DE102015220164A1 - Arrangement for actuating a central valve - Google Patents

Abstract

The invention relates to an arrangement for actuating a central valve (2) by means of an electromagnet (6), with a pressure pin (4) axially movable by the electromagnet (6) along a first axis of movement (A), which at its free end has a front surface (13 , 13a), with a control piston (1) of the central valve (2) which is arranged axially displaceably in a central valve housing (8) along a second movement axis (B), wherein the control piston (1) pointing at its pressure pin (4) free end has a contact surface (12, 12a), and in which the front surface (13, 13a) of the pressure pin (4) and the contact surface (12, 12a) of the control piston (1) are in contact. In this arrangement, according to the invention, it is provided that the diameter ratio (d1 / d2) of the front surface (13, 13a) of the pressure pin (4) to the contact surface (12, 12a) of the control piston (1) or the diameter ratio (d2 / d1) of Contact surface (12, 12a) of the control piston 1 to the front surface (13, 13a) of the pressure pin (4) has a value between 1.0 and 2.0, and that the first axis of movement (A) in parallel and at a radial distance (x) is offset to the second movement axis (B), wherein the offset of the two axes of movement (A, B) from 0.35 to 0.45 times the respective larger diameter (d1, d2) of the contact surface (12, 12a) or the front surface (13, 13a) corresponds.

Description

The invention relates to an arrangement for actuating a central valve by means of an electromagnet, with a by the electromagnet along a first axis of movement axially movable pressure pin having a front surface at its free end, with a control piston of the central valve, which in a central valve housing along a second axis of movement axially slidably disposed, wherein the control piston has a contact surface at its free end facing the pressure pin, and wherein the front surface of the pressure pin and the contact surface of the control piston are in contact.

In internal combustion engines, camshafts are used to actuate the local gas exchange valves. The cams of the camshafts are usually on cam followers. If a camshaft is rotated, the cams roll on the cam followers, which in turn actuate the gas exchange valves. An angular displacement of the camshaft with respect to the rotational angle of the crankshaft of the internal combustion engine to achieve optimized timing for different speed and load conditions is referred to as camshaft adjustment. A constructive variant of a camshaft adjusting device operates, for example, according to the known swing motor principle. The camshaft adjusting device is firmly mounted on the camshaft. A central valve controls the supply of control pressure oil to the camshaft adjuster, which can be supplied from the oil circuit of the internal combustion engine. The access openings or the outlet openings of the central valve are formed in a central valve housing. In the interior of the central valve housing a control piston is arranged axially displaceable. The control piston is coupled via a pressure pin with an electromagnet, wherein the electromagnet is adapted to move the control piston by means of the pressure pin axially in the central valve housing. This is for example from the DE 10 2010 050 813 A1 and not pre-published DE 10 2013 209 862 A1 known.

In known central valve applications, attempts are made to obstruct the pressure pin and the control piston without radial axial offset, so that their contact surfaces are arranged centrally relative to one another. This requires a high accuracy during assembly. Furthermore, no or only a slight relative movement of control piston and pressure pin to each other by this centric or within the permissible positional deviation little eccentric alignment of pressure pin and control piston. During the relative movement occurring during operation, the control piston rotates and the pressure pin is radially stationary. A small or missing sliding speed of the two sliding partners to each other prevents or hinders the construction of a stable hydrodynamic lubricating film between them and thus favors the wear of the associated sliding surfaces due to lack of lubrication and increased friction. Thus, it comes to a dry friction, in practice, in particular, the surface roughness of the control piston leads to wear of the pressure pin.

Against this background, the invention has the object, an arrangement for actuating a central valve by means of an electromagnet form such that the usual requirements for the accuracy of the alignment of the pressure pin and control piston reduces each other, a stable hydrodynamic lubricant film between the contact surfaces of pressure pin and control piston produced and wear of a contact surface of the sliding partner control piston and pressure pin is at least greatly reduced.

This object is achieved by an arrangement for actuating a central valve by means of an electromagnet with the features of claim 1. Advantageous developments are mentioned in the subclaims and the description.

Accordingly, the invention is based on an arrangement for actuating a central valve by means of an electromagnet, with a by the electromagnet along a first axis of movement axially movable pressure pin, which has a front surface at its free end, with a control piston of the central valve, which in a central valve housing along a second movement axis is arranged axially displaceable, wherein the control piston has a contact surface at its free end facing the pressure pin, and wherein the front surface of the pressure pin and the contact surface of the control piston are in contact. To achieve the object, it is provided that the diameter ratio of the front surface of the pressure pin to the contact surface of the control piston or the diameter ratio of the contact surface of the control piston to the front surface of the pressure pin has a value between 1.0 and 2.0, and that the first axis of movement in parallel with a radial distance to the second axis of movement is arranged offset, wherein the offset of the two axes of movement corresponds to 0.35 times to 0.45 times the respective larger diameter of the contact surface or the front surface.

