Cam shaft phase setter comprising a control valve for hydraulically adjusting the phase position of a cam shaft

Abstract

A cam shaft phase setter for adjusting the rotational angular position of a cam shaft relative to a crankshaft of an internal combustion engine by a hydraulic fluid, the cam shaft phase setter including: a stator connected to the crankshaft; a pressure chamber; a rotor connected to the cam shaft, the rotor being adjustable relative to the stator by introducing the fluid into the pressure chamber; a control valve including a valve housing and a valve piston; and an actuating unit for axially adjusting the valve piston; wherein the cam shaft phase setter is configured such that fluid flowing through the control valve flows back into an engine housing which rotatably mounts the cam shaft.

Claims

1. A cam shaft phase setter comprising: (a) a control valve for controlling feeding and draining of a hydraulic fluid into and out of pressure chambers which serve to adjust the rotational angular position of a cam shaft relative to a crankshaft of an internal combustion engine, (b) the pressure chambers comprising a first chamber and a second chamber, one of the first chamber and second chamber for adjusting the cam shaft to lead relative to the crankshaft when the pressure is applied, and the other of the first chamber and the second chamber for adjusting the cam shaft to trail when the pressure is applied, (c) the phase position of the cam shaft being set by introducing the pressurised fluid by the control valve into either the first chamber or the second chamber, and connecting the other type of pressure chambers in each case to a low-pressure side of the fluid, (d) the control valve comprising: (d1) a valve housing connectable, rotationally fixed, to the cam shaft or being formed by the cam shaft, such that when the cam shaft rotates, the control valve rotates together with the cam shaft, the valve housing comprising a first operating port for feeding said pressure fluid to the first chamber, a second operating port for feeding said pressure fluid to the second chamber, the second operating port being axially spaced from the first operating port, and a reservoir port for draining the fluid to a reservoir provided on the low-pressure side of the fluid, (d2) a valve piston which can be axially adjusted back and forth in the valve housing between a first piston position and a second piston position and comprises an axial hollow space, a piston inlet for introducing fluid into the hollow space, and a piston outlet which leads out of the hollow space, (d3) the piston outlet being connected to the first operating port in the first piston position and separated from the first operating port in the second piston position, the piston outlet being connected to the second operating port in the second piston position and separated from the second operating port in the first piston position, and (e) the cam shaft phase setter further comprising an actuating unit, coupled to the valve piston, for axially adjusting the valve piston, (f) wherein the valve piston comprises a recess which connects the first operation port of the valve housing to the reservoir port in the first position of the valve piston, and (g) wherein behind the piston outlet, as viewed in the axial direction from the recess, a further axially extending recess is formed on the outer circumference of the valve piston, the further radial recess connected to the reservoir in the first position of the valve piston.

2. The cam shaft phase setter according to claim 1, wherein the reservoir port extends outwards into a phase setter housing such that the fluid is drained through the reservoir port near the actuating unit into the phase setter housing and via the phase setter housing back into an engine housing or otherwise into a reservoir for the fluid.

3. The cam shaft phase setter according to claim 1, wherein the first operating port extends radially through the circumference of the valve housing.

4. The cam shaft phase setter according to claim 1, wherein the second operating port extends radially through the circumference of the valve housing.

5. The cam shaft phase setter according to claim 1, wherein the piston outlet is a radial outlet on the circumference of the valve piston.

6. The cam shaft phase setter according to claim 1, wherein the piston inlet leads axially into the hollow space on an axially facing side of the valve piston.

7. The cam shaft phase setter according to claim 1, wherein the valve housing comprises a housing inlet for the fluid which flows to the control valve, and wherein the housing inlet is formed either on an axially facing side of the valve housing such that the fluid flows axially into the control valve, or as a radial inlet on the circumference of the valve housing.

8. The cam shaft phase setter according to claim 1, wherein the valve piston comprises, on its circumference, a radial recess connecting the first operating port to the reservoir port in the second position of the valve piston.

9. The cam shaft phase setter according to claim 8, wherein the recess is connected to the reservoir port in the first position of the valve piston and is fluidically separated from the first operating port in the first position of the valve piston by a sealing web of the valve piston.

10. The cam shaft phase setter according to claim 8, wherein the recess connects the first operating port to the reservoir port in the second position of the valve piston such that the fluid can flow off from the first chamber and depressurise the first chamber.

