DE10340911A1 - Adapter sleeve with temperature compensation - Google Patents

Abstract

It is proposed a clamping sleeve 19, in which by appropriate choice of material and a favorable geometric configuration of the clamping sleeve 19, the temperature dependence of a biasing force F¶V¶ between an injector 1 and a cylinder head 3 can be largely or even completely compensated.

Description

State of technology

at many temperature-leading Components that are braced together, the problem arises Uneven thermal expansions when the strained together Components made of materials with different coefficients of thermal expansion getting produced. As a result, the force is with the two against each other braced components are pressed against each other dependent from the temperature of these components. This change in contact pressure is in many cases undesirable, especially where the contact force over a wide temperature range, for example, from -40 ° C to + 140 ° C within must be certain limits.

One case in which this problem may arise relates to the tension of an injector or an injector with the cylinder head of an internal combustion engine. Typically, the cylinder heads of modern internal combustion engines are made of aluminum, while the injectors or Einspitzventile are made of steel. The temperature expansion coefficient α _Al of aluminum is about 23.8 × 10 ^-6 1 / K while the coefficient of thermal expansion of α _St of steel is about 11.5 × 10 ^-6 1 / K.

If in the context of the invention always spoken only by injectors so are also injectors, nozzle holders but also others temperature-leading Components meant. The description of the invention is given only for reasons the clarity the example of the attachment of an injector to a cylinder head, being there for the skilled person is clear that in connection with the invention described technical teaching also readily on other similar stored Use cases transferable is.

Of course, that depends Temperature expansion of temperature-carrying components not only from Thermal expansion coefficient of the component, but also of its effective length from. The longer a component is the bigger the thermal expansion and vice versa.

Out In the prior art it is known, a clamping sleeve, the at one end supports the injector and at the other end one Spannpratze is subjected to a compressive stress, for clamping to provide an injector with a cylinder head. The clamping claw is about a Stud bolt and a nut connected to the cylinder head and preloaded. The clamping sleeves used so far exist, as well as the injectors, made of steel.

Advantages of invention

at a clamping sleeve for bracing a first component made of a first material with a second component made of a second material, wherein the Thermal expansion coefficients of first material and second Material are different, with a bearing surface of the first component the second component and a location of the force introduction of the biasing force in the second component in the direction of a longitudinal axis of the first component have an offset and wherein the offset is at least partially is bridged by a clamping sleeve is provided according to the invention, that an effective coefficient of thermal expansion of the clamping sleeve is selected that the different effective temperature expansions of the first component and the second component are substantially compensated.

Thereby Is it possible, the contact pressure of the first component on the second component independent of Keep the temperature of both components constant, so that over the entire operating range constant contact conditions. This is guaranteed that on the one hand none of the components is overloaded and on the other hand always a sufficient contact force between the first component and second component is present. As a result, the tightness is between injector and cylinder head regardless of the operating temperature the internal combustion engine always guaranteed.

advantageous Embodiments of the invention provide that the clamping sleeve n pressure ears, with n greater or equal to 1, and n-1 Consists of draft tubes, and that the coefficient of thermal expansion the pressure pipes of the temperature expansion coefficient of the draw pipes is different.

If n = 1, such a clamping sleeve consists only of a pressure tube and has no drawpipe. In other words: The clamping sleeve is made a cylindrical pipe piece. In this case, the effective coefficient of thermal expansion corresponds the coefficient of thermal expansion of the material from which the clamping sleeve is made.

If now, for example, the offset between the supporting surface of the first component to the second component, and the location is offset of the first component to a _total length of force application of the biasing force of l in the second component in the direction of the longitudinal axis and at the same time the length of the clamping sleeve l _H smaller than the length l is _total , then by selecting a suitable material of the clamping sleeve a complete temperature compensation can be achieved. In the case already mentioned above, that a steel injector with an aluminum cylinder head is to be braced, this means that the coefficient of thermal expansion of the clamping sleeve must be greater than the thermal expansion coefficient of the cylinder head in order to achieve complete compensation of the temperature expansions. Full temperature compensation is given if the following condition is met: l total × α al = l injector × α St + l H × α H ,

With:
l _total : offset between the bearing surface of the first component on the second component and the location of initiation of the biasing force in the second component in the direction of a longitudinal axis of the first component.
α _Al : coefficient of thermal expansion of the material (here: aluminum) of the second component, namely the cylinder head.
l _injector : length of the section of the second component (here: injector), the temperature expansion of which contributes to the change in the preload force.
α _St : coefficient of thermal expansion of the first component.
l _H : length of the clamping sleeve and
α _H : coefficient of thermal expansion of the clamping sleeve.