According to a development, the contact surface of the control piston or the front surface of the pressure pin can be made spherical. In addition, it can be provided that the diameter d _{1 of} the front surface on the pressure pin is smaller than that Diameter d _{2 of} the contact surface on the control piston. Alternatively, it may be provided that the diameter d _{1 of} the front surface on the pressure pin is equal to or greater than the diameter d _{2 of} the contact surface on the control piston.

In order to achieve an axial offset in the range of predetermined values, the control piston facing free end of the pressure pin or the pressure pin facing the free end of the control piston may be provided with a plate whose diameter is equal to the diameter d _{1 of} the front surface on the pressure pin or the same is large as the diameter d _{2 of} the contact surface on the control piston. This makes it possible to realize a desired radial offset of the axes of movement of the control piston and pressure pin of several millimeters, and yet such identical parts can be used which are suitable for no or only a small axial offset up to a large axial offset of several millimeters.

The pressure pin with the mentioned plate can be made in one piece as a rotary or extruded part. However, it is also possible to produce the pressure pin and the plate in two parts, which are then material, force or positively connected by welding, gluing, screwing, pressing or caulking each other.

In view of the fact that the space between the electromagnet and the camshaft adjuster is lubricious oil-containing, a hydraulic sticking of the plate to the pole core of the electromagnet can occur. To avoid this can be provided according to another embodiment, that the electromagnet has a pressure pin radially encompassing pole core, that the pole core has a planar support surface for contacting a pole core facing side of the plate of the pressure pin, and that the support surface of the pole core facing Side of the plate has radially extending grooves. These grooves reduce the contact surface of the relatively large diameter plate, so that a hydraulic sticking of the plate on the pole core is successfully avoided.

Due to the radial offset of the movement axis of the pressure pin with respect to the movement axis of the control piston, a relative movement of the contact surface of the control piston and the front surface of the pressure pin takes place during operation of the camshaft actuator. In this case, the axis of movement of the pressure pin on the contact surface of the control piston describes a circular path.

In order to achieve the installation position, ie the radial distance of the first movement axis to the second movement axis of the arrangement, the electromagnet is deliberately eccentric together with the pressure pin with respect to the central valve and installed over the known from the prior art mounting accuracy usual position deviations, so that the axis of movement of the pressure pin and the movement axis of the control piston parallel and spaced from each other.

The resulting from the installation position relative movement of the contact surface of the control piston and the front surface of the pressure pin, that is, by the circular motion of the front surface of the pressure pin on the contact surface of the control piston, forms a stable hydrodynamic lubricant film due to a high sliding speed which occurs during operation. This stable hydrodynamic lubricant film can reduce the friction between the control piston and the pressure pin. This ultimately leads to the fact that the wear on the contact surfaces of the sliding partners is at least reduced.

Exemplary embodiments of the invention and their advantages will be explained in greater detail below with reference to the attached figures. The proportions in the figures do not always correspond to the actual size ratios, as some shapes are simplified and other shapes are shown enlarged in relation to other elements for ease of illustration. It shows

1 a longitudinal section through an inventive arrangement for actuating a central valve by means of an electromagnet according to a first embodiment,

2 a view of the contact point of the pressure pin and the control piston in the axial direction,

3 a longitudinal section through an inventive arrangement for actuating a central valve by means of an electromagnet according to a second embodiment, and

4 a longitudinal section through the electromagnet of an arrangement for actuating a central valve according to a third embodiment.

For identical or equivalent elements of the invention, identical reference numerals have been used in the figures. Furthermore, for clarity, only reference numerals in the individual figures are shown, which are required for the description of the respective figure. The illustrated embodiments are only examples of how the inventive arrangement of an electromagnet and the pressure pin for driving a central valve can be configured, and thus do not constitute a final limitation of the invention.

