EP1078148B1 - Device for adjusting the phase position of a shaft - Google Patents

Abstract

The device for adjusting the phase position of a shaft, especially a camshaft that can be rotated by a drive shaft, more particularly a crankshaft, by a transmission device with at least one transmission wheel, is configured as a rotary piston machine according to the orbit principle. The inventive device adjusts the rotary position of the transmission wheel in relation to the shaft. The rotary pistol machine includes a stator with inner teeth, an annular rotary piston with outer teeth that engage with the inner teeth of the stator, a driven part that can be rotated by the rotary piston and a valve that can be rotated by the rotary piston and a valve device. In order to control the movement of the rotary piston, the valve device enables rotating partial areas of the working area between the stator and the rotary piston to be joined to a fluid supply device at high or low pressure. The fluid supply device includes a control mechanism, a phase position detector and at least one control valve. It enables a theoretical phase position to be adjusted by actuating the valve in a corresponding manner. Fluidic connection to be adjustment device occurs by two angular rotational connections.

Description

The invention relates to an adjusting device for adjusting the Phase position of a shaft, in particular a camshaft, according to the generic term of claim 1.

The valves of internal combustion engines, in particular reciprocating piston internal combustion engines, are operated by camshafts. The camshafts are from a drive shaft, or from the crankshaft, via a Transfer device set in rotary motion. To the opening and Closing times of valves to the current output and / or To be able to adjust the speed of the engine are transmission devices with adjusters for adjusting the phase position of the camshaft rotation alignment used. Such adjusters enable needs-based influencing the timing of the intake and / or exhaust valves, so that especially the so-called overlap of the valve lift curves can be changed. At the moment it is preferred to use these rotary angle adjusters with the Intake valve camshafts. However, to an increasing extent at the same time the camshafts of the exhaust valves are also rotated.

The adjuster preferably sits between that of a chain or one Timing belt driven camshaft sprocket and the camshaft. Corresponding the respective transmission device would, however, also be one another arrangement of the adjuster, for example between the drive shaft and the drive shaft gear. The relative rotational position between the The camshaft sprocket and the camshaft are in a predetermined angular range variable. A camshaft rotation range of 0 ° is preferably sufficient up to 30 °. In four-stroke engines where the camshaft is at half the speed the crankshaft rotates, this range corresponds to a crankshaft rotation range from 0 ° to 60 °. If both camshafts at the same time are adjustable, one speaks of a double variable camshaft control (Double vanos). It causes a fuller torque curve of the engine and optimizes the mixture preparation so that the pollutants in the exhaust gas be reduced.

The task of the adjuster is to determine the beginning and the end of the Valve stroke through the camshaft from "late" to "early" and vice versa adjust. This must be achievable over a wide engine speed range his. The adjustment should preferably take place continuously and automatically. The Advantages of correct adjustment are: more torque in the lower and medium speed range, less unburned residual gases at idle, Improved idling, lower pollutant emissions, internal exhaust gas recirculation even at low speed, faster warm-up of the catalyst and lower raw emissions after the cold start, special functions for the Mixture adjustment during warm-up, reduced fuel consumption and one lower engine noise.

The invention particularly relates to adjusters which are actuated hydraulically. If necessary, the adjuster is operated by an additional hydraulic pump fed. Preferably, however, a supply by the lubricating oil pump of the Motors are sufficient, which is particularly cost-effective and economical.

The camshaft experiences strong when the valve is actuated Torque fluctuations that the transmission device can withstand got to. A preferred adjuster should have any desired angle adjustment regardless of the torque acting on the camshaft can set and hold for a sufficiently short time. To do this must be Work capacity or its adjustment performance must be correspondingly large. At a Feeding through the lubricating oil pump occurs at high oil temperature and even at low speed of the motor and thus the pump due to problems of the low available oil pressure. It will be high Adjustment speed desired. The required feed pressure and / or Feed flow should be as low as possible. At the same time, the building dimensions should be so small be that no further structural changes to the engine are necessary become. The adjuster should preferably be located radially within the Find the camshaft sprocket and build it axially short.

