Camshaft adjuster

Abstract

A camshaft adjuster (1) is provided, including a drive element (2) and a driven element (3), which can be rotated in relation to the drive element within an angular range and can be connected to a camshaft, wherein pressurizable working chambers (4) for rotating the drive element (2) with respect to the driven element (3) are formed between the drive element (2) and the driven element (3), wherein the camshaft adjuster (1) has a volume accumulator (5) for collecting hydraulic medium, wherein the volume accumulator (5) supplies the hydraulic medium to a vacuum-pressurized working chamber (4) via a check valve (6) in that the vacuum in the working chamber (4) opens the check valve (6), characterized in that the check valve (6) is arranged in an axial position between the working chamber (4) and the volume accumulator (5), and the volume accumulator (5) is formed by a cover element (7) connected to the drive element (2) for conjoint rotation.

Claims

1. A camshaft adjuster comprising: a drive element, a driven element that is configured to rotate relative to the drive element within an angular range and is adapted to be connected to a camshaft, work chambers located between the drive element and the driven element, the work chambers are configured to rotate the driven element relative to the drive element, a volume accumulator adapted to collect hydraulic medium and formed by a sealing cover and a spring cover, the spring cover being locked in rotation with the drive element, a check valve allocated to each of the work chambers, the volume accumulator feeds the hydraulic medium via the check valve of a vacuum-pressurized one of the work chambers via vacuum pressure in the work chamber opening the check valve, each of the check valves is arranged in an axial position between the work chambers and the volume accumulator.

2. The camshaft adjuster according to claim 1, wherein the check valves are formed by an intermediate washer arranged between the drive element and the spring cover.

3. The camshaft adjuster according to claim 2, wherein the intermediate washer is a sheet-metal part and the check valves are each constructed as a sheet-metal flap formed integrally with the sheet-metal part.

4. The camshaft adjuster according to claim 1, wherein the check valves each project into an associated one of the work chambers in an open state.

5. The camshaft adjuster according to claim 1, wherein an opening path of each of the check valves is bounded by a stop formed by the drive element.

6. A camshaft adjuster comprising: a drive element, a driven element that is configured to rotate relative to the drive element within an angular range and is adapted to be connected to a camshaft, work chambers located between the drive element and the driven element, the work chambers being configured to rotate the driven element relative to the drive element, a volume accumulator adapted to collect hydraulic medium and formed by a sealing cover and a spring cover, the spring cover being locked in rotation with the drive element, a check valve allocated to each of the work chambers in an axial position between the work chambers and the volume accumulator, and wherein the volume accumulator feeds the hydraulic medium via the check valves to the work chambers upon a vacuum pressure in the work chambers opening the check valves.

7. The camshaft adjuster of claim 6, further comprising an intermediate washer arranged between the drive element and the spring cover, and the check valves are formed on the intermediate washer.

8. The camshaft adjuster of claim 7, wherein the check valves are flaps formed integrally with the intermediate washer.

9. The camshaft adjuster of claim 6, wherein the check valves project into a respective one of the work chambers in an open state.

10. The camshaft adjuster of claim 6, further comprising a stop formed on the drive element, and an opening path of the check valves is bounded by the stop.

11. A camshaft adjuster comprising: a drive element, a driven element that is configured to rotate relative to the drive element within an angular range and is adapted to be connected to a camshaft, work chambers located between the drive element and the driven element, the work chambers being configured to rotate the driven element relative to the drive element, a volume accumulator adapted to collect hydraulic medium and formed by a sealing cover and a spring cover, the spring cover being locked in rotation with the drive element, a check valve allocated to each of the work chambers in an axial position between the work chambers and the volume accumulator, wherein an opening stroke of each of the check valves is bounded by a stop formed by the drive element, wherein the volume accumulator feeds the hydraulic medium via the check valves to the work chambers upon a vacuum pressure in the work chambers opening the check valves.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Embodiments of the invention are shown in the figures.