Out The above equation implies that it is suitably dimensioned the first component, the second component and the clamping sleeve and a coordinated choice of materials of these components is possible, the temperature expansion-related changes in the preload force between the injector and a cylinder head of an internal combustion engine compensate. It is also possible, The changes not fully compensate or, if desired, even overcompensate.

The actual Design of a tension between an injector and a cylinder head can depending on the application on the basis of the above Equation by a skilled person readily done.

If the clamping sleeve from more than one pressure pipe and a corresponding number of draw pipes exists, there are further degrees of freedom in the interpretation of Tension between injector and cylinder head.

A full Compensation of the temperature expansions is achieved when the sum of the temperature expansions in the pressure pipes and on Pressure loaded portion of the first component and possibly existing other pressure-loaded components equal to the Sum of the thermal expansions of the stretched section of the second component.

A only partial compensation of the thermal expansion, for example then reached when the only pressure tube of the clamping sleeve from the same material as the second component is produced.

The Clamping sleeve according to the invention can Particularly advantageous when clamping an injector, a Einspitzdüse or a nozzle holder, which is referred to in the context of the invention as the first component is, and a cylinder head of an internal combustion engine, which in Used in connection with the invention as a second component is used become.

Further Advantages and advantageous embodiments of the invention are the subsequent drawing, the description and the claims can be removed. All the features mentioned there can both individually and in any combination with each other invention essential be.

drawing

It demonstrate:

1 a first embodiment of a clamping sleeve according to the invention and

2 A second embodiment of a clamping sleeve according to the invention

3 : A schematic representation of an internal combustion engine with injectors according to the invention.

description the embodiments

In 1 is a known per se from the prior art installation situation of an injector 1 in a cylinder head 3 an internal combustion engine shown in section.

How out 1 As can be seen, the injector 1 in a stepped bore 5 of the cylinder head 3 introduced that a bit 7 of the injector 1 with not shown spray holes in a combustion chamber 9 of the cylinder head 3 protrudes.

On a paragraph 11 the stepped bore 5 there is a gasket 13 , which may be made of brass, for example. The injector 1 in turn relies on a paragraph 15 on the gasket 13 from.

So that a gas-tight connection between the paragraph 11 of the cylinder head 3 , the sealing disc 13 and the paragraph 15 of the injector 1 arises, it is necessary to use the injector 1 with the cylinder head 3 to tense. This is done, as already known from the prior art, by a clamping claw 17 and a clamping sleeve 19 ,

The clamping claw 17 indicates to her the injector 1 facing end of a bifurcated configuration with two prongs, of which only one prong 21 in 1 is visible.

At her the tines 21 opposite end is the clamping claw 17 on a top edge 23 of the cylinder head 3 on. Approximately in the middle of the clamping claw 17 this has a through hole 25 on, through the one with the cylinder head 3 bolted studs 27 protrudes. By putting on a nut 29 on the studs 27 screwed on, can the necessary contact force between the clamping claw 17 and the clamping sleeve 19 being constructed.

At her the chuck 17 turned away end, the clamping sleeve is supported 19 indirectly to the injector 1 and transfers so from the clamping claw 17 in the clamping sleeve 19 initiated contact pressure on the injector 1 , For a space-saving and at the same time simple power transmission of the biasing force of the clamping sleeve 19 on the injector 1 to ensure is in the injector 1 a circumferential groove 31 formed into a wire ring 33 is inserted. The depth of the circumferential groove 31 is like that with the diameter of the wire ring 33 tuned that part of the wire ring 33 in the radial direction over the injector 1 protrudes and so supporting the clamping sleeve 19 on the wire ring 33 allows.

Due to the design of the clamping sleeve 19 at her the wire ring 33 facing end in the form of a quarter radius (see 2 ) ensures that the wire ring 33 not from the circumferential groove 31 can jump. Of course, the invention is not on this type of introduction of the clamping force in the clamping sleeve by a claw 17 and the transmission of this clamping force by means of a circumferential groove 31 and a wire ring 33 in the injector 1 limited.

