WO2014056499A1

WO2014056499A1 - Hydraulic tensioning device

Info

Publication number: WO2014056499A1
Application number: PCT/DE2013/200204
Authority: WO
Inventors: Marco Kowalski; Benjamin Wolf
Original assignee: Schaeffler Technologies AG & Co. KG
Priority date: 2012-10-11
Filing date: 2013-10-08
Publication date: 2014-04-17
Also published as: DE102012218524A1

Abstract

The invention relates to a hydraulic tensioning device (1, 1'') comprising a pressure relief valve (15), the pressure relief thereof being adjustable, according to operation, by means of an actuator (20, 20').

Description

i

Hydraulic power supply

The invention relates to a hululary Spannvcrnchtung, This includes

~ piston, which with the

a hydraulic chamber and a check valve connecting the supply jet to the pressure chamber, the check valve closing when the pressure in the druokraym exceeds the pressure in the chamber;

and a positive control valve connecting the dry-lock to the pre-sarcom, in which the dry-off relief valve opens against the biasing force of a valve when the pressure in the pressure space exceeds a threshold pressure set by the torque-biasing force.

HIriter§rut * cf cter!

Such »tensioner assemblies are typically belt tensioners that bias the belt of the engine assembly of an internal combustion engine by means of a tensioning roller actuated by the belt tensioner. W While the iemenvcrspannkralt dyrch di force a generated between the cylinder and the ol ben clamped Dryekfeder which Hydrauiiktel the belt tensioner atten the vibrations of the belt drive Mitteis so-called Leek- spälf steam UNCP In Einfahrbewegyngen of the piston in the cylinder and accordingly ^"speaking pressure increase in Pressure chamber is a part of the contained Hydraullkmittels back over the small leakage gap between piston and cylinder In the Vorratsraym Oer during this compression phase to be overcome Drosselwiderstan korrespondied with the damping of the belt tensioner,

To limit the maximum pressure in the pressure chamber and, consequently, to limit the maximum operating tension of the belt, it is known to perform the piston hollowly and with an extension on the side of the pressure chamber in which a pressure relief valve is inserted. The valve of a valve spring In Sehlaßnehtyng heaufsc stored valve opens when one with the Ven- In the pressure space, the pressure in the pressure chamber is exceeded so that it can relieve the pressure in the reservoir and the pressure in the pressure chamber is essentially limited to this pressure. A hydraulic RJeroenspanner with limited Reakti- § onskräffen as a result of such Druekenflastung is for example from DE 10 mfQ 034 290 AI and DE EP 2 1Ö1 082 A2,

Based on this, the present invention is based on the Aufgehe, e ne t yd ulfsct Spannvorriebtung of the type mentioned with an improved? Indicate the characteristic of the pressure relief,

X Isamni nfasang the Erflriduog

5

The solution for this is that the tensioner includes a controllable actuator for operational change in the valve spring biasing force. Since the maximum limit pressure in the pressure space corresponds to the pre-throttle pressure of the dryeketvalve valve spring, the force-displacement map can do the tensioning pre-zero; to be adjusted as needed, at least in principle, in the limits of a comparable prestressing without syndrome, that is. with infinitely high limit pressure on the one hand, and with immediate Drockentiastung, i. with: Bypass pressure on the other hand, can be changed S The adjustment depth of the pressure equipment makes it possible, for example, for the clamping device during startup of the internal combustion engine to be subject to a high pressure limit pressure up to a completely lacking dry ice load with high reaction forces and accordingly closer Damping will affect. This is especially hot-burning muffles with start-stop-0 puncture and thus lends itself to numerous rewards

Another AnfaodungsfaJ may be the belt drive of an internal combustion engine with a starter generator, short RSG. In this coat are at the start of the Brennkra maschlne exchanged by means of the SG Zug- and leertfym the belt drive, wherein the dnn in Z gtruni Spannvcrrichlyng also with: bober damping; d, h, are operated with high: limit pressure or entirely: pressure relief

The variable drainage of the clamping device may also be expedient if the belt drive is operated in a speed range of the combustion engine with pronounced oscillation and in this operating mode a strong damping of the tensioning device is required.

