Patent Application
20210254513
This disclosure relates to a control valve for a hydraulic camshaft phaser of an internal combustion engine and also to a component consisting of this control valve with a hydraulic camshaft phaser.
Generic control valves are already sufficiently known from the prior art. For example, DE 10 2005 052 481 A1 and U.S. Pat. No. 7,389,756 B2 disclose a control valve for a device for the variable setting of the control times of gas exchange valves of an internal combustion engine. A hollow formed valve housing of the control valve has at least one inlet connection, at least one outlet connection, and at least two working connections. A hollow pressure medium guide insert is arranged inside the valve housing, in order to thus form at least one pressure medium channel extending essentially in the axial direction. The pressure medium guide insert consists of a plastic.
A disadvantage of the generic embodiments with a hydraulic guide element made of plastic has been found to be disadvantageous in that in certain cases, depending on the production-related tolerances within the tolerance limits, either a leak, and thus a relatively high leakage of the control valve, occurs during operation, or relatively difficult adjustment, including jamming of the control piston, occurs.
It is therefore the object of the present disclosure to eliminate the disadvantages known from the prior art and, in particular, to provide a control valve which has both the lowest possible leakage and effortless adjustability.
This is achieved according to the disclosure in that, on a radial outside of the hydraulic guide element, there is provided a sealing contour, resting against the screw body and sealing the pressure medium channels from one another and/or to the axial ends of the hydraulic guide element.
This sealing contour provides a sealing geometry that protrudes radially outward and that significantly reduces the total surface area of the hydraulic guide element contacting the screw body. As a result, a pressure force acting radially inward from the screw body on the hydraulic guide element is reduced and the risk of the control piston jamming during operation is reduced. At the same time, due to the nature of the sealing contour, the respective connection remains reliably sealed off from the other connections. This also ensures that operation is largely leak-free.
Further advantageous embodiments are explained in more detail below.
Accordingly, it is also expedient if the sealing contour is dimensioned and designed such that it is compressible/elastically deformable in a radial direction. In this way, the manufacturing tolerances that occur are compensated for in a simple manner by pressing the hydraulic guide element into the screw body.
With regard to the formation of the sealing contour, it is also expedient if a first sealing portion of the sealing contour is arranged to act in a circumferential direction between a first pressure medium channel, optionally connected to an inlet connection, and a second pressure medium channel, optionally connected to a first working connection.
If the first sealing portion is formed by an elevation extending along the longitudinal axis (optionally extending in a straight line), the first sealing portion is implemented in a particularly compact manner.
In this context, it should also be pointed out that it is expedient if a plurality of the first pressure medium channels and/or the second pressure medium channels are arranged distributed along the circumference of the hydraulic guide element and a first sealing portion is provided on each of two opposite circumferential sides of the first pressure medium channel and/or the second pressure medium channel.
A second sealing portion of the sealing contour can be arranged to act in an axial direction of the longitudinal axis and/or in the circumferential direction between the first pressure medium channel and a third pressure medium channel, and optionally connected to a second working connection.
If the second sealing portion is embodied as an elevation that extends in a curved manner in the circumferential direction, the compressive force acting on the hydraulic guide element by the screw body is distributed as evenly as possible in the axial direction.
Furthermore, it is expedient if a third sealing portion of the sealing contour is attached so as to act in the axial direction between the second pressure medium channel and the third pressure medium channel.
The third sealing portion can be a sealing portion extending in a curved manner in the circumferential direction and which in turn is embodied as an elevation. Together with the second sealing portion, the third sealing portion can further form an undulating course of part of the sealing contour in the circumferential direction. This results in an even distribution of the pressure force between the screw body and the hydraulic guide element.
If a fourth sealing portion of the sealing contour, which seals at least one pressure medium channel from an outlet, is attached towards a first end of the hydraulic guide element in the axial direction, the sealing contour assumes further sealing functions. In this context, it is advantageous if the fourth sealing portion extends essentially along an imaginary annular circular line.
Furthermore, it is advantageous if a fifth sealing portion of the sealing contour, sealing at least one pressure medium channel from an inlet, is attached towards a second end of the hydraulic guide element in the axial direction. This fifth sealing portion is, in turn, embodied as an elevation extending arcuately in the circumferential direction.
If the sealing contour is embodied as an integral component of an outer part of the hydraulic guide element made of plastic, the sealing contour is implemented particularly robustly with the outer part as a whole.
