DE102009051559A1 - Rotary piston adjuster for internal combustion engine of motor vehicle, has outer rotor and inner rotor which is rotatably connected with camshaft, and outer rotor is brought in drive connection with crankshaft - Google Patents

Abstract

The rotary piston adjuster (1) has an outer rotor and an inner rotor which is rotatably connected with a camshaft. The outer rotor is brought in drive connection with a crankshaft. A hydraulic actuator is provided through which both the rotors are adjustable within an adjustment area. Two pressure chambers (14,15) are provided which are limited by a slider (19) which is connected with the inner rotor. The slider has a pressurizing medium line which fluidically connects the pressure chambers with a displacement chamber (28).

Description

Field of the invention

The invention is in the technical field of internal combustion engines and relates, according to its type, to a hydraulic rotary piston adjuster according to the preamble of patent claim 1.

State of the art

In internal combustion engines with mechanical valve control, gas exchange valves are actuated by the cams of a camshaft driven by a crankshaft, the timing of the gas exchange valves being able to be fixed via the arrangement and shape of the cams. Well known is the use of special devices for optional adjustment of the phase angle between the crankshaft and camshaft, which are often referred to as "camshaft adjuster". Camshaft adjusters allow influencing the timing of the gas exchange valves, whereby a number of beneficial effects, such as a reduction in fuel consumption and the production of pollutants, can be achieved.

Generally include camshaft adjuster via a drive wheel with the crankshaft in drive connection standing drive part and a camshaft fixed output member, and an actuator connected between input and output part, which transmits the torque from arrival to the output part and an adjustment and fixation of the rotational position between arrival and Abtriebsteil allows.

In hydraulic camshaft adjusters, the actuator comprises at least one counteracting pressure chamber pair, which can be acted upon with pressure medium in order to bring about a change in the rotational position between the input and output part by generating a pressure gradient across the two pressure chambers.

In a construction known as a "rotary piston adjuster", a camshaft-fixed internal rotor ("rotor") is mounted so as to be adjustable in rotation about an external rotor ("stator") driven by the crankshaft about a common axis of rotation. Typically, the stator forms a plurality of circumferentially distributed pressure chambers, in each of which a rotor connected to the radial sealing element ("wings") extends, whereby each pressure chamber is divided into two oppositely acting pressure chambers. Based on the drive or working direction of the camshaft each wing divides the associated pressure chamber in a leading pressure chamber (pressure chamber B) and a trailing pressure chamber (pressure chamber A). By generating an overpressure in the pressure chambers A, the wings can be adjusted within the pressure chambers in the drive direction of the camshaft, wherein the volumes of the pressure chambers A increase at the expense of the volumes of the pressure chambers B. Conversely, by generating an overpressure in the pressure chambers B, the wings can be adjusted counter to the drive direction of the camshaft, wherein the volumes of the pressure chambers B increase at the expense of the volumes of the pressure chambers A. A pressurization of the pressure chambers A corresponds to an early adjustment of the phase position between the crankshaft and camshaft, whereas a pressurization of the pressure chambers B corresponds to a retardation.

Hydraulic Rotationskolbenversteller have already found many entry into the patent literature. Merely by way of example is to the generic pamphlets DE 20 2005 008 264 U1 . EP 1596040 A2 . DE 10 2005 013 141 A1 and DE 19908934 A1 the applicant referenced in which rotary piston adjuster are described in detail.

Now, in the practical application of hydraulic rotary piston adjusters has been shown that when adjusting the phase at low speeds, especially at idle speed, relatively large Rückschwingbewegungen the wing (Rückschwingwinkel) can occur within the pressure chambers. This represents a not insignificant problem, since the Rotationskolbenversteller can thereby reach an unstable control state in which the desired phase position can not be adjusted. This problem occurs increasingly at relatively low pressure ratios, which are increasingly used in practice.

Object of the invention

In contrast, the object of the present invention is to provide a hydraulic rotary piston adjuster for an internal combustion engine, can be avoided by the above problem. So should such a rotary piston adjuster a hydraulic control of the phase angle between the crankshaft and camshaft reliably and safely even at low speeds, especially idle speed, and at low pressure ratios.

Solution of the task

These and other objects are achieved according to the proposal of the invention by a hydraulic Rotationskolbenversteller with the features of the independent claim. Advantageous embodiments of the invention are indicated by the features of the subclaims.

