DE102017114071A1 - Automatic hydraulic tension or lash adjuster - Google Patents

Abstract

An automatic hydraulic tension or play compensation device (1) has a pot-shaped first actuating element (2), in which a second piston-like adjusting element (3) is guided longitudinally displaceable to form a leakage gap (18). Both adjusting elements (2 and 3) delimit a hydraulic pressure chamber (4) whose pressure medium inlet is controlled via a non-return valve (6) arranged in one of the adjusting elements (2, 3), wherein the stroke limit of the two adjusting elements (2 and 3) to each other on the second Adjusting element (3) has a retaining ring (21) is fixed in an annular groove (22) which engages radially to the Hubbegrenzung in a in an inner circumferential surface (17) of the first actuating element (2) provided recess (19). To improve the safety function of the intended for stroke limiting circlip of the circlip (21) of a ring member (23) and of this radially outwardly, on the second actuator (3) radially projecting spring elements (24) consist.

Description

Field of the invention

The invention relates to an automatic hydraulic tensioning or lash adjuster with a cup-shaped first actuator in which a second piston-like actuator is guided longitudinally displaceable to form a leakage gap, wherein the two control elements delimit a hydraulic pressure chamber, the pressure medium supply via a arranged in one of the control elements check valve is controlled, and wherein the stroke limitation of the two adjusting elements to each other on the second actuating element, a securing ring is fixed in an annular groove which engages radially to the Hubbegrenzung in a provided in an inner circumferential surface of the first actuating element recess.

State of the art

Corresponding hydraulic tension or lash adjusters are preferably used in hydraulic linear tensioners for chain or belt drives and in valve lash adjusters of valve trains. In both cases, these devices cause a hydraulic tracking, that is, for example, in chain drives to achieve a chain tension as constant as possible and valve gears to compensate for a valve clearance occurring. Between the two longitudinally displaceable actuating elements designed as a helical spring compression spring is arranged, which actuates the second piston-like actuating element in the direction of enlargement of the hydraulic pressure chamber.

An oil feed of the mostly coming from the lubricating oil circuit of the engine oil in the pressure chamber via a check valve. The engaging in a step-like recess of the first actuator locking ring prevents the second actuator is pushed out of the first pot-shaped actuator, and thus acts as a decay.

A corresponding tensioning device is arranged in the slack side of the traction mechanism drive and causes in addition to the tension of the traction means and a damping of the forces acting on the tensioning device shocks by oil exiting from the pressure chamber via a provided between the actuating elements leakage gap while overcoming the fluid friction. Since the damping behavior depends on the viscosity of the oil, an appropriate dimensioning of the leakage gap must be used to achieve optimum damping behavior over the largest possible temperature range of the oil.

Valve lash adjusters are provided in a valvetrain of a reciprocating internal combustion engine to automatically compensate for a backlash occurring as a result of wear, thermal expansion and / or manufacturing tolerances. These valve lash adjusters are used both in valve drives with lever-type cam followers and in valve drives with bucket tappets and have two adjustable in the axial direction of adjusting elements, which compensate in this way a occurring during a base circle phase of the corresponding cam of the camshaft game automatically. The adjusting elements of the valve lash adjusters also form a leakage gap, via which a sinking characteristic of the lash adjuster element is determined. This ensures that despite temperature-related changes in length, in particular an exhaust valve is always achieved that the exhaust valve closes completely.

An automatic hydraulic tensioning device of the type described in the preamble of claim 1 is known from DE 10 2008 033 260 A1 known. In this case, the first cup-shaped control element is slidably inserted into a tensioner housing and receives in its interior the second actuator. The securing ring arranged in the second adjusting element protrudes radially into a recess of the first adjusting element and effects a stroke limitation of the two adjusting elements relative to one another. Incidentally, a transport securing pin should be provided between the first adjusting element and the tensioner housing, which is received by a Ölauslassöffnung during transport of the tensioning device, ie before installation in an internal combustion engine.

Furthermore, from the DE 44 27 943 A1 a hydraulic clearance compensation element is known, which is provided to compensate for a valve clearance on a drag lever drive. In this a circular shaped spring ring or, alternatively, a polygon ring in an annular groove of a hollow cylindrical housing is arranged. The corresponding polygon ring protrudes with peripheral partial surfaces a bore of the housing and engages in a recess of a piston.

Disclosure of the invention

It is an object of the present invention to improve the safety function of the intended for stroke limiting circlip.

This object is achieved by the independent claim 1. Advantageous embodiments are given in the dependent claims, taken individually or in various combinations with each other may constitute an aspect of the invention.

Thereafter, an automatic hydraulic tensioning or clearance compensation device should have a cup-shaped first actuating element, in which a second piston-like actuating element is guided longitudinally displaceable to form a leakage gap. The two control elements delimit a hydraulic pressure chamber whose pressure medium inlet is controlled via a non-return valve arranged in one of the adjusting elements. For a stroke limitation of the two adjusting elements to each other, a securing ring is fixed in an annular groove on the second adjusting element, which engages radially to the Hubbegrenzung in a recess which is provided in an inner circumferential surface of the first adjusting element. The recess is formed circumferentially in the first control element and has a certain the stroke of the retaining ring limiting length. In this case, the retaining ring is moved against axial stops of the recess.