A known adjuster uses an axially acting hydraulic piston axial adjustment of a sleeve. The sleeve includes an internal and an external helical toothing, the two gears with opposite pitch are trained. The external toothing of the sleeve engages with the Cam gear connected internal teeth and the internal teeth of the The sleeve engages in a toothing connected to the camshaft. Through a axial adjustment of the sleeve becomes an angle adjustment between the Camshaft gear and the camshaft achieved. The adjustment range is because of the limited axial length. If the helix angle is increased, the working piston must have the same transferable torque be enlarged, which in turn leads to a larger piston diameter leads. It also makes the inevitable backlash more effective, which is undesirable due to the periodically changing torques of the camshaft Noise and increased wear. That the Hydraulic piston actuating oil, can be in the wrong during torque peaks Flow direction, especially if at low engine speed the Actuation oil pressure is lower than that of the camshaft torque outgoing squeeze pressure. In this way the adjustment speed and the positioning accuracy is reduced. If this is to be avoided, it must the oil pump can be dimensioned much larger. This leads, in particular at high engine speeds, to higher energy losses. Another disadvantage opposing helical gears are their complex manufacture.

Another known adjuster is designed as a so-called wing adjuster. An outer housing part is firmly connected to the camshaft sprocket and includes radially inwardly projecting areas that form an annulus into subspaces divide. Wings stand from a shaft part fastened to the camshaft radially outwards into a subspace. These wings are laterally and radially on the outside close to the subspace boundary, so that a rotary lobe system arises. By adding oil to one side of all wings and that Draining oil on the other side of all wings can cause a twist can be achieved between the outer housing part and the shaft part. By an integration of the product of radius and working pressure over the A transmission and adjustment torque is determined for the wing surfaces. The more The wings are arranged around the circumference, the higher that is given Oil pressure generated torque. At the same time, however, with a larger number Wing the maximum adjustment angle is reduced, because yes the installation space in Circumferential direction is limited.

When starting the engine and possibly also at a high oil temperature the oil pressure of the lubricating oil pump is too low to torque in the adjuster generate that is greater than the maximum camshaft torques. The Tips of the camshaft torques adjust the rotational position of the adjuster until the wings touch a subspace boundary. Because the camshaft torques oscillate between positive and negative maxima, the If the oil pressure is too low, adjuster away from a desired rotational position alternately deflected in both directions of rotation until the wings touch. This leads to excessive wear and unpleasant noises. To this To reduce the undesirable effect, a braking element is used, for example, that dampens the oscillating movements at low oil pressure.

To adjust and hold the rotary position is an oil supply valve, one Rotational position detection and a control designed so that deviations from a target position can be corrected by an appropriate valve actuation. The required oil pressure and accordingly the leakage-related oil consumption this rotary lobe adjuster is high because the full pressure also holds a set twist position or for transmitting the camshaft torques is needed. Corresponding to that in both directions of rotation occurring maximum camshaft torques occur in the Working areas of the rotary lobe system have high peak values. If the oil supply valve is closed, these high pinch pressures only interfere in the Way that correspondingly high leakage losses occur. In the adjustment phase Open valve can change the oil into the wrong during torque peaks Flow in the direction because, especially at low engine speeds, the Actuation oil pressure is lower than the pinch pressure. In this way the Adjustment speed and positioning accuracy reduced, so that at such engines the oil pump must be dimensioned much larger. This leads to higher ones, especially at high engine speeds Energy losses.

The invention is based on the object of finding an adjuster, each desirable angular adjustment even with torques acting on the shaft, especially in the one transmitted from the valves to a camshaft Torque curve, makes adjustable. His work ability or his Adjustment performance should be as large as possible even at low actuation fluid pressure. At the same time, the construction dimensions and the manufacturing effort should be small.

This object is solved by the features of claim 1. The dependent ones Claims describe alternative or advantageous design variants.