Usually injector 1 and cylinder head 3 during engine mounting at room temperature by tightening the nut 29 braced together. In this case, such a clamping force is constructed that between the sealing disc 13 and the paragraphs 11 the cylinder head and the paragraph 15 of the injector 1 despite the in the combustion chamber 9 prevailing high pressures a gas-tight seal between the injector 1 and cylinder head 3 will be produced.

Of course, this sealing compound at all operating temperatures occurring in practice, ie, be from about -40 ° C to + 140 ° C, gas-tight. This promotion is achieved by an inventive design of the clamping sleeve 19 fulfilled without further notice, namely, if the different temperature expansions of the cylinder head 3 , the injector 1 and the clamping sleeve 19 , as well as the sealing ring 13 be suitably matched to each other.

Basically measured The temperature expansion of a component according to the formula .DELTA.l = .DELTA.T × α × l.

With:
Δl: Temperature-related change in length of the component.
ΔT: temperature change of the component.
α: coefficient of thermal expansion of the component (substance size).
l: Effective length of the component.

Assuming that both the injector 1 , the cylinder head 3 , the clamping sleeve 19 and the sealing washer 13 always have the same temperatures, is thus a complete compensation of the temperature-induced change in the clamping force F _V given if the following equation is satisfied: α Zylindrkopf × l total = α H × l H + α injector × l injector + l DS × α DS

With:
l _total: Axial offset between the paragraph 11 the blind hole 5 and the top edge 13 of the cylinder head 3 ,
α _{Cylinder head} : coefficient of _{thermal expansion of} the cylinder head 3 ,
l _H : length of the clamping sleeve 19 ,
α _{Adapter sleeve} : effective thermal expansion coefficient of the adapter sleeve 19 ,
l _Injector : Effective injector length 1 ,
α _injector : coefficient of thermal expansion of the injector 1 ,
l _DS : Thickness of the gasket 13 and
α _DS : coefficient of thermal expansion of the sealing disc 13 ,

Generally speaking, the sum of the thermal expansions of the components subjected to tension (here: cylinder head 3 ) and the sum of the temperature expansions of the components subjected to pressure (here: clamping sleeve 19 , Injector 1 in the area between the circumferential groove 31 and the paragraph 15 as well as sealing washer 13 ) be equal. If this condition is met, then the biasing force F _{V is} between the injector 1 , the sealing disc 13 and the paragraph 11 of the cylinder head 3 regardless of the component temperature. It follows from the above-described equation that, depending on the used materials for the cylinder head 3 , the injector 5 , the clamping sleeve 19 , the sealing washer 13 as well as the lengths l _total , l _H , l _injector , l _DS the fulfillment of this equation is possible. It is readily possible for a person skilled in the art of engine construction from the above, a temperature-compensated tension between the injector according to the invention 1 and cylinder head 3 produce, if it the given for a specific application constraints, in particular dimensions of the components and the available materials are known.

If desired, the biasing force F _V can be dependent on the temperature of the injector 1 , the cylinder head 3 , the clamping sleeve 19 and the sealing washer 13 be more or less overcompensated, if this is desired in a specific application. This overcompensation or undercompensation is also borne by the claimed inventive idea.

Below is an embodiment of a clamping sleeve according to the invention 19 described, consisting of two pressure pipes 37 and 39 and an intermediate draft tube 41 consists.

The pressure pipes 37 and 39 as well as the draft tube 41 are arranged so that the upper end of the clamping claw, not shown 17 in the pressure tube 37 introduced preload force F _V in 2 on the left half of the picture by an arrow 43 indicated meander-shaped power flow has until the biasing force F _V finally on the wire ring, not shown 33 in the injector 1 is initiated (see also 1 ).

