DE19537205C2 - Shock absorber - Google Patents

Description

The invention relates to a shock absorber as a fuse link between a bumper and the frame of a Motor vehicle according to the features in the preamble of the An saying 1.

Such a shock absorber counts through US 3,899,047 the state of the art. In this type, the In inner tube has a rounded one in cross section lacing. A constriction fits into this constriction of the outer tube. Both in the area of constrictions and the outside is also in front of and behind the constrictions flat with its inside on the outside of the Inner tube. The face of the outer tube is on the Welded surface of the inner tube. Inner tube and Outer tube have the same wall thickness.

In the shock absorber of DE 43 00 284 A1 is the inner one annular projection on the outer tube also by a circumferential constriction formed. The cross section of the  two constrictions in the axial direction of the shock absorber seen is semicircular to V-shaped. In the constriction a welding bead is placed around the outer tube Reinforcing the area of the outer tube. This is not just a lot of effort, but also an inconvenient technical influence on the material of the shock absorber connected.

The invention is based on the prior art Task based on a shock absorber as a securing member between a bumper and the frame of a motor vehicle to create stuff that is easier to manufacture and at which is a tightly tolerated constant force over you predetermined deformation path even after a long loading ready state can be realized.

According to the invention, this object is achieved in those listed in claim 1 Characteristics.

In addition to the indispensable fasteners the shock absorber according to the invention consists of only two concentrically nested pipes. The The outer tube takes on the function of a deformation limbs and the inner tube that of an ele to be deformed true. Due to the trapezoidal design of the cross cut the constriction on the inner tube and the projection on the outer tube is a simple and inexpensive ferti possible. This also keeps the shock absorber in the standby position is in principle unlimited wanted functionality at. In particular, however now through a precise coordination of the configuration of constriction and lead in relation to one greater wall thickness than the outside having the inner tube pipe an extremely tightly tolerated force over a pre given way to be realized.  

The fact that the neigh the free end of the outer tube Beard length section the inner tube with a radial distance overlaps and the fastening element of the inner tube facing conical length ranges of the constriction so like the projection different inclination angles point, the deformation is targeted to the together act on the projection on the outer tube with the inner tube limits. There is a linear arrangement of the over starts from the conical length of the constriction the lengths overlapped by the outer tube cut the inner tube on the inner surface of the conical Length range of the projection. Thus, with an up only the inner tube is deformed. Other length ranges of outer tube and inner tube are from this together basically exempt. In the gap between the outer tube and the inner tube is next to the projection or the constriction lubricant introduced. Also this fact contributes to the force / path ver to be able to tolerate the relationship closely.

In the event of a crash, the outer tube and inner tube become relative moved to each other, the molded on the outer tube jump from its standby position in the Constriction of the inner tube and the adjoining one Length section of the inner tube due to the lini radial contact of the conical length regions pressure, thereby continuously deforming the inner tube and consequently evenly impact energy is absorbed. This ensures form-fitting and sealed to the outer surface of the inner tube fit free end of the outer tube for a flawless Leadership especially in cases where lateral forces occur ten.

The design of the shock absorber according to the invention allows in addition, various material combinations in large toles  ranc borders. For example, it is possible that The outer tube and the inner tube are made of steel. Both Pipes can also be formed from aluminum. Fer ner it is conceivable that either the outer tube or Inner tube made of steel and then the other tube Aluminum. This way the specific Requirements of a shock absorber for the respective one special purpose are taken into account.

Furthermore, the invention allows the cross sections of outer tube and inner tube deviating from a round one To design the cross-section differently.

If less than the outer tube Wall thickness of the inner tube is mentioned, so it is in the frame men of the invention advantageous if the wall thicknesses of outer tube and inner tube in a ratio of about 3: 2 move.

The arrangement of the constricting free ones Face of the inner tube in a transverse plane, which is approximately in the middle of the assigned conical length range of the Projection extends (claim 2), guaranteed on the the clear location of the outer tube and In tube in the standby position in the form of an off anti-trap, but also on the other side cher that in the event of a crash, the front face closing conical expansion of the constriction of the In no negative effects on the preparation agreed force / path ratio.

According to claim 3, the projection by a radial Constriction of the outer tube can be formed.  

