Camshaft adjusting system with means for catching hydraulic fluid draining from a valve in order to directly recirculate the fluid into the camshaft adjuster

The invention relates to a camshaft adjusting system (1) for an internal combustion engine of a motor vehicle, including a hydraulic camshaft adjuster (2) which has a stator (3), a rotor (4) that is rotatably mounted in the stator (3), and a hydraulic control system (6) that has a valve (5). The rotor (4) has at least one vane which protrudes into a pressure chamber formed between the rotor (4) and the stator (3) such that the pressure chamber is divided into two sub-chambers, each of which interacts with the hydraulic control system (6) such that a hydraulic pressure ratio is established between the two sub-chambers, said ratio specifying a relative rotational position between the rotor (4) and the stator (3), and is adjusted on the basis of the position of the valve (5). The camshaft adjusting system also includes an actuator (7) which is arranged adjacently in the axial direction of the camshaft adjuster (2) and which acts on the valve (5) for adjusting purposes. A hydraulic fluid section (8) is arranged on an actuator (7) face facing the camshaft adjuster (2), with this hydraulic fluid section (8) being designed to deflect a flow of hydraulic fluid exiting the valve (5) into the surroundings of the camshaft adjuster (2) back into the camshaft adjuster (2) in an operational state.

BACKGROUND

The invention relates to a camshaft adjusting system for an internal combustion engine, for example, a diesel or gasoline engine, of a motor vehicle, such as a passenger car, truck, bus, or agricultural commercial vehicle, comprising a hydraulic camshaft adjuster (of the vane cell type) which has a stator, a rotor that is rotatably mounted/held in the stator, and a hydraulic control system that comprises a valve, wherein the rotor has at least one vane which extends into a pressure chamber formed between the rotor and the stator such that this pressure chamber is divided into two sub-chambers, each of which interacts with/is connected to the hydraulic control system such that a hydraulic pressure ratio is applied between the two sub-chambers, said ratio specifying a relative rotational position between the rotor and the stator, that is adjusted on the basis of the position of the valve, wherein the camshaft adjusting system also comprises an actuator which is arranged adjacently in the axial direction of the camshaft adjuster and which acts on the valve for adjusting purposes. The camshaft adjusting system is therefore also designated as an assembly set/arrangement consisting of a camshaft adjuster and an actuator actuating this camshaft adjuster.

Camshaft adjusting systems according to the class have been known from the prior art for a long time. For example, DE 10 2007 020 525 A1 discloses a camshaft adjuster for an internal combustion engine that is mounted on one end on a camshaft and acts as a transmission element to a drive wheel for the rotational drive of the camshaft. The camshaft adjuster has an inner gear arranged rotationally locked to the camshaft and a coaxially arranged outer gear that can rotate relative to the inner gear, wherein a control valve with a valve slide is provided coaxial to the inner gear, wherein this control slide is provided for controlling a fluid for loading pressure chambers arranged between the inner gear and the outer gear, in order to adjust the angle between the inner gear and the outer gear. The inner gear has a central valve slide space that extends axially toward the camshaft and holds the valve slide so that it can move axially and has at least one control edge with which the valve slide interacts to form a seal.

In these known camshaft adjusting systems, the hydraulic fluid, preferably oil, draining from the valve of the camshaft adjuster, for example, through the T-port, usually runs directly back into a tank that usually causes relatively long delivery distances of the hydraulic fluid. In order to make the hydraulic fluid available again for delivery after draining into the tank, an oil pump is required, because there is no intermediate reservoir provided for adjusting the rotor relative to the stator, wherein this reservoir provided hydraulic fluid/oil to the camshaft adjuster for adjustment procedures. Due to this long delivery system, the inertia of the system is also relatively high.

SUMMARY

Therefore, the object of the present invention is to eliminate these disadvantages known from the prior art and especially to disclose a camshaft adjusting system in which draining hydraulic fluid is made available again on the shortest possible paths for adjusting the camshaft adjuster.

This objective is achieved according to the invention in that a hydraulic fluid guide section is arranged on a (preferably axial) side of the actuator facing the camshaft adjuster, wherein this hydraulic fluid guide section is formed so that a flow of hydraulic fluid existing from the valve into the surroundings of the camshaft adjuster is deflected/guided back into the camshaft adjuster in an operational state.

