An internal combustion engine having a device for hydraulically adjusting the angle of rotation of the camshaft thereof relative to the crankshaft thereof is provided, which also includes a vacuum pump for a servo load. The device includes a drive unit that is connected in a driving manner to the crankshaft and an output unit which is connected in a torsion-proof manner to the camshaft. The lubricating oil of the internal combustion engine, which is fed from a radial bearing of the camshaft in the cylinder head, is used as a hydraulic pressurizing medium for the device. Thee vacuum pump includes a housing that has a flanged connection to the cylinder head cover, and a rotor that is disposed therein and is provided with a drive shaft via which the vacuum pump is driven and lubricated. The vacuum pump is arranged in an axial direction relative to the device, while the device is provided with additional coupling elements via which the drive shaft od the vacuum pump is connected in a driving manner to the device. The vacuum pump is lubricated by lubricating oil from the internal combustion engine, which is delivered to the device as the pressurizing medium.
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0. 8. Internal-combustion engine with a device for hydraulically adjusting an angle of rotation of a camshaft of the engine relative to a crankshaft of the engine and with a vacuum pump for a servo load, comprising:
the device for hydraulically adjusting the angle of rotation is arranged on a drive-side end of the camshaft supported in several radial bearings in a cylinder head of the internal-combustion engine and is formed as a hydraulic actuator;
the device includes a drive unit connected in a driving manner to the crankshaft of the internal-combustion engine and a driven unit connected in a torsion-proof manner to the camshaft of the internal-combustion engine;
the driven unit is fixed to the camshaft and the drive unit is provided as a hollow cylinder, which surrounds the driven unit and which is sealed tight relative to a pressurizing medium by two axial side walls;
the drive unit is connected in a force-transferring manner to the driven unit of the device through at least two compression chambers, which are formed within the device and which can be pressurized alternately or simultaneously with a hydraulic pressurizing medium;
a lubricating oil of the internal-combustion engine is used as the hydraulic pressurizing medium for the device;
the vacuum pump for the servo load includes a housing connected to the cylinder head cover of the internal-combustion engine and a rotor arranged therein with a drive shaft,
the drive shaft projects toward the cylinder head of the internal-combustion engine and includes an end-face coupling for a transfer of rotational movement of the camshaft to the vacuum pump; and
the vacuum pump is arranged in an axial direction relative to the device on a common longitudinal axis and the device includes additional coupling elements for connection with the drive shaft of the vacuum pump in a driving manner to the device,
whereby the additional coupling elements are formed into the side wall of the device, which faces away from the camshaft.
1. Internal-combustion engine with a device for hydraulically adjusting an angle of rotation of a camshaft of the engine relative to a crankshaft of the engine, as well as with a vacuum pump for a servo load, comprising
the device (1) for hydraulically adjusting the angle of rotation is arranged on a drive-side end (2) of the camshaft (3) supported in several radial bearings (4) in a cylinder head (5) of the internal-combustion engine and is formed as a hydraulic actuator,
the device (1) includes a drive unit (6) connected in a driving manner to the crankshaft of the internal-combustion engine and a driven unit (7) connected in a torsion-proof manner to the camshaft (3) of the internal-combustion engine,
the driven unit (7) is fixed by an axial central screw (8) on the camshaft (3) and the drive unit (6) is provided as a hollow cylinder, which surrounds the driven unit (7) and which is sealed tight relative to a pressurizing medium by two axial side walls (12, 13),
the drive unit (6) is connected in a force-transferring manner to the driven unit (7) of the device (1) through at least two compression chambers, which are formed within the device (1) and which can be pressurized alternately or simultaneously with a hydraulic pressurizing medium,
a lubricating oil of the internal-combustion engine taken from one of the radial bearings (4) of the camshaft (3) is used as the hydraulic pressurizing medium for the device (1), and is supplied via radial and axial oil channels (15, 16) into the camshaft (3) of the device (1),
the vacuum pump (17) for the servo load comprises a vane pump and includes a housing (19) connected to the cylinder head cover (18) of the internal-combustion engine and a rotor arranged therein with a drive shaft (20),
the drive shaft (20) projects toward the cylinder head (5) of the internal-combustion engine and includes an end-face coupling (22) for a transfer of rotational movement of the camshaft (3) to the vacuum pump (17), as well as lubrication of the vacuum pump with the lubricating oil of the internal-combustion engine,
the vacuum pump (17) is arranged in an axial direction relative to the device (1) on a common longitudinal axis and the device (1) is includes an additional coupling element for connection with the drive shaft (20) of the vacuum pump (17) in a driving manner to the device (1),
the lubrication of the vacuum pump (17) is provided via a central connecting tube (23) arranged in the drive shaft (20) of the vacuum pump that projects into the device (1) which receives the lubricating oil of the internal-combustion engine delivered to the device (1) as the pressurizing medium.
