WO2001040633A1

WO2001040633A1 - Device for adjusting the angle of rotation of a camshaft

Info

Publication number: WO2001040633A1
Application number: PCT/EP2000/011328
Authority: WO
Inventors: Eduard Golovatai-Schmidt; Jens Schäfer
Original assignee: Ina-Schaeffler Kg
Priority date: 1999-12-04
Filing date: 2000-11-16
Publication date: 2001-06-07
Also published as: DE19958541A1

Abstract

The invention relates to a wing cell adjuster for adjusting a camshaft turning angle in an internal combustion engine. Adjusters of this type require an oil circulation duct, which usually runs the risk of developing leakages and is susceptible to corrosion. These ducts (22) disadvantages are avoided by providing the oil circulation with a continuous fluidic connection to a hydraulic fluid source (23) via a supply line and a control line. Discontinuous distribution of the hydraulic fluid to working chambers (A and B) is executed by a distributing device on the inside of the inner rotor (4).

Description

Name of the invention

Device for adjusting the angle of rotation of a camshaft

description

Field of the Invention

The invention relates to a device for adjusting the angle of rotation of a camshaft of an internal combustion engine, with a camshaft adjuster, preferably a rotary piston adjuster, in particular according to the preamble of claim 1.

Background of the Invention

Rotary piston adjusters require hydraulic fluid to adjust the angle of rotation of the camshaft, which passes through an old rotating bushing from the stationary area of the internal combustion engine into the rotary piston adjuster. The old turning bushing can be combined with a camshaft bearing or designed as a separate unit. The latter requires more construction work and additional length, the combination with a camshaft bearing requires an uninterrupted supply of lubricating oil in order to avoid bearing seizures. The general rule is that the loss of pressure fluid leakage, which is relatively high with conventional oil feedthroughs, should be kept small because of the efficiency. The way there via wide old rotary feedthroughs with long sealing gaps is effective but takes up space and costs.

DE 196 23 818 A1 describes a rotary piston adjuster which has a driven outer rotor with at least one hydraulic chamber and an inner rotor connected to the camshaft with at least one wing has, which seals the hydraulic chamber into two working chambers A, B, which can be acted upon alternately or together with hydraulic fluid. In this rotary piston adjuster, a camshaft bearing is designed as an old turning bushing. Two ring grooves in the camshaft, which are in flow connection with one of the working spaces A and B, are alternately pressurized with hydraulic fluid via a hydraulic valve. The pressure-free time between the switching operations harbors the risk of a bearing eater due to a lack of lubricating oil. In addition, the ring grooves have a large leakage cross-section to the outside and with each other.

Object of the invention

The invention is based on the object of providing a camshaft adjuster according to the preamble of claim 1, which has a reliable, fretting-proof and low-leakage old turning procedure.

Summary of the invention

The object is achieved according to the invention by the characterizing features of claim 1. Since the pressure fluid directly from the pressure source, ie. H. without interruption by a conventional hydraulic valve to which the old turning bushing is passed, its or the camshaft bearing's complete lubrication is ensured. As a result, bearings are avoided more easily. This statement also applies to a separately trained old turning system.

It is advantageous that the control line branches off from the supply line, as seen in the flow direction, before the oil is passed through, and that a preferably electrically controllable throttle element is arranged in the control line. This enables simple cable routing. The pressure in the control line is modulated by the throttle element. To actuate the throttle element, an actuator that is smaller in size than the usual hydraulic valve is sufficient. The throttle element can be designed, for example, as an adjustable throttle or as a pressure reducing valve. A further development of the invention consists in the fact that the distribution element is a valve piston which is arranged coaxially in the inner rotor and can be hydraulically displaced against the force of a second compression spring and is in flow connection with the supply line and the control line. In conjunction with the inner rotor that guides it, this valve piston simply replaces a stationary hydraulic valve, which requires a relatively complex production.

DE 39 22 962 describes a rotary adjuster which also has a valve piston in the inner rotor. However, this valve piston is axially displaced by a stationary electromagnet, which has a considerable axial space requirement. In addition, this valve piston controls only one working chamber at a time, since the other only works under spring load.

In contrast, the hydraulic adjustment of the valve piston according to the invention saves space and enables pressurized fluid to be applied to both working chambers. As a result, the rotation adjuster can also be fixed in intermediate positions.