Using the arrow 43 also becomes clear that the pressure pipes 37 and 39 be subjected to pressure while the draft tube 41 is claimed on train. So that the draft tube 41 a clamping force F _V from the pressure tube 37 on the pressure tube 39 can transmit, has the drawbar 41 at his in 2 lower end a first radially outwardly directed paragraph 45 on. The power transmission of the biasing force F _V from the draft tube 41 on the second pressure tube 39 takes place at the upper end of the draw tube 41 by a radially inwardly directed second paragraph 47 ,

If now, as provided according to the invention, the pressure pipes 37 and 39 made of a material with a different coefficient of thermal expansion α than the draft tube 41 is produced, with the same length l _{H, total of} the clamping sleeve 19 Compensate for the ability to compensate for temperature-induced changes in biasing force F _V. Namely, when the clamping sleeve according to the invention 19 according to 2 instead of in 1 drawn clamping sleeve 19 is installed and the temperature expansion coefficient of the pressure pipes 37 and 39 greater than the coefficient of thermal expansion of the draft tube 41 , then results, based on the length l _{H of} the clamping sleeve 19 an effective thermal expansion coefficient α _effective , which can be calculated according to the following equation. l H × α effective = l 37 × α Pressure pipe 37 + l 39 × α Pressure tube 39 - l 41 × α Drawbar 41 ,

With
l _H length of the clamping sleeve 19 ,
α _effective effective coefficient of thermal expansion
l ₃₇ Length of the first pressure tube 37
α _{Pressure tube 37} Temperature expansion coefficient of the pressure tube 37
l ₃₉ : Length of the second pressure tube 39
α _{pressure tube 39} : coefficient of thermal expansion of the second pressure tube 39
l ₄₁ : Length of the draft tube 41
α _{draft tube 41} : coefficient of thermal expansion of the draft tube.

By looking at the above formula, it is clear that the effective or effective temperature coefficient of expansion α greater is _effective, the larger the difference between the coefficient of thermal expansion _{α-pressure pipe 37} and _{α-pressure pipe 39} on the one hand and the coefficient of thermal expansion α _{draft tube 41} on the other hand. Of course, the temperature compensation can also be influenced by changing the lengths l ₃₉ , l ₃₇ and l ₄₁ .

• 1. Längenänderung f_Z in Folge einer Temperaturänderung ΔT von 100 K des Zylinderkopfs 3, des Injektors 1, der Spannhülse 19 aus Stahl und der Dichtscheibe (DS) 13 bei einer Ausführung nach 1: fZ = ΔlZyl.Kopf – (ΔlInj,St + ΔlSpannhülse + ΔlDS) fZ = 0,238 mm – 0,045 mm – 0,0712 mm = 0,1216 mm
• 2. Wie Beispiel 1, aber mit einer Spannhülse 19 aus Aluminium: fZ = ΔlZyl.Kopf – (ΔlH,Al + ΔlInj,St + ΔhDS) fZ = 0,238 mm – 0,1428 mm – 0,0437 mm – 0,0479 mm = 0,048 mmDas heißt durch die Verwendung einer Spannhülse aus Aluminium ergibt sich eine Reduzierung des Setzbetrags f_Z um ca. 60%.
• 3. Längenänderung f_Z in Folge einer Temperaturänderung ΔT von 100 K bei einer Ausführung nach 2 mit zwei Druckrohren 37 und 39 und einem Zugrohr 41: l_H,37 = 57 mm l_H,39 = 53,5 mm l_H,41= 51,5 mm fZ = ΔlZyl.Kopf – (ΔlH,gesamt + ΔlInj,St + ΔhDS) ΔlH,gesamt = [(lH,37 + lH,39)·αAl – lH,41·αSt]·ΔT = 0,2038 mm fZ = 0,238 mm – (0,2038 mm + 0,047 mm) = –0,0132 mm

Hereinafter, three simplified calculation examples (without screws, without clamping claw) based on the embodiments according to 1 and 2 shown:
l _total = 100 mm
l _H = 60 mm
l _injector 38 mm
h _DS = 2 mm (material: brass)
α _CuZn = 18.5 × 10 ^-6 1 / K
α _Al = 23.8 × 10 ^-6 1 / K
α _St = 11.5 × 10 ^-6 1 / K
ΔT = 100 K (temperature change)