According to the characterizing part of claim 1, the securing ring of a ring member and of this radially outwardly facing, on the second actuator radially projecting spring elements. The ring member should thus be taken up substantially by the annular groove, while the radially projecting from this spring elements are resiliently snapped into the recess. In this case, the spring elements cooperate with an axial stop so that the securing ring can not be moved out of the recess even when high axial forces occur.

In contrast, according to the DE 10 2008 033 260 A1 a spring ring is provided, which has a circular cross-section and whose spring wire is annular, wherein this is arranged in a shape adapted to its groove. After DE 44 27 943 A1 should also be used such a spring ring, or it may alternatively serve as a retaining ring polygon ring. In all cases, it is slotted rings that expand radially spring. These lie after snapping into the recess only partially within the extension of the annular groove, so that they can not be loaded with high axial forces.

In a further embodiment of the invention, the ring member should be arranged completely in the annular groove. This ring member thus does not engage in the first actuator and takes over the corresponding maximum stroke no disabling function but is the carrier of the spring elements. Preferably, the ring member is provided with a slot extending in the axial direction, so that the ring member is mounted in the annular groove.

Furthermore, it is provided that the ring part has a substantially rectangular cross-section. The cross section of the annular groove is also rectangular. In a first portion of the annular groove, the annular part is fixed, while the spring elements received by this annular part can be deflected radially into a second partial region of the annular groove.

In addition, the leakage gap may have a gap s> 100μm. With these leakage gap sizes, it is not possible to achieve a sufficient decay protection of the tensioning element with a radially expanding spring ring. In some applications, however, such gaps are sought for functional reasons. In addition, of course, the retaining ring has an excellent security function even with smaller gaps.

As further proposed, are intended to run from the closed ring member a plurality of circumferentially distributed as spring elements serving spring tabs which are arranged in the compressed state within the annular groove and extend in the radially rebound state at an obtuse angle to the ring member. Such a retaining ring can be produced with little manufacturing effort. When the two adjusting elements are pushed together, the spring tabs overrun the inner lateral surface of the first actuating element and then snap into the recess. Upon reaching a position in which a stroke limitation, the ends of the spring tabs abut against the stop formed in the recess.

Finally, the locking ring may be made of spring steel, wherein the spring tabs forming portion is deformed to an outwardly facing cone. Thus, the circlip with the aforementioned advantages can be easily produced in mass production. Alternatively, it is possible to make the locking ring made of plastic.

The invention is not limited to the specified combination of the features of independent claim 1 and the dependent claims. In addition, there are further possibilities of combining individual features, in particular if 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 by the use of reference numerals is not intended to limit the scope of the claims to the illustrated embodiment examples.

list of figures

• 1 einen Längsschnitt durch eine hydraulische Spanneinrichtung für einen Kettenspanner, die aus zwei längsverschiebbar zueinander geführten Stellelementen besteht,
• 2 eine vergrößerte Ansicht II aus der 1, die insbesondere einen Querschnitt eines erfindungsgemäß ausgebildeten Sicherungsringes zeigt,
• 3 eine perspektivische Ansicht des Sicherungsringes und
• 4 eine Seitenansicht des Sicherungsringes.

For further explanation of the invention reference is made to the drawing, in which an embodiment is shown in simplified form. Show it:

• 1 a longitudinal section through a hydraulic tensioning device for a chain tensioner, which consists of two longitudinally displaceable guided to each other control elements,
• 2 an enlarged view II from the 1 particularly showing a cross-section of a retaining ring according to the invention,
• 3 a perspective view of the retaining ring and
• 4 a side view of the retaining ring.

Detailed description of the drawing

In the 1 1 is a hydraulic tensioning device for a chain tensioner of a reciprocating internal combustion engine, the one in a non-illustrated crankcase or a lid which closes the crankcase on the front side, abstützbares first actuating element 2 having. This first control element 2 is designed pot-shaped and takes in its interior sliding a second actuator 3 on, which is designed as a piston. A suitably designed clamping device can also be used for a linear-acting belt tensioner.

The two control elements 2 and 3 close a high pressure room 4 one, into the oil over one in a soil 5 of the first control element 2 arranged check valve 6 can occur, the check valve 6 a leakage of the oil from the high-pressure chamber 4 locks. The check valve 6 has a valve hole 7 , a valve seat 8th , a valve ball 9 and a valve spring 10 on. Here is the valve spring 10 at one on the ground 5 fixed valve cap 11 supported.