In a structurally advantageous embodiment, the clamping device can comprise a tensioner housing with a housing extension, on which the rear view door! The reservoir space is delimited by the tensioner body and by the catcher, and the pressure damper and the atduator are arranged in the piston, apart from an electric con fi guration of the actuator - bayraymneutrai.

The valve spring preload force may be variable in steps or infinitely variable. Suitable as an eccentric actuator is, in particular, an electrically actuated piezo actuator with infinitely variable voltage supply. The piezo-steer is arranged in series with the valve spring, whose pre-pan bureau changes with the extension of the Pe ez actuator. Here, pressure venting valves are a rat valve and the valve spring is a sleeve provided with a plurality of transverse flashes, which is clamped between the Venfilplaite and the Fiezo pedestal. Such a sleeve can be executed with a considerably larger Federsfeifgk lf than, for example, a visual catching spring and is in this respect ideally combined with the Piezo _^ -Steller whose axiffiah stroke reaches only very small values

Further Mierfemal of the invention will be apparent from the following description. and ms are the factors in which two belt-anchors for the Neber-Jagregate belt lift of a Brennkrafirnasehine as Äusfö rungsbelsplele for a erfindungsgemäfi clamping device made d, are. Oils invention is therefore not limited to the shown: belt anner limited, but H nm structurally adapted form even with tensioners I chain drives e en un find. In this case, for example, the hydraulic reserve space can unfold in the tensioning zone when the chain tensioner, ie the usual one, is connected to the central drive circuit of the internal combustion engine. 1 shows the first belt tensioner in longitudinal section.

Figure 2: the pressure relief valve spring of the Rien enspanners as Elnzeitet

Figure 3 shows the structure of the valve spring of Figure 2 in sterker magnification;

Figure the second iemenspanne in longitudinal section;

Figure 5 is a schematic raft-V ^ eg Diagrarnm the erfindnngsgemalSen belt tensioner for unterschiedlieh set Dimpfkratbegennungen;

Figure B a Rie

clamping device with controlled dimple power supply :,

Unless otherwise stated: are the same or fynktionsglelehe features öder components with the same Bezugszahien embroider.

Efsfihrlieh description of the Zeicbnungen

FIG. 1 shows a hydraulic belt tensioner 1 for generating the belt pretension. In the accessory belt drive, an internal combustion engine. The following substantially comprises the following: A sprocket 2 _S for this purpose is a piston 3, and the tensioner hydraulic - Lich to the environment sealing elastomeric neck 4 and a piston part and s the tensioner hanger towards the constrictor ® trailing arm tensioner sechray spring 5, The outer end sections of the piston part and the tensioner hanger are with locking eyes 6 ynd? provided, on which the belt tensioner on the internal combustion engine on the one hand yn and on a (not shown) tensioning lever with Riemenspannrolie the other hand angelenki

The tensioner housing 2 is formed topfartartlcf and provided with a cylinder 8 stiffening upwards from a Gehänse oden 9 Pas Pas piston part 3 u holds a bohizyiindrischen piston 1Ö _; the laogshewegllefe _. Is guided in the cylinder and with the cylinder a Mi mi Hydraulikmittei geföilten Druekraum 11 limited. The latter communicates with a precursor sprayer, which is exposed to the surface of the casing, with a precursor spray for 3 _s, which is bounded by a tensioning chamber in the form of an annular space partly filled with hydraulic fluid, and bounded internally by the cylinder. The check valve is designed as a Kygelventil the Ventilkygei is closed _> if the Hydrautlkmitteldryok In the Dfuckraum is greater than Im Vörrat Faum. This is the case when the tension of the belt is shortened, with the piston entering the cylinder and a portion of the compressed hydraulic cylinder passing through the small gap between the piston and the cylinder between the piston and the cylinder Reservoir »is displaced. The case overcoming throttle restriction diminishes the Reiativbewegung of the piston and cylinder and consequently the vibrations in the belt drive, oils on shortening following extension of the belt tensioner causes an expansion of the Druckrayms, wherein hydraulic fluid with the Ventilkygei open the check valve from the Vorratsraym In the Druekraum to suction equalized becomes.