1 shows therefore a longitudinal section through an arrangement for actuating a central valve 2 by means of an electromagnet 6 in a camshaft adjuster 10 , The electromagnet 6 is designed as an actuator, with a not further described housing and a radially inwardly arranged pressure pin 4 when energizing the electromagnet 6 is axially movable along a first axis of movement A. The pressure pin 4 acts with its free end on the free end of an axially spring-loaded control piston 1 of the central valve 2 which is in a central valve housing 8th is arranged axially displaceable along a second axis of movement B. The movement axis A of the pressure pin 4 extends parallel and at a radial distance x to the movement axis B of the control piston 1 , This spaced arrangement of the first movement axis A with respect to the second movement axis B allows that during operation a frontal contact surface 12 of the control piston 1 and a frontal front surface 13 of the printing pin 4 move at a relative speed to each other. It describes in a contact situation of pressure pin 4 and control piston 1 , as 2 shows, the axial movement axis A of the pressure pin 4 on the contact surface 12 of the control piston 1 a circular path 14 ,

To this arrangement, in particular the relative movement between the pressure pin 4 and control piston 1 to reach is the electromagnet 6 with the pressure pin 4 in relation to the central valve 2 eccentrically installed in a surrounding structure, so that the movement axis A of the pressure pin 4 in comparison to the movement axis B of the control piston 1 parallel and radially spaced from the second axis of movement B (distance x). Through this targeted eccentric installation of the electromagnet 6 including pressure pin 4 in relation to the control piston 1 of the central valve 2 above normal permissible position deviations of the components to each other, the sliding speed of the contact surface 12 of the control piston 1 on the front surface 13 of the printing pin 4 significantly increased compared to known technical solutions. This leads to the desired formation of a hydrodynamic lubricant film between the control piston 1 and the pressure pin 4 , This is the wear of the contact surface 12 of the control piston 1 and the front surface 13 of the printing pin 4 at least greatly reduced. The diameter d _{1 of} the front surface 13 of the printing pin 4 is in the in the 1 and 2 shown embodiment smaller than the diameter d _{2 of} the contact surface 12 of the control piston 1 , wherein the diameter ratio d ₂ / d _{1 of} the contact surface 12 of the control piston 1 to the front surface 13 of the printing pin 4 has a value between> 1 and 2. In addition, it can be seen that the movement axis A of the pressure pin 4 parallel and with a radial distance x to the movement axis B of the control piston 1 by about 0.35 to 0.45 times the diameter d ₂ of the contact area 12 of the control piston 1 is arranged offset.

The embodiment according to 3 differs in terms of the structure of the electromagnet 6 and the central valve 2 not essential to the embodiment according to the 1 and 2 , The only differences are that the contact surface 12a of the control piston 1 now crowned, and that the pressure pin 4 at its free end with a plate 15 connected, whose front surface 13a with the crowned contact surface 12a of the control piston 1 interacts. Recognizable has the contact surface 12a of the control piston 1 a smaller diameter than the front surface 13a of the plate 15 of the printing pin 4 , Due to the large diameter of the plate 15 can the distance x between the axis of movement A of the pressure pin 4 and the movement axis B of the central valve 2 be greater than in the embodiment according to 1 , In practice, several millimeters distance are possible.

Between one of the pole core 17 facing side 16 of the plate 15 of the printing pin 4 and an associated planar bearing surface 18 of the pole core 17 can form an oil film, which is a lifting of the plate 15 from the pole core 17 upon actuation of the electromagnet 6 hinders, namely a hydraulic sticking of the plate 15 on the support surface 18 causes. To prevent this, the plate can 15 of the printing pin 4 according to the in 4 illustrated embodiment radially extending grooves 19 in the pole core 17 facing side 16 of the plate 15 exhibit. These radial grooves 19 reduce the hydraulically effective contact surface of the plate 15 and allow rapid penetration of oil and / or air into the area between the pole core 17 facing side 16 of the plate 15 and the bearing surface 18 of the pole core 17 so that sticking is prevented.

It is also possible, the embodiment according to 1 to modify so that the contact surface 12 on the control piston 1 is designed as a plate and the front surface 13 at the pressure pin 4 has a spherical shape.

All the features mentioned in the preceding description of the figures, in the claims and in the introduction to the description can be used both individually and in any combination with one another. The invention is thus not limited to the described and claimed feature combinations, but all feature combinations are to be regarded as disclosed.