In this way, the actuator is used directly as a guide part that is otherwise mounted in the camshaft adjusting system, in order to deflect the corresponding flow of hydraulic fluid in the desired direction.

Additional advantageous embodiments are explained in more detail below.

If the hydraulic fluid guide section is arranged/mounted housing-fixed on the actuator, the hydraulic fluid guide section is always positioned at a certain distance relative to the camshaft adjuster, independent of the position of the valve. In this way, the flow of hydraulic fluid is reliably and reproducibly guided in every operational state.

The hydraulic fluid guide section is preferably mounted/arranged directly on an actuator housing of the actuator or is connected to a bearing unit that is held fixed in the actuator housing and guides a tappet of the actuator in the direction that it can move. For a construction of the actuator as a magnetic actuator, it is especially advantageous if the bearing unit is a direct component of a pole core of this actuator. In this way, the configuration is significantly simplified.

It is further advantageous if the hydraulic fluid guide section is constructed by an individual/materially integrated deflection plate mounted on the actuator. The term “plate” should not be understood here to limit the materials to a metal, but only in the sense that the deflection plate has a thin-walled construction. The deflection plate is definitely preferably made from a metal (as a metal plate), but could alternatively also be made from a plastic material. Through this construction of the hydraulic fluid guide section, existing actuators and also actuators already being produced in series production can be easily adapted, which also has positive effects on the production costs.

It is also advantageous if the actuator has a tappet that is guided so that it can move in a bearing unit of the actuator and the hydraulic fluid guide section is alternatively a materially integrated component of this bearing unit. Then the construction of a separate guide plate can be eliminated, and the existing outer contour of the actuator can be used directly as the hydraulic fluid guide section. In this way, the number of components is further reduced.

In this context, it is especially advantageous if the bearing unit is constructed in turn as a pole core or comprises this pole core that has a shifting effect on the tappet. In this way, the actuator has an especially effective action as a magnetic actuator.

It is also preferred if the hydraulic fluid guide section has a ring-shaped collar oriented in the axial direction toward the camshaft adjuster, wherein this collar is arranged so that it deflects the flow of hydraulic fluid existing from the valve into the surroundings of the camshaft adjuster toward the camshaft adjuster in the axial direction. In this way, the flow of hydraulic fluid is guided on especially short paths.

In this context, it is also advantageous if a collection plate forming a hollow space is mounted on a stator-fixed area of the camshaft adjuster, wherein this collection plate covers the hydraulic fluid guide section radially from the outside in the axial direction by a certain distance. In this way, due to the rotation of the camshaft adjuster in its operational state, the hydraulic fluid can be guided directly by the effective centrifugal force reliably back to the camshaft adjuster.

It is also advantageous if the hollow space is coupled/can be coupled hydraulically by a non-return valve that is preferably constructed as a non-return flap to a reservoir formed/mounted in the rotor and/or stator. The reservoir is preferably arranged hydraulically, in turn, between the sub-chambers and the valve, so that it can have a supporting effect on building up pressure in the respective sub-chamber in each position of the valve. In this way, the camshaft adjuster is especially effective.

It is also advantageous if a return spring pretensioning the rotor relative to the stator in a rotational direction is arranged in the hollow space that is formed by the collection plate. In this way, the collection plate can be used simultaneously as a protective cover for this return spring.

If the valve is a central valve that is held/arranged radially within the rotor, the flow of hydraulic fluid is integrated in a hydraulic circuit in an especially clever way.

Furthermore, it is advantageous if the valve is constructed so that, in a first position of a control slide of the valve, a first sub-chamber is opened hydraulically to the surroundings and in a second position of the control slide, a second sub-chamber is opened hydraulically to the surroundings. In this way, in both positions, the hydraulic fluid can be guided effectively by the hydraulic fluid guide section and fed back to the camshaft adjuster.

Expressed in other words, a device for collecting hydraulic fluid/oil for camshaft adjustments is provided. The system according to the invention relates to a central valve and to a central magnet for camshaft adjustments (VIP/“smart phaser”). The design according to the invention has an oil guide contour (the hydraulic fluid guide section) that is arranged on the central valve body (actuator housing) or on the C-pole of the magnet.