An expansion of the is also conceivable according to claim 4 lengths adjoining the projection on both sides sections of the outlet pipe.

The inner and outer tubes are separated during manufacture preformed from each other, then assembled and ultimately connected by thorning. Then brew Chen only the fasteners the two Pipes to be assigned.

According to the features of claim 5, the front but also jump through a thickening of the wall then one smooth cylindrical outer surface having exterior tubes are formed. In this case, the Wall thickening formed on the inside of the outer tube. On then the inner tube is inserted into the outer tube and the constriction adapted to the projection.

In this context, it can be useful if according to claim 6, the free end of the outer tube radially zy is molded lindrisch and on the cylindrical outer Surface of its fastener adjacent Length section of the inner tube lies sealingly. Herewith a very simple embodiment is created which can also be manufactured extremely economically.

The starting workpiece forms both in the outer tube and a continuous cylindrical tube also for the inner tube cut uniform wall thickness. In two parallel ares working aisles are on one side of the lead on Outer tube and on the other side one in diameter indented end section made on the inner tube. On finally the outer tube and the inner tube become together quantity added, being in the final phase of the assembly the free end of the outer tube is inserted radially cylindrical forms and seals to the outer surface of the inside  Case of undeformed length section of the inner tube ge is pressed. Before inserting the inner tube into the The outer tube is still drawn into the diameter End portion of the inner tube given a lubricant. In the collapsed position is in through knife-drawn end section of the inner tube in the area the projection of the outer tube. Now with help a mandrel inserted through the outer tube also the Fastener of the outer tube adjacent conical Length range formed at the end of the inner tube. Outer tube and inner tube are now connected.

The embodiment characterized in claim 7 sees a tapered free end of the outer tube. This is due to a conical transition section between an undeformed longitudinal section of the inside tubes and a smaller diameter cylinder rule length section of the inner tube. Such an embodiment is then preferred when the outer tube is a continuous cylindrical has outer surface and the inner annular front jump formed by a wall thickening of the outer tube is.

Another advantageous embodiment of the invention is characterized in the features of claim 8. The Deformation of the two length ranges is preferred made the inside diameter of the in diameter largest length range about the outside diameter of the length closest to a fastener Section of the inner tube corresponds, whereas the outside diameter of the reduced length range about the inside diameter of the fastener neighboring length section of the inner tube is adapted.  

In this case it can be advantageous if the inner Projection of the outer tube also by a constriction tion is formed, then according to claim 9, the free End of the outer tube is drawn in and out on the surface of the deformed cylindrical lengths section of the inner tube is supported.

The invention is based on in the drawings gene illustrated embodiments explained in more detail. Show it:

Fig. 1 a shock absorber in vertical longitudinal section;

Fig. 2 on an enlarged scale the detail II of Fig. 1;

Fig. 3 in vertical longitudinal section a further imple mentation form of a shock absorber and

Fig. 4 in vertical longitudinal section a third imple mentation form of a shock absorber.

Figs. 1 to 4 show the shock absorbers 1, 1 a, 1 b, which can be incorporated as securing members between a not further illustrated bumper and likewise not illustrated frame of a passenger car.

The shock absorber 1 of FIGS. 1 and 2 is generally composed of a cylindrical outer tube 2 as a deformation member and a cylindrical inner tube 3 as a deformable member. Fastening elements 4 , 5 are provided at the end of the outer tube 2 and inner tube 3 , via which the shock absorber 1 can be connected on the one hand to the bumper and on the other hand to the frame.

Outer tube 2 and inner tube 3 are made of steel. The wall thickness D of the outer tube 2 is in comparison to the wall thickness D1 of the inner tube 3 as about 3: dimensioned. 2

The over its predominant length smooth cylindrical In nenrohr 3 is at the end of the fastener 5 th end with an axially trapezoidal lacing 6 is provided. Consequently, the constriction 6 consists of a central cylindrical length region 7 and two adjoining conical length regions 8 , 9 . The conical length ranges 8 , 9 are dimensioned in the axial direction of the inner tube 3 significantly shorter than the cylindrical length range 7 . The outer diameter AD of the cylindrical length region 7 corresponds approximately to the inner diameter ID of an undeformed length section 10 of the inner tube 3 . The cone angle α of the conical length regions 8 , 9 is approximately 40 °.