When solving the problem it was recognized that a hydrostatic Rotary piston machine according to the orbit principle also with a deep one Actuating oil pressure makes the required adjustment performance achievable. Such Machines include at least one stator, one rotor or rotary piston, an output part and a valve device, the rotating portions of the Working space between stator and rotor connects with high and low pressure. The number of teeth on the internal teeth of the stator is preferably one than that of the external toothing of the rotary piston. The individual components a rotary piston machine can be done with little effort, in particular by means of sintered. The ring-shaped machine parts and the work area take up little space. An adjuster according to the invention is preferred be placed directly between the camshaft and the camshaft sprocket, wherein the camshaft gear is in particular formed directly on the stator, so that only an extremely small additional installation space is required.

Another advantage is that an arbitrarily large change in rotational position or twisting between a shaft and a shaft wheel sitting on it is achievable. By designing the rotary position adjuster as a rotary piston machine or hydraulic motor with two ring-shaped rotary connections for starting and closing Discharge of pressure fluid can, for example, in addition to Camshafts require adjustment tasks in other applications Take over the drive task. That is the adjuster according to the invention both as an alignment or positioning unit and as a movement unit rotating shafts can be used. In the most general case, the Phase position and / or the rotational speed of a width that of a Drive shaft via a transmission device with at least one on one Shaft-mounted transmission wheel is rotatable, the rotational position or Speed of rotation of the transmission wheel relative to the shaft with pressurized fluid, the can be fed in and out via two ring-shaped rotary connections. to Actuation is a fluid supply device with a controller, a Rotational position or rotational speed detection and at least one Control valve inserted so that the setting of a target rotational position or - Speed, or acceleration by a corresponding Valve actuation can be achieved.

If only the phase position of a camshaft within a predetermined Angle range should be adjustable, especially a sufficiently large Drive torque required even with low fluid or oil pressure. Preferably a rotary piston machine is now provided, in which the rotation transmission from Rotary piston on the driven part with the speed ratio 1: 1. The Valve device of the rotary piston machine then preferably includes the Output part rotating, in particular formed thereon, first and second, evenly distributed over the circumference. radial valve channels with inner Connection areas of radial, evenly distributed over the circumference, Interact stator channels. The outer connection areas of the Stator channels open between the teeth of the internal teeth of the stator the workspace. The number of first and second valve channels differs differ from the number of stator channels by one channel, so that the inner Connection areas of the stator channels in a first circumferential partial area first valve channels and in a second circumferential section with second Valve channels are connected. The first valve channels are via an inner one Ring channel in the output part to the one ring-shaped rotary connection and the second valve channels via a space between the output part and the Rotary pistons and an outer connecting channel in the stripping section to the others circular rotary connector connected.

To a speed ratio of 1: 1 between the rotary piston and the To achieve the output part, there must be a power transmission between the rotating Eccentricity around the axis of the driven part and the rotary piston Output part are formed. According to CH 676 490, the force or Torque transmission, for example with a cardan shaft. This would lead to a large overall length in the axial direction. Another, in the transmission device mentioned in CH 676 490 comprises a coupling by means of bolts, which in one part have matching bores and in the other part in bores with twice the eccentricity larger diameter than that Bolt diameters are added. The bolts roll during rotation transmission along the boundary surfaces of the larger holes. This too Bolt transmission leads to an increased overall length in the axial direction. A preferred solution according to CH 676 490 due to the small overall length an internal toothing on the rotary piston and an external toothing on the driven part. Around to ensure that with a driven part driven by the rotary piston, whose axis of rotation can be stationary, interacting teeth with Tooth contours are provided, which are adapted to the existing eccentricity.