In order to limit the pressure in the Druekraum 11 on ei en upper örenxdryck, the Druckraym is also connected via a Druckentlastunvgsventll 15 and a bore 1: 8 in the piston 10 with the Vwrafsraurn 13. The Druekenfiastyngsventil is designed as Rfet envenfll whose Ventllplatte 17 of a Valve spring 18 is sealingly gedryckt against a valve seat 19 on dryckraumseitigen Koibenende. The örenzdruek in Dr ekraum is proportional to the biasing force of the valve spring; the one between the valve plate on the part of the Pruekrayms and one in the operation of the Rie ~ a

The mrl ei he external control 21 e kt isc kaktivarte Aktuafor is m with regard to the given space in the piston small dimensioned piezo stepladder, the height of which see the voltage applied thereto changed and changed due to the Reihnensphaltyng to VenLlieder their clamping length / biasing force,

In concrete terms: if, on the one hand, the electrical voltage at the Pfezo-Sfeller 20 is increased, then the height decreases as the piezoelectric element expands, causing the valve spring 18 to lose its preload and its biasing force to grow. Consequently, increases in Drucf space 11 of Grenzdruok, ah the valve plate 17 from the valve seat 19 with relief of the Pruckraums lifts, so that a Dnickentias »tion of the pressure chamber takes place only at this high Gremsdruek. The highest limit pressure corresponds to the excessive preload force of the valve spring and consequently to the maximum height of the energizing actuator. On the other hand, if the electrical voltage at the piezo actuator is reduced or switched off, the height of the piezos going together decreases to its supermost height that clamping of Ventiffede increases _s and their Vorspannkrafi is kielner. Consequently, in this case, the pressure drops in the pressure chamber, the limit pressure from which the Ventllplafte lifts from the valve seat so that a pressure relief of Druckraurnurn ready at this low limit pressure. The lowest limit pressure corresponds to the minimum preload force of the valve spring and foiojob the height of the current supply actuator,

As should be clearly understood from Figures 2 and 3, the valve spring 18 is a sleeve circumferentially provided with a plurality of transverse slots 22. In this case, they are arranged with regular circumferential offset from one another at regular intervals. Such Hulsenfedern are supplied as Stan biegefelte and find hei Piezclnjektoren for diesel engines. The Fedelflgkelt Is significantly larger compared to Schranbendrucktedern; and for the present application, it can be between 1-oleo N / mm and 26O0 N / mm with a maximum spring travel of 1 mm. The piezoelectric sensor 20 sets the biasing force of the hollow spring in the range between about 500 and 2000 M, where depending on A iu 21, either I discrete force levels or steplessly.

At optima! matched configuration of Piezö-Stelter 2Q, sleeve spring 18 in the diameter of the valve seat. 19 limited Ye ilbohryng .23 Figure 1) is already a very small öffeongshuh the Ventilpl tl © 1? sufficient for the desired test flattening. In Versyehen, even with a stroke of the valve of 0.02 mm, a sufficiently low-resistance vibration signal is present at the pressure relief valve 1.5, so that a precise pressure and damping rim limitation is achieved during the H clray likymifieiöbedritts from the pressure chamber 11 in the Verratsranm 13 : urde. The dynamic Kerrnfeld of the limit pressure Depending on the Äktuatorbestromung can be determined during the ontageprozeß of the belt tensioner 1 via an electronic calibration and for each Riemanspanner individually deposited in §§ § 20 for the Plezö-Sfetler.

The belt tensioner 1 shown in figure ⁴ differs from dam belt tensioner 1 Gemis Figure 1 only by the di Oestaltung Plezö-Sfeilers 2NC '. _: which in this case is not formed as a flat disk, but from elongated Zyii - de with a plurality stacked Piezoeiernente

