Information
-
Patent Grant
-
6418897
-
Patent Number
6,418,897
-
Date Filed
Friday, August 17, 200123 years ago
-
Date Issued
Tuesday, July 16, 200222 years ago
-
Inventors
-
Original Assignees
-
Examiners
Agents
- Bierman, Muserlian and Lucas
-
CPC
-
US Classifications
Field of Search
US
- 123 9015
- 123 9017
- 123 9031
- 123 9033
- 123 9037
- 074 568 R
- 464 1
- 464 2
- 464 160
-
International Classifications
-
Abstract
The invention concerns a device for the angular adjustment of a camshaft relative to the crankshaft of an internal combustion engine, particularly a vane-type adjuster (1) comprising a stator (12) that is driven by the crankshaft preferably through a traction element and a drive pinion (11), and a vane rotor (18) that can be pressurized by pressure oil and is rotationally fixed to the camshaft while possessing a means, preferably an axially displaceable fixing pin (37) for effecting a releasable, rotational fixing of the vane rotor. The drawback of oil leakage in common vane-type adjusters is avoided by the fact that all components of the vane-type adjuster (1) that have contact with pressure oil are arranged in an oil-tight housing (2).
Description
DESCRIPTION
Field of the Invention
The invention concerns a device for the angular adjustment of a camshaft relative to the crankshaft of an internal combustion engine, particularly a vane-type adjuster comprising a stator that is driven by the crankshaft preferably through a traction element and a drive pinion, and a vane rotor that is rotationally fixed to the camshaft and possesses a means, preferably an axially displaceable fixing pin for effecting a releasable, rotational fixing of the vane rotor.
BACKGROUND OF THE INVENTION
A generic device of the pre-cited type is known from DE 196 23 818 A1. In this device, the stator is screwed to a front plate and a chain sprocket which together form a housing with hydraulic chambers in which a vane rotor with vanes sub-dividing the hydraulic chambers is arranged for pivoting. The individual chambers can be pressurized by pressure oil delivered through hydraulic ducts, so that the vane rotor can pivot within a defined angular range or be fixed in any desired intermediate position. If the oil pressure falls below a certain minimum value (at a standstill or starting of the engine, or at a low engine speed), a locking member that is mounted for axial displacement in one of the vanes of the vane rotor, is pushed by spring force into an opening of the front plate. This causes the vane rotor and the stator to be non-rotatably coupled to each other, so that the camshaft is then driven directly by the chain sprocket. In this way, rattling noises are prevented at low engine speeds and an optimal adjustment of the inlet camshaft for starting the engine is assured. With increasing engine speed and a concomitant rise of the oil pressure, the locking of the vane rotor is released so that the angular adjustment function becomes effective again.
A drawback of this device is its lack of oil-tightness so that the device is only suitable for oil-tight encapsulated drives with a chain or gearwheel. For toothed belt drives, that are interesting from the cost and noise point of view, the aforesaid drive does not come into question.
OBJECT OF THE INVENTION
The object of the invention is therefore to provide a device for the angular adjustment of a camshaft that is also suitable for a toothed belt drive and can be economically manufactured.
SUMMARY OF THE INVENTION
This invention achieves this object by the fact that all components of the vane-type adjuster that have contact with pressure oil are arranged in an oil-tight housing. These components include at least the stator and the vane rotor and a means for a releasable, rotational fixing. Due to the oil-tight design of the vane-type adjuster, this can be driven by a toothed belt.
The oil-tight housing can be made, for example, as a turned part or by investment casting, injection molding, sinter molding or forging. Particularly economically, it is made as a deep drawn part out of steel sheet. Deep drawing permits the use of an inexpensive base material that can be given the final shape by a simple shaping method and only a small amount of subsequent machining. Due to the fact that the oil-tight housing comprises a camshaft-proximate housing part and a camshaft-distal housing part having approximately the same depth of deformation, an economic fabrication of the housing is assured.
Advantageously, the housing parts have a flat bottom whose periphery merges into a cylindrical section which continues into an outwardly extending flange. The housing is rendered oil-tight by a sealing of the individual flange connections. It is also conceivable to omit the cylindrical section on one of the housing parts and let its flat bottom merge directly into the radial flange. It is further conceivable to make this flange continue into an outer cylindrical portion having the profile of the toothed belt pulley rolled into its outer peripheral surface. This measure would eliminate the need of a separate toothed belt pulley and its fixing means.