According to the invention, a hydraulic rotary piston adjuster for an internal combustion engine is shown. The rotary piston adjuster generically comprises an outer rotor which can be brought into driving connection with a crankshaft and an inner rotor which can be connected in a rotationally fixed manner to a camshaft and which is mounted concentrically with the outer rotor so as to be rotatable about a common axis of rotation. By means of a hydraulic actuator, a torque can be transmitted from the outer rotor to the inner rotor and a rotational position between the outer and inner rotor can be adjusted within an adjustment range. The actuator comprises at least one of the outer or inner rotor shaped pressure chamber which is divided by a connected to the respective other rotor sealing element in a pair of mutually acting pressure chambers. In general, a plurality of circumferentially distributed pressure chambers are provided, which are each divided by a sealing element in a pressure chamber pair. For example, the pressure chambers are formed by the outer rotor, immersed in the radial rotor connected to the inner rotor as sealing elements.

The rotary piston adjuster according to the invention is characterized essentially by the fact that the two pressure chambers of each pressure chamber each comprise a slide delimiting the pressure chamber, which is connected to one of the two rotors. In this case, the slide in a working space, hereinafter referred to as "Verschieberaum", guided translationally displaceable. The sliding space is formed by the rotor connected to the sliders.

Each slide is loaded by the spring force of a compression spring received in the sliding chamber so that it is pushed out of the sliding chamber.

In addition, each slide has at least one pressure medium line, through which the pressure chamber delimited by the slide is fluid-conductively connected (fluidically) to the associated displacement space. This ensures that when loading the pressure chamber with pressure medium of the displacement chamber is acted upon in a corresponding manner. A pressure gradient across the slide can thus be avoided.

It is furthermore essential for the invention that the slides are each provided with a sliding surface (hereinafter referred to as "first sliding surface" for ease of reference) on which a sliding surface formed by the respective other rotor (hereinafter referred to as "second sliding surface for ease of reference "Designated) can slide off. These pairs of bearings are designed so that the slides are urged depending on the adjustment of the inner rotor relative to the outer rotor alternately against the spring force of the spring at least partially into the Verschieberäume. Based on the working direction of the camshaft, the slide of the leading pressure chambers are urged by the sliding pairs in the displacement chambers in advance, whereas these slides are pressed at late adjustment without loading by the sliding pairings by the spring forces from the Verschieberäumen. On the other hand, the slide of the trailing pressure chambers are pressed at early adjustment without loading by the sliding pairings by the spring forces from the Verschiebräumen, whereas these slides are pushed back in late adjustment by the sliding mating in the Verschieberäume.

It can thus be achieved by the slide, that increases in advance the volumes of the leading pressure chambers and the volumes of the trailing pressure chambers are reduced. On the other hand, in the case of late adjustment, the volumes of the leading pressure chambers are reduced and the volumes of the trailing pressure chambers are increased.

By this measure, the hydraulic rigidity can be increased in an advantageous manner, which effectively counteracts the generation of large Rückschwingbewegungen the sealing elements within the pressure chambers.

In an advantageous embodiment of the rotary piston adjuster according to the invention, the second sliding surfaces are formed by the adjusting area limiting (for example, radial) walls of the pressure chamber, so that the complete adjustment is available for a change in the phase position between the crankshaft and camshaft.

In a further advantageous embodiment of the rotary piston adjuster according to the invention, the first sliding surfaces of the slide in the form of sliding ramps are formed, which have, for example, an at least approximately S-shaped contour in the radial section. It may also be advantageous if the first sliding surfaces go kink or edge-free in an outer circumferential surface of the associated with the sliders rotor. By this measure, the pairings can be realized in a simple manner functionally particularly effective.

In a further advantageous embodiment of the rotary piston adjuster according to the invention, the slides are connected to the rotor connected to the sealing element, wherein the slide can in this case be connected in particular to the inner rotor. In particular, in this case, it may also be advantageous if the displacement space is limited by the sealing element. In addition, it may be advantageous if the slides are each arranged adjacent to the sealing element and in this case in particular displaceably guided by the sealing element. These measures enable a particularly simple realization of the rotary piston adjuster in industrial series production.

The invention further extends to an internal combustion engine which is equipped with at least one Rotationskolbenversteller as described above.

In addition, the invention extends to a motor vehicle with an internal combustion engine which is equipped with at least one Rotationskolbenversteller as described above.

Short description of the drawing

The invention will now be explained in more detail with reference to an embodiment, reference being made to the accompanying drawings. In the single drawing, a section of the rotary piston adjuster according to the invention is shown with reference to a schematic radial section.