FIG. 6 shows in a schematic representation the crutch-displacement diagram of the belt tensioners _s V with the hysteresis loops circulating in a clockwise direction. Oils ordinates are the longitudinal crests which the belt tensioner compresses by about 1 mm corresponding to increasing abs and is expansion according to decreasing Afos issenwerte generated. The solid curve with an increase in force of 1000 M to about. 41 ÖÖ N results in a setting of the Yenfilfeder- vcrspan force :, at which the pressure in the Dryckraum 11 below the set Grenzdruoks: remains so that the Diuekentlastyngsventll 15 does not open. In this case, the belt tensioner on a force curve that corresponds to that of a sernenspanners without Druekentlastyngsventli. The broken curves represent exemplary pinch limits to maximum strains of the belt tensioner S300 N (dotted Lm | e, 28DÖ (dashed line) and 2000 H {dot-dash line) corresponding to a decreasing strain force! the valve spring 18 and earlier opening of the Drükent! lsttmgsventi! s. In the event that $$ the current position of the belt tensioners 1, ^* known: st, due to the extremely small reaction times of Piezoaktuatoreo also vvg lusgetreue control of Drnekhegreniung vörg we'll take that. This is shown in Figure § The curve shown with thick Sfrlehsfarke again results in heavily biased Venfiifeder 18, the Druckentlasfyugsventil 15 remains closed during the entire compression phase of the belt tensioner The drawn with thin BtriehstSoke curve results from the valve spring at the beginning of Spannerkompr Ssion is comparatively low responsive to a low pressure Oren pressure relief valve is biased. s that the force of the belt tensioner does not exceed about 2100 N. After a Kompresslonshub of the belt tensioner by about 0.38 mm, the electrical voltage on the plezo actuator 20 and, accordingly, the Öffhungsdruck of Druckentlastyngsv ntils is increased, so that the belt tensioner during further compression Force increase to the maximum value of 4100 Mi generated. However, the curve shown represents only one of numerous possible evre of the zvkl faithful control of Dr cfeentiastu gsventils dan Thus, the posiflonsa hangige setting the ör pressure even in several stages and also starting from a higher to a lower internal pressure.

1 belt tensioner

2 tensioner housing

3 piston part

4 Elias zebra

S Schrayhendruckfeder

8 fixing eye

? fastening eye 9 floors!

10 pistons

11 Dryckraurn

12 Return valve 13 Supply rack

14 tecs

15 Pressure test valve 6 Bore In the piston

17 Ventif iatte

18 Ventiffecter / HM iron spring

19 valve seat

20 Pje ^ o-Steler

21 Actuator of Fi s-S 23 Valve bolt

Claims

1, hydraulic tensioning device _: comprising

A cylinder (8) and a piston (10) guided in it, which with dam cylinder (8) delimits a hydraulic pressure chamber (11),

- a hydraulic Vörraisraum (13) and e non-return valve (12), the de storage chamber (13) with the Druckrau n (11) connects said ds return ^"sehlagventl (12) closes when de Pressure: in Druekraum (11) the pressure in the Vorraisraum (13) exceeds.

And a pressure flow valve (16) which connects the pressure chamber (11) to the reservoir space (13) or which opens the pressure release valve (15) against the orcing force of a valve spring (18) when the pressure in the pressure chamber (11) exceeds an oil pressure that is predetermined by the valve spring preload force!

dad rcb geker iizeicbfietj that the tensioning device (1, I ^s ) comprises a controllable Aktaator (2CX 0 ^J ) for operational change of the Ventllfedervor- tension force,

2. Clamping device according to claim 1, d dumb

in that the tensioning device (1, 1 ') comprises a tensioner housing (2) with a Qehäuseboden (9), on which the check valve (12) extends and extends from the sieve of the cylinder (8), wherein the Vorratsrayrn (13) is limited by the tensioner frame (2) and by the cylinder (8), and wherein the orifice load valve (15) and the actuator (20, 2CF) are arranged in the piston (10).

3. Clamping device according to claim 1, characterized by the fact that the valve locking force can be variably adjusted in steps. Spannverhchtung according to claim 1 _: facf urc gekenn ele fiet that de Äkt- tuator (20, 20 ') is an electrically controlled Piezo ~ Stelier «is arranged in Reihenschaityng: to Ventlifeder (18) whose Vorspanhkrafl with the Expansion of the Fie o-Stellers ver rgert According to the preamble of claim 4, the damper valve (15) is a flat valve and the spring (S) is a sleeve filled with a plurality of quorlities (22). the vibrator is clamped on the filer (7) and the ezo actuator (20, 20)