11. The cam shaft phase setter according to claim 1, wherein the valve piston comprises, on its circumference, a radial recess connecting the second operating port of the valve housing to the reservoir in the first position of the valve piston.

12. The cam shaft phase setter according to claim 1, wherein the valve housing is inserted at an axial end of the cam shaft into a central accommodating space which is open towards the axially facing end of the cam shaft, from the axially facing end, or is placed at the axially facing end of the cam shaft.

13. The cam shaft phase setter according to claim 1, wherein the valve housing is inserted into an accommodating space of the cam shaft and is screwed to the cam shaft or axially secured by a securing device.

14. The cam shaft phase setter according to claim 13, wherein a tensioning screw which can be screwed to the cam shaft forms the valve housing.

15. The cam shaft phase setter according to claim 1, comprising a stator which can be rotary-driven by the crankshaft, and a rotor which is connected, rotationally fixed, to the cam shaft and coupled to the stator such that torque is transmitted and which can be adjusted in its rotational angle relative to the stator by introducing the fluid into one of the first pressure chamber or the second pressure chamber.

16. The cam shaft phase setter according to claim 1, further comprising a spring unit acting on the valve piston in the direction of the first position, wherein the actuating unit acts on the valve piston in the direction of the second position.

17. The cam shaft phase setter according to claim 1, wherein the actuating unit comprises an electromagnetic coil which is connected, rotationally fixed, to an engine housing of the internal combustion engine, and an anchor which can be axially moved relative to the coil in order to transmit an axial actuating force of the actuating unit onto the valve piston.

18. The cam shaft phase setter according to claim 17, wherein the valve piston can be rotated relative to the anchor.

19. The cam shaft phase setter according to claim 1, wherein the actuating unit is arranged on the low-pressure side of the fluid.

20. The cam shaft phase setter according to claim 1, wherein the actuating unit comprises an electromagnetic coil which is connected, rotationally fixed, to an engine housing of the internal combustion engine, the coil being connected, rotationally fixed, to a cover which is in turn fixedly connected to a phase setter housing which is mounted on the engine housing.

21. The cam shaft phase setter according to claim 1, wherein the actuating unit comprises an electromagnetic coil which is connected, rotationally fixed, to an engine housing of the internal combustion engine, and an anchor which can be axially moved relative to the coil, and wherein the phase setter comprises a coupling member which extends axially between the valve piston and the anchor in order to transmit an axial actuating force of the actuating unit onto the valve piston.

22. The cam shaft phase setter according to claim 21, wherein the coupling member protrudes through an axially facing closure wall which closes off the valve housing.

23. A cam shaft phase setter comprising: (a) a control valve for controlling the feeding and draining of a hydraulic fluid into and out of pressure chambers which serve to adjust the rotational angular position of a cam shaft relative to a crankshaft of an internal combustion engine, (b) the pressure chambers comprising a first chamber and a second chamber, one of the first chamber and second chamber for adjusting the cam shaft to lead relative to the crankshaft when the pressure is applied, and the other of the first chamber and the second chamber for adjusting the cam shaft to trail when the pressure is applied, (c) the phase position of the cam shaft being set by introducing the pressurised fluid by the control valve into either the first chamber or the second chamber, and connecting the other type of pressure chambers in each case to a low-pressure side of the fluid, (d) the control valve comprising: (d1) a valve housing connectable, rotationally fixed, to the cam shaft or being formed by the cam shaft, such that when the cam shaft rotates, the control valve rotates together with the cam shaft, the valve housing comprising a first operating port for feeding said pressure fluid to the first chamber, a second operating port for feeding said pressure fluid to the second chamber, the second operating port being axially spaced from the first operating port, and a reservoir port for draining the fluid to a reservoir provided on the low-pressure side of the fluid, (d2) a valve piston which can be axially adjusted back and forth in the valve housing between a first piston position and a second piston position and comprises an axial hollow space, a piston inlet for introducing fluid into the hollow space, and a piston outlet which leads out of the hollow space, and (d3) the piston outlet being connected to the first operating port in the first piston position and separated from the first operating port in the second piston position, the piston outlet being connected to the second operating port in the second piston position and separated from the second operating port in the first piston position, and (e) the cam shaft phase setter further comprising an actuating unit, coupled to the valve piston, for axially adjusting the valve piston, (f) wherein the reservoir port extends obliquely through a circumference of the valve housing to an outside of the valve housing.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Example embodiments of the invention are explained below on the basis of figures. Features disclosed by the example embodiments, each individually and in any combination of features, advantageously develop the subjects of the claims and the embodiments described above. There is shown:

