EP1749146A1

EP1749146A1 - Camshaft adjuster

Info

Publication number: EP1749146A1
Application number: EP05737740A
Authority: EP
Inventors: Mike Kohrs; Udo Friedsmann
Original assignee: Schaeffler KG
Current assignee: Schaeffler Technologies AG and Co KG
Priority date: 2004-05-22
Filing date: 2005-05-04
Publication date: 2007-02-07
Anticipated expiration: 2025-05-04
Also published as: EP1749146B1; DE102004025215A1; DE502005011305D1; WO2005113943A1; US20070169730A1

Abstract

The invention relates to a camshaft adjuster, for the relative angular adjustment of a camshaft with relation to a driving crankshaft, comprising a hydraulically-operated adjuster device with chambers, into which and from which a hydraulic fluid may be alternately introduced or drained through pressure medium channels specific for the chambers to adjust the angle, and a control valve through which the hydraulic fluid supplied by a pump may be introduced into the pressure medium channels or drained from the pressure medium channels into a tank, whereby working connections (A) and (B), leading to the pressure medium channels, a pressure connector (P), coupled to the pump and a drain connector (T), coupled to the tank, are provided on the valve body of the control valve. Said working connections (A) and (B) may be selectively coupled to the pressure connector (P), or the drain connector (T) depending on the desired angle adjustment, by means of a valve piston, the displacement of which is controlled by a remote push- or pull-type solenoid, arranged outside the camshaft, whereby the fluid distribution chamber in the control valve (1, 20, 26, 34) is embodied such that the hydraulic fluid acts on essentially opposed surfaces of the valve piston (4, 22, 28, 36) such that local and essentially opposed forces (Fp1, Fp2) act on said valve piston (4, 22, 28, 36).

Description

Description of the invention camshaft adjuster

description

Field of the Invention

The invention relates to a camshaft adjuster for the relative angular adjustment of a camshaft with respect to a driving crankshaft, with a hydraulically actuated adjusting device with chambers into and from which hydraulic fluid can be alternately supplied and removed for adjusting the angle via chamber-specific pressure medium channels, and with a control valve via that the hydraulic fluid supplied via a pump can be supplied to the pressure medium channels or can be removed from the pressure medium channels into a tank, working connections A and B leading to the pressure medium channels on the valve body of the control valve, a pressure connection P which can be coupled to the pump and a pressure port P which can be coupled to the tank Drain connection T is provided, which working connections A and B, depending on the desired angle adjustment, can be moved via a valve piston controlled by a decoupled pull or pressure magnet arranged externally to the camshaft adjuster can be coupled to the pressure port P or the drain port T in some cases.

Background of the Invention

In known internal combustion engines, the camshaft, via which the valve movement of the intake and exhaust valves of the internal combustion engine is controlled, is motionally coupled to the crankshaft of the engine via a timing chain or a timing belt, that is, the camshaft is Belwelle driven. In order to be able to adjust the actuation time of the intake and / or exhaust valves depending on the operating situation, so that the valves open a little earlier or later in relation to the respective work cycle, camshaft adjusters are integrated, via which the relative angle that the camshaft has to the crankshaft occupies, can be adjusted. This means that both shafts can be rotated somewhat relative to each other, which means that the actuation time of the valves actuated via the camshaft changes.

Known camshaft adjusters are designed, for example, as vane-cell adjusters and comprise a rotor which is connected to the camshaft in a rotationally fixed manner and a stator which is coupled to the crankshaft via the timing chain or the timing belt. Radially outwardly projecting vanes are provided on the rotor, which engage between stops projecting radially inward on the stator, which limit the twisting movement on the one hand and form chamber walls on the other. The chambers are delimited by the respective side of a rotor-side wing and by the sides of the stator-side stops. In these chambers - depending on the number of blades, several pairs of chambers are realized - a hydraulic fluid is now pressed or withdrawn to rotate the rotor with respect to the stator and thus to adjust the angle, for which purpose a control valve, usually a 4/3-way valve, is used , Working connections A and B are provided on this, each leading to a chamber A and a chamber B of a respective pair of chambers. In the case of the camshaft adjuster design in question, the control valve itself is designed as a central valve, it is inserted centrally, centrally in the camshaft adjuster or in its rotor and connected to the camshaft, that is to say the control valve thus rotates with the adjuster or the rotor.

