DE10044125A1 - Tension system for traction mechanism drive has hydraulic and mechanical tension units, which include damping units for damping adjustment movement - Google Patents

Abstract

The tension system (1) combines a hydraulic tension unit (2) and a mechanical tension unit (3) for supporting the tension roller (10) of the traction belt. The tension units include damping units for damping the adjustment movement of the tension roller carrier (7).

Description

Field of application of the invention

The present invention relates to a tensioning device, in particular for a belt of a traction mechanism drive, preferably used to drive Aggregates of an internal combustion engine. The tensioning device includes a Base part as well as a swiveling tension roller carrier, which in in an installation position via a tension roller on the traction mechanism Is supported.

Background of the Invention

A tensioning device is known from US Pat. No. 4,472,162, in which between a base part designed as a housing and a tension roller support a torsion spring is inserted. The partially interlocking and through the force of the torsion spring axially pressed components, the housing and the tensioner pulley, are centered by means of one of the two components setting screw in a sleeve on an internal combustion engine attached. For vibration damping of the tension roller carrier shows the be Known device from a thermoplastic or an elastomer introduced friction bushing on the one hand on the tension roller carrier and on the other hand with is connected to the housing.  

DE 196 09 420 A1 shows a clamping device with a mechanical hydraulic actuator provided with a housing in which zen trisch a cylinder is formed in which a piston is guided. In axial ver Extension of the piston is provided at the end with a fastening eye to which the hydraulic element can be pivotally attached to the tensioning roller carrier gen is. Another mounting eye is arranged on the housing with which the clamping device, for example, stationary, but pivotable on the burner engine to be attached. This known clamping device is with egg spring-loaded, guided longitudinally in the cylinder and a pressure chamber in the cylinder delimiting piston. A col benbewegung causes a volume exchange of the hydraulic fluid between the pressure chamber and the housing.

The purely mechanical clamping device in connection with the damping unit direction enables basic damping regardless of speed of the adjusting movements of the tension pulley carrier and thereby allows priority damping of low-frequency vibrations of the tension pulley carrier. The further clamping device, provided with a mechanical-hydraulic loading Actuating element in which the biasing force on the tensioning roller carrier by means of a pressure spring integrated in the hydraulic element, in connection with a effective lever arm takes place, enables a speed-dependent Damping. The damping force increases at higher frequencies and / or large vibration amplitudes. Both jigs have proven and have a high level of functional reliability. Due to the each application of this known instep is different devices a compromise in terms of damping characteristics. Wei Furthermore, each of these tensioners is limited in terms of preload force. For driving large-sized generators or stater generator Conceivable traction mechanism drives require high preload forces. A purely mechanical tensioning device has the disadvantage that the spring wire diameter of the torsion spring to generate a sufficient pre clamping force must be dimensioned very large, which is due to the size  rigidity complicates the assembly and continues to be a disadvantageously large construction space is required. An exclusively hydraulic clamping device on the other hand, an exclusively proportional speed is disadvantageously Damping characteristic.

Summary of the invention

The invention is based on the object of a tensioning device to realize increased preload, which at the same time is sufficient Has damping property that is inexpensive to display and easy to assemble.

According to the invention, this problem is solved by a clamping system, that involves both a mechanical and a hydraulic component summarizes. According to the invention, the clamping system is ge with two from each other separated devices, a mechanical clamping device and one hydraulic clamping device combined, which form a unit to ge to realize an increased preload together. The combined structure enables the moments generated by the tensioning devices to be added, d. H. on the one hand that of the torsion spring of the mechanical tensioning device tion generated moment introduced into the tension roller carrier and others on the other hand from the compression spring of the hydraulic tensioning device in connection dung with the effective lever arm, d. H. the pivot point of this clamping device direction generated on the idler pulley.

