EP1972779B1 - Hydraulic coupler - Google Patents

Description

State of the art

The present invention relates to a hydraulic coupler, and more particularly to a hydraulic coupler for an injector for injecting a fuel.

Hydraulic couplers for injectors are known from the prior art in various configurations. Such hydraulic couplers have u.a. the task to compensate occurring during operation of the injector length changes of components. The known couplers use at least two corrugated bellows for sealing a coupler volume. However, this construction makes the coupler volume very large. This leads to large axial strokes of a piston of the coupler occurring during temperature changes. However, this results in the operation of the injector large drag losses, i. Oil losses due to axial movement. Furthermore, the known couplers consist of a plurality of individual parts, and in particular the corrugated bellows, which ensure the mobility of the coupler, lead to very high production costs. It would therefore be desirable to have a coupler, which can be produced in addition to a simple structure in particular also cost.

From the WO 2005/054662 A1 A hydraulic coupler is already known which comprises a first coupler part and a second coupler part and a coupler space arranged between the first coupler part and the second coupler part and which is filled with a coupler medium. Furthermore, the hydraulic coupler has a sealing element, which seals in a certain way the coupler space. The sealing element is designed as a membrane-like flexible portion which is resilient and is deformed in the operating condition. A biasing force can be exerted on the sealing element with a spring to produce a predetermined pressure on the coupling medium in the compensation space. The sealing element is arranged as a cup-shaped membrane such that it covers the two coupler parts on the side opposite the coupler space.

Further hydraulic couplers for injectors are off EP 1 391 608 A known.

Advantages of the invention

The hydraulic coupler according to the invention with the features of claim 1, in contrast, has the advantage that it does not require Wellbälge. Thus, the hydraulic coupler according to the invention can be provided very inexpensively. Furthermore, the coupler according to the invention has a simple and compact construction, which guarantees a long service life. The hydraulic coupler according to the present invention has only a very small coupler volume, which results in virtually no losses of the coupler medium during operation. The hydraulic coupler according to the present invention comprises a first coupler part and a second coupler part, and a coupler space disposed between the first and second coupler parts, which is filled with the coupler medium.

Further, a sealing element for sealing the coupler space and a biasing means is provided, which exerts a biasing force on the sealing element, thereby to generate a predetermined pressure of the coupling medium in the coupler space. Thus, in addition to the sealing function, the sealing element of the coupler according to the invention additionally has the function of generating the coupler pressure in the coupler medium. Thus, the coupler according to the invention can have only a minimal number of individual parts and it is also possible to choose an enlarged piston diameter for the first and second coupler part. This leads to a significant improvement in the function of the hydraulic coupler.

The sealing element is arranged in an annular gap between the first coupler part and the second coupler part and seals there.

The dependent claims show preferred developments of the invention.

According to a preferred embodiment of the present invention, the sealing element is annular. This allows a particularly simple and inexpensive sealing element can be used.

More preferably, the biasing means, which exerts the biasing force on the sealing element, a spring, in particular a cylindrical spring.

In order to ensure a uniform distribution of the biasing force on the sealing element, the hydraulic coupler preferably further comprises a pressure plate, which is on the one hand with the sealing element and on the other hand with the biasing means in contact. The thrust washer further ensures that the biasing means does not damage the sealing element.

The pressure disk preferably has an inner guide region on a radial inner side and an outer guide region on a radial outer side. In this case, the inner guide region is in contact with the first coupler part and the outer guide region is in contact with the second coupler part. As a result, the thrust washer can additionally assume a guiding function and a bearing function between the first coupler part and the second coupler part. Thus, if the first coupler part is guided on the second coupler part and additionally the pressure disk is provided with an inner and an outer guide region, it is particularly preferable for the first coupler part to be guided at two spaced-apart locations, so that in particular tilting of the first coupler part relative to second Kopplerteil can be avoided.

According to a further preferred embodiment of the invention, the hydraulic coupler comprises a spring plate, which is fixed to the first coupler part and supports one end of the biasing device. The spring plate is preferably connected to the first coupler part by a press fit or a weld or an adhesive bond or a solder joint. Depending on a position of the spring plate on the first coupler part can be adjusted in particular a bias of the biasing device and thus, depending on the application requirements in a simple manner, the biasing force can be changed to the coupler fluid.