(2) FIG. 1 a cam shaft phase setter of a first example embodiment, in a longitudinal section;

(3) FIG. 2 a top view onto the axially facing side of the phase setter which faces away from the cam shaft, with the cover removed;

(4) FIG. 3 a control valve of the phase setter, in the cross-section A-A from FIG. 1;

(5) FIG. 4 a central region of the cam shaft phase setter of FIG. 1;

(6) FIG. 5 a cam shaft phase setter of a second example embodiment;

(7) FIG. 6 a cam shaft phase setter of a third example embodiment;

(8) FIG. 7 the control valve, in the cross-section A-A from FIG. 6; and

(9) FIG. 8 a cam shaft phase setter of a fourth example embodiment.

DETAILED DESCRIPTION OF THE INVENTION

(10) FIG. 1 shows a cam shaft phase setter in a longitudinal section. The cam shaft phase setter is arranged at an end of a cam shaft 1 on the axially facing side and serves to adjust the phase position, i.e. the rotational angular position, of the cam shaft 1 relative to a crankshaft of an internal combustion engine, for example a drive motor of a motor vehicle. The cam shaft 1 is rotatably mounted such that it can be rotated about a rotational axis R in an engine housing 2 of the internal combustion engine, usually in a cylinder head housing.

(11) The cam shaft phase setter comprises a stator 3 which can be rotary-driven by the crankshaft, and a rotor 7 which is connected, rotationally fixed, to the cam shaft 1. The stator 3 is composed of a drive wheel 4, for example a sprocket, a cover 6 and an impeller wheel 5 which is axially arranged between the drive wheel 4 and the cover 6. The drive wheel 4, the impeller wheel 5 and the cover 6 are connected, rotationally fixed, to each other. The stator 3 and the rotor 7 form a hydraulic pivoting motor.

(12) FIG. 2 shows the stator-rotor arrangement 3, 7 in a top view on the axially facing side. The cover 6 of the stator 3 is removed, such that the impeller wheel 5 of the stator 3 and the rotor 7 which is formed as an impeller counter wheel can be seen. The impeller wheel 5 forms the outer component, and the rotor 7 the inner component, of the pivoting motor. The inner circumference of the hollow impeller wheel 5 comprises vanes which project radially inwards. The rotor 7 comprises vanes which project radially outwards and form first pressure chambers 8 and second pressure chambers 9 with the vanes of the impeller wheel 5. The pressure chambers 8 are each arranged to the left of the vanes of the rotor 7 in the circumferential direction, and the pressure chambers 9 are each arranged to the right of the vanes of the rotor 7 in the circumferential direction. If the pressure chambers 8 are pressurised and the pressure chambers 9 are depressurised, the rotor 7 rotates relative to the stator 3, clockwise in FIG. 2, at most as far as the end position assumed in FIG. 2. If the pressure chambers 9 are pressurised and the pressure chambers 8 are depressurised, the rotor 7 rotates anti-clockwise. The rotational movement performed relative to the stator 3 in one rotational direction corresponds to the cam shaft 1 leading relative to the crankshaft, and the relative rotational movement in the other direction corresponds to the cam shaft 1 trailing relative to the crankshaft.

(13) The cam shaft phase setter comprises a control valve which is arranged centrally in relation to the stator-rotor arrangement 3, 7 and comprises a valve housing 10 and a valve piston 20 which is arranged such that it can be axially moved back and forth in the valve housing 10 and thus axially adjusted. The valve piston 20 is hollow and comprises an axially extending hollow space 21, a piston inlet 22 at one axial end and a piston outlet 23 which leads radially through a casing of the valve piston 20 which surrounds the hollow space 21. The other axial end of the valve piston 20, which faces away from the piston inlet 22, comprises a coupling member 25 for a coupling to an actuating unit 15 which effects the axial adjustment of the valve piston 20. The coupling member 25 acts as an operating plunger for the valve piston 20. The coupling member 25 can be formed in one piece with the piston casing which surrounds the hollow space 21 or can as applicable be joined, axially fixed, to it. It projects at the axially facing end of the valve piston 20 which axially faces the actuating unit 15. The coupling member 25 protrudes through an axially facing closure wall 11 of the valve housing 10. The axially facing closure wall 11 surrounds the coupling member 25 in a tight fit and thus ensures that the valve housing 10 is closed off, fluidically sealed, despite the coupling member 25 being able to move back and forth.