It has proved to be of advantage that the flanges and the drive pinion can be connected to one another by flange screws equally spaced around the periphery of the vane-type adjuster and that the flange screws are configured as fitting screws that can be screwed into threaded bores of the drive pinion. Due to the fact that the flange screws are situated outside the pressure oil region, they cannot cause any oil leakage problems. The configuration of the flange screws as fitting screws assures a reliable transmission of the camshaft torque irrespective of the magnitude of the surface pressure between the flanges.
According to a further advantageous feature of the invention, a flat, appropriately sized compensating washer is arranged between at least one of the flat bottoms and the stator, and the diameter of this washer, with clearance, corresponds to the inner diameter of the cylindrical section. Compensating washers are available in a variety of thicknesses and permit a compensation of manufacturing tolerances of the deep drawn housing parts and their deformation caused by the tightening of the flange screws. This permits the setting of the axial play between the flanges that is needed for producing the bracing between the inner components of the vane-type adjuster required for the transmission of the camshaft torque. The radial and axial play of the vane rotor required for the freedom of movement and sealing of the vane rotor is assured by an appropriate working of the vane rotor and the stator.
The transmission of the camshaft torque is achieved by the fact that the drive pinion, the flanges, the housing parts, the compensating washers and the stator can be braced rotationally fast to one another with the help of the flange screws. An advantage of this is that the biasing force of the flange screws acts, above all, in the peripheral region of the friction members and therefore at the largest friction radius. The resulting friction forces are augmented by the fact that the braced surfaces, especially the side surfaces of the stator are profiled. In this way, the friction engagement is enhanced by additional positive engagement.
Another advantageous feature of the invention is that the compensating washer that is arranged on the side of the vane rotor from which the fixing pin extends, has a locking bore into which the fixing pin can snap. By reason of the locking bore, the compensating washer is at the same time a locking disc. The locking bore in the form of a through-bore is simple to make. The flat bottom serves as a stop for the fixing pin.
Due to the fact that an O-ring seal is arranged in a groove between the inner surfaces of the cylindrical sections and the flanges that is formed by the transition radius resulting from the manufacturing process, a groove that already exists is utilized for sealing the flanges.
To summarize, it will be appreciated that, due to the oil-tight encapsulation of all the components that are pressurized by the pressure oil, the vane-type adjuster of the invention permits the use of an economic and low-noise toothed belt drive for the camshaft. The use of deep drawn components for the oil-tight housing offers additional cost advantages.
Further features of the invention will become obvious from the following description of the drawings and from the drawings themselves which give a schematic representation of one example of embodiment of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will now be described more closely with reference to an example of embodiment and the appended drawings.
FIG. 1
is a longitudinal section through a vane-type adjuster configured according to the invention;
FIG. 2
is a sectional view A—A through the vane-type adjuster of FIG.
1
.
DETAILED DESCRIPTION OF THE DRAWINGS
FIGS. 1 and 2
show a vane-type adjuster
1
that serves to adjust the angle of rotation of a camshaft relative to the crankshaft of an internal combustion engine. The gas exchange valves of the internal combustion engine are activated with the help of the camshaft. Their optimum timing varies with the engine speed. With increasing engine speed the optimum timing is offset in delay direction in the case of the inlet valves, and in the case of the outlet valves, in advance direction. In engines having separate camshafts for the inlet and outlet valves, it is possible to realize an engine-speed dependent adaptation of valve timing in a simple manner by an appropriate rotation of the camshafts. The vane-type adjuster
1
of the invention serves this purpose. It comprises a housing
2
for the oil-tight encapsulation of all components that have contact with pressure oil. The housing
2
comprises a camshaft-proximate housing part
3
and a camshaft-distal housing part
4
. Each housing part
3
,
4
comprises a flat bottom
5
,
6
whose periphery merges into a cylindrical section
7
,
8
that in its turn, merges into an outwardly extending flange
9
,
10
. The flanges
9
,
10
are connected to a drive pinion
11
by eight equally spaced flange screws
37
. These flange screws
37
are configured as fitting screws and are screwed into threaded bores of the drive pinion
11
which is configured as a toothed belt pulley. A stator
12
with a slight radial clearance to the cylindrical sections
7
,
8
is inserted into the housing
2
. Compensating washers
13
,
14
whose diameter corresponds, with clearance, to the inner diameter of the cylindrical sections
7
,
8
are disposed between the stator
12
and the flat bottoms
5
,
6
.