Because the valve piston can be displaced by the pressure difference between the unthrottled supply line and the throttled control line, normal pressure fluctuations in the hydraulic fluid do not affect the differential pressure and thus the axial position of the hydraulic piston.

It is also advantageous that the valve piston has a central longitudinal bore which is closed by a bottom on the camshaft side and into which radial inlet bores and first control bores and second control bores of the same end. In addition, the inside of the base is preferably under the pressure of the supply line and the outside thereof is preferably under the pressure of the control line and additionally under the force of the second compression spring. This creates a balance between the two different hydraulic pressure forces and the spring force. The control line and the supply line can also be interchanged if the pressure spring is simultaneously moved to the end of the valve piston remote from the camshaft.

Because the control line has a defined leak in the area downstream of the throttle element up to the valve piston, pressure compensation in the control line upstream and downstream of the throttle element is prevented and a modulation of the control pressure is thus only possible.

The necessary leakage in the control line can be achieved by arranging it in the edge area of the old turning bushing. The resulting small sealing gap length up to the edge of the old turning leadthrough causes a natural leakage without leakage holes to be specially made. With regard to the supply line, the old turning leadthrough is particularly low-leakage, since the supply line is arranged in the middle area (long sealing gaps) and in the area of the smallest bearing play of the old turning leadthrough. This largely eliminates the need for steel sealing rings.

It has proven to be advantageous that the throttling intensity is dependent on the engine speed and engine load and also on the pressure level of the hydraulic fluid. The throttle element is controlled by a control unit, which forms an actuating signal for the throttle element as a function of engine speed and load. However, it also detects the pressure of the hydraulic fluid in order to provide short-term correction signals in the event of strong jumps in oil pressure, e.g. B. caused by speed jumps to dampen. As a result, axial vibrations of the valve piston can be avoided, which would lead to torsional vibrations of the adjuster and the camshaft. For reasons of convenience, the hydraulic fluid is usually lubricating oil and its pressure source is the engine's lubricating oil pump.

The fact that a non-return valve opens in the direction of flow of the hydraulic fluid in the central longitudinal bore in the area between the inlet bores and the first control bores or in the first radial bore or in the supply bores, an unwanted backflow of the pressure fluid from the working chambers A and B into the supply line is prevented as a result of the changing torque peaks of the camshaft. The non-return valve, which acts as a hydraulic freewheel, thus increases the torsional stiffness and the rotational position of the rotary piston adjuster.

Further features of the invention result from the patent claims, the following description and the drawings, in which exemplary embodiments of the invention are shown schematically.

Brief description of the drawings

The invention is explained in more detail below on the basis of exemplary embodiments. In the accompanying drawings:

Figure 1 shows a cross section through a vane adjuster with a coaxial valve piston and an Oldreh bushing;

Figure 1a shows the cross section through a vane adjuster of Figure 1, but with a check valve in a valve piston;

Figure 2 shows the section A-A through the old turning implementation of Figure 1.

Detailed description of the drawings

The cross section of FIG. 1 shows a vane adjuster 1 for adjusting the angle of rotation of a camshaft 2. Vane adjuster 1 has an outer rotor 3 and an inner rotor 4. The outer rotor 3 is firmly connected on its side near the camshaft by countersunk screws 5 to a drive wheel 6 and on its side remote from the camshaft by Allen screws 7 with a cover 8. The inner rotor 4 is by means of a central screw 9 firmly connected to the camshaft 2. It has vanes 10 which are guided in radial guide grooves 11 and move back and forth with a sealing play relative to the inner contour of the outer rotor 3, drive wheel 6 and cover 8. A wing pressure spring 12 ensures that the wings 10 rest radially at a standstill. In addition, an axial pin 14 loaded with a first compression spring 13 is provided in the inner rotor 4 and can be snapped into a pocket opening 15 in the cover 8. The axial pin 14 is guided in a pin bore 16 which is vented to the outside through a vent opening 17.