2. Device according to
3. Device according to
4. Device according to
5. Device according to
6. Device according to
7. Device according to
0. 9. Device according to claim 8, wherein the additional coupling elements are formed as radial slots.
0. 10. Device according to claim 8, wherein the driven unit is fixed to the camshaft by an axial central screw.
0. 11. Device according to claim 10, wherein the axial central screw has a screw head that is arranged countersunk in an expanded diameter section of a screw bore in the driven unit, and a side wall of the device facing away from the camshaft has an axial through hole of equal diameter.
0. 12. Device according to claim 11, wherein the radial slots are formed as pocket grooves extending from the through hole to the expanded diameter section in the driven unit.
0. 13. Device according to claim 8, wherein the lubricating oil is taken from one of the radial bearings of the camshaft.
0. 14. Device according to claim 8, wherein the hydraulic pressurizing medium is supplied to the device via radial and axial oil channels located within the camshaft.
0. 15. Device according to claim 8, wherein the vacuum pump is formed as a vane pump.
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This application is a continuation of PCT/EP2003/013337, filed Nov. 27, 2003, which is incorporated by reference as fully set forth herein.
The invention relates to an internal-combustion engine comprising a device for hydraulically adjusting the angle of rotation of the camshaft of the engine relative to the crankshaft of the engine, as well as to a vacuum pump for a servo load, especially for a brake booster.
For the person skilled in the art in the field of automotive technology, it is generally known that, in addition to a plurality of aggregate systems, modern internal-combustion engines are also equipped with a device for hydraulically adjusting the angle of rotation of the camshaft of the engine relative to the crankshaft of the engine, as well as with a vacuum pump for a servo load, in order, on one hand, to be able to continuously change the opening and closing valve timing of the gas-exchange valves of the internal-combustion engine with the device and, on the other hand, to generate with the vacuum pump the low pressure needed, for example, for a brake booster of a motor vehicle.
The typical devices for adjusting the angle of rotation are provided, in principle, as hydraulic actuators, which are configured either as so-called axial piston adjusters or as so-called rotary piston adjusters similar to the device known from EP 0 818 609 B1. This device is arranged on the drive-side end of the camshaft supported in several radial bearings in the cylinder head of the internal-combustion engine, and essentially consists of a drive unit connected in a driving manner to the crankshaft of the internal-combustion engine and a driven unit connected in a torsion-proof manner to the camshaft of the internal-combustion engine. The actual driven unit is provided as an impeller and fixed by an axial central screw to the camshaft, while the drive unit is provided as a hollow cylinder, which surrounds the driven unit and which can be sealed tight relative to a pressurizing medium by two axial side walls. Through four radial limiting walls in the drive unit and four radial vanes on the driven unit, two compression chambers, which can be pressurized alternately or simultaneously with a hydraulic pressurizing medium and via which the drive unit is connected in a force-transferring way to the driven unit, are then formed between two limiting walls within the device. Here, the lubricating oil fed from one of the radial bearings of the camshaft for the internal-combustion engine is used. This oil is supplied via radial and axial oil channels of the device as hydraulic pressurizing medium for the device.