(14) The actuating unit 15 is an electromagnetic actuating unitin the example embodiment, an axial stroke electromagnetcomprising a coil 16 which can be supplied with current and an anchor 17 which the coil 16 surrounds. The coil 16 is connected, rotationally fixed, to the engine housing 2 of the internal combustion engine. In the example embodiment, the coil 16 is connected, rotationally fixed, to a cover 2b which is in turn fixedly connected to a phase setter housing 2a which is mounted on the engine housing 2. The anchor 17 can be axially moved relative to the coil 16. The anchor 17 and the coupling member 25 are directly in a coupling engagement which is formed as an axial pressure contact. When the coil 16 is supplied with current, an actuating force which is directed axially towards the coupling member 25 acts on the anchor 17 and acts on the coupling member 25 in the coupling engagement, a purely axial pressure contact, and thus on the valve piston 20. Preferably, only point contact exists at the separation point between the valve piston 20 which rotates with the cam shaft 1 during operation and the actuating unit 15 which does not rotate. The end of the anchor 17 which contacts the coupling member 25 preferably exhibits a spherical surface. Alternatively, the coupling member 25 could exhibit a spherical surface at its axially facing end. In one development, the contact end of the anchor 17 is formed as a spherical slide bearing by rotatably mounting a sphere, freely and spherically, in a socket of the anchor 17 there.

(15) The control valve comprises a spring unit 14, the spring force of which counteracts the actuating force of the actuating unit 15. The spring unit 14 is directly supported on the valve housing 10 and supported in the direction of the actuating unit 15 on the valve piston 20. The actuating unit 15 is controlled, i.e. supplied with current, by a controller of the internal combustion engine. It is preferably controlled using a characteristic map which is stored in a memory of the engine controller, for example in accordance with the rotational speed of the crankshaft, the load or other and/or additional parameters which are relevant to the operation of the internal combustion engine.

(16) The valve piston 20 is arranged in a central axial hollow space of the valve housing 10 such that it can be moved back and forth in the way explained. Its axial end facing away from the axially facing closure wall 11 comprises a housing inlet P.sub.a which leads axially and centrally into the hollow space of the housing and to which pressurised fluid can be fed via the cam shaft 1, i.e. a pressure inlet P of the cam shaft 1. The fluid can in particular be a lubricating oil which serves to lubricate the internal combustion engine and also serves to lubricate for example the pivot bearing of the cam shaft 1. The pressure fluid is fed to the control valve, for example by the pivot bearing of the cam shaft 1 as is preferred, i.e. the pressure port P is connected to the lubricating oil supply for the pivot bearing. This pressure fluid flows into the cam shaft 1 at P, through the axial housing inlet P.sub.a into the valve housing 10, and through the piston inlet 22 which is axially flush with the housing inlet P.sub.at into the hollow space 21. A piston outlet 23 branches laterally off from the hollow space 21, for example in the radial direction as is preferred, and the pressure fluid is fed through the piston outlet 23 to either the pressure chambers 8 or the pressure chambers 9 in accordance with the axial position of the valve piston 20, in order to set the phase position of the rotor 7 relative to the stator 3 and thus the phase position of the cam shaft 1 relative to the crankshaft. The piston outlet 23 is formed by radial passages through the casing of the valve piston 20 which are arranged in a distribution over the circumference of the valve piston 20. The piston outlet 23 is arranged in an axially middle portion of the valve piston 20.

(17) The valve housing 10 comprises ports, which lead through its casing, for feeding and draining the fluid to and from the pressure chambers 8 and 9. These include an operating port A and an operating port B, a reservoir port T.sub.A which is assigned to the operating port A, and a reservoir port T.sub.B which is assigned to the operating port B. The ports A to T.sub.B are each linear passages through the casing of the valve housing 10. The ports A, B and T.sub.A extend radially through the casing by the shortest path. The reservoir port T.sub.B extends obliquely outwards into the phase setter housing 2a.