A valve piston, which is axially movable, is integrated in the control valve itself, its displacement being controlled by means of a tension or compression magnet positioned externally to the camshaft adjuster, for example arranged on an engine or other third-party object. The magnet is So embodiment not integrated in the adjuster. Depending on the position of the valve piston, one or the other working port A or B is now coupled to the pressure port P, so that hydraulic fluid is led into the assigned chamber A or B, while the other chamber is connected to the valve-side drain port, so that the liquid in the unloaded chamber can be drawn off to the tank via the drain connection. In this way, the rotor can be rotated hydraulically with respect to the stator. To maintain a set angle of rotation between the stops, the valve piston can almost close both working ports A and B and thus the associated chambers.

In known camshaft adjusters with the control valve in question, the pressure connection P is provided on the end face of the valve body in alignment with the longitudinal axis of the valve. The hydraulic fluid supplied under pressure presses against an end face of the often hollow cylindrical valve piston before it passes into the respective working port A or B depending on the piston position. The result of this is that, as a result of the liquid supply, a considerable force is exerted on the piston, which the external control magnet has to overcome in order to move the valve piston in an opposite direction. The magnetic force is counteracted by the spring acting on the valve piston, which moves the valve piston into its basic position (P - B - A - T) when the electromagnet is de-energized. The spring is matched to the system (magnetic force, hydraulic flow and pressure forces, piston travel, piston friction, etc.). If, in addition, the fluid-related force acting in the opposite direction now has to be overcome, this can, in extreme cases with high fluid pressure, result in the magnetic force acting not being strong enough to displace the valve piston or that of the electrical force applied to the magnet Power-assigned movement path of the valve piston is not completely covered. Summary of the invention

The invention is therefore based on the problem of specifying a camshaft adjuster which allows the valve piston to be set securely even when the fluid pressure is high.

To solve this problem, it is provided according to the invention in a camshaft adjuster of the type mentioned at the outset that the fluid distribution space in the control valve, that is to say in the valve body or the valve piston or between the two, is designed in such a way that the hydraulic fluid on surfaces which are essentially oppositely directed of the valve piston, so that local and essentially opposite forces act on the valve piston.

In the case of the camshaft adjuster according to the invention, the flow path for the hydraulic fluid, as soon as it enters the valve body and before it passes to one of the working ports A or B, is designed such that the valve piston is loaded by the liquid on two opposite surfaces, so that this directed load set opposite forces acting on the valve piston, which at least partially compensate each other. As a result of this flow guidance, the total force resulting from the liquid supply and acting on the valve piston is significantly reduced in comparison with the designs of the prior art, which leads to the fact that the control rod extending from the external control magnet to the valve piston or its extended control rod, which points towards the magnet force to be exerted is significantly reduced. In this way, any pressure peaks in the supply of the hydraulic fluid can in no case have an adverse effect on the valve control.

It is expedient if the opposing forces which are generated by the surface application according to the invention are essentially of the same size, for which purpose the surfaces which are acted upon should also be essentially of the same size. According to a first embodiment of the invention, the pressure port P can be perpendicular to the valve axis and open into an annular channel formed between the valve piston and the valve body and which, depending on the position, can be connected to the working port A and which leads into the hollow cylindrical valve piston, the cavity of which is position-dependent and closed can be connected to the working connection B, the end cavity surfaces being pressurized by the hydraulic fluid. The surfaces over which the oppositely directed forces are introduced into the valve piston are, in this embodiment, the end surfaces delimiting the end face of the cavity. Since it is a hollow cylindrical piston part with a constant cavity diameter, the surfaces are consequently essentially the same size, so that forces of essentially the same size and in opposite directions are also established.

Already at this point it should be pointed out that - depending on the design of the control valve and the adjusting device - instead of the working connection A, the working connection B can also be connected to the ring channel or instead of the working connection B, the working connection A can be connected to the cavity, that is, the respective work connections can also be interchanged. This applies to all the embodiments described below.