Preferably, the sealing element comprises an annular lip seal with an inner sealing lip and an outer sealing lip. In this case, an annular recess is arranged between the inner sealing lip and the outer sealing lip. This recess is filled with coupler fluid, so that the pressure of the coupler fluid in particular acts in the radial direction of the inner and outer sealing lips.

According to a further embodiment, the pressure disk has an inner groove-shaped recess and an outer groove-shaped recess. Furthermore, the sealing element comprises a first sealing ring and a second sealing ring, wherein the first sealing ring is arranged in the inner groove-shaped recess and the second sealing ring in the outer groove-shaped recess. In this embodiment, simple sealing rings for the sealing element can be used, which can be mounted in a particularly simple and secure manner in the pressure disk. This embodiment is not part of the claimed subject matter.

The first piston part is designed as a stepped piston, wherein the stepped piston has a central first bore, a central second bore with a smaller diameter than the central first bore, a radial third bore, a lateral fourth bore parallel to the first bore and a throttle bore. The throttle bore is located at the end of the fourth bore. This configuration makes it possible that the first piston part can be made very simple and inexpensive only by drilling.

According to a further preferred embodiment of the present invention, the hydraulic coupler further comprises a cover which partially seals at least the biasing means. This ensures a long life of the hydraulic coupler.

drawing

Figur 1

eine schematische Schnittansicht eines hydraulischen Kopplers gemäß einem ersten Ausführungsbeispiel der vorliegenden Erfindung,

Figur 2

eine schematische, vergrößerte Teilschnittansicht eines hydraulischen Kopplers gemäß einem zweiten Ausführungsbeispiel, das nicht beansprucht wird, und

Figur 3

eine schematische, vergrößerte Teilschnittansicht eines hydraulischen Kopplers gemäß einem weiteren Ausführungsbeispiel der vorliegenden Erfindung.

Hereinafter, preferred embodiments of the invention will be described in detail with reference to the accompanying drawings. In the drawing is:

FIG. 1

FIG. 2 is a schematic sectional view of a hydraulic coupler according to a first embodiment of the present invention; FIG.

FIG. 2

a schematic, enlarged partial sectional view of a hydraulic coupler according to a second embodiment, which is not claimed, and

FIG. 3

a schematic, enlarged partial sectional view of a hydraulic coupler according to another embodiment of the present invention.

Preferred embodiments of the invention

The following is with reference to FIG. 1 a hydraulic coupler 1 according to a first preferred embodiment of the invention described in detail.

How out FIG. 1 1, the hydraulic coupler 1 comprises a first coupler part 2 and a second coupler part 3. The first coupler part 2 comprises a piston region 20 and an elongated shaft region 21 formed integrally thereon. The first coupler part 2 is thus designed as a stepped piston. The second coupler part 3 comprises a cylinder region 30 and a connecting region 31 formed integrally thereon. The connecting region 31 serves for connection to a further component. Thus, the second coupler part 3, as in FIG FIG. 1 shown, the first coupler part 2 in the cylinder portion 30 in itself. Between the first coupler part 2 and the second coupler part 3, a cylindrical coupler space 4 is formed. The coupler space 4 is filled with a coupler medium, such as oil.

How farther FIG. 1 it can be seen, a plurality of holes are provided in the first coupler part 2. More specifically, the first coupler part 2 comprises a first central bore 22 having a first diameter D1 along a central axis XX, a second central bore 23 having a second diameter D2, the second diameter D2 being smaller than the first diameter D1. Further, the first coupler part 2 comprises a third radial bore 24, which is formed perpendicular to the second bore 23, a fourth bore 25, which in turn is formed perpendicular to the third bore 24 and parallel to the first and second bore is located, and a throttle bore 26, which opens at an end face 2a of the first coupler part 2. Thus, the plurality of holes in the first coupler part 2 are connected to the coupler space 4 and together with the coupler space 4 form the coupler volume of the hydraulic coupler.