DETAILED DESCRIPTION

The figures are only of a schematic nature and are used only for understanding the invention. The same elements are provided with the same reference symbols. The different features of the different embodiments can also be freely combined with each other.

InFIG. 1, a camshaft adjusting system1according to a preferred first embodiment is shown in a diagram. The camshaft adjusting system1consists of a camshaft adjuster2and an actuator7with an adjusting effect on this camshaft adjuster2.

The camshaft adjuster2is here basically constructed as a hydraulic camshaft adjuster2. The camshaft adjuster2is constructed according to the vane cell type/vane cell configuration. Accordingly, the camshaft adjuster2has an outer part designated as stator3. The stator3is connected rotationally fixed to a traction mechanism, namely a chain, of a traction mechanism drive by a traction mechanism holder18when the internal combustion engine is in an operational state, wherein the traction mechanism is typically locked in rotation with a crankshaft of the internal combustion engine. The traction mechanism holder18is also designated as a drive wheel.

The stator3has, on its radial inner side, multiple pressure chambers that extend both in the radial direction and also in the circumferential direction and are not shown here for the sake of clarity.

A rotor4is supported so that it can rotate in the stator3over a certain range of angles/adjustment area. In each pressure chamber of the stator3, a vane of the rotor4extends in the radial direction, wherein the vanes are also not shown in more detail for the sake of clarity. The vanes are mounted/fastened rotationally locked to the rotor4. In an operational state, the rotor4is, in turn, rotationally locked with a camshaft of the internal combustion engine, also not shown here for the sake of clarity. The vanes of the rotor4thus extend into the pressure chambers of the stator, so that each pressure chamber is divided into two sub-chambers/sub-spaces hydraulically separated/sealed relative to each other, namely into a first sub-chamber and a second sub-chamber. These sub-chambers are hydraulically separated from each other in the circumferential direction by a vane. Together with the vanes, the rotor4can rotate relative to the stator3over the width of the pressure chamber in the circumferential direction.

Each sub-chamber of the pressure chambers interacts with a valve5. The valve5is here oriented centrally, i.e., coaxial to the rotational axis19of the camshaft adjuster2. The valve5is therefore also designated below as a central valve5. The central valve5is part of a hydraulic control system6. The central valve5has a valve housing20that is arranged radially within the rotor4and is rotationally locked with this rotor. Within the valve housing20, a control slide17is supported so that it can move in the axial direction of the rotational axis19. In particular, this control slide17can move between a first position and a second position, as described below with reference to the second embodiment. The central valve5is connected at an inlet with a hydraulic fluid source. The first sub-chamber of the camshaft adjuster2is connected to the control valve5by a first radial channel21in the form of a first hole and the second sub-chamber of the camshaft adjuster2is connected to the control valve5by a second radial channel22in the form of a second hole.

For adjusting the valve5, the actuator7is provided in the camshaft adjusting system1. The actuator7is here constructed as a magnetic actuator. This actuator7is mounted with its actuator housing23in the operational state on an area fixed to the internal combustion engine, for example, an internal combustion engine housing. The actuator7has a tappet10arranged in the axial direction and coaxial to the control slide17/rotational axis19. The tappet10can move in the axial direction. The tappet10interacts with an axial end side of the control slide17, in order to move this back and forth between a first and a second position and thus specifying the position of the valve5. A spring24in the form of a compression spring is, in turn, mounted on a side of the control slide17facing away from the tappet10, in order to bring the control slide17back into its original position (the first position) after its adjustment by the tappet10into the second position.

The actuator7also has a bearing unit11that is arranged in the actuator housing23and is used for the movable support of the tappet10. In this bearing unit11, a pole winding is already formed, in order to have a shifting effect on the tappet10in the operational state by inducing a magnetic field.