The outer tube 2 is provided on the circumferential side of the constriction 6 on the inner tube 3 with an inner projection 11 adapted to the constriction 6 . The projection 11 is formed by a trapezoidal constriction of the outer tube 2 . Accordingly, the projection 11 is composed of a zy-cylindrical length range 12 and two conical Längenbe ranges 13 , 14 together.

The constriction 6 free end face 15 of the inner tube 3 extends in a transverse plane EE, which extends approximately in the center of the conical length region 13 of the jump 11 before.

The ratio of the axial length L of the projection 11 on the outer tube 2 to the axial length L1 of the extending from the free end face 16 of the outer tube 2 to the projection 11 extending portion 17 of the outer tube 2 be in the illustrated embodiment about 1: 1. Otherwise, this is Ratio freely selectable or determined by design and shear force requirements.

The adjoining the projection 11 Längenab section 18 of the outer tube 2 extends at a radial distance A to the undeformed length section 10 of the inner tube 3rd The free end 19 of the outer tube 2 is formed in a radially cylindrical shape and is in a form-fitting and sealing manner against the outer surface 20 of the undeformed length section 10 . The length L2 of the cylindrically molded free end 19 is approximately 1/9 of the length L3 of the Längenab section 18th This length L3 corresponds approximately to two times the axial length L of the projection 11 .

As can be seen in FIG. 2 in more detail, care is taken by a different angular arrangement of the conical length regions 9 of the constriction 6 and 14 of the projection 12 that the transition U from the conical Längenbe region 9 of the constriction 6 to the cylindrical lengths section 10 on the inner surface 29 of the conical length region 14 of the projection 11 comes to rest. This results in a linear contact between the transition U and the inner surface 29 .

The annular gap SP formed by the radial distance A between the cylindrical length section 10 and the length section 18 of the outer tube 2 can be at least partially filled with a lubricant.

The manufacture of the shock absorber 1 according to FIGS. 1 and 2 is carried out approximately as follows:
Starting workpieces for the outer tube 2 and the inner tube 3 form cylindrical tube sections with wall thicknesses D and D1, which are not illustrated in any more detail.

To produce the outer tube 2 , two mandrels, not shown, are inserted into the tube section from the end faces. The outer contour of the mandrels corresponds to the desired inner contour of the projection 11 . By means of radially movable mold jaws before the jump 11 is generated.

Parallel to the manufacture of the outer tube 2 , an end section of the tube section determined as the inner tube 3 is drawn in with the aid of shaped jaws, so that the largest part of the outer contour and the inner contour of the constriction 6 results.

Now the inner tube 3 is inserted into the outer tube 2 . In this case, the end section which is drawn in in diameter and forms part of the constriction 6 is sprayed beforehand with a lubricant. In addition, a form ring is placed on the circumferential side of the inner tube 3 at the point where the free end 19 of the longitudinal section 18 of the outer tube 2 is to be drawn in.

Upon insertion of the inner tube 3 in the outer tube 2 of the outer will tube 2 produces a mandrel inserted and placed by the inner tube 3 remote from end face of the free end 19 can create the outer tube 2 to the pull, the end face of the inner tube 3 in radial A.

Following this, the support mandrel is removed from the outer tube 2 and a cone mandrel is inserted for this purpose, which presses the conical length region 8 of the constriction 6 on the inside against the conical length region 13 of the projection 11 .

Ultimately, the conical mandrel and the shaped ring are moved away from the outer tube 2 and the inner tube 3 . The shock absorber fer 1 is finished except for the end fasteners 4 , 5 . These can then be attached to the end of the outer tube 2 and inner tube 3 in the manner required union.

In the embodiment of a shock absorber 1 a according to FIG. 3, an outer tube 2 a and an inner tube 3 a are in turn joined together concentrically. The outer tube 2 a sits a continuous outer cylindrical surface 21st The inner annular projection 11 a is formed by a thickening of the wall of the outer tube 2 a.

The the fastening element 4 facing away from free end 19 a of the outer tube 2 a is drawn conically and is located on a conical transition section 22 of the inner tube 3 a non-deformed between a larger diameter zy-cylindrical length section 23 and a deformed diameter cylindrical longitudinal portion 10 a of the inner pipe 3 a form-fitting and sealing. The inside diameter ID1 of the undeformed cylindrical length section 23 corresponds approximately to the outside diameter AD1 of the reduced-diameter cylindrical Längenab section 10 a.