Detailed description of the drawing

In 1 is a total with the reference number 1 designated, based on the vane principle rotary piston adjuster 1 illustrated. As a drive part, the rotary piston adjuster comprises an external rotor or stator that is in drive connection with a crankshaft (not shown), for example via a sprocket 2 and as a stripping section one in a central cavity 4 of the stator 2 concentrically arranged inner rotor or rotor 3 , The rotor 3 For example, by means of a screw connection with a (not shown) camshaft rotatably connected. The stator 2 is rotated synchronously with the crankshaft, whereby the working or driving direction of the camshaft is fixed. For example, suppose here that in the view of 1 the working direction of the camshaft corresponds to the clockwise direction.

One the central cavity 4 of the stator 2 limiting inner lateral surface 5 is arranged with a plurality of circumferentially distributed, radial recesses 6 which are hereinafter referred to as "Statorausnehmungen" for ease of reference. The stator recesses 6 are of radial sidewalls 7 , which are hereinafter referred to as "first side walls" for ease of reference, and an outer peripheral wall 8th are limited. About inner peripheral walls 9 which is an outer circumferential surface 10 of the rotor 3 abut, is the stator 2 rotatable on the rotor 3 stored. The stator 2 and the rotor 3 can be in concentric arrangement about a common axis of rotation 13 be adjusted.

The outer circumferential surface 10 of the rotor 3 is in juxtaposition to the Statorausnehmungen 6 with a plurality of recesses distributed in the circumferential direction 16 which are hereinafter referred to as "rotor recesses" for ease of reference. The rotor recesses 16 are each of sidewalls 17 , which are hereinafter referred to as "second side walls" for ease of reference, and a bottom wall 18 limited.

In the rotor and Statorausnehmungen 6 . 16 protrude, starting from the rotor 3 , radial wings 12 through which the recesses rotor and Statorausnehmungen 6 . 16 be divided at least approximately pressure-tight.

On both sides of the wing 12 There are two slides each 19 arranged at least mentally in a guide section 20 and a sliding surface portion 21 can be divided. The sliders 19 are at the lead sections 20 from a second side wall 17 and the wing 12 guided translationally displaceable. More precisely, a first side surface 23 of the guide section 20 from a second side wall 17 and a second side surface 24 of the guide section 20 from the wing 12 guided translationally displaceable. The person skilled in the basic structure of such a displacement mechanism is known, so that it need not be discussed in detail here. For example only, it should be noted that the slide 12 can be performed for example via a pin-groove guide.

Every wing 12 divided a rotor recess 16 , each wing sharing a floor surface 22 the slider, the bottom wall 18 and the second side wall 17 a sliding room 28 to move the slider 19 shaped. Each rotor recess 16 is thus through the wing 12 in two displacement rooms 28 divided. The sliders 19 can over their leadership sections 20 within the displacement rooms 28 be moved translationally.

The sliders 19 are each from one in the sliding room 28 recorded compression spring 26 loaded, which is formed here, for example, as a helical compression spring. For this purpose, the compression springs are based 26 each with its one end to the bottom surface 22 of the slider 19 and with her other end on the bottom wall 18 from.

The sliding surface sections 21 the slider 19 each have a sliding surface 25 which will be referred to hereinafter as "first Sliding surface "is designated. The first sliding surfaces 25 are provided in radial section in the manner of a sliding ramp with an at least approximately S-shaped contour. The stator recesses 6 mold together with the first sliding surfaces 25 and (not shown) axial sealing surfaces in the circumferential direction uniformly distributed hydraulic pressure chambers 11 , The radial wings protrude 12 in every pressure room 11 , causing the pressure chamber 11 in a pair of opposing pressure chambers 14 . 15 is shared. Relative to the drive direction of the stator 2 These are a leading pressure chamber 15 ("Pressure chamber B") and a trailing pressure chamber 14 (Pressure chamber "A"). The stator 2 a total of one forms the rotor 3 pressure-tight encapsulating housing, resulting in 1 not shown in detail. In the two pressure chambers A, B of each pressure chamber 11 each open (not shown) pressure fluid channels through which pressure medium (eg hydraulic oil) the pressure chambers A, B can be supplied or derived from these. By targeted application of pressure medium can between the pressure chamber pair A, B of each pressure chamber 11 a pressure gradient can be built, causing a pivoting of the wings 12 and thus a change in the relative rotational position (phase angle) of the rotor 3 to the stator 2 is effected.

Every slider 19 is still with a pressure medium channel 27 provided, which by the slider 19 limited pressure chamber A, B and the associated displacement chamber 28 fluid conducting interconnects.

The adjustment range of the rotary piston adjuster 1 is through the first two side walls 7 of the pressure chamber 11 set, for example, as a stop for the wing received therein 12 can serve. In the transition area 29 to the inner peripheral walls 9 the inner circumferential surface 5 are the first side walls 7 rounded, creating a sliding surface 30 , hereinafter referred to as "second sliding surface" for ease of reference, for a sliding mating with the first sliding surface 25 in the same pressure chamber 14 . 15 located slider 19 provided.