To dampen adjustment movements of the tension pulley or tension arm, ver caused by the rotational irregularity of the internal combustion engine, which too Each has own vibrations of the traction device and thus the tension pulley Clamping device of the clamping system according to the invention a damping direction. A basic damping between the tension roller carrier and the Ba Sis part of the mechanical tensioning device takes place by means of a put friction element. The hydraulic tensioning device causes one  Damping by a force acting against the spring force of the traction device Hydraulic fluid displaced from the pressure chamber through a leakage gap.

This advantageously dampens the mechanical tensioning device set friction element regardless of the speed of the actuating movement low-frequency vibrations of the tension pulley carrier and thus ensures effective basic damping. In contrast, the hydraulic Tensioning device a speed-dependent damping of the positioning conditions of the tension pulley carrier, whereby at higher frequencies and / or large vibration amplitudes increases the damping force.

The invention also fulfills the requirements regarding increased Biasing force of the traction mechanism drive, for example for driving a large di dimensioned generator.

Further advantageous embodiments of the invention are the subject of dependent claims 2 to 9.

The tensioning system according to the invention is preferably suitable for a belt driven starter generator concept of internal combustion engines. The starterge nerator takes on both the function of the generator and that of Starter of an internal combustion engine. The high generated by the clamping system Preload is sufficient for a starter generator drive in which there is a change of direction between the start mode and normal mode of the torque. During the start operation, the starter generator initiated a torque in the traction device, while in the Nor paint the torque from the crankshaft pulley of the Brenn engine is introduced into the traction device. This involves a change sel of the train strand and the empty strand. The combined mechanical and hy Draulic tensioning device of the tensioning system according to the invention generated advantageously a pre-tensioning force of the traction device that is independent of the starting or normal operation including a slip-free drive for all units of the starter generator.  

The preferred structure of the tensioning system according to the invention comprises a Base part as well as a tension roller carrier, which are partially concentric to each other are arranged, the tensioning roller on one end of the tensioning rollers Carrier arranged pivot arm is attached. The mechanical clamping device direction also has a torsion spring designed as a coil spring the one that encloses a cylindrical hub of the tension roller carrier and their Spring ends are attached to the base part or the tension roller carrier. It is the spring is wound so that the swivel arm and the associated The tensioning roller of the tensioning roller carrier is non-positively when installed the traction means are supported.

The further hydraulic clamping device of the Spannsy according to the invention stems comprises a mechanical-hydraulic actuating element that is equipped with an egg Nem end stationary, for example on the housing of the internal combustion engine Stigt and with the further end on the swivel arm of the idler pulley gers attacks. The construction of the hydraulic tensioning device includes one spring-loaded piston guided in a cylinder, the one Limited pressure space. The pressure chamber is through a one-way valve from ei Nem surrounding the cylinder, partially filled with a hydraulic fluid Interior separated, which is in a housing enclosing the cylinder forms. A volume exchange of the hydraulic fluid between the pressure chamber and the interior, due to a piston movement, is dependent from the direction of movement of the piston via the one-way valve or via egg leakage gap that occurs between the piston and the cylinder wall. The torque generated by the hydraulic tensioner is determined by the force of the spring acting on the piston in connection with the Lever arm with which the hydraulic tensioning device on the tensioning pulley eng attacks.

Both the mechanical clamping device and the hydraulic clamping device effect device of the combined clamping system according to the invention damping the adjusting movements of the tension pulley. One from the traction mechanism  the tension roller and thus triggered on the hydraulic tensioning device Force causes the hydraulic fluid to be displaced from the pressure chamber the leakage gap between the piston and the cylinder wall, whereby due to the shear forces of the pressure medium displacement damping Adjusting the tensioner pulley movement. The further mechanical tensioning device tion has an axial load only belement, preferably designed as an annular friction disc, the is arranged between the base part and the tension roller carrier.