(2) Shown are:

(3) FIG. 1 a camshaft adjuster according to the invention in an exploded-view diagram,

(4) FIG. 2 the camshaft adjuster according to the invention according to FIG. 1 in longitudinal section,

(5) FIG. 3 a detail view of the camshaft adjuster according to FIG. 2,

(6) FIG. 4 a perspective view of the intermediate washer of the camshaft adjuster according to FIG. 1,

(7) FIG. 5 a perspective view of the sealing cover of the camshaft adjuster according to FIG. 1,

(8) FIG. 6 a schematic view of the camshaft adjuster according to the invention with fill level optimization, and

(9) FIG. 7 a perspective view of the drive element 2 with axial open areas 22.

DETAILED DESCRIPTION

(10) FIG. 1 shows a camshaft adjuster 1 according to the invention in an exploded-view diagram.

(11) The camshaft adjuster 1 has a drive element 2, a driven element 3, an intermediate washer 8, a sealing cover 11, a spring 13, and a spring cover 12. The previously specified components are arranged in the axial direction in the specified sequence one after the other. The drive element 2 and the driven element 3 form multiple work chambers 4 that can be pressurized with hydraulic medium. A check valve 6 that is formed integrally with the intermediate washer 8 is allocated to each work chamber 4. The intermediate washer 8 is a thin-walled sheet-metal part. The contour of the check valves 6 is stamped so that the spring force loading of the check valve 6 is realized as a bending beam for returning into the rest position in which the check valve 6 covers an opening 14. The check valve 6 covers the circular opening 14 with the circular end. A hydraulic medium flow initially flows into the opening 14, a vacuum pressure in the work chamber 4 opens the corresponding check valve 6 in which it draws the check valve 6 formed as a sheet-metal flap into the work chamber 4 and then the hydraulic medium can flow out of the opening 14 into the work chamber 4 and can equalize the deficient volume due to the vacuum pressure. In this way, the adjustment speed increases. The openings 14 of the sealing cover 11 are passage holes and open into the volume accumulator 7 that is formed by the spring cover 12. The volume accumulator 7 is filled by hydraulic medium ejected from the camshaft adjuster 1, advantageously from a tank connection of a central valve (shown partially in FIG. 2). The spring cover 12 also covers, in addition to the function of the volume accumulator 7, the spring 13 that tensions the drive element 2 and the driven element 3 to each other in a circumferential direction.

(12) FIG. 2 shows the camshaft adjuster 1 according to the invention in accordance with FIG. 1 in a longitudinal section.

(13) A central valve 15 (here shown simplified as a central screw) fastens the driven element 3 locked in rotation with a camshaft not shown here. A flow of hydraulic medium is shown by the line with arrows. The end-side outflow of hydraulic medium from the central valve 15 is collected during operation of the camshaft adjuster 1 by the funnel-shaped construction of the spring cover 12 and collects in a volume accumulator 5 on the radially outer inner edge of the spring cover 12 due to centrifugal force. The spring 13 is omitted for better illustrating the hydraulic medium path. After a certain fill level in the volume accumulator 5 is exceeded, a part of the collected hydraulic medium can be fed via an opening 14 through a check valve 6 of the work chamber 4 or is suctioned due to the check valve 6 opening into the work chamber 4 due to the vacuum pressure in the work chamber 4 caused by alternating moments of the camshaft. The intermediate washer 8 is clamped by the sealing cover 11 and the drive element 2. The oil holes 14 that are covered by the check valves 6 are arranged radially spaced apart relative to the rotational axis of the camshaft adjuster 1 such that a minimum fill level in the volume accumulator 5 already provides sufficient hydraulic medium for equalizing the hydraulic medium deficiency caused by the vacuum pressure in the work chamber 4. In this embodiment, the openings 14 are adjacent to the radially outer walls of the work chamber 4. Alternatively, the openings 14 can also be arranged adjacent to a radially inner wall of the work chamber 4. Another alternative provides that the openings 14 are preferably arranged centrally between the two previously mentioned conceivable positions.

(14) FIG. 3 shows a detailed view of the camshaft adjuster 1 according to FIG. 2.