The inner end of the inner tube 3 a is provided in accordance with the embodiment of FIGS. 1 and 2 with a constriction trapezoidal in the axial direction 6 a. The constriction 6 a consequently has a conical length area 9 a at which the end closer to the fastening element 5 and a conical length area 8 a next to the end face 15 a of the inner tube 3 a. The two conical length regions 8 a and 9 a are connected to one another by a cylindrical length region 7 a. The constriction 6 a is adapted to the projection 11 a of the outer tube 3 a. The projection 11 a, like the projection 11 of the embodiment of FIGS. 1 and 2, has a cylindrical length region 12 a and regions 12 a on both sides adjoining conical Längenbe regions 13 a and 14 a.

The design of the transition from the conical length area 9 a to the cylindrical length section 23 and its adaptation to the conical length area 14 corresponds to that of the embodiment of FIG. 1, so that a further explanation is unnecessary.

. Also in the embodiment of Figure 3, the Ver amounts ratio of the wall thickness D of the outer tube 2 a and D1 of the inner tube 3 a is about 3: 2. The ratio of the length L of the projection 11 a on the outer tube 2 a to the length L4 of the diameter Larger length section 23 of the inner tube 3 a with a radial distance A1 overlapping length section 18 a of the outer tube 2 a in the exemplary embodiment is approximately 3: 4. The projection 11 a is located approximately in the middle of the outer tube 2 a. The gap SP1 formed by the radial distance AI can be at least partially filled with a lubricant.

The end face 15 a of the inner tube 3 a extends - as in the embodiment of FIG. 1 - in a transverse plane EE, which runs through the conical length region 13 a of the jump 11 a before.

In the manufacture of the inner tube 3 a, the starting diameter in the region of the cylindrical Längenab section 23 is assumed and then the adjacent conical length regions 9 a, 22 as well as the adjacent longitudinal sections 10 a, 12 a and the length range ko 8 a generated by a diameter reduction. The shaping of the conical length region 8 a to the conical length region 13 a takes place adequately to the embodiment of FIGS. 1 and 2.

In Fig. 4 an embodiment of a shock absorber fers 1 b is illustrated, in which in turn an outer tube 2 b and an inner tube 3 b are concentrically inserted into one another. The inner end of the inner tube 3 b is just in case with an axially trapezoidal constriction 6 b corresponding to the constrictions 6 and 6 a of the imple mentation forms of FIGS . 1 and 2 and 3 respectively. This constriction 6 b consequently has two conical length ranges 8 b and 9 b and a cylindrical length range 7 b connecting the conical length ranges 8 b and 9 b.

The outer tube 2 b, like the embodiment of FIGS. 1 and 2 or 3, has an inner projection 11 b which is adapted to the constriction 6 b and is formed by a constriction of the outer tube 2 b. In this respect, the projection 11 b consists of a cylindrical Längenbe range 12 b and adjacent conical length ranges 13 b and 14 b together.

The length section 24 of the inner tube 3 b between the projection 11 b on the outer tube 2 b and the free end 19 b be consists of two cylindrical length regions 26 , 27 connected by a conical transition section 25 . The undeformed length region 26 adjacent to the protrusion 11 b has an outer diameter that is larger than the outer diameter AD1 of the deformed length section 10 b of the inner tube 3 b and the other length region 27 has an outer diameter AD2 that is reduced in diameter compared to the outer diameter AD1 of the deformed length section 10 b on. In this way, the longitudinal section 18 b of the outer tube 2 b encloses the reduced-diameter section 27 with a radial distance from A2. The inner diameter ID2 of the larger-diameter length of region 26 corresponds approximately to the external diameter AD1 of the deformed length portion 10 b, whereas the outer diameter AD2 region of the reduced lengths 27 about the deformed length portion 10 b corresponds to the inner diameter ID.

The free end 19 b of the outer tube 2 b is cylindrically molded as in the embodiment from FIG. 1 and is positively and sealingly on the outer surface 20 b of the deformed length portion 10 b.