In the embodiment described, it can further be provided that the two working connections can be connected via a ring channel formed between the valve piston and the valve body, depending on the position, to the drain connection lying at an angle, preferably perpendicular to the longitudinal axis of the valve. In this valve design, all connections, that is to say both the pressure connection P and the drain connection T and the working connections A and B, are expediently arranged perpendicular to the valve axis and arranged in the order B - T - A - P or A - T - B - P In the latter case, a tension spring is used to switch the valve to the basic position P - B - A - T when de-energized, ie without a magnet. An alternative embodiment of a control valve provides that the pressure connection P lies at an angle, preferably perpendicular to the valve axis, and opens into an annular space formed between the valve piston and the valve body and can be connected to the working connection A or B depending on the position, the working connections A, B depending on the position Can be connected via connecting bores to the cavity of the hollow cylindrical valve piston, which cavity leads to the outlet connection T, which in this embodiment runs axially in alignment with the longitudinal valve axis. Here, too, the pressure connection P and the working connections A and B can expediently run perpendicular to the longitudinal axis of the valve and be arranged in the order A-P-B.

A further embodiment variant provides that the pressure connection P lies in the longitudinal axis of the valve and opens via deflection channels into an annular space formed between the valve piston and the valve body and which can be connected to the working connection A or B depending on the position, the working connections A, B depending on the position via connecting bores with the cavity of the hollow cylindrical valve piston can be connected, which cavity leads to the drain port T.

Finally, a further valve embodiment provides that the pressure connection P runs in alignment with the longitudinal valve axis and opens into the hollow cylindrical valve piston, at which radial openings are provided, through which the hydraulic fluid reaches the annular space formed between the valve piston and the valve body, which is from the front side of the valve piston is limited. In this embodiment, similar to the prior art, the hydraulic fluid is guided axially into the hollow cylindrical valve piston. As a result of the piston openings provided according to the invention, the liquid from the piston enters the rear annular space formed between the piston and the valve body, where it is virtually deflected and presses on the piston outer surface lying opposite the cavity end wall. In this embodiment, too, quasi are opposed to one another directed surfaces acted on, so that oppositely directed local forces act on the valve piston.

Brief description of the drawings

1 shows a sectional view of a control valve of a first embodiment,

2 shows a camshaft adjuster according to the invention with the integrated control valve from FIG. 1,

3 shows a camshaft adjuster according to the invention of a second embodiment with an integrated control valve of a second embodiment,

Fig. 4 shows a control valve of a third embodiment, and

5 shows a control valve of a fourth embodiment. Detailed description of the drawings

1 shows a control valve 1 consisting of a valve body 2, on which, in the exemplary embodiment shown, an external thread 3 is provided, by means of which the valve body is screwed on the camshaft side after insertion into the rotor of an adjusting device. A valve piston 4 is axially movably guided in the valve body 2 and can be moved against a restoring force generated by a spring 5. For movement, a push rod 6 is arranged on the valve piston 4 and cooperates with an external control magnet, not shown in more detail, in order to move the valve piston in the other direction against the spring or with spring support. As described, the control magnet is arranged externally on the motor, for example, so it does not move, unlike the control valve 1, which rotates with the rotor. The control valve 1 is encapsulated in the housing of the camshaft adjuster, via which housing the push rod 6 interacts with the magnet.

Several different connections are provided on the valve body 2. On the one hand, a working port A and a working port B are shown, via which a hydraulic fluid can be conveyed into corresponding chambers of the device designed as a vane-cell adjusting device, depending on the position of the valve piston 4. Also shown is a pressure port P through which one does not Pump shown in detail, the hydraulic fluid is supplied. Furthermore, a drain connection T is shown, via which hydraulic fluid to be discharged is conveyed into a tank (not shown in more detail).

Various control edges 7a (which are assigned to working port A) and 7b (which are assigned to working port B) are provided on valve piston 4. Depending on the position of the valve piston, the working connections A and B are connected via these control edges to either the pressure connection P or the drain connection T via the channel 41, depending on whether liquid is supplied to and from the chambers in the chambers which are assigned to the working connection A , which are assigned to the working connection B, liquid is to be discharged and conveyed into the tank via the drain connection T, or vice versa. The position is controlled by the magnet, not shown in detail.