It has now been shown that in the transmission of rotation between the rotary piston and Output part with an internal and an external toothing a self-locking Effect is achieved between the stator and the driven part. That means an on the driven part torque is applied to the rotary piston Stator transmitted. Because the rotary piston practically does not rotate is displaceable, it is an essentially form-fitting Torque transmission, in particular through an approximation of the Tooth contour to a triangular shape can still be increased. The adjuster can can only be adjusted in its angle of rotation position by supplying oil, however not by applying torque from the outside. This ensures that high torque peaks of the camshaft do not lead to high crushing pressures can lead the working chambers of the hydraulic system and that for the Normal operation, i.e. if there is no angle adjustment, no support pressure for the torque transmission is necessary. During the adjustment-free Phases essentially no oil leakage occurs, resulting in a small one medium oil throughput. In addition, during the adjustment-free Phases of an accumulator are pressurized with oil, which is then in Adjustment phases is available. This would remove the oil pressure pump required amount of pressure oil reduces what the requirements for the pump and reduced according to their power loss.

The adjuster is preferred for adjusting the camshaft phase position on the camshaft, but possibly on the drive or on one additional transmission shaft arranged.

The preferred adjusters work according to the orbit principle in the High-pressure hydraulics known high-torque hydraulic motors. This results in an extremely high work capacity. The rotational position is adjusted stepless and has no angle restriction. Because of the interlocking Tooth shapes, and the trained in the preferred designs Self-locking, no beating noises occur. In addition, they are adjusters according to the invention are simple to manufacture and require only a few Parts.

In the above-mentioned and described below using the example Embodiment with an output part that with the speed of the rotary piston is rotatable about a fixed axis and in particular a control part of the Valve device includes, it is a solution that also as advantageous, slow-running hydraulic motor can be used. It goes without saying even that such a slow-running hydromotor also with a fixed arranged output part and a rotating stator can be formed. In this case, rotating connections could then be dispensed with. Slow speed, In particular, hydraulic motors arranged on shafts can, for example can be used advantageously as drives in machine tools.

Fig. 1

einen vertikalen Schnitt entlang der Nockenwellenachse durch einen an der Nockenwelle befestigten Versteller

Fig. 2

einen vertikalen Schnitt E-E gemäss Fig. 1

Fig. 3

einen vertikalen Schnitt D-D gemäss Fig. 1

Fig. 4

einen vertikalen Schnitt C-C gemäss Fig. 1

Fig. 5

eine Ansicht des Nockenwellenendes mit dem Versteller

The drawings explain the invention using an exemplary embodiment. It shows

Fig. 1

a vertical section along the camshaft axis through an adjuster attached to the camshaft

Fig. 2

a vertical section EE according to FIG. 1

Fig. 3

2 shows a vertical section DD according to FIG. 1

Fig. 4

a vertical section CC according to FIG. 1st

Fig. 5

a view of the camshaft end with the adjuster

1 shows an adjuster 1, which is attached to a free end of a camshaft 2 is arranged. The adjuster 1 is designed as a rotary piston machine and includes at least one driven part 3, a rotary piston 4 and one Stator 5. An external toothing 6 of the stator 5 forms the camshaft gear 6 ', which could possibly also be attached to the stator 5 as a separate part. By rotating the rotary piston 4 by one Camshaft axis 2a rotating eccentric axis is a twist between Stator 5 and stripping section 3 achieved. About this rotary piston rotation to drive, a part of working chambers 7 between the stator 5 and the rotary piston 4 selectively fed pressurized fluid or oil under pressure and out another part of working chambers 7 fluid can be drained. The Working chambers 7 are formed according to FIG. 2 between a stator internal toothing 5a and a circular piston external toothing 4a. The is preferably Number of teeth of the stator internal teeth 5a twelve and those of the rotary piston external teeth 4a eleven. The rotary motion of the rotary piston is caused by the fluid supply-related expansion of the working chambers 7 of the one Half of the circumference and the corresponding reduction in the size of the working chambers 7 other half of the circumference. To control the fluid supply or the To connect working chambers 7 so rotating with high or low pressure that the desired rotary piston movement is a valve device intended.