The friction element between a base of the base part and egg is advantageous Nem arranged non-rotatably connected to the tension roller carrier ring flange. The structure provides that the ring is non-rotatably connected to the base part flange is supported on the tensioning roller carrier via the friction element. Alterna A mechanical tensioning device is also suitable for this purpose, its rotationally fixed the ring flange connected to the tension roller carrier attaches itself via the friction element supports the base part. The arrangement of the friction element in the mechani The clamping device ensures basic damping, especially with the re low-frequency vibrations of the tension roller carrier effectively damped become. The different damping characteristics of the mechanical and the hydraulic tensioning device complement each other and cause an in effective damping of the instep according to the invention in all operating situations system.

To further explain the invention reference is made to the drawings.

Brief description of the drawings

Show it:

Fig. 1 in a view tensioning system according to the invention;

Fig. 2 is a sectional view of the clamping system shown in Figure 1 along the line II-II, which illustrates the structure of the mechanical clamping device.

Fig. 3 in an enlarged scale a longitudinal section of the hydraulic clamp of the clamping system according to the invention;

Fig. 4 is a schematic diagram of a traction mechanism drive, in the clamping system of the invention is integrated;

Fig. 5 is a characteristic diagram illustrating the operation of the mechanical tensioning device;

Figure 6 shows the dependence of the damping force on the frequency, shown in a map for a hydraulic clamping device.

FIG. 7 shows the characteristic diagram of the tensioning system according to the invention, which includes both a mechanical and a hydraulic tensioner;

Fig. 8, the characteristic field of a combined mechanical-hydraulically acting clamping device according to Fig. 7 with respect to a changed frequency.

Detailed description of the drawings

A clamping system 1 shown in FIGS . 1 and 2 comprises a hydraulic clamping device 2 and a mechanical clamping device 3 . The clamping system 1 comprises a base part 4 , in the support tube 6 a screwing 5 is used, with which the clamping system 1, for example on the Ge housing of an internal combustion engine are arranged stationary. On a Manttelflä surface of the support tube 6 , a tension roller support 7 is rotatably guided via a hub 8 . On the front side, the tensioning roller carrier 7 forms a tensioning arm 9 , on the end of which a rotatable tensioning roller 10 is arranged, which in the built-in state was supported on a traction means 11 , in particular a belt, under force.

The frictional support of the tensioning roller 10 on the traction means 11 is achieved by the combination according to the invention of the hydraulic tensioning device 2 with the mechanical tensioning device 3 . The structure of the mechanical tensioning device 3 comprises a torsion spring 12 which is fixed in position with a spring end on the base part 4 and with the further spring end on the swivel arm 9 . The hydraulic clamping device 2 , the structure and mode of operation of which is shown in FIG. 3, has a first fastening eye 13 a with which the clamping device 2 is fastened, for example, to the internal combustion engine. With the further mounting eye 13 b, the Spannvorrich device 2 is coupled to the swivel arm 9 of the tension roller support 7 . The tensioning devices 2 , 3 are designed and designed such that their spring forces add up, so as to realize a high pretensioning force of the traction means 11 . Such a tensioning system 1 can be used, for example, for a starter generator concept, in which a change in direction of the torque in the traction mechanism 11 occurs, depending on the starting function or operating function of the starter generator.

Each tensioning device of the tensioning system 1 according to the invention also has damping, the mechanical tensioning device 3 comprising a friction element 14 inserted between the base part 4 and the tensioning roller carrier 7 . As a friction element 14 serves an annular disc, which is between a torsionally rigid on the support tube 6 of the base part 4 arranged ring flange 15 and an end face of the tension roller carrier 7 is inserted. The friction element 14 is exclusively stressed by an axial force of the torsion spring 12 and effects basic damping, regardless of the actuating speed of the swivel arm 9 . The damping of the hydraulic clamping device 2 is explained in the description of FIG. 3. The biasing force with which the tensioning roller 10 is supported on the traction means 11 can be influenced by the design of the torsion spring 12 , for example by the wire diameter and by the articulation of the hydraulic tensioning device 2 on the swivel arm 9 , with which the effective lever arm is fixed, which determines the moment to be applied.