(15) The opened check valve 6 contacts the stop 10. The stop 10 is formed by the drive element 2 as an integrally formed projection and is arranged partially within a vane of the drive element 2. If the drive element 2 contacts the driven element 3 in the circumferential direction, axial open areas 22 are provided that form, on one hand, the stops 10 and whose individual contours are largely adapted to the respective contours of the check valve 6. For example, through the axial open area 22 on the drive element 2 it is possible that the check valves 6 can then still open if the drive element 2 contacts the driven element 3 in the circumferential direction or both elements 2, 3 contact each other. The axial open areas 22 are easily visible in FIG. 7. The cover 16 arranged on the side of the camshaft adjuster 1 facing the camshaft and locked in rotation with the drive element 2 closes the work chambers 4 essentially sealed against the pressurizing medium. The funnel-shaped construction of the spring cover 12 promotes the collection of the flowing hydraulic medium.

(16) FIG. 4 shows a perspective view of the intermediate washer 8 of the camshaft adjuster 1 according to FIG. 1.

(17) The intermediate washer 8 is constructed as a thin-walled sheet and has four pairs of check valves 6 that are allocated to the work chambers 4. The contour of the check valves 6 can be easily punched from sheet metal. In addition, four openings 17 are provided on which each is arranged between a pair of check valves 6 and are provided for the passage of the fastening screws that tension the sealing cover 11 and the cover 16 with the drive element 2. In addition, the intermediate washer 8 has an opening 18 that can be passed through by a locking piston that can couple the drive element 2 with the driven element 3 or can allow decoupling for exerting a relative rotation. The locking piston is held by the driven element 3 and can engage in a locking connecting link 19 that is provided for this purpose and is arranged in the sealing cover 11. Because the intermediate washer 8 is arranged between the sealing cover 11 and the drive element 2, the opening 18 provides the necessary clearance so that the locking piston can come in contact with the locking connecting link 19. The opening 18 is only optional and is caused by the arrangement of the locking connecting link 19 in the directly adjacent component. If the locking connecting link 19 is located on the axially opposite side of the camshaft adjuster 1 on another cover, then this opening 18 on the intermediate washer 8 can be omitted.

(18) FIG. 5 shows a perspective view of the sealing cover 11 of the camshaft adjuster 1 according to FIG. 1.

(19) The sealing cover 11 has the openings 17 provided for the fastening screws. These openings 17 are flanked by the oil holes 14 that are covered in the assembly of the camshaft adjuster 1 by the check valves 6 of the intermediate washer 8. In addition, the locking connecting link 19 is formed by the sealing cover 11, which—as shown here—can have a circular shape or can be constructed as a groove. An insert element can also be provided for insertion into the locking connecting link 19, with which the locking piston can come in contact.

(20) FIG. 6 shows a schematic diagram of the camshaft adjuster 1 according to the invention with fill level optimization.

(21) The volume accumulator 5 formed by a cover element 7 can deviate from the circular ring shape shown in the previous figures. In FIG. 6, with reference to the profile of the fill contour 20, it is shown how the shape of the volume accumulator 5 can be optimized with respect to the accessibility of the stored hydraulic medium to the check valves 6. For example, as seen in the circumferential direction, the profile is formed with a slight radial distance to the rotational axis or center of the camshaft adjuster approximately in the middle between two check valves 6. The radial distance increases in the areas of the check valves 6 and ideally completely surrounds the check valves 6. Thus, advantageously the hydraulic medium collected by the funnel-shaped cover element 7 is forced by the centrifugal force during operation of the camshaft adjuster 1 into the pockets of the volume accumulator 5 and can be fed to the work chamber 4 controlled by the check valve 6 arranged in this area. Thus, the maximum fill level 21 is applied for each check valve 6. The volume of hydraulic medium in the pocket-shaped areas of the volume accumulator with the maximum fill level 21 ideally corresponds at least to the needs of the corresponding work chamber 4. The fill contour 20 can be formed by the cover element 7 forming the volume accumulator 5 or by a separate fill contour component that is joined to the cover element 7.

LIST OF REFERENCE SYMBOLS

(22) 1) Camshaft adjuster 2) Drive element 3) Driven element 4) Work chamber 5) Volume accumulator 6) Check valve 7) Cover element 8) Intermediate washer 9) Sheet-metal flap 10) Stop 11) Sealing cover 12) Spring cover 13) Spring 14) Oil hole 15) Central valve 16) Cover 17) Opening (for screw) 18) Opening (for locking piston) 19) Locking connecting link 20) Fill contour 21) Fill level 22) Axial open area