(18) FIG. 3 shows only the control valve comprising the valve housing 10 and the valve piston 20, in the cross-section A-A from FIG. 1. The sectional representation shows in particular the piston outlet 23 of the valve piston 20 and the operating port B of the valve housing 10 which is likewise formed by radially extending and therefore short passages through the casing of the valve housing 10 which are arranged in a distribution over the circumference of the valve housing 10. The ports A, T.sub.A and T.sub.B are likewise each formed by a plurality of passage channels which are arranged in a distribution around the central axis R.

(19) FIG. 4 shows only the central region of the cam shaft phase setter from FIG. 1. FIGS. 1, 3 and 4 show the valve piston 20 in a first axial piston position in which it is held by the spring unit 14. In the first piston position, the piston outlet 23 is connected to the operating port B. The pressure fluid which is fed to the cam shaft 1 via the pressure port P flows in the axial direction through the axial housing inlet P.sub.a and the piston inlet 22 into the hollow space 21 of the valve piston 20 and from there through the branching piston outlet 23 to the pressure chambers 8 which in accordance with the representation in FIG. 2 are assigned to the operating port B. The pressure chambers 9 which are connected to the operating port A are connected to the reservoir port T.sub.A via the operating port A and a recess 26 formed on the outer circumference of the valve piston 20, and to the reservoir via the reservoir port T.sub.A and a feedback 4 which rotates with the cam shaft 1, and are thus depressurised. The recess 26 extends over the entire outer circumference of the valve piston 20. Behind the piston outlet 23, as viewed in the axial direction from the recess 26, another axially extending recess 27 is formed on the outer circumference of the valve piston 20 and likewise extends over the entire outer circumference of the valve piston 20. The recess 27 is connected to the reservoir port T.sub.B in the first piston position. The reservoir port T.sub.B is assigned to the operating port B. However, it is fluidically separated from the operating port B in the first piston position by means of a sealing web of the valve piston 20 which is formed between the piston outlet 23 and the recess 27.

(20) If an actuating force which exceeds the spring force of the spring unit 14 is applied to the anchor 17 by correspondingly supplying the actuating unit 15 with current, the actuating unit 15 pushes the valve piston 20 out of the first piston position shown, axially towards the housing inlet P.sub.a and, if the actuating force is correspondingly large, as far as an axially second piston position in which it is no longer the operating port B but rather the other operating port A which is connected to the piston outlet 23. In the second piston position, a sealing web of the valve piston 20 which is formed between the piston outlet 23 and the recess 26 separates the operating port A from its assigned reservoir port T.sub.A, such that the pressure fluid is applied to the pressure chambers 9 in the second piston position. In the second piston position, the recess 27 also connects the operating port B to the reservoir port T.sub.B, such that the fluid can flow off from the pressure chambers 8 and depressurise them. The rotor 7 is correspondingly moved, anti-clockwise in the representation in FIG. 2, relative to the impeller wheel 5 and thus relative to the stator 3. The cam shaft 1 which is connected, rotationally fixed, to the rotor 7 is adjusted in its piston position relative to the crankshaft by the same rotational angle.

(21) The fluid of the high-pressure side which flows through the housing inlet P.sub.a into the control valve applies a first axial force, which acts in the direction of the actuating unit 15, to the valve piston 20. In order to compensate for this first axial force, fluid can flow through the valve piston 20 in the direction of the actuating unit 15, such that a fluid pressure builds up at its rear side facing the actuating unit 15, between said rear side and the axially facing closure wall 11, wherein said fluid pressure exerts a counter forcea second axial forceon the rear side of the valve piston 20. Since the projection area to which the pressure fluid can be applied is reduced by the cross-sectional area over which the coupling member 25 protrudes through the axially facing closure wall 11, the axial counter forcethe second axial forcewould be smaller than the first axial force, in accordance with the cross-sectional area of the coupling member 25. A resultant axial thrust would arise which would change in accordance with the difference between the projection areas in accordance with the fluid pressure. The characteristic curve of the control valve would correspondingly change, which can lead to significant distortions, since the fluid pressure can fluctuate during operation of the internal combustion engine.