In the central screw 9, which is sealed off from the outside by a round sealing ring 52, a valve piston 18 is sealingly guided in a coaxial blind bore 19. The valve piston 18 is in continuous flow communication with a pressure fluid source 23 via a supply line 20 and a control line 21 as well as an oldreh bushing 22. The control line 21 branches off from the supply line 20, as seen in the flow direction, before the oil passage 22. An electrically controllable throttle element 24 is arranged in the control line 21 before the old turning passage 22. The old turning bushing 22 is designed as a camshaft bearing. The supply line 20 and the control line 21 come into contact with the camshaft bearing in the region of the slightest bearing play. Since the supply line 20 is arranged in the center area of the camshaft bearing and thus has the longest possible sealing gaps, its leakage losses are low. A certain amount of leakage is required in the control line 21 in order to make it possible to lower the pressure at all. This is achieved in a simple manner by the position of the control line 21 in the edge area of the camshaft bearing (short sealing length). In the camshaft 2, the supply line 20 is continued as the supply bore 25 and the control line 21 as the control bore 26. The supply bore 25 opens into a first outer annular groove 27 of the central screw 9. From there, the pressure fluid passes through a first radial bore 28 to a first inner annular groove 29 of the central screw 9. The control bore 26 leads into a control chamber 30 and further to the blind bore 19.

The valve piston 18 sealingly guided in the blind bore 19 has a central tral longitudinal bore 31, which is closed on the camshaft side by a bottom 32. In addition, the valve piston 18 has radial inlet bores 33 and first control bores 34 and second control bores 35, all of which open into the central longitudinal bore 31. In addition, a control piston groove 36 is provided on the circumference thereof. The inside of the base 32 is under the pressure of the supply bore 25 via the first inner annular groove 29 and the inlet bores 33, while the outside of the base 32 is under the pressure of the control bore 26 via the control chamber 30. Furthermore, the spring force of a second compression spring 37 acts on the outside of the base 32. The valve piston 18 is accordingly acted upon by the pressure difference between the supply line 20 and the control line 21 and the spring force of the second compression spring 37.

The central screw 9 is designed as a valve housing. It has a second radial bore 38 with a second inner annular groove 39 and a third radial bore 40 with a third inner annular groove 41 and a fourth radial bore 42. The second radial bore 38 opens into a first inner rotor groove 43 which is in flow connection with the working chamber A. The third radial bore 40 opens into a second inner rotor groove 44, which is in flow connection with the working chamber B. The fourth radial bore 42 is in flow connection via a third inner rotor groove 45 with a tank line 46 and a drive wheel groove 47 as well as the ventilation opening 17.

The throttle element 24 is controlled by a control device, not shown. This forms an actuating signal for the throttle element 24 as a function of engine load and speed. In addition, the pressure of the hydraulic fluid, as a rule the pressure of the lubricating oil, is taken into account in order to dampen the oil pressure jump caused by rapid speed changes.

FIG. 1a shows the cross section of FIG. 1, but with a check valve 53 in the central longitudinal bore 31 of the valve piston 18 in the area between the inlet bores 33 and the first control bores 37, which opens in the direction of flow of the pressure fluid. The check valve til 53 can alternatively be installed in the first radial bore 28 or in the supply bores 25.

FIG. 2 shows a section A-A through the old rotary feedthrough 22 with the indicated motor housing 48 and bearing cover 49. A bearing groove 50 for the supply line 20 and one, but not shown, for the control line 21 are provided in the bearing cover 49. The section through the camshaft 2 shows the supply bore 25 and the central screw 9 with the first outer annular groove 27, the first radial bore 28 and the first inner annular groove 29. In addition, the valve piston 18 is shown with the inlet bores 33 and the central longitudinal bore 31. On the lower circumference of the camshaft 2, the bearing play 51 shown in an exaggerated manner can be seen.

The device according to the invention functions as follows: In FIG. 1, the valve piston 18 is in the control position, ie. H. in the middle position. The valve piston 18 closes the second radial bore 38 and the third radial bore 40. If the control pressure rises more than the supply pressure, the valve piston 18 is displaced in the direction of the end of the blind bore 19. As a result, pressure oil can flow through the first control bores 34 and via the second inner annular groove 39 and the second radial bore 38 into the first inner rotor groove 43 and from there into the working chamber A. At the same time, pressureless oil can flow from the working chamber B via the second inner rotor groove 44 and the third radial bore 40 and the third inner annular groove 41 into the control piston groove 36. From there, the pressureless oil reaches the tank line 46 via the fourth radial bore 42 and the third inner rotor groove 45 and further via the drive wheel groove 47 and the ventilation opening 17 to the outside.