In order to avoid that a force is exerted on the valve piston by the hydraulic fluid supplied at a relatively high pressure, which force would have to be additionally overcome by the magnet, which is moved to move the valve piston 4 against the spring force, in the control valve 1 Ring channel 8 is provided, into which the pressure port P opens. Via openings 9 on the valve piston side, the annular channel 8 - which, depending on the piston position, can be connected to the working port A if necessary - opens into the cavity 10 of the valve piston 4. Depending on the piston position, the cavity 10 can be connected to the working port B via corresponding openings 11, if the latter the hydraulic fluid is to be supplied. The hydraulic fluid presses in the cavity 10 on two mutually opposite end faces 12, 13, which axially limit the cavity. This results in a force F _p1 or Fp ₂ acting in each case on the valve piston, which are obviously directed in opposite directions. The two forces - which in the ideal case are of equal magnitude - thus compensate for one another, so that the valve piston 4 is ideally depressurized to the extent that forces act on it via the liquid supply.

2 shows a camshaft adjuster 14 according to the invention, with a rotor 15 and a stator 16. The rotor 15 is connected in a rotationally fixed manner to the control valve 1, this facial expression is related to the stator 16, which is connected to the timing chain or the timing belt to the crankshaft, rotatably. As is known, a plurality of vanes 17 are provided on the rotor, which bear tightly against the inner wall 18 of the stator and are delimited by the two chambers, each of which is supplied with fluid via a working connection A or B or from there via the respective working connections fluid can be deducted. It is not necessary to go into this in greater detail after the basic structure of such camshaft adjusters is sufficiently known.

3 shows a further embodiment of a camshaft adjuster 19 according to the invention, which corresponds in principle to the camshaft adjuster 14 from FIG. 2, but the integrated control valve 20 is constructed differently. It also has a P pressure connection and the two working connections A and B as well as a drain connection T. However, here the pressure connection P, which is guided inwards from the outside via the valve body 21, is located quasi-centrally between the working connections A and B, which via the position of the valve piston 22 in a corresponding manner as described with respect to the control valve 1 with the pressure connection P or the outlet connection T, which here runs axially with the valve along the longitudinal axis, can be connected. Also in this embodiment, in which the valve piston 22 is also controlled by a control magnet, not shown, against one, not shown Return spring is movable, the liquid supply takes place in such a way that largely compensating forces resulting from the pressed-in liquid act on the valve piston 22. The pressure port P opens into an annular channel 23 which is delimited by the control flanks 24, 25, via which the connection to the working ports A and B are opened or closed. The liquid therefore presses on these oppositely directed flanks, so that inevitably opposite forces are created which compensate for one another. Here, too, a liquid distribution space is realized that allows force compensation.

Finally, FIG. 4 shows a further control valve 26 which can likewise be integrated into a camshaft adjuster as shown in the previous figures. This control valve also has a valve body 27 and a valve piston 28. The pressure port P is located axially to the longitudinal axis of the valve, while the working ports A and B, not shown, and the drain port T are vertical to the longitudinal valve axis.

As can be seen, the valve piston is also supported here against a return spring 29. It is hollow cylindrical, the liquid supplied enters it. However, a plurality of openings 30 are provided on the opposite side, so that the liquid can enter the annular space 31 surrounding this piston end. There, the liquid presses on the piston outer surface 32, which lies opposite the end surface 33 in the interior of the piston. Here, too, two oppositely directed surfaces are again exposed to the fluid, so that oppositely directed forces result which act on the valve piston 28.

Finally, FIG. 5 shows a further control valve 34 according to the invention, the pressure connection P of which also runs axially, the working connections A and B go off on the valve body 35 perpendicular to the longitudinal axis, while the outlet connection T goes out of the valve piston 36 vertically to the longitudinal axis. Here, too, the hydraulic fluid is first deflected via corresponding guide channels 37 and then placed in an annular space 38 which is closed by two surfaces 39, 40 on the valve piston 36 is limited. This embodiment corresponds essentially to the valve design from FIG. 3; here, too, forces of the same size, but oppositely directed, occur on the valve piston 36. However, the supply of the hydraulic fluid is axial here, while it takes place from the side in the valve in FIG. 3.