In contrast, the vacuum pumps typically used in internal-combustion engines for a servo load are usually provided as vane pumps, like those that follow, for example, from DE 85 18 157 U1. This vacuum pump is arranged on a common longitudinal axis with the camshaft on the cylinder head of the internal-combustion engine, and essentially consists of a housing flanged to the cylinder head cover of the internal-combustion engine with a pillow block and a rotor arranged in the housing with a drive shaft, which is supported in a rotating manner in the pillow block of the housing projecting into the cylinder head of the internal-combustion engine. Here, two recesses, in which two coupling tabs formed on the end face of the camshaft engage, are machined into the end face of the drive shaft and thus the rotational movement of the camshaft is transferred to the drive shaft of the vacuum pump. In addition, the camshaft also has an axial lubricating oil channel, which leads to the end face of the camshaft and which is connected, on one side, via a coupling tube to an axial lubricating oil collection space in the drive shaft of the vacuum pump and, on the other side, to the lubricating oil circuit of the internal-combustion engine, so that the vacuum pump is simultaneously lubricated with the lubricating oil of the internal-combustion engine.
However, it has proven to be disadvantageous that for many engine designs, due to lack of space, there is no other economical option than to arrange the vacuum pump for the servo load opposite the drive-side end of the camshaft or one of the camshafts of the internal-combustion engine. However, if a device for hydraulically adjusting the angle of rotation is also provided on this end of the camshaft, then the driving and lubrication of the vacuum pump in the described manner via the camshaft of the internal-combustion engine is no longer possible, so that very expensive measures are usually necessary to realize the driving and lubrication of the vacuum pump in some other way. Here, primarily changing the vacuum pump in its structure must be taken into consideration, such that it can be integrated in a suitable way in the primary or secondary drive of the internal-combustion engine, as well as in the lubricating-oil circuit thereof, so that in each case, considerable extra expense for the internal-combustion engine must be taken into account.
Therefore, the invention is based on the objective of providing an internal-combustion engine with a device for adjusting the angle of rotation of the camshaft of the engine relative to the crankshaft of the engine, as well as with a vacuum pump for a servo load, especially for a brake booster, in which, despite a device for adjusting the angle of rotation fixed on the drive-side end of the camshaft of the engine, a vacuum pump arranged typically on the cylinder head of the internal-combustion engine can be used with economical driving and simple lubrication.
According to the invention, this objective is met for an internal-combustion engine according to the invention in which the vacuum pump is arranged in the axial direction relative to the device for adjusting the angle of rotation on a common longitudinal axis with the device on the cylinder head of the internal-combustion engine and the device is provided with additional coupling elements, through which the drive shaft of the vacuum pump is connected in a driving manner to the device, and the lubrication of the vacuum pump is realized by a central connecting tube, which is arranged in the drive shaft of the pump and which projects into the device, with the lubricating oil of the internal-combustion engine supplied to the device as a pressurizing medium.
In one embodiment of the internal-combustion engine according to the invention, the coupling arranged on the drive shaft for the vacuum pump is formed preferably by two radial teeth arranged coaxial on its end face facing the device, while the additional coupling elements are formed on the device preferably as two radial slots complementary to the radial teeth on the drive shaft. It has proven to be especially advantageous to provide the two radial teeth as rectangular extensions, which project from the end face of the drive shaft facing the device, which are arranged directly opposite each other offset by 180°, and which are formed integrally with the drive shaft. In similar corresponding embodiments, however, it is also possible to arrange more than two radial teeth symmetrically or asymmetrically on the end face of the drive shaft and/or to attach these as separate parts, for example, in corresponding grooves or also as pins in corresponding bores, on the end face of the drive shaft of the vacuum pump.
In another embodiment of the internal-combustion engine according to the invention, the opposite side (from the camshaft) of the device for adjusting the angle of rotation is then formed such that the axial central screw of the device is arranged countersunk with its screw head pointing towards the vacuum pump into an expanded diameter section of the screw bore in the driven unit of the device, wherein the side wall of the device facing away from the camshaft has an axial through hole with the same diameter as the expanded diameter section of the screw bore in the drive unit of the device, through which the axial central screw is led.