LIST OF REFERENCE NUMBERS

1

 spool

2

 central valve

4

 pushpin

6

 electromagnet

8th

 Central valve housing

10

 Phaser

12

 Plane contact surface on the control piston

12a

 Balanced contact surface on the control piston

13

 Front surface pressure pin

14

 orbit

15

 Plate

15a

Front surface plate 15

16

The Polkern 15 facing side of the plate 15

17

 pole core

18

 bearing surface

19

 groove

A

 First movement axis

B

 Second movement axis

x

 distance

d ₁

Diameter of the front surface 13 . 13a of the printing pin 4

d ₂

Diameter of the contact surface 12 . 12a of the control piston 1

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102010050813 A1 [0002]
• DE 102013209862 A1 [0002]

Claims (10)

Arrangement for actuating a central valve ( 2 ) by means of an electromagnet ( 6 ), with a through the electromagnet ( 6 ) along a first axis of movement (A) axially movable pressure pin ( 4 ), which at its free end a front surface ( 13 . 13a ), with a control piston ( 1 ) of the central valve ( 2 ), which in a central valve housing ( 8th ) is arranged axially displaceable along a second movement axis (B), wherein the control piston ( 1 ) at its to the pressure pin ( 4 ) pointing free end a contact surface ( 12 . 12a ), and in which the front surface ( 13 . 13a ) of the printing pin ( 4 ) as well as the contact surface ( 12 . 12a ) of the control piston ( 1 ) are in contact with each other, characterized in that the diameter ratio (d1 / d2) of the front surface ( 13 . 13a ) of the printing pin ( 4 ) to the contact surface ( 12 . 12a ) of the control piston ( 1 ) or the diameter ratio (d2 / d1) of the contact surface ( 12 . 12a ) of the control piston 1 to the front surface ( 13 . 13a ) of the printing pin ( 4 ) has a value between 1.0 and 2.0, and in that the first movement axis (A) is arranged offset in parallel and at a radial distance (x) from the second movement axis (B), wherein the offset of the two movement axes (A, B ) from 0.35 to 0.45 times the respective larger diameter (d ₁ ; d ₂ ) of the contact surface ( 12 . 12a ) or the front surface ( 13 . 13a ) corresponds. Arrangement according to claim 1, characterized in that the contact surface ( 12 . 12a ) of the control piston ( 1 ) or the front surface ( 13 . 13a ) of the printing pin ( 4 ) is executed crowned. Arrangement according to claim 1 or 2, characterized in that the diameter (d ₁ ) of the front surface ( 13 . 13a ) on the pressure pin ( 4 ) is smaller than the diameter (d ₂ ) of the contact surface ( 12 . 12a ) on the control piston ( 1 ). Arrangement according to claim 1 or 2, characterized in that the diameter (d ₁ ) of the front surface ( 13 . 13a ) on the pressure pin ( 4 ) Equal to or greater than the diameter (d ₂₎ of the contact surface ( 12 . 12a ) on the control piston ( 1 ). Arrangement according to one of claims 1 to 4, characterized in that the control piston ( 1 ) facing the end of the printing pin ( 4 ) or the pressure pin ( 4 ) facing the end of the control piston ( 1 ) with a plate ( 15 ) whose diameter is equal to the diameter (d ₁ ) of the front surface ( 13 . 13a ) on the pressure pin ( 4 ) or equal to the diameter (d ₂ ) of the contact surface ( 12 . 12a ) on the control piston ( 1 ). Arrangement according to claim 5, characterized in that the pressure pin ( 4 ) with the plate ( 15 ) is made in one piece as a rotary or extruded part. Arrangement according to claim 5, characterized in that the pressure pin ( 4 ) and the plate ( 15 ) are in two parts and material, non-positive or positive by welding, gluing, screwing, pressing or caulking are connected to each other. Arrangement according to one of claims 5 to 7, characterized in that the electromagnet ( 6 ) a pressure pin ( 4 ) radially encircling pole core ( 17 ), that the pole core ( 17 ) a plane bearing surface ( 18 ) to create a pole core ( 17 ) facing side ( 16 ) of the plate ( 15 ) of the printing pin ( 4 ), and that the support surface ( 18 ) of the pole core ( 17 ) facing side ( 16 ) of the plate ( 15 ) radially extending grooves ( 19 ) having. Arrangement according to one of claims 1 to 8, characterized in that the first movement axis (A) of the pressure pin ( 4 ) during operation on the contact surface ( 12 . 12a ) on the control piston ( 1 ) or the second movement axis (B) on the control piston ( 1 ) on the front surface ( 13 . 13a ) on the pressure pin ( 4 ) a circular path ( 14 ) describes. Arrangement according to one of claims 1 to 9, characterized in that the electromagnet ( 6 ) together with the pressure pin ( 4 ) in relation to the central valve ( 2 ) is mounted eccentrically, so that the movement axis (A) of the pressure pin ( 4 ) and the movement axis (B) of the control piston ( 1 ) are arranged parallel and radially offset from one another.

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