The valve device comprises a rotating with the speed of the rotary piston 4 (FIG. 3) and a channel system that is firmly connected to the stator 5 (FIG. 4). Because the rotating channel system of the illustrated embodiment on the driven part 3 2, the driven part 3 is preferably by the Interaction of an external output gear 3a and a rotary piston internal gear 4b rotated. The rotary transmission from the rotary piston 4 on the output part 3 takes place with the speed ratio 1: 1, which is why Number of teeth of the output external gear 3a with that of the rotary piston internal gear 4b matches. It is also shown in the Embodiment also the number of teeth of the circular piston outer toothing 4a same size as that of the circular piston internal teeth 4b. The valve device comprises with the driven part 3 rotating, preferably formed thereon, first 8 and second 9, radial evenly distributed over the circumference Valve channels, with inner connection areas 10 of radial, even Distributed over the circumference, stator channels 11 cooperate, the outer Connection areas 12 between the teeth of the internal teeth 5a of the stator 5 open into the working chambers. The number of the first or second Valve channels 8, 9 differ from the number of stator channels 11 by a channel so that the inner connection regions 10 of the stator channels 11 in a first peripheral portion with first valve channels 8 and in a second Circumferential portion are connected to second valve channels 9. The inner ones and outer connection areas 10 and 12 of the stator channels 11 are bores by a control disk 19 firmly connected to the stator 5 educated. The stator channels 11 are preferably as recesses in the outside Stator cover 20 formed.

The first valve channels 8 close via an inner ring channel 13 in the Output part 3 and in the camshaft 2, and at least one first Radial bore 15a to an annular first rotary connection 14a. The second valve channels 9 close via a space 16 between the Output part 3 and the rotary piston 4, an outer connecting channel 17 in Output part 3 and a radial bore 15b in the camshaft 2 to a second annular rotary connector 14b. In the axial direction on both sides of the Rotary connections 14a and 14b are ring grooves 18 for receiving Sealing elements formed.

The stator housing includes the outer stator cover 20 Control disc 19, the stator 5 and an inner stator cover 21st The stator housing is held together by screws 22. The rotary piston 4 is in the axial direction with the inside of the control disc 19 and the inside Stator cover 21 in sliding contact. The stator housing is in Axial direction rotatably held on abrasion part 3. The driven part 3 is non-rotatable connected to the camshaft 2, preferably one on the Camshaft 2 screwed, axially arranged screw part 23 through a Output end part 24 and the output part 3 extends. Between the Screw part 23 and the driven part 3, the inner ring channel 13 is formed. The stator housing is in an annular groove between the driven end part 24 and the driven part 3 rotatably and by means of a sealing unit 25th sealed to the outside. To form a rotary guide or seal for the inner stator cover 21 is a guide ring 26 between the Output part and the camshaft end inserted.

For applications in which the rotational position adjustment to a predetermined Angular range is limited, is preferably between the Output end part 24 and the outer stator cover 20 a Range of rotation limitation formed. This includes, for example, two radially outwardly projecting end part abutment surfaces 27 each one Stator stop surface 28 is assigned so that the adjustment only within a predetermined range of rotation angle is possible. By arranging the The range of rotation of the outer stator cover 20 is one simple visual inspection shows in which rotational position the camshaft 2 is.

The stator 5 with the internal toothing and / or the rotary piston 4 and / or the Output part 3 and / or the stator cover 20, 21 are preferably in powder metallurgical process. If necessary, a rotary piston 4 used from plastic. To reduce the weight are in Rotary piston 4 optionally formed axial cavities 29.

Claims (13)