The driving torque of the camshaft is transmitted by frictional engagement from the drive pinion
11
through the flanges
9
,
10
, the housing parts
3
,
4
and the compensating washers
13
,
14
to the stator
12
. The pressure bracing of the frictionally engaged members is effected by the screw force of the eight flange screws
37
. Because the screw force is required to act both on the flanges
9
,
10
and, parallel thereto, on the flat bottoms
5
,
6
, the play between the flanges
9
,
10
has to be exactly defined. If this play is equal to zero before the tightening of the flange screws
37
, 100% of the screw force goes into the flanges
9
,
10
, while the flat bottoms
5
,
6
are completely devoid of force. If the play between the flanges
9
,
10
before the tightening of the flange screws
37
is chosen so that it is exactly zero when the flange screws
37
have been tightened, i.e. the flanges
9
,
10
just about touch each other, the entire screw force goes into the flat bottoms
5
,
6
and there is no frictional engagement between the flanges
9
,
10
. If there is a slight play between the flanges
9
,
10
before the tightening of the flange screws
37
, the distribution of the screw force lies between the two extremes. By configuring the eight flange screws
37
as fitting screws, the half camshaft torque to be transmitted from the flange
9
to the other flange
10
can be transmitted exclusively by shearing force, so that the entire screw force is available for the internal frictional engagement between the bottoms
5
,
6
, the compensating washers
13
,
14
and the stator
12
.
On its periphery, the stator
12
comprises four equally spaced intermediate walls
15
that extend from an outer ring
16
up to a hub ring
17
of a vane rotor
18
. The four intermediate walls
15
enclose four intermediate spaces
19
, each of which is divided into two hydraulic chambers
21
by a vane
20
of the vane rotor
18
. The intermediate walls
15
and the vanes
20
are conical in shape, with their non-parallel limiting surfaces
22
,
23
being oriented toward the axis of the vane-type adjuster
1
.
The vane rotor
18
is sealed relative to the stator
12
by seal gaps at the hub ring
17
and at the outer ring
16
. The parallel limiting walls
24
,
25
of the vane rotor
18
are sealed relative to the compensating washers
13
,
14
in a similar manner. In the installed state of the vane-type adjuster
1
, the vane rotor
18
is braced against a connecting sleeve
26
that is mounted in a cylindrical extension
27
of the camshaft-proximate housing part
3
. An oil guide tube
28
arranged concentric to the connecting sleeve
26
serves to guide the flow of pressure oil. The cylindrical extension
27
and, with it, the entire vane-type adjuster
1
are protected from an escape of oil by an engine-side seal
38
acting on the outer peripheral surface of the extension
27
.
A threaded opening
29
serves for the mounting of a fixing screw, not shown, with which the vane-type adjuster
1
is screwed to the camshaft. The threaded opening
29
is sealed oil-tight by a closing plug
30
comprising an O-ring seal
31
. Another O-ring seal
32
serves for the pressure-oil sealing of the flanges
9
,
10
. It is arranged in a groove between the inner surfaces of the cylindrical sections
7
,
8
and the flanges
9
,
10
that is formed by the transition radius resulting from the manufacturing process.
An axially displaceable fixing pin
33
whose stepped end face can be loaded by the pressure oil is arranged in one of the vanes
20
. As long as oil pressure exists, the fixing pin
33
bears against a stop
34
in the vane
20
and thus permits a pivoting of the vane rotor
18
. When the oil pressure falls below a certain level (e.g. at a standstill or starting of the engine, or at a low engine speed), the fixing pin
33
is pushed into a locking bore
36
of the compensating washer
14
by a compression spring
35
that is supported on the bottom of a pocket bore in the vane
20
. By this, the vane rotor
18
and the stator
12
are firmly coupled to each other thus preventing clattering noises, especially during the starting of the engine. The locking of the vane rotor
18
is effected in a position that is optimal for the starting of the engine. The locking bore
36
is configured as a through-bore. The locked fixing pin
33
bears against the camshaft-distal housing part
4
and therefore does not cause any oil leakage.
