DE102019116884A1 - Hydraulic camshaft adjuster for adjusting the timing of gas exchange valves of an internal combustion engine - Google Patents

Abstract

A hydraulic camshaft adjuster (1) for adjusting the timing of gas exchange valves of an internal combustion engine has a crankshaft-driven control of the pressure medium supply to pressure chambers via a central valve (24) arranged centrally in the rotor hub (4). In order to simplify the construction of the hydraulic camshaft adjuster, which is provided with a central valve and a pressure booster, control openings or edges (39, 40) of a valve housing (45) of the central valve (24) and a control slide (37) slidably guided in it should interact in this way that the central valve (24) for actuation of the camshaft adjuster (1) in the "early" direction assumes a switching position when the pressure of the pressure medium supply is sufficient, in which it connects the pressure medium supply exclusively to the first group (A) of pressure chambers, while a working connection ( Pressure medium path ATP) of the working chamber is blocked and a working connection of a second group (B) of pressure chambers is connected to the tank via the return (T).

Description

Field of invention

The invention relates to a hydraulic camshaft adjuster for adjusting the control times of gas exchange valves of an internal combustion engine with a stator driven by a crankshaft and a rotor that is rotatable with respect to this and connected to a camshaft Vane jointly form pressure chambers, of which a first group of pressure chambers effect an adjustment of the camshaft in the "advance" direction, which counteract the friction and drag torques of the camshaft, and a second group of pressure chambers effect an adjustment of the camshaft in the "retarded" direction , whereby the camshaft adjuster controls the pressure medium supply to the pressure chambers via a central valve arranged centrally in the rotor hub and designed as a 5/4-way valve and in the "early" direction an additional pressure transducer that can be switched on via the central valve has etting device with which at least one further working chamber can be switched on, and wherein the central valve for an adjustment in the "early" direction at a minimum pressure of the pressure medium supply assumes a switching position in which this pressure medium supply with the first group of pressure chambers and the at least one further The working chamber connects, while the second group of pressure chambers is connected to a tank via a return line.

State of the art

With hydraulic camshaft adjusters, which adjust the phase between the crankshaft and camshaft of an internal combustion engine, the control times of the gas exchange valves actuated via the camshaft and thus the gas exchange can be changed in order to adapt them to the respective load condition of the internal combustion engine. This results in a gain in power and torque as well as fuel savings, i.e. an overall increase in the efficiency of the internal combustion engine. Hydraulic camshaft adjusters are known from the prior art, which function on the principle of a swivel motor and have several vanes arranged on a rotor hub of a rotor connected to the camshaft.

The stator is provided with a chain or toothed belt wheel of a traction mechanism driven by the crankshaft. Two different groups of pressure chambers are formed between the stator and the rotor by means of the radially extending vanes and webs extending radially from the stator. Depending on the application of a hydraulic pressure medium to the pressure chambers, the position of the rotor in relation to the stator and thus also the rotational position of the camshaft in relation to the crankshaft can be adjusted in the "early" or "late" direction.

A hydraulic camshaft adjuster for adjusting the control times of gas exchange valves of an internal combustion engine of the type specified in the preamble of claim 1 is from WO 2018/196904 A1 known. It is provided that the hydraulic camshaft adjuster has an additional, connectable pressure booster device, at least in one effective direction, with which the rotor can be rotated relative to the stator. This pressure intensification should take place by hydraulically connecting at least one additional working chamber. By connecting a pressure ratio, the adjustment forces for adjusting the rotor should be increased as required, so that neither the increased adjustment torque has to be provided in the entire operation of the hydraulic camshaft adjuster, nor is there a risk that adjustment is not possible due to an unfavorable control position.

As a result, the oil throughput through the hydraulic camshaft adjuster can be reduced, which reduces the energy requirement. In this way, the mechanical efficiency of the internal combustion engine assigned to the camshaft adjuster can be increased. The pressure intensification is intended to generate an additional adjusting force in exactly one effective direction, with the precisely one effective direction of the pressure intensification being oriented against the effective direction of the drag torques of the camshaft. Due to the drag torques of the camshaft acting on the rotor, an adjustment of the rotor in the “early” direction requires a significantly higher adjustment torque than an adjustment of the rotor in the “retarded” direction, in which the rotation is supported by the drag torque. Furthermore, the pressure intensification should be effective when the oil pressure system of the internal combustion engine has a low pressure level.