According to the invention, a hydraulic fluid guide section8is mounted on the actuator7. In the embodiment according toFIGS. 1 and 2, the hydraulic fluid guide section8is formed as a deflection plate9that is produced separately from the actuator7and is connected to this actuator fixed to the housing. In particular, the hydraulic fluid guide section8is mounted in this embodiment fixed on the actuator housing23. The hydraulic fluid guide section8has a ring-shaped construction. The hydraulic fluid guide section8is mounted on an axial side of the actuator housing23facing the camshaft adjuster2and also radially outside the tappet10. The hydraulic fluid guide section8has a similarly ring-shaped collar12on a radial outer area. The collar12is mounted radially outside of the valve5so that a flow of hydraulic fluid26in an operational state, as can be seen especially well, in turn, inFIG. 2, exits from the valve5/control valve in the axial direction and is fed by this collar12back to the camshaft adjuster2at a radially outer position after its exit from the valve5.

Furthermore, a collection plate15is mounted on a stator-fixed area13, here on a side cover25of the stator3, wherein this collection plate15covers the hydraulic fluid guide section8radially from the outside. The flow of hydraulic fluid26that experiences a centrifugal force in the operational state of the camshaft adjuster2is guided back to the camshaft adjuster2in the axial direction by the collar12. The collection plate15here has an essentially pot-shaped construction, wherein the hydraulic fluid guide section8extends with its collar12through a central opening.

Between itself and the stator3, the collection plate15forms a hollow space14. A return spring16of the camshaft adjuster is also arranged in this hollow space14. This return spring16is here constructed as a spiral spring that is connected with one end fixed to the stator and with the other end fixed to the rotor, in order to rotate the stator and rotor3and4relative to each other in a non-pressurized state of the camshaft adjuster2/hydraulic control system6into a preferred position.

The camshaft adjuster2also has a non-return valve in the form of a non-return flap also not shown in more detail for the sake of clarity. This is mounted preferably in the rotor, alternatively also in the stator. In this way, a hydraulic fluid volume collecting in the collection plate15, which was previously guided there by the flow of hydraulic fluid26, can move the non-return valve automatically into an opened position if there is sufficient pressure generated by the centrifugal force and can flow in the direction of the stator and/or rotor interior, for example, toward a reservoir in the rotor4. The non-return valve is here mounted in the camshaft adjuster2so that a flow of the hydraulic fluid through this non-return valve from the rotor4is simultaneously prevented.

According to the second embodiment, as shown inFIGS. 3 to 5, however, the hydraulic fluid guide section8can also have a somewhat different construction. As can be seen inFIG. 3, the hydraulic fluid guide section8is constructed according to the second embodiment as an integral component of the bearing unit11. The hydraulic fluid guide section8has, in turn, a collar12extending in the radial direction radially outside the control valve5. The collar12is at a distance from an end side of the bearing unit11facing the camshaft adjuster2in the axial direction, so that the flow of hydraulic fluid26is fed, in turn, into the camshaft adjuster2as can be seen inFIGS. 4 and 5.

InFIG. 4, the first position of the valve5is shown schematically, while inFIG. 5the second position of the valve5is shown. In the first position, the first channel21marked with “A” is opened to the surroundings of the camshaft adjuster2, i.e., is essentially non-pressurized, while the second channel22marked with “B” is loaded with an inlet-side hydraulic fluid pressure of the valve5, namely by a hydraulic fluid source. In this way, the volume of the first sub-chamber is minimized, while the volume of the second sub-chamber is maximized. This is the case, e.g., in an advanced position of the camshaft adjuster2. In the second position according toFIG. 5, the first sub-chamber is connected to the hydraulic source and the second channel22/the second sub-chamber is opened to the surroundings, i.e., non-pressurized. In this way, the volume of the second sub-chamber is minimized, while the volume of the first sub-chamber is maximized. This is the case, e.g., in a retarded position of the camshaft adjuster2.

Expressed in other words, according to the invention a system design (camshaft adjuster system1) is provided in which the oil (hydraulic fluid) exiting from the valve5is captured with a kind of funnel (collection plate15) of the adjuster (camshaft adjuster2) and is provided to the adjuster2again for later adjustment processes (smart phasing). In addition, a feature (hydraulic fluid guide section8) is mounted on the central magnet (actuator7), wherein this feature prevents the draining of the oil into the tank and provides a kind of “forced orientation” for the oil. The feature8can be implemented by the additional mounting of a component (guide plate9) on the central magnet7or modifying a component located on the central magnet7. In this way, the exiting oil is always captured or deflected and thus prevented from draining directly into the tank.

LIST OF REFERENCE SYMBOLS