For sealing between the first coupler part 2 and the second coupler part 3, as in FIG. 1 seen, a sealing element 5 is provided. The sealing element 5 is a sealing ring which seals with a radial inner side on the shaft region 21 of the first coupler part and with a radial outer side on the inner side of the cylinder region 30 of the second coupler part 3. Like this FIG. 1 it can be seen, while an annular space is formed between the sealing element 5 and the step-shaped first coupler part 2, which is also filled with coupler medium and thus also counts to the total coupler volume. At the side remote from the coupler medium side of the sealing element 5, a pressure plate 7 is arranged, which is in contact with a biasing device 6 in the form of a cylindrical coil spring. The cylindrical helical spring orbits the shaft region 21 of the first coupler part 2 and is supported on a spring plate 8, which is firmly fixed to the shaft region 21 of the first coupler part 2. As a result, the pretensioning device 6 exerts a pressure force on the pressure plate 7 and the sealing element 5 on the coupling medium. Depending on a positioning of the spring plate 8, the biasing force can be adjusted to the coupler medium during assembly of the hydraulic coupler.

Next, a closure ball 10 is provided, which seals the coupler volume in the second bore 23. The seal by means of the closure ball 10 takes place after a filling of the coupler volume with the coupler medium. The closure ball 10 can in this case for example be pressed into the second bore 23. To protect the biasing device 6, a cover 9 is further provided, which is attached at one end to the second coupler part 3 and with its other end on the spring plate 8.

The inventive hydraulic coupler 1 according to the first embodiment thus has a simple coupler construction with only a small number of individual parts. In comparison with the known hydraulic couplers, which include so-called "bellows", the inventive hydraulic coupler 1 can be provided very inexpensively. Furthermore, the hydraulic coupler 1 has only a minimal volume for the coupler medium. As a result, in particular an axial stroke of the sealing element 5 due to a thermal expansion of the coupling medium can be reduced to a minimum. This results in operation due to the small Axialhübe significantly less drag losses of coupler medium on the sealing medium 5. Thus, the coupler according to the invention operates virtually leak-free.

How out FIG. 1 can be seen, the pressure plates 7 further ensures that tilting between the first coupler part 2 and the second coupler part 3 is significantly minimized during operation. The pressure disk 7 has an inner guide region 7a and an outer guide region 7b. The inner guide portion 7a is in contact with the shaft portion 21, and the outer guide portion 7b is in contact with the cylinder portion 30 of the second coupler portion. As a result, the first coupler part 2 is guided twice in the second coupler part 3, namely on the one hand in the area of the piston area 20 and of the cylinder area 30 and in the area of the pressure disk 7.

The cover 9 is preferably an elastomer and prevents a possible escape of coupler medium, which could pass into the region of the biasing device 6 due to the operation of the sealing element 5 over. It should be noted that the cover 9 may be omitted, in particular, if an actuator can not be damaged by coupler oil or leakage through the sealing element 5 are negligible. The cover 9 also serves as protection against dirt and damage.

It should be noted that the sealing element 5 is further preferably designed such that the sealing element 5 compensates for the lifting movement predominantly by a material deformation. For this purpose, the sealing element 5 must be as soft as possible and have the highest possible coefficient of friction for the first coupler part 2 and the second coupler part 3. Furthermore, it is preferred that the sealing element 5 has the largest possible cord thickness.

As actuators, with which one of the two coupler parts 2, 3 is connected, in principle, in particular magnetic actuators or piezo actuators in question. The inventive hydraulic coupler 1 is particularly preferably used in injectors for the injection of fuels in vehicle engines.

Hereinafter, a hydraulic coupler 1 according to a second embodiment will be described in detail with reference to FIG FIG. 2 described. Identical or functionally identical parts are again denoted by the same reference numerals as in the first embodiment.

FIG. 2 shows only an enlarged section of the hydraulic coupler 1, which illustrates the difference to the hydraulic coupler of the first embodiment. How out FIG. 2 it can be seen, the thrust washer 7 and the sealing element are formed differently in the hydraulic coupler 1 of the second embodiment. The hydraulic coupler of the second embodiment comprises a sealing element as a first sealing ring 11 and a second sealing ring 12. The two sealing rings 11, 12 are constructed substantially the same, but have different diameters. In the pressure disk 7, an outer groove-shaped recess 71 is formed on a radial outer side, which receives the first sealing ring 11 and on an inner radial side an inner groove-shaped recess 72 is formed, which receives the second sealing ring 12. Thus, in the second embodiment, instead of a single sealing element, two separate sealing elements, namely the first sealing ring 11 and the second sealing ring 12, are provided. In each case, a sealing ring only has to seal on one side. The hydraulic coupler of the second embodiment has the advantage that the sealing element is integrated into the thrust washer 7. In this case, an even more compact design and in particular a simple assembly can be ensured. Otherwise, this embodiment corresponds to the first embodiment, so that reference may be made to the description given there.