The wall thicknesses D, D1 of the outer tube 2 b and the inner tube 3 b are approximately in a ratio of 3: 2. The length L of the projection 11 b is approximately 1: 1 to the length L5 of the length range 26 with a larger diameter. The length L5 of the length range 26 with a larger diameter compared to the length L6 of the length range 27 with a reduced diameter is also approximately 1: 1. The conical length section 25 between the length ranges 26 and 27 and the conical length section 28 between the length range 27 and the length section 10 b are axially significantly shorter than the cylindrical length regions 26 and 27 . As in the embodiment of FIG. 1, the cone angle α is approximately 40 °.

The length region 26 can be overlapped by the length section 18 b of the outer tube 2 b at a radial distance. A lubricant can be filled into the gap formed thereby.

In the manufacture of the shock absorber 1 b of FIG. 4, an initial diameter is assumed, as is present in the cylindrical length range 26 . In contrast, all other length ranges are reduced in diameter cylin drically or conically.

The material of the shock absorbers 1 a, 1 b of FIGS. 3 and 4 is steel as in the embodiment of FIGS. 1 and 2.

Reference list

1

Shock absorber

1

a shock absorber

1

b shock absorber

2nd

Outer tube

2nd

a outer tube v.

1

a

2nd

b outer tube v.

1

b

3rd

Inner tube

3rd

a inner tube v.

1

a

3rd

b inner tube v.

1

b

4th

Fastener on

2nd

,

2nd

a,

2nd

b

5

Fastener on

3rd

,

3rd

a,

3rd

b

6

Constriction

3rd

6

a constriction

3rd

a

6

b constriction

3rd

b

7

cylindrical length range v.

6

7

a cylindrical length range v.

6

a

7

b cylindrical length range v.

6

b

8th

conical length range v.

6

8th

a conical length range v.

6

a

8th

b conical length range v.

6

b

9

conical length range v.

6

9

a conical length range v.

6

a

9

b conical length range v.

6

b

10th

Longitudinal section v.

3rd

10th

a length section v.

3rd

a

10th

b length section v.

3rd

b

11

Head start

2nd

11

a lead

2nd

a

11

b Head start

2nd

b

12th

cylindrical length range v.

11

12th

a cylindrical length range v.

11

a

12th

b cylindrical length range v.

11

b

13

conical length range v.

11

13

a conical length range v.

11

a

13

b conical length range v.

11

b

14

conical length range v.

11

14

a conical length range v.

11

a

14

b conical length range v.

11

b

15

Front of v.

3rd

15

a front v.

3rd

a

15

b front v.

3rd

b

16

Front of v.

2nd

17th

Longitudinal section v.

2nd

17th

b length section v.

2nd

b

18th

Longitudinal section v.

2nd

18th

a length section v.

2nd

a

18th

b length section v.

2nd

b

19th

free end of

2nd

19th

a free end v.

2nd

a

19th

b free end v.

2nd

b

20th

Surface v.

10th

20th

b surface v.

3rd

b

21

Surface v.

2nd

a

22

Transition section v.

3rd

a

23

cylindrical length section v.

3rd

a

24th

Longitudinal section v.

3rd

b

25th

conical transition section between

26

u.

27

26

cylindrical length range v.

24th

27

cylindrical length range v.

24th

28

conical length section between

27

u.

10th

b

29

inner surface v.

14

A radial distance between

10th

u.

18th

A1 radial distance between

18th

a u.

23

A2 radial distance between

18th

b u.

27

AD outer diameter of

7

AD1 outer diameter of

10th

,

10th

a,

10th

b
AD2 outer diameter of

27

D wall thickness v.

2nd

,

2nd

a,

2nd

b
D

1

Wall thickness v.

3rd

,

3rd

a,

3rd

b
EE transverse plane
ID inside diameter of

10th

,

10th

a,

10th

b
ID1 inner diameter of

23

ID2 inner diameter of

26

L length from

11

,

11

a,

11

b
L1 length from

17th

L2 length from

19th

L3 length from

18th

L4 length from

18th

a
L5 length from

26

L6 length from

27

SP gap
SP1 gap
Ü transition from

9

on

10th

α cone angle.