Disclosure of the invention

The object of the present invention is to simplify the structural design of the hydraulic camshaft adjuster provided with a central valve and a pressure transmission.

This object is achieved by the features of the characterizing part of independent patent claim 1. Advantageous refinements are given in the patent claims dependent thereon, which can represent an aspect of the invention either individually or in various combinations with one another.

According to this, the invention is based on a hydraulic camshaft adjuster for adjusting the control times of gas exchange valves of an internal combustion engine with a stator driven by a crankshaft and a rotor connected to a camshaft that can be rotated relative to this. In this case, radially extending webs go from the stator and vanes arranged in a rotor hub from the rotor, which together form pressure spaces. By applying pressure to a first group of pressure chambers, an adjustment of the rotor in the “advance” direction is effected, with friction and drag torques of the camshaft counteracting the adjustment of the camshaft in the “advance” direction during operation of the internal combustion engine. Applying pressure to a second group of pressure chambers causes the rotor to be adjusted in the “late” direction. The camshaft adjuster has a control of the pressure medium supply to the pressure chambers via a central valve arranged centrally in the rotor hub, designed as a 5/4-way valve and in the adjustment direction "early" an additional pressure booster device that can be switched via the central valve, with which at least one further working chamber can be switched on . The central valve assumes a switching position for an adjustment in the "early" direction at a minimum pressure of the pressure medium supply, in which it connects the pressure medium supply with the first group of pressure chambers and the at least one further working chamber, while the second group of pressure chambers is via a return connected to a tank.

According to the invention it is provided that control openings or edges of a valve housing of the central valve and a control slide displaceably guided in this cooperate in such a way that the central valve assumes a switching position for actuating the camshaft adjuster in the "early" direction when there is sufficient pressure of the pressure medium supply Pressure medium supply connects exclusively to the first group of pressure chambers, while a working connection of the working chamber is blocked and a working connection of the second group of pressure chambers is connected to the tank via the return. A simpler structural design with an optimal design of the central valve can thus be implemented.

In a further embodiment of the invention, a receiving bore provided in the rotor hub for the central valve should have annular grooves, which are each connected to the first group of pressure chambers, the second group of pressure chambers and the at least one working chamber, the valve housing being made up of an outer sleeve having working connections and an inner sleeve inserted therein, and wherein a hollow cylindrical guide element extends between an inner jacket surface of the outer sleeve and an outer jacket surface, which guide element forms control spaces.

Furthermore, the control slide should be designed as a hollow piston provided with control edges, which, adjacent to its end that interacts with an actuator, is provided with a radial return bore.

In addition, the hollow cylindrical guide element should be made of plastic, which both encloses the inner sleeve on its outer shell and closes it at its end facing away from an actuator in the form of a plug, a valve spring cooperating with the control slide being supported on the plug.

The invention is not limited to the specified combination of the features of independent claim 1 and the claims dependent thereon. In addition, there are further possibilities for combining individual features with one another, in particular when they result from the patent claims, the following description of the exemplary embodiments or directly from the figures. In addition, the reference of the claims to the figures through the use of reference signs should in no way limit the scope of protection of the claims to the illustrated embodiment examples.