If the control pressure drops more than the supply pressure, the valve piston 18 is displaced in the direction of the camshaft 2. As a result, the pressure oil flows in the direction of the working chamber B and the unpressurized oil flows out of the working chamber A via the vent opening 17 to the outside. In both cases, the supply pressure is continuously applied to the old rotary passage 22 in the supply line 20 and in the supply bore 25. As a result, prevail in the Oldrehdurchführung 22 optimal because constant lubrication. This avoids bearing seizures and increases the reliability of the old turning bushing 22. The controllable throttle member 24 requires a smaller version of the actuator than the usual cartridge valve for actuation, thereby reducing installation space and costs. The guidance of the valve piston 18 is easier to manufacture than the housing of the cartridge valve. The integration of the guide of the valve spool 18 in the inner rotor 4 saves space and costs.

The check valve 53 prevents the hydraulic fluid from flowing back from the working chambers A and B into the supply lines 20. This increases the pressure rigidity and the rotational position of the rotary piston adjuster under the alternating torques of the camshaft.

LIST OF REFERENCE NUMBERS

Vane adjuster 30 28 first radial bore

Camshaft 29 first inner annular groove

External rotor 30 control room

Inner rotor 31 central longitudinal bore

Countersunk screw 32 bottom

Drive wheel 35 33 inlet bore

Allen screw 34 first control hole

Cover 35 second control hole

Central screw 36 spool groove

Wing 37 second compression spring

Guide groove 40 38 second radial bore

Wing pressure spring 39 second inner annular groove first pressure spring 40 third radial bore

Axialpin 41 third inner ring groove

Blind opening 42 fourth radial bore

Pin bore 45 43 first inner rotor groove

Vent opening 44 second inner rotor groove

Valve piston 45 third internal rotor groove

Blind hole 46 tank line

Supply line 47 drive wheel groove

Control line 50 48 motor housing

Oldreh bushing 49 bearing cover

Hydraulic fluid source 50 bearing groove

Throttle body 51 bearing play

Supply hole 52 O-ring

Control bore 55 53 Check valve first outer ring groove

Claims

claims

1. Device for adjusting the angle of rotation of a camshaft of an internal combustion engine, with a camshaft adjuster, preferably a rotary piston adjuster, which has a driven outer rotor with at least one hydraulic chamber and an inner rotor connected to the camshaft with at least one vane which divides the hydraulic chamber into two

Working chambers (A and B) are subdivided, which can be acted upon alternately or together with hydraulic fluid, the hydraulic fluid entering the inner rotor via an old turning bushing serving as a camshaft bearing, characterized in that the old turning bushing (22) via a supply line (20) and a control line ( 21) in continuous

There is a flow connection to a pressure fluid source (23) and that the discontinuous distribution of the pressure fluid to the working chambers (A and B) is carried out by a distribution element arranged in the inner rotor (4).

2. Device according to claim 1, characterized in that the control line (21), viewed in the flow direction, branches off from the supply line (20) before the oil feedthrough (22) and that in the control line (21) a preferably electrically controllable throttle element (24) is attached. is arranged.

3. Device according to claim 2, characterized in that the distributing member is a coaxially arranged in the inner rotor (4), against the force of a second compression spring (37) hydraulically displaceable valve piston (18), which is in flow connection with the supply line (20) and Control line (21) is.

4. The device according to claim 3, characterized in that the valve piston (18) is displaceable by the pressure difference between the unthrottled supply line (20) and the throttled control line (21).

5. The device according to claim 4, characterized in that the valve piston (18) has a central longitudinal bore (31) which is closed on the camshaft side by a base (32) and in the radial inlet bores (33) and first control bores (34) and second control bores (35) of the same open.

6. The device according to claim 5, characterized in that the inside of the bottom (32) preferably under the pressure of the supply line (20) and the outside thereof preferably under the pressure of the control line (21) and additionally under the force of the second compression spring ( 37) stand.

7. The device according to claim 6, characterized in that the control line (26) in the region downstream of the throttle member (24) to the valve piston (18) has a defined leak.

8. The device according to claim 7, characterized in that the control line (21) in the edge region of the old turning bushing (22) and the supply line (20) are arranged in their central region and in the region of the smallest bearing play.

9. The device according to claim 8, characterized in that the throttling intensity is dependent on the engine speed and load and also on the pressure level of the hydraulic fluid.

10. The device according to claim 9, characterized in that the pressure fluid lubricating oil and its pressure source (23) is a lubricating oil pump.

1. Device according to claim 10, characterized in that in each case one check valve (53) opening in the flow direction of the pressure fluid in the central longitudinal bore (31) in the region between the inlet bores (33) and the first control bores (34) or in the first radial bore (28) or in the supply bores (25).