(22) In order to increase the second axial force, the valve piston 20 comprises a radially widened piston portion 28, referred to in the following as the widening 28, and the valve housing 10 comprises a complementarily widened housing portion 18 which surrounds the widening 28 in a tight fit. Providing the valve housing 10 and the valve piston 20 co-operate in a seal, the valve piston 20 exhibits for example the same cylindrical cross-section on the whole of its outer circumference, with the exception of the widening 28. In order to guide the pressure fluid onto the rear side of the valve piston 20, the valve piston 20 comprises a feed 24axially behind the piston outlet 23 as viewed from the housing inlet 22which is formed by a plurality of passage channels in a base of the valve piston 20 which are distributed around the central axis R. The widening 28 and correspondingly the housing portion 18 are dimensioned such that the increase in the projection area F.sub.28 facing the actuating unit 15 which is provided by the widening 28 at least predominantly balances out the cross-sectional area F.sub.25 of the coupling member 25 which is lost to compensating. The compensating area is an outer annular area of the projection area F.sub.28. The additional projection area which axially faces the axially facing closure wall 11the compensating area of the widening 28is preferably exactly as large as the cross-sectional area F.sub.25 over which the coupling member 25 protrudes through the axially facing closure wall 11. The result of this is that the first axial force which acts in the direction of the actuating unit 15 is compensated for by the opposing second axial force, and a resultant axial thrust cannot arise. The projection areas, which each generate an axial force when fluid flows through the valve piston 20, are of equal size in both axial directions.

(23) The widening 28 is formed at the end of the valve piston 20 on the axially facing side, which faces the actuating unit 15, as is preferred. The widened housing portion 18 exhibits a sufficient axial extension to enable the adjusting movements of the valve piston 20. The widening 28 forms the end of the recess 27 which faces the actuating unit 15. The widened housing portion 18 tapers at 13 to the narrower cross-section which is constant in the subsequent axial profile. The taper 13 is formed within the recess 27, axially for example in the region of the reservoir port T.sub.B.

(24) A latching element 30 latches the rotor 7 in a particular rotational angular position relative to the stator 3. The latching element 30 is biased into the latching position by means of a spring unit. The fluid pressure acts in the other direction, such that when the fluid pressure increases, it is moved out of the latching position.

(25) FIG. 5 shows a cam shaft phase setter of a second example embodiment, likewise in a longitudinal section which includes the rotational axis R of the cam shaft 1. Unlike the first example embodiment, the valve housing 10 is not formed as a tensioning screw for the phase setter and is also not connected to the cam shaft 1 by means of a screw connection. The valve housing 10 is embodied as a housing cartridge which is inserted through the open end of the cam shaft 1 on the axially facing side into its central accommodating space 1a, up to and against an abutment, and once inserted is positioned in the hollow cam shaft 1 in a radially tight fit. The valve housing 10 is axially secured relative to the cam shaft 1 by means of a securing element 31, for example a securing ring.

(26) Unlike the first example embodiment, the accommodating space 1a extends within the cam shaft 1 in an axial continuation. The accommodating space 1a is separated, in particular fluidically, from the continuative hollow space by means of a separating element 1b which is inserted into the cam shaft 1, in order to guide the fluid through the pressure port P of the cam shaft 1 into the accommodating space 1a and from there through the likewise axial housing inlet P.sub.a into the valve piston 20.

(27) Unlike the first example embodiment, the reservoir port T.sub.B which is further away from the housing inlet P.sub.a is formed, like the other ports A, B and T.sub.A, as a short radial passage in the casing of the valve housing 10. The valve piston 20 itself, as compared to the valve piston 20 of the first example embodiment, is only modified in terms of the feed 24 which serves to compensate for the axial force and does not, as in the first example embodiment, axially extend substantially in the direction of the axially facing closure wall 11 but rather runs obliquely outwards from the hollow space 21 of the piston. As in the first example embodiment, it is a plurality of passage bores which are arranged on the rear side of the valve piston 20 in a distribution around the central axis R.

(28) The phase setter of the second example embodiment otherwise corresponds to the phase setter of the first example embodiment.