|
List of reference numerals
|
|
|
1
Vane-type adjuster
20
Vane
|
2
Housing
21
Working chambers
|
3
Camshaft-proximate housing
22
Non-parallel limiting surface
|
part
|
4
Camshaft-distal housing part
23
Non-parallel limiting surface
|
5
Flat bottom
24
Parallel limiting surface
|
6
Flat bottom
25
Parallel limiting surface
|
7
Cylindrical section
26
Connecting sleeve
|
8
Cylindrical section
27
Cylindrical extension
|
9
Flange
28
Oil guide tube
|
10
Flange
29
Threaded opening
|
11
Drive pinion
30
Closing plug
|
12
Toothed rim
31
O-ring seal
|
13
Side plate
32
Another O-ring seal
|
14
Side plate
33
Fixing pin
|
15
Intermediate wall
34
Stop
|
16
Outer ring
35
Compression spring
|
17
Hub ring
36
Locking bore
|
18
Vane rotor
37
Flange screw
|
19a
Pressure chamber
38
Sealing ring
|
19b
Pressure chamber
|
|
Claims
- 1. A device for the angular adjustment of a camshaft relative to the crankshaft of an internal combustion engine including a vane-type adjuster (1) comprising:a drive pinion (11) that is connected in driving relationship to the crankshaft of the internal combustion engine by a traction element and a toothed rim (12), in which drive pinion (11), a plurality of hydraulic working chambers (21) are formed by a hollow cylindrical outer ring (16) having a plurality of radial intermediate walls (15) and two side plates (13, 14) bearing against the outer ring, the vane-type adjuster (1) further comprising a vane rotor (18) that is rotationally fixed to the camshaft of the internal combustion engine, a plurality of vanes (20) being arranged radially on a hub ring (17) of the vane rotor (18), said vanes extending into the working chambers (21) of the drive pinion (11) and dividing each working chamber (21) into two oppositely acting hydraulic pressure chambers (19a, 19b), an axially displaceable fixing pin (33) having a compression spring (35) being arranged in one of the vanes (20) of the vane rotor (18), which fixing pin can be displaced into a locking bore (36) in one of the side plates (13, 14) of the drive pinion (11) when pressure medium pressure falls short of a defined value, so that the vane rotor (18) and the drive pinion (11) are mechanically coupled to each other, characterized in thatthe hollow cylindrical outer ring (16) with the radial intermediate walls (15) and the side plates (13, 14) of the drive pinion (11) of the vane-type adjuster (1) are enclosed pressure medium-tight by an additional housing (2), the housing (2) comprises a camshaft-proximate housing part (3) and a camshaft-distal housing part (4), both these housing parts being made as sheet steel deep drawn parts that are connected to each other by a flange connection, the toothed rim (12) of the drive pinion (11) is fixed to this flange connection by which the side plates (13, 14), at least one of which is a flat, appropriately sized axial tolerance compensating washer being braced against the outer ring (16) by force-locking.
- 2. A device according to claim 1, characterized in that each housing part(3,4) comprises a flat bottom (5, 6) whose periphery merges into a cylindrical section (7, 8) that continues into an outwardly extending flange (9, 10), the deep drawing depths of the two housing parts (3, 4) corresponding to the height difference between the bottom (5, 6) and the flange (9, 10) being approximately equal to each other.
- 3. A device according to claim 1, characterized in that the flange connection between the flanges (9, 10) of the housing parts (3, 4) and the toothed rim (12) of the drive pinion (11) is effected by flange screws (37) configured as fitting screws that are equally spaced over the periphery of the vane-type adjuster (1) and can be screwed into threaded bores of the toothed rim (12).
- 4. A device according to claim 2, characterized in that the surfaces of the braced elements of the vane-type adjuster (1), including the outer surfaces of the side plates (13, 14) of the drive pinion (11) and the inner surfaces of the flat bottoms (5, 6) of the housing parts are slightly profiled for increasing frictional engagement.
- 5. A device according to claim 1, characterized in that the side plate (14) that is arranged on that side of the vane rotor (18) from which the fixing pin (33) extends comprises the locking bore (36) for a snapping-in of the fixing pin (33), said locking bore (36) being configured as a through-bore.
- 6. A device according to claim 2, characterized in that, for sealing the vane-type adjuster (1), an O-ring seal (32) is arranged in a groove within the housing (2), which groove is formed between the inner surfaces of the cylindrical sections (7, 8) and the flanges (9, 10) of the housing parts (3, 4) by the transition radius resulting from the manufacturing process.
Priority Claims (1)
Number |
Date |
Country |
Kind |
199 08 934 |
Mar 1999 |
DE |
|
PCT Information
Filing Document |
Filing Date |
Country |
Kind |
PCT/EP00/01017 |
|
WO |
00 |
Publishing Document |
Publishing Date |
Country |
Kind |
WO00/52308 |
9/8/2000 |
WO |
A |
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Number |
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Sep 1997 |
A |
5836277 |
Kira et al. |
Nov 1998 |
A |
5865151 |
Fukaya et al. |
Feb 1999 |
A |
6035818 |
Sato et al. |
Mar 2000 |
A |
6089198 |
Goppelt et al. |
Jul 2000 |
A |
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Number |
Date |
Country |
4417959 |
Nov 1995 |
DE |
0799976 |
Oct 1997 |
EP |
0848141 |
Jun 1998 |
EP |
0859130 |
Aug 1998 |
EP |