Claims (9)

1. Shock absorber as a securing member between a bumper and the frame of a motor vehicle, in particular a passenger car, which has two concentrically interlocking tubes with fastening elements, the inner end of the inner tube being provided with a circumferential constriction, into which an inner ring provided on the outer tube eng engages the projection and the constriction and the projection have a trapezoidal cross-section in the axial direction, the cylindrical Längenbe ranges of the constriction and the projection touch surface and the fastening element facing away from the free end of the outer tube in a positive and sealing manner to the outer surface of the inner tube is fitted, characterized in that the inner tube ( 3 , 3 a, 3 b) compared to the outer tube ( 2 , 2 a, 2 b) has a smaller wall thickness (D1), the length (L) of the trapezoidal cross-section about the outside diameter (AD1) of the B e fastening element ( 5 ) adjacent length section ( 10 , 10 a, 10 b) of the inner tube ( 3 , 3 a, 3 b) corresponds to the conical length regions ( 3 , 3 a, 3 b) facing the fastening element ( 5 ) 9 , 9 a, 9 b; 14 , 14 a, 14 b) of the constriction ( 6 , 6 a, 6 b) and the projection ( 11 , 11 a, 11 b) are in line contact by different angular arrangement, which the free end ( 19 , 19 a, 19 b ) adjacent Längenab section ( 18 , 18 a, 18 b) of the outer tube ( 2 , 2 a, 2 b), the inner tube ( 3 , 3 a, 3 b) overlaps with a radial distance (A, A1, A2) and by the radial distance (A, A1, A2) formed annular gap is at least partially filled with a lubricant. 2. Shock absorber according to claim 1, characterized in that the constriction ( 6 , 6 a, 6 b) delimiting free end face ( 15 , 15 a, 15 b) of the inner tube ( 3 , 3 a, 3 b) in a transverse plane ( EE), which extends approximately in the center of the associated conical length range ( 13 , 13 a, 13 b) of the pre jump ( 11 , 11 a, 11 b). 3. Shock absorber according to claim 1 or 2, characterized in that the projection ( 11 , 11 b) is formed by a radial constriction of the outer tube ( 2 , 2 b). 4. Shock absorber according to claim 1 or 2, characterized in that the projection ( 11 , 11 b) by widening the to the projection ( 11 , 11 b) adjoining lengths ( 17 , 17 b and 18 , 18 b) of Outer tube ( 2 , 2 b) is formed. 5. Shock absorber according to claim 1 or 2, characterized in that the projection ( 11 a) is formed by a thickening of the wall of the cylindrical outer surface ( 21 ) having the outer tube ( 2 a). 6. Shock absorber according to one of claims 1 to 3, characterized in that the free end ( 19 , 19 b) of the outer tube ( 2 , 2 b) is formed radially cylindrical and on the cylindrical outer surface ( 20 , 20 b) of the Fastening element ( 5 ) adjacent length section ( 10 , 10 b) of the inner tube ( 3 , 3 b) lies sealingly. 7. Shock absorber according to one of claims 1 to 5, characterized in that the free end ( 19 a) of the outer tube ( 2 a) is conically drawn in and on a conical transition section ( 22 ) between an undeformed zy-cylindrical longitudinal section ( 23rd ) and a smaller diameter, the fastener ( 5 ) be adjacent cylindrical length section ( 10 a) of the inner tube ( 3 a). 8. Shock absorber according to one of claims 1 to 5, characterized in that the longitudinal section ( 24 ) of the inner tube ( 3 b) between the projection ( 11 b) and the free end ( 19 b) of the outer tube ( 2 b) from two by a conical transition section ( 25 ) interconnected cylindrical length regions ( 26 , 27 ), of which the projection ( 11 b) adjacent undeformed length region ( 26 ) with respect to the outer diameter (AD1) of the fastening element ( 5 ) adjacent deformed length gene section ( 10 b) of the inner tube ( 3 b) forms larger and the other length range ( 27 ) compared to the outer diameter (AD1) of the fastening element ( 5 ) adjacent deformed length portion ( 10 b) of the inner tube ( 3 b) is reduced. 9. Shock absorber according to claim 8, characterized in that the reduced length range ( 27 ) by a conical transition section ( 28 ) with the free cylindrical end ( 19 b) of the outer tube ( 2 b) encompassed ver shaped length section ( 10 b ) of the inner tube ( 3 b) is connected.