reference numerals

Control valve 31 annulus

Valve body 32 piston outer surface

External thread 33 end face

Valve piston 34 control valve

Spring 35 valve body

Push rod 36 valve piston control edges 37 guide channels

Annular channel 38 annulus

Openings 39 areas

Cavity 40 areas

Openings 41 channel

faces

End faces A working connection

Camshaft adjuster B working connection

Rotor P pressure connection

Stator T drain connection

Wing F _P1 force

Inner wall Fp2 force

Phaser

control valve

valve body

plunger

annular channel

control edges

control valve

Valve body

plunger

Return spring

openings

Claims

claims

1.Camshaft adjuster for the relative angular adjustment of a camshaft with respect to a driving crankshaft, with a hydraulically actuated adjusting device with chambers into and from which hydraulic fluid can be alternately fed and discharged via chamber-specific pressure medium channels, and with a control valve via which the Hydraulic fluid supplied to the pump can be fed to the pressure medium channels or can be discharged from the pressure medium channels into a tank, with work connections A and B leading to the pressure medium channels leading to the valve body of the control valve, a pressure connection P which can be coupled to the pump, and a drain connection T which can be coupled to the tank Which working connections A and B, depending on the desired angle adjustment, can optionally be moved with the pressure connection via a valve piston that is controlled by a decoupled pull or pressure magnet that is externally arranged to the camshaft adjuster s P or the drain port T can be coupled, characterized in that the liquid distribution space in the control valve (1, 20, 26, 34) is designed in such a way that the hydraulic fluid on surfaces of the valve piston (4, 22, 28, 36) that are essentially opposite to each other ) attacks, so that local and essentially opposite forces (F _p1 , Fp2) act on the valve piston (4, 22, 28, 36).

2. Camshaft adjuster according to claim 1, characterized in that the opposing forces (F _p1 , Fp2) are substantially the same size.

Camshaft adjuster according to claim 1 or 2, characterized in that the pressure port P is at an angle, preferably perpendicular to the valve axis and in one between the valve piston (4) and the valve body (2) formed, depending on the position connectable to the working port A ring channel (8) which leads into the hollow cylindrical valve piston (4) closed on both ends, the cavity (10) of which can be connected to the working port B depending on the position , wherein the end face cavity surfaces (12, 13) are pressurized by the hydraulic fluid.

4. Camshaft adjuster according to claim 3, characterized in that the two working connections A, B can be connected via an annular channel (41) formed between the valve piston (4) and the valve body (2) in a position-dependent manner to the outlet connection T lying perpendicular to the longitudinal axis of the valve.

5. camshaft adjuster according to claim 3 or 4, characterized in that the pressure port P, the drain port T and the working ports A and B perpendicular to the valve longitudinal axis and in the order B -T - A - P or A - T - B - P are arranged.

6. Camshaft adjuster according to claim 1 or 2, characterized in that the pressure port P is at an angle, preferably perpendicular to the valve longitudinal axis and in a position-dependent with the working port A or formed between the valve piston (22) and the valve body (21) B connectable annular space (23) opens, the working connections A, B depending on the position can be connected via connecting openings to the hollow space of the hollow cylindrical valve piston (22), which hollow space leads to the drain connection T.

7. Camshaft adjuster according to claim 6, characterized in that the pressure connection P and the working connections A and B are perpendicular to the valve longitudinal axis and are arranged in the order A - P - B.

8. Camshaft adjuster according to claim 1 or 2, characterized in that the pressure port P lies in the valve longitudinal axis and via deflection channels (37) in a position-dependent with the working port A or formed between the valve piston (36) and the valve body (35) B connectable annular space (38) opens, the working connections A, B depending on the position can be connected to the hollow space of the hollow cylindrical valve piston (36) via connecting openings, which hollow space leads to the drain connection T.

9. camshaft adjuster according to claim 1 or 2, characterized in that the pressure port P is aligned with the valve longitudinal axis and opens into the hollow cylindrical valve piston (28), are provided at the radial openings (30) through which the hydraulic fluid in between the valve piston (28) and the valve body (27) formed annular space (31), which is limited by the end face of the valve piston.

10. Camshaft adjuster according to claim 1, characterized in that the control valve is integrated centrally in the adjusting device and rotates with it.