The outer part can be firmly connected to an inner part of the hydraulic guide element made of a metal. In one embodiment the outer part is formed as an overmold around the inner part.
For the lowest possible strain on the hydraulic element inwards in the radial direction, the outside of the hydraulic guide element can be arranged axially and/or in the circumferential direction between the sealing portions of the sealing contour with a gap/play in the radial direction towards the screw body.
Furthermore, the different sealing portions of the sealing contour can have a ramp extending in the axial direction/a ramp-shaped transition so that they can be installed as easily as possible when the hydraulic guide element is inserted into the screw body during installation.
The disclosure also relates to a component consisting of a hydraulic camshaft phaser and a control valve according to the disclosure according to at least one of the embodiments described above.
In other words, according to the disclosure, a sealing contour is thus implemented on an oil guide sleeve (hydraulic guide element) of a central valve (control valve). The individual sealing contour is positioned on the outside of the plastic oil guide sleeve.
In the following, the invention is now explained in more detail with reference to figures.
In the figures:
The figures are only schematic in nature and serve only for understanding the disclosure. The same elements are provided with the same reference symbols.
The control valve 1 has a hollow formed screw body 4, having connections 3a to 3d, which body, during operation, is screwed onto a corresponding receptacle on a camshaft, affixing a rotor of the camshaft phaser to the camshaft. Therefore, on a radial outer side of the screw body 4, there is provided, among other things, a threaded area 28 and a support area 29, formed offset from the threaded area 28 in an axial direction (i. e., along a longitudinal axis 16). In this context, for the sake of completeness, it should be noted that the directional information used, axially, radially and in the circumferential direction, is used in relation to the central longitudinal axis 16. The screw body 4 in this embodiment is open towards its two opposite axial ends. A first axial end of the screw body 4 forms a first connection 3a in the form of an inlet connection; a second end of the screw body 4, opposite the first end, forms a further connection 3d (hereinafter referred to as the fourth connection 3d) in the form of an outlet connection. The first connection 3a is consequently hydraulically connected to the inlet 24 during operation; the fourth connection 3d is hydraulically connected to the outlet 21.
The screw body 4, which is formed to be hollow over its entire length, thus forms a cavity 2 on its radial inside. Within this cavity 2, a hydraulic medium guide element 5 is firmly inserted into the screw body 4. The hydraulic medium guide element 5 is fixed on the screw body 4 radially by means of a form fit and axially by means of a locking ring and an axial surface of the screw body 4, alternatively a pressed-in ring. The screw body 4 itself is formed from a metal, whereas the hydraulic medium guide element 5 can consist at least partially of a plastic. The hydraulic medium guide element 5, together with the control piston 10 serves to guide hydraulic medium, depending on the displacement position of the control piston 10, from the inlet 24 to a second connection 3b or a third connection 3c on the side of the working chambers, or from the respective second or third connection 3b, 3c to the connection 3d. For this purpose, the hydraulic medium guide element 5, as can also be seen in connection with
A first pressure medium channel 7 of the hydraulic medium guide element 5 extends in the axial direction and penetrates the hydraulic medium guide element 5 towards one axial end in the radial direction. The first pressure medium channel 7 hydraulically connects the first connection 3a to the radial interior 6 of the hydraulic medium guide element 5. A second pressure medium channel 8, which is also embodied as a radial passage, is arranged offset in the circumferential direction with respect to the first pressure medium channel 7. The second pressure medium channel 8 is hydraulically connected to the second connection 3b, and consequently to a first working chamber A of the camshaft phaser. A third pressure medium channel 9, which also penetrates the hydraulic medium guide element 5 in the radial direction, is offset in the axial direction from the second pressure medium channel 8 or offset in the circumferential direction, and offset in the axial direction from the first pressure medium channel 7. The third pressure medium channel 9 is hydraulically connected to the third connection 3c, and consequently to a second working chamber B of the camshaft phaser.
In the interior 6 of the hydraulic medium guide element 5, the control piston 10 is arranged, in a typical manner, displaceably in the axial direction in order to implement the various positions of the control valve 1 and thus to connect the second and third connections 3b and 3c to the first connection 3a or to the fourth connection 3d or to each other.