Figure list

• 1 als perspektivische Ansicht eine Schnittdarstellung eines hydraulischen Nockenwellenverstellers,
• 2 einen Längsschnitt durch den Nockenwellenversteller und eine Seitenansicht eines mit diesem zusammenwirkenden Aktuators,
• 3 als Teilansicht einen unter 90° vorgenommenen Längsschnitt durch den Nockenwellenversteller im Bereich eines Zentralventils, das sich in einer Schaltstellung für eine Verstellung nach „spät“ befindet,
• 3a die Schaltstellung nach 3 mit einem Längsschnitt durch das Zentralventil unter 135°,
• 3b als Hydraulikschema das Zentralventil in seiner Schaltstellung gemäß den 3 und 3a,
• 4 als Teilansicht einen unter 90° vorgenommenen Längsschnitt durch den Nockenwellenversteller im Bereich eines Zentralventils, das sich in einer Schaltstellung für eine Verstellung nach „früh“ bei ausreichendem Systemdruck befindet,
• 4a die Schaltstellung nach 4 mit einem Längsschnitt durch das Zentralventil unter 135°,
• 4b als Hydraulikschema das Zentralventil in seiner Schaltstellung gemäß den 4 und 4a,
• 5 als Teilansicht einen unter 90° vorgenommenen Längsschnitt durch den Nockenwellenversteller im Bereich eines Zentralventils, das sich in einer Schaltstellung für eine Verstellung nach „früh“ bei minimalem Systemdruck und erforderlicher Druckübersetzung befindet,
• 5a die Schaltstellung nach 5 mit einem Längsschnitt durch das Zentralventil unter 135°,
• 5a als Hydraulikschema das Zentralventil in seiner Schaltstellung gemäß den 5 und 5a.

To further explain the invention, reference is made to the drawings, in which an exemplary embodiment is shown in simplified form. Show it:

• 1 as a perspective view a sectional view of a hydraulic camshaft adjuster,
• 2 a longitudinal section through the camshaft adjuster and a side view of an actuator interacting with it,
• 3 a partial view of a longitudinal section made at 90 ° through the camshaft adjuster in the area of a central valve, which is in a switching position for an adjustment to "late",
• 3a the switch position after 3 with a longitudinal section through the central valve at 135 °,
• 3b the central valve in its switching position according to the hydraulic diagram 3 and 3a ,
• 4th a partial view of a longitudinal section made at 90 ° through the camshaft adjuster in the area of a central valve, which is in a switching position for an adjustment after "early" when there is sufficient system pressure,
• 4a the switch position after 4th with a longitudinal section through the central valve at 135 °,
• 4b the central valve in its switching position according to the hydraulic diagram 4th and 4a ,
• 5 a partial view of a longitudinal section made at 90 ° through the camshaft adjuster in the area of a central valve, which is in a switching position for an adjustment to "early" with minimum system pressure and required pressure intensification,
• 5a the switch position after 5 with a longitudinal section through the central valve at 135 °,
• 5a the central valve in its switching position according to the hydraulic diagram 5 and 5a .

Detailed description of the drawing

In the 1 1 is a hydraulic camshaft adjuster 1 referred to, which is designed as a vane cell adjuster and one of a crankshaft, not shown, of an internal combustion engine via a drive gear 28 drivable stator 2 and a rotor which can be connected non-rotatably to a camshaft, also not shown 3 having. The rotor 3 is with a rotor hub 4th provided, from which several wings extend in the radial direction 5 , 6th and 7th extend. According to the number of wings 5 , 6th and 7th instructs the stator 2 Bridges 8th , 9 and 10 which extends radially up to an outer circumferential surface of the rotor hub 4th extend and an annulus 11 between the stator 2 and the rotor 3 in several work rooms 12th , 13 and 14th subdivide. The work rooms 12th , 13 and 14th are in turn due to the wings running within them 5 , 6th and 7th of the rotor 3 in pressure rooms 15th , 16 and 17th a first group A. as well as pressure rooms 18th , 19th and 20th a second group B. divided (see also the following figures).

The cam phaser 1 also has a pressure booster 23 with a pressure intensifier vane 23a on, in addition to the usual work spaces 12th , 13 with a pressure translation work room 23b is provided. This is through the pressure booster vane 23a into a pressure chamber that effects the pressure intensification 34 and another pressure space facing away from this 32 divided.

The rotor 3 has a pressure accumulator 21st for a pressure medium for actuating the hydraulic camshaft adjuster 1 on, which is essentially in the rotor hub 4th is trained. The rotor 3 has a central mounting hole 31 on, in which a central valve 24 to control the pressure medium supply of the pressure chambers 15th , 16 and 17th such as 18th , 19th , 20th and 34 can be used. The pressure medium accumulator 21st is hydraulic with the working chamber 15th , 16 and 17th such as 18th , 19th and 20th connected. These are in the wings 5 , 6th , 7th and 23a of the rotor 3 Check valves 22nd , 33 , 35 and 36 arranged at a negative pressure in one of the pressure chambers 15th , 16 , 17th , 18th , 19th , 20th , 34 a subsequent flow of the pressure medium from the pressure medium reservoir 21st to enable.