• 1. Length change f _Z as a result of a temperature change ΔT of 100 K of the cylinder head 3 , the injector 1 , the clamping sleeve 19 made of steel and the sealing disc (DS) 13 in one execution 1 : f Z = Δl Zyl.Kopf - (Δl Inj, St + Δl clamping sleeve + Δl DS ) f Z = 0.238 mm - 0.045 mm - 0.0712 mm = 0.1216 mm
• 2. As Example 1, but with a clamping sleeve 19 made of aluminium: f Z = Δl Zyl.Kopf - (Δl H, Al + Δl Inj, St + Δh DS ) f Z = 0.238 mm - 0.1428 mm - 0.0437 mm - 0.0479 mm = 0.048 mm This means that the use of a clamping sleeve made of aluminum results in a reduction of the setting amount f _Z by approximately 60%.
• 3. Length change f _Z as a result of a temperature change ΔT of 100 K in one embodiment after 2 with two pressure pipes 37 and 39 and a draft tube 41 : l _{H, 37} = 57 mm _{H, 39} = 53.5 mm _{H, 41} = 51.5 mm f Z = Δl Zyl.Kopf - (Δl H, total + Δl Inj, St + Δh DS ) .DELTA.l H, total = [(l H, 37 + l H, 39 ) · Α al - l H, 41 · α St ] · ΔT = 0.2038 mm f Z = 0.238 mm - (0.2038 mm + 0.047 mm) = -0.0132 mm

D. H. in this embodiment increases the contact pressure even slightly with increasing temperature.

By An adaptation of the geometry or material selection can influence the temperature on the contact pressure and the drop in contact pressure Flow processes in the Dividing joints are compensated to 100.

Based on 3 is explained below as an injector 1 in a fuel injection system 102 an internal combustion engine is integrated. The fuel injection system 102 includes a fuel tank 104 , from the fuel 106 by an electric or mechanical fuel pump 108 is encouraged. Via a low-pressure fuel line 110 becomes the fuel 106 to a high pressure fuel pump 111 promoted. From the high pressure fuel pump 111 the fuel gets 106 via a high pressure fuel line 112 to a common rail 114 , At the common rail are several injectors 1 connected the fuel 106 directly in combustion chambers 118 inject an internal combustion engine, not shown.

Claims (7)

Clamping sleeve for clamping a first component ( 1 ) of a first material (St) with a second component ( 3 ) of a second material (Al), wherein the coefficients of thermal expansion (α) of first material (St) and second material (Al) are different, wherein a bearing surface ( 15 ) of the first component ( 1 ) on the second component ( 3 ) and a place ( 23 ) the force introduction of the biasing force in the second component ( 3 ) in the direction of a longitudinal axis of the first component ( 1 ) have an offset (l _total ), and wherein the offset (l _total ) at least partially by a clamping sleeve ( 19 ) is bridged, characterized in that an effective thermal expansion coefficient (α _effective ) of the clamping sleeve ( 19 ) is selected so that the different thermal expansions of the first component ( 1 ) and second component ( 3 ) are substantially compensated. Clamping sleeve according to claim 1, characterized in that the clamping sleeve ( 19 ) from n pressure pipes ( 37 . 39 ), with n greater than or equal to 1, and n-1 draft tubes ( 41 ), and that the temperature expansion coefficient (α _Al ) of the pressure pipes ( 37 . 39 ) of the coefficient of thermal expansion (α _St ) of the draw pipe (s) ( 41 ) is different. Clamping sleeve according to claim 1 or 2, characterized in that the sum of the thermal expansions of the n pressure pipes ( 37 . 39 ) and the pressure-loaded portion of the first component ( 1 ) as well as any other components subjected to pressure ( 13 ) is substantially equal to the sum of the thermal expansions of a section claimed as a train (l _total ) of the second component ( 3 ). Clamping sleeve according to claim 3, characterized in that the effective temperature coefficient (α _effective ) of the clamping sleeve ( 19 ) from the lengths (l ₃₇ l ₃₉ ) of the pressure pipes ( 37 . 39 ) and the effective lengths of the drawbar (s) ( 41 ) and their thermal expansion coefficient is determined. Clamping sleeve according to claim 1, characterized in that the pressure tube ( 37 . 39 ) of the clamping sleeve ( 19 ) made of the same material as the second component ( 3 ) getting produced. Clamping sleeve according to one of the preceding claims, characterized in that the first component is an injector ( 1 ), an injection nozzle or a nozzle holder of an internal combustion engine. Clamping sleeve according to one of the preceding claims, characterized in that the second component is a cylinder head ( 3 ) is an internal combustion engine.