In one embodiment of the internal-combustion engine according to the invention, this expanded diameter section for the screw head of the central screw in the driven unit is connected to one of the oil channels for supplying pressurizing medium to the device and can be sealed oil tight by a cap that can be screwed into the through hole of equal size in the side wall of the device facing away from the camshaft. For this purpose, the essentially disk-shaped cap is provided with a coaxial annular projection with an external thread on its seal side, whose length corresponds approximately to a thickness of the side wall of the device that faces away from the camshaft and formed with an internal thread in its through hole. This cap then has the two radial slots provided as two pocket grooves for the coupling of the vacuum pump, which has two radial teeth on the end face of the drive shaft. The grooves extend from the edge of the cap and which are offset by 180° relative to each other or are directly opposite each other. By means of these teeth, the vacuum pump is driven by the device for adjusting the angle of rotation. In addition, in a central axial bore in this cap, the connecting tube of the vacuum pump is held in a sealed manner relative to the device for adjusting the angle of rotation, through which a portion of the pressurizing medium led in the expanded diameter section for the screw head of the central screw is further guided to the device without leakage as lubricating oil into the vacuum pump.
In contrast, in another embodiment of the internal-combustion engine embodied according to the invention, it is proposed to not connect the expanded diameter section for the screw head of the central screw in the driven unit of the device to the pressurizing medium supply to the device and consequently also not to use an additional cap that can be screwed into the side wall of the device facing away from the camshaft for sealing. In this embodiment, for realizing the drive of the vacuum pump by the device for adjusting the angle of rotation, the two radial slots for the coupling of the vacuum pump through the two radial teeth on the end face of the drive shaft are preferably provided as pocket grooves, which are machined directly into the side wall of the device facing away from the camshaft and which extend into the side wall of the device in front of the through hole leading to the expanded diameter section for the screw head of the central screw and are likewise arranged offset by 180° relative to each other or directly opposite each other. In the opening on the side of the screw head for a continuous longitudinal bore provided for supplying pressurizing medium to the device in the axial screw head of the device for adjusting the angle of rotation, then the connecting tube of the vacuum pump is held in a sealed manner relative to the device, through which, similar to the first embodiment, a portion of the pressurizing medium led into the device is further led without leakage as lubricating oil into the vacuum pump.
The internal-combustion engine provided according to the invention with a device for hydraulically adjusting the angle of rotation of the camshaft of the engine relative to the crankshaft of the engine and also with a vacuum pump for a servo load, especially for a brake booster, has the advantage, in comparison with the internal-combustion engines known from the state of the art, that it is now possible through the creation of an economical drive connection between the device for adjusting the angle of rotation and the vacuum pump through a positive-fit coupling, as well as through the simultaneous use of a portion of the pressurizing medium of the device as lubricating oil for the vacuum pump by means of a simple connecting tube between the device and the vacuum pump, despite the presence of the device for adjusting the angle of rotation arranged at the drive-side end of the camshaft, to arrange the vacuum pump typically on a common longitudinal axis with the camshaft on the cylinder head cover of the internal-combustion engine. Therefore, the vacuum pump does not have to be adapted either in its structure or in its arrangement to a different drive and/or to different lubrication, so that the extra cost required for this purpose for the internal-combustion engine can be saved. However, by leaving out the connecting tube between the vacuum pump and the device for adjusting the angle of rotation and configuring the cap sealing, the expanded diameter section in the device without a central axial bore or formation of the through hole in the central screw as a basic bore, it is also possible to realize only the drive of the vacuum pump in a way according to the invention by the device for adjusting the angle of rotation and to provide a separate lubricating oil supply for the vacuum pump.
The invention is explained in more detail below with reference to two preferred embodiments which are shown schematically in the associated drawings. In the drawings:
In contrast, the vacuum pump 17, shown schematically in
In addition, it follows from
In the first embodiment of the internal-combustion engine formed according to the invention shown in
In contrast, in the second embodiment of the internal-combustion engine formed according to the invention shown in
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