1. An adjusting device (1) for adjusting the phase position of a shaft, especially a camshaft (2), which can be caused to rotate by a drive shaft, in particular a crankshaft, via a transmission device having at least one transmission wheel (6') located on a shaft, the adjusting device making it possible to adjust the rotational position of the transmission wheel (6') relative to the shaft (2) by means of hydraulic fluid which can be fed in and removed via two annular rotational connections (14a, 14b) and a fluid supply device comprising a control, a rotational position detector and at least one control valve making it possible to set a setpoint rotational position by a corresponding valve actuation, wherein the adjusting device (1) is a rotary piston machine based on the orbit principle, which comprises a stator (5) having an inner gear (5a), an annular rotary piston (4) having an outer gear (4a) engaging the inner gear of the stator (5a), a driven part (3) which can be caused to rotate by the rotary piston (4) and a valve device (8-12), which, for controlling the rotary piston movement, makes it possible to connect rotating regions of the working area (7) between stator (5) and rotary piston (4) to high or low pressure of the fluid supply device.
2. The adjusting device (1) as claimed in claim 1, wherein the number of teeth of the inner gear of the stator (5a) is greater by one than that of the outer gear of the rotary piston (4a).
3. The adjusting device as claimed in claim 1 or 2, wherein the transmission of rotation from the rotary piston (4) to the driven part (3) is effected with the speed ratio 1:1 and the valve device (8-12) comprises first and second, radial valve channels (8, 9) which rotate with the drive part (3), are preferably formed thereon, are uniformly distributed over the circumference and cooperate with the inner connection regions (10) of radial stator channels (11) which are uniformly distributed over the circumference and whose outer connection regions (12) open into the working area (7), between the teeth of the inner gear of the stator (5a), the number of first or second valve channels (8, 9) differing from the number of stator channels (11) by one channel in each case, so that the inner connection regions (10) of the stator channels (11) are connected in a first circumferential segment, to first valve channels (8) and, in a second circumferential segment, to second valve channels (9).
4. The adjusting device as claimed in claim 3, wherein the first valve channels (8) connect via an inner annular channel (13) in the driven part (3) to one annular rotational connection (14b) and the second valve channels (9) connect via a space (16) between the driven part (3) and the rotary piston (4) and an outer connecting channel (17) in the driven part (3) to the other annular rotational connection (14a).
5. The adjusting device as claimed in claim 3 or 4, wherein the inner and outer connection regions (10, 12) of the stator channels (11) are formed in a plate cam (19) firmly connected to the stator (5) and the stator channels (11) are preferably formed as depressions in the stator cover (20).
6. The adjusting device as claimed in any of claims 1 to 5, wherein an outer gear of the driven part (3a) engages an inner gear of the rotary piston (4b), preferably the number of teeth and/or the tooth shapes being chosen so that the rotational connection between the driven part (3) and the stator (5) is self-locking, so that each rotational position is essentially held in an interlocking manner even in the absence of hydraulic fluid and at high torques between the stator (5) and the driven part (3).
7. The adjusting device as claimed in claim 6, wherein the two gears of the rotary piston (4a, 4b) have identical numbers of teeth, this number of teeth preferably being eleven and in particular the number of teeth for the inner gear of the stator (5a) being twelve.
8. The adjusting device as claimed in any of claims 1 to 7, wherein axial cavities (29) are formed in the rotary piston (5) for reducing the weight.
9. The adjusting device as claimed in any of claims 1 to 8, wherein the stator part having the inner gear (5a) and/or the rotary piston (4) and/or the driven part (3) and/or the stator cover (20, 21) are produced by the powder metallurgical process.
10. The adjusting device as claimed in any of claims 1 to 9, wherein the rotary piston (4) is produced from plastic.
11. The adjusting device as claimed in any of claims 1 to 10, wherein the driven part (3) can be nonrotatably connected to the camshaft (2), an axially arranged screw part (23) screwed to the camshaft (2) preferably extending through a driven end part (24) and the driven part (3), the stator (5) being held in particular in an annular groove between the driven end part (24) and the driven part (3) and optionally consisting of four parts held together by means of screws, namely a first and a second stator cover (20, 21), a plate cam (19) and a gear part (5).
12. The adjusting device as claimed in claim 11, wherein a rotational range limiting means is formed between the driven end part (24) and the stator cover (20), preferably in the form of two end part stop surfaces (27) which project radially outward and with each of which a stator stop surface (28) is coordinated so that the adjustment is possible only within a predetermined rotary angle range.
13. The adjusting device as claimed in any of claims 1 to 12, wherein the transmission wheel (6') is fastened on the stator (5), in particular is formed directly thereon, the transmission wheel (6') preferably comprising a chain gear or toothed-belt gear.

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