Furthermore, in the high pressure room 4 a compression spring 12 arranged in a cylindrical recess 13 of the second control element 3 is guided and on the one hand on the ground 5 of the first actuator and on the other hand on a floor 14 of the second control element 3 supported. This pressure spring 12 causes the extension of the second actuator 3 whose front side 15 preferably acts on the Lostrum of the chain drive via a clamping rail, with respect to the first actuating element 2 , If the second actuator 3 from the first actuator 2 extends and thus the volume of the high-pressure chamber 4 enlarged, passes through the check valve 6 a corresponding additional amount of oil in the high-pressure chamber 4 ,

As between an outer circumferential surface 16 of the second control element 3 and an inner circumferential surface 17 of the first control element 2 a leakage gap 18 is provided, can about these during retraction of the second control element 3 Oil from the high pressure room 4 be displaced, so that due to a corresponding fluid friction damping of the first actuator 2 acting power surges can be achieved. This leak gap 18 has a gap s. Incidentally, one is above the ground 5 extending portion in the inner circumferential surface 17 a radial recess 19 provided on the one hand by the ground 5 and on the other hand by an annular stop 20 is limited.

As continues from the 1 in conjunction with the enlarged section in 2 shows, engages in this recess 19 , which limits the axial stroke movement of the second actuating element 3 has a predetermined axial extent, one on the second actuator 3 fixed circlip 21 a, thus radially over the outer circumferential surface 16 protrudes. Starting from the outer circumferential surface 16 is in the actuator 3 an annular groove 22 made with rectangular cross section, which is the circlip 21 receives.

In this case, there is the circlip 21 from a ring part 23 , which is integral with spring elements 24 is formed, being how the 3 and 4 show through longitudinal slots 25 manufactured spring tabs 26 as spring elements 24 serve. One of these longitudinal slots 25a is continuous, ie in the axial direction through the ring part 23 running, leaving the circlip 21 overall designed as a slotted ring. From the illustrations it is clear that the circlip 21 by the formed on this spring tabs 26 with radially outwardly resilient ends 27 has a total expandable geometry, ie, that the spring tabs 26 in a state in which they are not acted upon by a radial force, run overall frusto-conical.

The width of the annular groove 22 is designed so that this both the ring part 23 as well as the spring tabs 26 can record. This is the case when the second actuator 3 in the first actuator 2 is introduced. When the circlip 21 in overlap with the recess 19 is, spread the spring tabs 26 outward and grab with their ends 27 into the recess 19 one. To limit the Auswärtshubes the second actuator 3 opposite the first actuator 2 beat the ends 27 to the annular stop 20 at.

LIST OF REFERENCE NUMBERS

1

hydraulic tensioning device

2

first actuator

3

second actuator

4

High-pressure chamber

5

Bottom of 2

6

check valve

7

valve bore

8th

valve seat

9

valve ball

10

valve spring

11

valve cap

12

compression spring

13

cylindrical recess in 3

14

Bottom of 3

15

Front side of 3

16

Outer surface of 3

17

Inner lateral surface of 2

18

leakage gap

19

radial recess

20

circular stop

21

circlip

22

Ring groove in 3

23

ring part

24

spring elements

25

longitudinal slots

25a

longitudinal slot

26

spring shackles

27

Ends of 26

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 102008033260 A1 [0006, 0012]
• DE 4427943 A1 [0007, 0012]

Claims (6)

An automatic hydraulic tensioning or lancing device (1) with a cup-shaped first control element (2) in which a second piston-like control element (3) is longitudinally displaceable to form a leakage gap (18), wherein the two control elements (2 and 3) a hydraulic Limit pressure chamber (4), the pressure medium supply via a in one of the adjusting elements (2, 3) arranged check valve (6) is controlled, and wherein the stroke limitation of the two adjusting elements (2 and 3) to each other on the second adjusting element (3) a locking ring (21 ) is fixed in an annular groove (22) which engages radially for limiting the stroke in a in an inner circumferential surface (17) of the first adjusting element (2) provided recess (19), characterized in that the retaining ring (21) consists of a ring member (23) and from this radially outwardly facing, via the second adjusting element (3) radially projecting spring elements (24). Automatic hydraulic tension or lash adjuster according to Claim 1 , characterized in that the ring part (23) is arranged completely in the annular groove (22). Automatic hydraulic tension or lash adjuster according to Claim 1 , characterized in that the ring part (23) has a substantially rectangular cross-section. Automatic hydraulic tension or lash adjuster according to Claim 1 , characterized in that the leakage gap (18) has a gap s> 100μm. Automatic hydraulic tension or lash adjuster according to Claim 1 , characterized in that from the closed ring part (23) a plurality of circumferentially distributed as spring elements (24) serving spring tongues (26) go out, which are arranged in the radially eingeschederten state within the annular groove (22) and in the rebounded state at an obtuse angle to Ring part (23) run. Automatic tension or lash adjuster according to Claim 5 , characterized in that the retaining ring (21) is made of spring steel, wherein the spring tabs (26) forming portion is deformed to an outwardly facing cone.

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