reliably guaranteed over the service life of the device. Simultaneously, due to the bypass arranged in the vane rotor hub, it is possible as before for the locking element to be moved hydraulically into its unlocked position in the vane rotor hub in a known way when the vane rotor has been pivoted into its base position.
The invention is explained in more detail below with reference to one embodiment and is shown schematically in the associated drawings.
Shown are:
From
In addition, in
Likewise, it is visible from
So that the locking element 14 is not constantly exposed to the applied pressure medium pressure when the A pressure chambers 12 are pressurized, in the device 1 according to the invention a local stop 20 shown clearly in
Number | Date | Country | Kind |
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103 55 502 | Nov 2003 | DE | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/EP2004/011850 | 10/20/2004 | WO | 00 | 4/10/2006 |
Publishing Document | Publishing Date | Country | Kind |
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WO2005/061860 | 7/7/2005 | WO | A |
Number | Name | Date | Kind |
---|---|---|---|
6405694 | Sato | Jun 2002 | B2 |
20010054406 | Okada et al. | Dec 2001 | A1 |
20020078913 | Fukuhara et al. | Jun 2002 | A1 |
Number | Date | Country |
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101 01 328 | Dec 2001 | DE |
101 33 445 | Jul 2002 | DE |
101 50 856 | Apr 2003 | DE |
102 46 838 | Apr 2004 | DE |
102 53 883 | May 2004 | DE |
2000179310 | Jun 2000 | JP |
Number | Date | Country | |
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20070039580 A1 | Feb 2007 | US |