(29) FIG. 6 shows a cam shaft phase setter of a third example embodiment, again in a longitudinal section which includes the rotational axis R of the cam shaft 1. FIG. 7 shows only the central control valve of this phase setter, comprising the valve housing 10 and the valve piston 20, in the cross-section A-A. The valve piston 20 corresponds to the valve piston 20 of the first example embodiment, with one exception. Unlike the first example embodiment, the piston outlet 23 is not formed by simple bores but rather by passages which extend in the manner of slits in the circumferential direction. The ports A to T.sub.B are short radial passages as in the second example embodiment, again for example passage bores in the valve housing 10 which are arranged in a distribution over the circumference.

(30) In the phase setter of the third example embodiment, the fluid is drained through the reservoir port T.sub.B near the actuating unit 15, not into the phase setter housing 2a and via the phase setter housing 2a back into the engine housing 2 or otherwise into a reservoir for the fluid but rather via a feedback which extends within the phase setter into the engine housing as far as the low-pressure side. The feedback comprises a feedback 7a which extends through the rotor 7 and comprises a plurality of feedback channels arranged in a distribution around the central axis R, one feedback channel 7a for each of the passages which jointly form the reservoir port T.sub.B. The feedback channels are for example each formed in the rotor 7 as an axially linear passage channel, as is preferred. The feedback 7a leads into a connecting feedback 4a which is delimited by the cam shaft 1 radially on the inside and by the stator 3, in this case the drive wheel 4, radially on the outside. Feeding the fluid drained through the reservoir port T.sub.B back within the phase setter which rotates together with the cam shaft 1 during operation of the internal combustion engine, preferably by its rotor 7, significantly reduces the expense of the feedback of fluid, since the feedback of any fluid required for the function of the phase setter is also automatically ensured by mounting the phase setter. The other reservoir port T.sub.A, near the housing inlet P.sub.a, leads back into the engine housing 2 to the low-pressure side by a short path, as in the first example embodiment above. This incidentally applies to all the example embodiments; what is new, by contrast, is the integrated feedback 4a, 7a also via reservoir port T.sub.B which lies axially further on the outside in relation to the cam shaft 1. The continuative feedback 4a is a common feedback for both reservoir ports T.sub.A and T.sub.B.

(31) Sealing the feedback 7a at the end on the axially facing side using the valve housing 10 is also advantageous in terms of a design configuration of the phase setter which is as simple as possible. The valve housing 10 is connected to the cam shaft 1 by means of a screw connection, as in the first example embodiment. In the third example embodiment, however, the screw head 19 serves an additional function as a seal for the feedback 7a, thus enabling its profile to be simplified, for example to a simply linear passage through the rotor 7. The connection between the reservoir port T.sub.B and the feedback 7a is also configured simply, i.e. in the form of radial grooves at the axially facing end of the rotor 7.

(32) The statements made with respect to the first example embodiment otherwise apply.

(33) FIG. 8 shows a cam shaft phase setter of a fourth example embodiment, likewise in a longitudinal section which includes the rotational axis R of the cam shaft 1. Unlike the other example embodiments, the fluid of the high-pressure side does not simply flow axially into the control valve but rather via a radial pressure port P.sub.r. The valve housing 10 is closed at its axially inner axially facing end. The ports A to T.sub.B are formed as in the second example embodiment. The statements made with respect to the first example embodiment also otherwise apply to the fourth example embodiment.

LIST OF REFERENCE SIGNS

(34) 1 cam shaft 1a accommodating space 1b separating element 2 pivot bearing, engine housing 2a phase setter housing 2b cover 3 stator 4 drive wheel 4 feedback 4a feedback 5 impeller wheel 6 cover 7 rotor 7a feedback 8 pressure chamber 9 pressure chamber 10 valve housing 11 axially facing closure wall 12 screw connection 13 taper 14 spring unit 15 actuating unit 16 coil 17 anchor 18 widened housing portion 19 screw head 20 valve piston 21 hollow space 22 piston inlet 23 piston outlet 24 compensating feed 25 coupling member 26 recess 27 recess 28 widening, widened piston portion 29 - 30 latching element 31 securing element A operating port B operating port P pressure port P.sub.a axial housing inlet P.sub.r radial housing inlet R rotational axis, central axis T.sub.A reservoir port T.sub.B reservoir port