In the middle position of the wings shown in the figure 12 inside the pressure chambers 11 have the first and second sliding surfaces 25 . 30 no physical contact, so that the slide 19 by the spring forces of the compression springs 26 with a maximum movement stroke in the pressure chambers 14 . 15 be pressed. Both pressure chambers A, B have in this position the wing 12 a minimal volume.

Now, starting from the middle position, the rotor 3 opposite the stator 2 vorverstellt what can be achieved by pressurizing the pressure chambers A with overpressure against the pressure chambers B, the wings 12 inside the pressure chambers 11 adjusted clockwise. This will get the first sliding surfaces 25 the slider 19 in the pressure chambers B after a slight adjustment in each case in touching contact with the second sliding surfaces 30 , With continued advance of the rotor 3 slide the second sliding surfaces 30 at the ramp-shaped first sliding surfaces 25 the slider 19 off, with the slider 19 the pressure chambers B in this case against the spring forces of the compression springs 26 in the transfer rooms 28 be urged. This has the consequence that the volumes of the pressure chambers B are reduced compared to the volumes of the pressure chambers A. In early-adjusted end position are the slides 19 the pressure chambers B with a maximum movement stroke in the Verschieberäume 28 pressed. Due to the S-shaped contour of the first sliding surfaces 25 is based on the center position of the wings 12 , at a low adjustment angle, a small change in volume, at a medium displacement a relatively large change in volume and at a large displacement again a relatively small change in volume of the pressure chambers B achieved, which can bring regulatory advantages with it.

Is starting from this early adjusted end position of the rotor 3 opposite the stator 2 retarded, what can be achieved by pressurizing the pressure chambers B with overpressure against the pressure chambers A, the wings 12 inside the pressure chambers 11 adjusted counterclockwise. In this case slide the second sliding surfaces 25 in the opposite direction to the first sliding surfaces 25 the slider 19 off, leaving the slider 19 , loaded by the compression springs 26 , from the sliding rooms 28 be pressed. The volumes of the pressure chambers B are increased. With continued retardation of the rotor 3 arrive the first sliding surfaces 25 the slider 19 the pressure chambers A in touching contact with the second sliding surfaces 30 the side walls 7 , wherein the second sliding surfaces 30 at the ramp-shaped first sliding surfaces 25 the slider 19 slide off, leaving the slider 19 the pressure chambers A against the spring forces of the compression springs 26 in the transfer rooms 28 be urged. As a result, the volumes of the pressure chambers A are reduced relative to the volumes of the pressure chambers B.

The sliders 19 the pressure chambers A and pressure chambers B are thus, depending on the adjustment of the rotor 3 opposite the stator 2 , alternately against the spring forces of the compression springs 26 in the transfer rooms 28 pressed. Due to the changing hydraulic stiffness of the pressure chambers A, B is a strong swing back the wings 12 inside the pressure chambers 11 effectively counteracted.

The first sliding surfaces 25 the slider 19 go kink or edge free in the inner peripheral walls 9 of the stator 3 above.

p:

Druck in den Druckkammern

B:

Bulk-Modulus von Öl (E-Modul, hydraulische Steifigkeit)

Q:

Ölvolumenstrom

V0:

Anfangsvolumen

Only for the sake of completeness should it be mentioned that the hydraulic rigidity of pressure medium, in this case for example an oil column, is described by the so-called bulk modulus for oil. This bulk modulus depends on the pressure level and the air content. The following equation (1)
(1)
describes the pressure build-up in a volume depending on the bulk modulus and the inflowing and outflowing oil, as well as the existing oil volume. Where:

p:

Pressure in the pressure chambers

B:

Bulk modulus of oil (modulus of elasticity, hydraulic stiffness)

Q:

Oil flow

V0:

initial volume

This means that with a small initial volume and a large bulk modulus and a large incoming volumetric flow, a large pressure builds up. The pressure chamber then has a high hydraulic rigidity.

Furthermore, equation (2) applies:
(2)

This means that a high air content is associated with a small bulk modulus. The pressure chamber is then not very stiff. However, this effect is difficult to influence. If the pressure chamber has a high pressure level, for example 1 bar absolute, the oil has a large bulk modulus and the pressure chamber is stiff. The aim is therefore to achieve a greater pressure level via a reduction in volume in order to increase the hydraulic rigidity.