This second embodiment does not belong to the claimed subject matter.

The following is with reference to FIG. 3 a hydraulic coupler 1 according to a third embodiment of the invention described in detail. Identical or functionally identical parts are again denoted by the same reference numerals as in the first embodiment.

The third embodiment substantially corresponds to the first embodiment, wherein, in contrast to the first embodiment, a sealing element 15 is provided, which is not designed as a sealing ring with a substantially circular cross-section, but as a lip seal. In this case, the lip sealing ring comprises a first lip 15a, which is in contact with an inner side of the cylindrical region 30 of the second coupler part 3, and a second sealing lip 15b, which is in communication with an outer side of the shaft region 21 of the first coupler part 2. Between the first sealing lip 15a and the second sealing lip 15b, a recess 15c is formed, which is also filled with Kopplermedium. The use of the lip seal has the particular advantage that on the one hand enables a better seal, so that the leakage through the sealing element 15 are very low, and on the other hand, a smaller volume for the coupler medium is possible. Otherwise, this embodiment corresponds to the previous embodiments, so that reference can be made to the description given there.

Claims (10)

1. Hydraulic coupler, comprising a first coupler part (2), a second coupler part (3) and a coupler space (4) which is arranged between the first coupler part (2) and the second coupler part (3) and is filled with a coupler medium, a sealing element (5; 11, 12; 15) which seals the coupler space (4), and a prestressing device (6) which exerts a prestressing force on the sealing element (5; 11, 12; 15), in order to generate a predefined pressure on the coupler medium in the coupler space (4), characterized in that the first coupler part (2) comprises a piston region (20) and a skirt region (21) of smaller diameter, with the result that there is a step piston, and the piston region (20) is guided on an inner wall of a cylinder region (30) of the second coupler part (3) and the sealing element (5; 11, 12; 15) is introduced between the first and the second coupler parts (2, 3) in such a way that it seals with a radial inner side on the skirt region (21) of the first coupler part (2) and with a radial outer side on the inner wall of the cylinder region (30) of the second coupler part (3).
2. Hydraulic coupler according to Claim 1, characterized in that the sealing element (5; 11, 12; 15) is of annular configuration.
3. Hydraulic coupler according to one of the preceding claims, characterized in that the prestressing device (6) is a spring, in particular a cylindrical spring.
4. Hydraulic coupler according to one of the preceding claims, comprising, furthermore, a pressure disc (7) which is in contact on one side with the sealing element (5; 11, 12; 15) and on the other side with the prestressing device (6).
5. Hydraulic coupler according to Claim 4, characterized in that the pressure disc (7) has an inner guide region (7a) on a radial inner side and an outer guide region (7b) on a radial outer side, the inner guide region (7a) guiding the first coupler part (2) and the outer guide region (7b) guiding the second coupler part (3).
6. Hydraulic coupler according to one of the preceding claims, comprising, furthermore, a spring collar (8) which is fixed on the first coupler part (2) and supports one end of the prestressing device (6).
7. Hydraulic coupler according to one of the preceding claims, characterized in that the sealing element (5; 11, 12) is an O-ring with a substantially circular cross section.
8. Hydraulic coupler according to one of Claims 1 to 6, characterized in that the sealing element is an annular lip seal (15) having a first sealing lip (15a) and a second sealing lip (15b), an annularly circumferential recess (15c) being formed between the first sealing lip (15a) and the second sealing lip (15b).
9. Hydraulic coupler according to one of the preceding claims, characterized in that the first coupler part (2) is configured as a step piston with the piston region (20) and the skirt region (21), the first coupler part (2) having a first central hole (22), a second central hole (23) with a smaller diameter (D2) than a diameter (D1) of the first central hole (22), a radial third hole (24), a fourth hole (25) which is parallel to the first hole (22), and a restrictor hole (26) which is arranged at the end of the fourth hole (25).
10. Hydraulic coupler according to one of the preceding claims, comprising, furthermore, a cover (9) which covers the prestressing device (6) at least partially.

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