In the 2 is the one with a camshaft 30th connected camshaft adjusters 1 that is the central valve 24 via the mounting hole 31 receives, shown in longitudinal section. The central valve 24 is via an actuator 29 operated, the one control spool 37 of the central valve 24 can move in a total of four different switching positions. The control spool is used for this purpose 37 slidable within an inner sleeve 38 guided and has control edges 39 and 40 on, between which a control room 41 is formed.

As also those explained below 3 , 3a , 4th , 4a , 5 and 5a can be removed is the inner sleeve 38 from a hollow cylindrical guide element 42 enclosed, which is preferably as a plastic part on the outer surface of the inner sleeve 38 is sprayed and control rooms 42a and 42b forms to deflect the pressure medium flow. This plastic part also forms one at the front end of the inner sleeve 38 provided plug 43 , on which one is with the control slide 37 cooperating valve spring 44 supports. The one from the inner sleeve 38 , the guide element 42 and the stopper 43 existing unit is in a valve housing 45 arranged and by means of a locking ring 45a fixed.

The mounting hole 31 has ring grooves 46 , 47 and 48 on, the ring groove 46 to the group A. of the first printing rooms 15th , 16 and 17th , the ring groove 47 to the group B. of the second pressure rooms 18th , 19th and 20th as well as the ring groove 48 to a pressure translation facility 23 leading path A _TP are connected. The individual pressure medium paths A. , B. and A _TP are in the 2 marked by corresponding arrows, which is intended to make it clear that pressure medium can be supplied or discharged via each of these paths.

The control slide 37 is designed as a hollow cylinder (see also 3 to 5b) , being about its interior 49 and radial holes 50 Pressurized fluid into a tank T can be derived. The camshaft adjuster 1 is with a camshaft 30th connected, via their bearing 25th and an oil supply channel 26th pressurized fluid P can be fed.

The 3 , 3a and 3b show the central valve 24 in a switching position in which the group B. , so the second pressure rooms 18th , 19th and 20th Pressure medium is supplied so that an adjustment of the camshaft 30th in the "late" direction. The two pressure medium paths are during this adjustment A. and A _TP about the interior 49 of the control spool 37 with the tank T connected. The 3b further shows that a pressure medium pump 51 , which is usually a lubricating oil pump of the internal combustion engine, via a check valve 52 Apply pressure to the group B. of the second pressure rooms 18th , 19th and 20th promotes (see also 1 ). Furthermore, the hydraulic diagram shows after 3b that the control spool 37 , starting from this switching position, can be shifted into a neutral position in which all connections are blocked.

After the 4th , 4a and 4b is the central valve 24 in a switching position in which an adjustment of the camshaft 30th in the "early" direction, this adjustment taking place without the support of the pressure booster device 23 takes place, that is, the annular groove 48 , so the pressure medium path A _TP is through the spool 37 locked so that an adjustment can only be made via the group A. of the first printing rooms 15th , 16 and 17th takes place while the group B. of the second pressure rooms 18th , 19th and 20th with the tank T connected is.

After all, they show 5 , 5a and 5b a switch position of the control slide 37 , in which with the support of the translation facility 23 an adjustment of the camshaft 30th in the "early" direction. In this case, a pressure medium is applied to the pressure chambers 15th , 16 and 17th the group A. and additionally the working chamber 34 the translation facility 23 so that on the camshaft adjuster 1 a greater torque is generated.