Fig. 3 shows the hydraulic clamp 2 in a longitudinal section. The largely cylindrical design has a pot-like housing 16 , which comprises an attachment eye 13 a at the end. On the opening side, a cylinder 17 is introduced centrally into the housing 16 , in which a piston 18 is guided so as to be longitudinally displaceable. The piston 18 delimits the pressure space 19 filled with a hydraulic fluid. A volume exchange of the hydraulic fluid between the pressure chamber 19 and an annular interior 20 , which occurs between the housing 16 and the cylinder 17 , is triggered by a piston movement. The piston 18 is connected at the end facing away from the pressure chamber 19 to the fastening eye 13 b on the swivel arm 9 of the tensioning roller carrier 7 , as shown in FIG. 1. Vibrations introduced into the tensioning system 1 by the traction means 11 are transmitted to the piston 18 , in connection with a volume exchange of the hydraulic fluid. Depending on the direction of movement of the piston 18 , hydraulic fluid is displaced via a leakage gap 22 , which is established between the piston 18 and the cylinder 17 , and enters the interior 20 , or the hydraulic fluid flows from the interior 20 via the one-way valve 21 into the pressure chamber 19 , The piston movement, which reduces the pressure chamber 19 and displaces the hydraulic fluid through the leakage gap 22 , causes an effective vibration damping, the damping force increasing at higher frequencies and / or large vibration amplitudes. The biasing force of the hydraulic Spannvor device 2 is caused by an inserted in the housing 16 coil spring 23 , the other end of which is supported on a position fixed on the piston 18 retaining slide 24 be.

In FIG. 4, in a schematic diagram of a traction mechanism, provided with the inventive clamping system 1 is shown. The triangle connected to the clamping system 1 indicates with "a" the pivot point of the clamping system 1 defined by the screw connection 5 ; "b" defines the point at which the hydraulic clamping device 2 engages the pivot arm 9 of the clamping system 1 . The pivot point of the tensioning roller 10 is marked with "c". The traction means 11 of the traction mechanism drive 25 of an internal combustion engine shown in FIG. 4 connects various units or pulleys. In detail, the traction means 11 connects pulleys which are connected to the crankshaft 26 , the air conditioning compressor 27 , the power steering pump 28 and the starter generator 29 . Between the crankshaft 26 and the starter generator 29 , the deflection roller 30 is arranged to achieve an increased wrap angle of these components. The tensioning system 1 is supported on the traction means 11 between the power steering pump 28 and the starter generator 29 . Due to the increased pretensioning force according to the invention, with which the tensioning system 1 acts on the traction means 11 , the tensioning system 1 is also suitable for starter generator operation in which a change in direction of the torque occurs, depending on the start or normal operation. Due to the dual function of the starter generator, the load strand and the empty strand in the traction means 11 change , depending on the operating mode of the starter generator.

FIGS. 5 and 6 show the different damping characteristics between the mechanical clamping device 3 (Fig. 5) and the hydraulic devices rule clamping device 2 (Fig. 6). The characteristic diagram of FIG. 5 is take ent that already after a slight adjustment movement of the tensioning roller carrier 7 of the mechanical clamping device 3, a high Dämp adjusts Fung force, a basic attenuation that is independent of the Stellge speed of the tension roller carrier 7. The mechanical clamping device 3 is therefore particularly suitable for damping low-frequency vibrations. The characteristic diagram shown in FIG. 6 illustrates the dependency of the damping force on the frequency of the hydraulic tensioning device 2 . The damping force then increases with the frequency increase and / or the vibration amplitudes.

In Figs. 7 and 8, the map of a combined mechanical-hydraulic tensioning device is illustrated. The map ( FIG. 7) that applies to the frequency “f,” shows an attenuation with a significantly higher force increased over the path compared to the map of FIG. 8, determined for the frequency “f ₂ ”. The frequency "f ₂ "<"f ₁ " is designed.