In the present invention changes with the adjustment, the initial volume V0 (it is smaller) and you can generate a larger pressure increase with the existing volume flow. The hydraulic stiffness of oil is a function of the pressure p (see Equation 2 above). Thus, with a larger pressure p, the bulk modulus is also larger and thus the system is hydraulically stiffer. A return swinging motion is reduced. This behavior is given in the rotary piston adjuster according to the invention for both adjustment directions. By the movement of the slide 19 in the direction of the axis of rotation 13 or center, the oil in the pressure chambers A or B additionally pressed and can still act as a pump. It is essential in the present invention that during an adjustment the volumes of the pressure chambers become smaller or do not increase so much.

The invention shows a Rotationskolbenversteller, which allows a hydraulic control of the phase angle between the crankshaft and camshaft reliably and safely even at low speeds, in particular idling speed, and at low pressure ratios.

LIST OF REFERENCE NUMBERS

1

Rotary piston adjuster

2

stator

3

rotor

4

cavity

5

Inner surface area

6

stator recess

7

first sidewall

8th

outer peripheral wall

9

inner peripheral wall

10

Outer casing surface

11

pressure chamber

12

wing

13

axis of rotation

14

Pressure chamber A

15

Pressure chamber B

16

rotor cavity

17

second side wall

18

bottom wall

19

pusher

20

guide section

21

sliding surface

22

floor area

23

first side surface

24

second side surface

25

first sliding surface

26

compression spring

27

Pressure medium line

28

shifting space

29

Transition area

30

second sliding surface

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 202005008264 U1 [0006]
• EP 1596040 A2 [0006]
• DE 102005013141 A1 [0006]
• DE 19908934 A1 [0006]

Claims (12)

Rotary piston adjuster ( 1 ) for an internal combustion engine, with an externally rotatable with a crankshaft outer rotor ( 2 ), with a camshaft rotatably connectable inner rotor ( 3 ) around a common axis of rotation ( 13 ) rotatable to the outer rotor ( 2 ) is mounted, and a hydraulic actuator through which the two rotors ( 2 . 3 ) are adjustable within an adjustment range, wherein the actuator at least one of two rotors shaped pressure chamber ( 11 ), which by a connected to the other rotor sealing element ( 12 ) into a pair of opposing pressure chambers ( 14 . 15 ), characterized in that - each pressure chamber ( 14 . 15 ) of a slide ( 19 ), which is accompanied by a 3 ) of the two rotors and in one of this rotor ( 3 ) shaped sliding room ( 28 ) is displaceably guided, wherein - the slide ( 19 ) in each case at least one pressure medium line ( 27 ), which the pressure chamber ( 14 . 15 ) with the sliding chamber ( 28 ) fluidically, and wherein - the slides ( 19 ) each with a first sliding surface ( 25 ) are provided on one of the other rotor ( 2 ) formed second sliding surface ( 30 ), in such a way that the slides ( 19 ) depending on the adjustment alternately against the spring force of a spring ( 26 ) at least in sections in the Verschieberäume ( 28 ). Rotary piston adjuster ( 1 ) according to claim 1, characterized in that the second sliding surfaces ( 30 ) through the adjustment of the pressure chamber ( 11 ) bounding walls ( 7 ) are formed. Rotary piston adjuster ( 1 ) according to one of claims 1 or 2, characterized in that the first sliding surfaces ( 25 ) the slider ( 19 ) are designed in the form of sliding ramps. Rotary piston adjuster ( 1 ) according to claim 3, characterized in that the first sliding surfaces ( 25 ) each have an at least approximately S-shaped contour in the radial section. Rotary piston adjuster ( 1 ) according to claim 4, characterized in that the first sliding surfaces ( 25 ) kink-free in an outer circumferential surface ( 10 ) of the slide ( 19 ) connected rotor ( 3 ) pass over. Rotary piston adjuster ( 1 ) according to one of claims 1 to 5, characterized in that the slides ( 19 ) with the with the sealing element ( 19 ) connected rotor ( 3 ) are connected. Rotary piston adjuster ( 1 ) according to claim 6, characterized in that the slides ( 19 ) with the inner rotor ( 3 ) are connected. Rotary piston adjuster ( 1 ) according to one of claims 6 or 7, characterized in that the sliding space ( 28 ) of the sealing element ( 12 ) is limited. Rotary piston adjuster ( 1 ) according to claim 8, characterized in that the slides ( 19 ) each adjacent to the sealing element ( 12 ) are arranged. Rotary piston adjuster ( 1 ) according to claim 9, characterized in that the slides ( 19 ) from the sealing element ( 12 ) are guided displaceably. Internal combustion engine with a rotary piston adjuster ( 1 ) according to one of claims 1 to 10. Motor vehicle with an internal combustion engine according to claim 11.

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