According to the disclosure, as illustrated in
The sealing contour 14 is formed by a plurality of sealing portions 15, 18, 20, 23, 25 in the form of elevations 17, 19, 22, 30, 31 on the outer side 11. The elongated sealing portions 15, 18, 20, 23, 25 each protrude in the radial direction from an outer jacket side 32 of the hydraulic medium guide element 5 and are in tight contact with an inner side of the screw body 4.
A first sealing portion 15 of the sealing contour 14 is formed as a first elevation 17 extending straight in the axial direction. This first sealing portion 15 serves to seal the first pressure medium channel 7 from the second pressure medium channel 8 in the circumferential direction. In this context, it can also be seen that a plurality of first pressure medium channels 7, second pressure medium channels 8, and third pressure medium channels 9 are arranged distributed in the circumferential direction. Viewed in the circumferential direction, one of the first pressure medium channels 7 is arranged between two second pressure medium channels 8 or between two third pressure medium channels 9. With respect to its first circumferential side and with respect to its second circumferential side, which is opposite the first circumferential side in the circumferential direction, the first pressure medium channel 7 is separated by a first sealing portion 15 each.
A second sealing portion 18 of the sealing contour 14 is inserted between the first pressure medium channel 7 and the third pressure medium channel 9. The second sealing portion 18 is implemented by a second elevation 19 that extends arcuately in the circumferential direction. The second sealing portion 18, together with the first sealing portion 15, thus forms a seal for the first pressure medium channel 7 in the circumferential direction and with respect to a (first) end 12 of the hydraulic medium guide element 5.
In order to seal the second pressure medium channel 8 with respect to the (first) end 12, a further third sealing portion 20 of the sealing contour 14 is provided, likewise extending arcuately in the circumferential direction. With respect to a further (second) end 13 of the hydraulic medium guide element 5, the second pressure medium channel 8 is sealed by a further (fifth) sealing portion 25 in the form of a fifth elevation 31. This fifth sealing portion 25 also extends arcuately in the circumferential direction. As can be seen in
A fourth sealing portion 23 seals the third pressure medium channel 9 with respect to the second end 13 in the axial direction. The fourth sealing portion 23 is implemented by a plurality of fourth elevations 30. Overall, a plurality of fourth elevations 30 are formed one after the other in the circumferential direction. The fourth sealing portion 23 extends essentially annularly.
Returning to
In
In other words, according to the disclosure, a soft sealing contour 14 on the outer diameter of the overmold (outer part 26) represents a type of tolerance compensation. The sealing contour 14 between the individual oil channels (pressure medium channels 7, 8, 9) is intended to significantly reduce the amount of material that overlaps for “minimum” parts and thus allow for greater overlap in these local areas, while still reducing the risk of jamming. For the same tolerances, the maximum gap is thus reduced by the sealing contour 14, reducing the risk of leakage. The tool for overmolding 26 the steel sleeve (inner part 27) consists of a plurality of sliders in order to be able to produce the oil channels 7, 8, 9 on the outer diameter. There are tool separation points between each of the sliders, creating a burr. Since these burrs can only be avoided or removed with relatively great effort, they are hidden in an axial groove. This groove creates a channel which increases the leakage; in order to avoid this leakage, the groove is laterally sealed by a bead (first elevation 17). This sealing bead 17 thus represents the axial sealing contour (first sealing portion 15) between the sliders, and thus between the P channels (first pressure medium channel 7) to the A and B channels (second pressure medium channel 8 and third pressure medium channel 9). In addition, there are sealing contours 18, 20, 23, 25 in the circumferential direction for sealing between the A channel 8 and the B channel 9 and with respect to the tank (outlet 21). The sealing contour 14 should not have any sharp edges in order to avoid damaging the contour 14 when it is joined into the housing (screw body 4). Soft transitions 33 in the axial direction ensure this. The sealing contour 14 represents a simplification for manufacturing, since a high-precision diameter tolerance and shape no longer need to be achieved on the entire cylinder, but primarily only in the area of the sealing contour 14. The plastic between the sealing areas 15, 18, 20, 23, 25 is deliberately designed with play in relation to the housing 4 so as not to generate any pressure on the steel sleeve 27 in these areas.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2018 115 343.0 | Jun 2018 | DE | national |
This application is the U.S. National Phase of PCT Application NO. PCT/DE2019/100378 filed on Apr. 24, 2019 which claims priority to DE 10 2018 115 343.0 filed on Jun. 26, 2018, the entire disclosures of which are incorporated by reference herein.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/DE2019/100378 | 4/24/2019 | WO | 00 |