LIST OF REFERENCE NUMBERS

1

clamping system

2

hydraulic tensioner

3

mechanical tensioner

4

base

5

screw

6

support tube

7

Utility Carrier

8th

hub

9

swivel arm

10

idler

11

traction means

12

torsion spring

13

a mounting eye

13

b mounting eye

14

friction

15

annular flange

16

casing

17

cylinder

18

piston

19

pressure chamber

20

inner space

21

one-way valve

22

leakage gap

23

coil spring

24

retaining washer

25

traction drive

26

crankshaft

27

air compressor

28

Power steering pump

29

starter generator

30

idler pulley

Claims (9)

1. tensioning system ( 1 ) for a traction mechanism drive ( 25 ), comprising a stationary base part ( 4 ), to which a pivotable tensioning roller carrier ( 7 ) is assigned, wherein a pivoting arm ( 9 ) connected in one piece to the tensioning roller carrier ( 7 ) by means of a tensioning roller arranged at the end ( 10 ) abuts on a traction mechanism ( 11 ) of the traction mechanism drive ( 25 ), to achieve a force-supported support of the tensioning roller ( 10 ) on the traction mechanism ( 11 ), the tensioning system ( 1 ) with a hydraulic tensioning device ( 2 ) and a mechanical tensioning device ( 3 ) combined, which have damping devices for damping actuating movements of the tensioning roller carrier ( 7 ). 2. Clamping system according to claim 1, provided for a starter generator concept, in which the torque is optionally initiated by a crankshaft egg ner internal combustion engine or a starter generator ( 29 ) in the train. 3. Tensioning system according to claim 1, wherein the tensioning roller carrier ( 7 ) and the base part ( 4 ) are partially arranged concentrically to one another and the tensioning roller ( 10 ) is fastened to the swivel arm ( 9 ) connected to the tensioning roller carrier ( 7 ) on the end face. 4. Clamping system according to claim 1, the mechanical clamping device ( 2 ) comprises a torsion spring ( 12 ) designed as a helical spring, which encloses a cylindrical hub ( 8 ) of the tensioning roller carrier ( 7 ) and its first spring end with the base part ( 4 ) and its second Fe the end of which is connected to the tensioning roller carrier ( 7 ) in a rotationally fixed manner. 5. Clamping system according to claim 1, wherein the hydraulic Spannvorrich device ( 2 ) is pivotally fixed at one end, for example attached to the internal combustion engine and the other end is directly or indirectly coupled to the swivel arm ( 9 ) of the tensioning roller carrier ( 7 ). 6. A clamping system according to claim 5, the hydraulic tensioner (2) a, comprises spring-loaded in a cylinder (17) guided and a pressure chamber (19) limiting piston (18), said filled with a hydraulic fluid pressure chamber (19) through a one-way valve ( 21 ) from a cylinder ( 17 ) surrounding, partially filled with hydraulic fluid interior ( 20 ) of a housing ( 16 ) and a volume exchange between the pressure chamber ( 19 ) and the interior ( 20 ) due to the piston movement, depending on the movement direction of the piston ( 18 ) via the one-way valve ( 21 ) or via a leakage gap ( 22 ) between the piston ( 18 ) and the cylinder ( 17 ). 7. Clamping system according to claim 1, in which an axial force of the gate spring ( 12 ) acted upon, annularly shaped friction element ( 14 ) between the base part ( 4 ) and the tensioning roller carrier ( 7 ) is inserted. 8. Clamping system according to claim 7, wherein the friction element ( 14 ) is arranged between a bottom of the base part ( 4 ) and a non-rotatably connected to the tension roller carrier ( 7 ) ring flange ( 15 ). 9. Clamping system according to claim 8, wherein the annular flange is supported on the tensioning roller carrier ( 7 ) via the friction element ( 14 ).