List of reference symbols

1

hydraulic camshaft adjuster

2

stator

3

rotor

4th

Rotor hub

5

wing

6th

wing

7th

wing

8th

web

9

web

10

web

11

Annulus

12

working space

13

working space

14th

working space

15th

Printing room

16

Printing room

17th

Printing room

18th

Printing room

19th

Printing room

20th

Printing room

21st

Pressure fluid reservoir

22nd

Check valve in 23a

23

Pressure booster

23a

Pressure intensifier vane

23b

Pressure booster room

24

Central valve

25th

Deposit of 30th

26th

Oil supply channel from 30th

28

Drive toothing

29

Actuator

30th

camshaft

31

centric mounting hole

32

Print room from 23

33

check valve

34

Labor Chamber

35

check valve

36

check valve

37

Control spool

38

inner sleeve

39

Control edge of 37

40

Control edge of 37

41

Control room from 37

42

hollow cylindrical guide element

42a

Control room in 42

42b

Control room in 42

43

Plug

44

Valve spring

45

Valve body

45a

Locking ring

46

Ring groove

47

Ring groove

48

Ring groove

49

Interior of 37

50

radial bore of 37

51

Pressure medium pump

52

check valve

A.

Group of first printing rooms 15th , 16 and 17th

B.

Group of second pressure rooms 18th , 19th and 20th

A _TP

Fluid path for 23

P

Pressure medium supply

T

Return to the tank

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was 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.

Patent literature cited

• WO 2018/196904 A1 [0004]

Claims (4)

Hydraulic camshaft adjuster (1) for adjusting the control times of gas exchange valves of an internal combustion engine with a stator (2) driven by a crankshaft and a rotor (3) connected to a camshaft (30) which can be rotated relative to it and radially from the stator (2) extending webs (8, 9 and 10) and vanes (5, 6 and 7) extending from the rotor (3) and arranged in a rotor hub (4) jointly form pressure spaces (15, 16, 17, 18, 19 and 20) from which, by applying pressure, cause a first group (A) of pressure chambers (15, 16 and 17) to adjust the camshaft (30) in the "advance" direction, which counteract the friction and drag torques of the camshaft (30), and a second group (B ) of pressure chambers (18, 19 and 20) effect an adjustment of the camshaft (30) in the "retarded" direction, the camshaft adjuster (1) controlling the pressure medium supply to the pressure chambers (15, 16, 17, 18, 19 and 20) a centric in the rotor hub (4) angeor has a central valve (24) designed as a 5/4-way valve and, in the "early" direction, an additional pressure booster device (23) which can be switched on via the central valve (24) and with which at least one further working chamber (34) can be switched on, and where the central valve (24) for an adjustment in the "early" direction at a minimum pressure of the pressure medium supply assumes a switching position in which this the pressure medium supply with the first group (A) of pressure chambers (15, 16 and 17) and the at least one further working chamber (34) connects, while the second group (B) of pressure chambers (18, 19 and 20) is connected to a tank via a return (T), characterized in that control openings or edges (39, 40) of a valve housing ( 45) of the central valve (24) and a control slide (37) slidably guided therein cooperate in such a way that the central valve (24) is sufficient for actuation of the camshaft adjuster (1) in the "advance" direction The pressure of the pressure medium supply assumes a switching position in which it connects the pressure medium supply exclusively to the first group (A) of pressure chambers (15, 16 and 17), while a working connection of the working chamber (34) is blocked and a working connection of the second group (B) of pressure chambers (18, 19 and 20) is connected to the tank via the return (T). Hydraulic camshaft adjuster according to Claim 1 , characterized in that a central receiving bore (31) provided in the rotor hub (4) for the central valve has annular grooves (46, 47 and 48) which are each connected to the first group (A) of pressure chambers (15, 16 and 17), the second group (B) of pressure chambers (18, 19 and 20) and via a pressure medium path (A _TP ) are connected to the at least one working chamber (34) that the valve housing (45) consists of an outer sleeve having working connections and an inner inner sleeve this inserted sleeve (38) consists, and that between an inner jacket surface of the outer sleeve and an outer jacket surface of the inner sleeve (38) runs a hollow cylindrical guide element (42) which forms control spaces (42a and 42b). Hydraulic camshaft adjuster according to Claim 1 , characterized in that the control slide (37) is designed as a hollow piston provided with control edges (39 and 40), which, adjacent to its end cooperating with an actuator (29), is provided with at least one radial return bore (50). Hydraulic camshaft adjuster according to patent claim, characterized in that the hollow cylindrical guide element (42) consists of plastic, which encloses both the inner sleeve (38) on its outer surface and this also on its end facing away from an actuator (29) in the form of a plug (43) ) closes, a valve spring (44) cooperating with the control slide (37) being supported on the stopper (43).

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