DE102014209865B4 - Camshaft adjuster with additional switchable short-circuit device - Google Patents

Abstract

Camshaft adjuster (1) for an internal combustion engine of a motor vehicle, with a stator (2) and with a rotor (4) which is accommodated within the stator (2) rotatably mounted relative to this and at least one rotor blade (5), which between the Stator (2) and the rotor (4) a first hydraulic chamber (6) and a second hydraulic chamber (7) is formed, which are hydraulically connected to one hydraulic line (8 and 9) and pressurized via this, and with a locking device (19 ) for causing a central locking of the rotor (4) relative to the stator (2), wherein in the at least one rotor blade (5) a hydraulic bypass (23) between the first and the second hydraulic chamber (6 and 7) for fluid transmission is provided is selectively releasable for reaching the center locking position, wherein the first and the second hydraulic chamber (6 and 7) via a further switchable Kurzschlusseinricht ung (24) are fluid-communicable with each other, characterized in that the further switchable Kurschlusseinrichtung (24) in a hydraulic central valve (10) of the camshaft adjuster (1) is integrated

Description

The invention relates to a camshaft adjuster for an internal combustion engine of a motor vehicle, such as a car, truck or other commercial vehicle, with a stator and a rotor which is rotatably supported within the stator relative to this and at least one rotor blade, which between the stator and the rotor forms a first hydraulic chamber and a second hydraulic chamber, which are hydraulically connected to a respective hydraulic line and optionally pressurizable, and with a locking device for locking the rotor and stator, wherein in the at least one rotor blade, a hydraulic bypass between the first and the second hydraulic chamber is provided for fluid transmission, which is selectively releasable for reaching the center locking position.

Such camshaft adjusters, for example in the manner of a vane-type adjuster, are already generally known from the prior art. They serve the load and / or speed-dependent controlled / controlled adjusting a camshaft of an internal combustion engine during their operation.

It is also known from the prior art that it is in certain operating phases of the internal combustion engine, for example, when stopping the same, so when stopping the engine. It may be useful to prevent an adjustment of the rotor relative to the stator. For this purpose, the camshaft adjuster can have a locking device with which the rotor and stator, for example in a center locking position, can be locked together if necessary. To reach the center locking position, it is necessary depending on the current position of the rotor, to rotate the rotor relative to the stator in a certain direction. Since a camshaft adjuster functioning in the manner of a vane-type adjuster has hydraulic chambers which are subjected to more or less hydraulic pressure during operation of the camshaft adjuster, a certain hydraulic adjusting resistor must be overcome for rotating the rotor. This adjustment is particularly due to the under hydraulic pressure hydraulic chambers.

In order to make the achievement of the center locking position by turning the rotor comparatively smoother, hydraulic bypasses are also proposed in the prior art, which are provided for fluid transmission between the mutually adjacent hydraulic chambers. For this, the hydraulic bypasses can be arranged in the rotor blades extending between the hydraulic chambers to be connected. Although these bypasses allow comparatively easier access to the center locking position, there is still a need for improvement in this regard.

The post-published DE 10 2013 207 615 A1 shows a Nockenwellenverstelleinrichtung with a vane with a connectable to a crankshaft of an internal combustion engine stator, and rotatably mounted in the stator, connectable to a camshaft rotor, and a center locking device for locking the rotor in a center locking position relative to the stator wherein in one or more of the wings together at least two pressure medium lines are provided, which each fluidly connect two working chambers of different effective direction, wherein in the pressure medium lines each check valves of different effective direction are provided, each depending on the direction of rotation of the rotor to the stator an overflow of the pressure medium in a direction between the working chambers allow and prevent in the other direction, and in the rotor hub at least a first switchable valve device is provided übe r which the working chambers, between which the overflow of the pressure medium is prevented in each case via the check valve, or between which no check valve is provided, are fluidically connectable to each other in a switching position.

The object of the invention is therefore to provide a camshaft adjuster, in which the adjustment resistance for a smoother and / or a faster reaching the center locking position can be further reduced using constructively simplest possible means.

This object is achieved in a generic camshaft adjuster according to the invention in that the first and the second hydraulic chamber via a further switchable short-circuit device are connected to each other fluid-transmitting.

This means that the camshaft adjuster has, in addition to the hydraulic bypass provided in the at least one rotor blade, also another, preferably in case of need (to) switchable, short-circuiting device. With this short-circuit device, the flow rate and / or the flow rate of a hydraulic fluid to be exchanged between the first and the second hydraulic chamber can be additionally increased. By this increase in exchanged between the hydraulic chambers or exchangeable amount of hydraulic fluid to be overcome the resistance to be overcome during rotation of the rotor or its at least one rotor blade against the stator effectively. This happens because the one hydraulic chamber, which is reduced in volume by the rotation of the at least one rotor blade, at least a portion of the hydraulic fluid therein both by the bypass and the other (optional) (to) switchable short-circuit device to the other, in terms of volume larger can give off expecting hydraulic chamber.

Thus, if the rotor of the camshaft adjuster is rotated in a certain direction of rotation in order to achieve a center locking position with respect to the stator, the adjustment resistance to be overcome for this, which is caused by the hydraulic fluid located in both hydraulic chambers and substantially incompressible, can be reduced by the hydraulic fluid can be displaced from one hydraulic chamber into the other hydraulic chamber both via the bypass and via the further switchable short-circuit device. By further in case of need (to) switchable short-circuiting device thus reaching the center locking position is facilitated by rotation of the rotor relative to the stator in a structurally simple manner by reducing the Verstellwiderstands to be overcome for this purpose and accelerated.

This positive effect of the camshaft adjuster according to the invention has an advantageous effect even at comparatively low hydraulic fluid and / or external temperatures, in which the hydraulic fluid is comparatively viscous, ie has a comparatively high viscosity. Because of the additionally releasable fluidic communication path between the two hydraulic chambers, despite a comparatively high viscosity, a rapid rotation of the rotor into the center locking position for locking the rotor and the stator can be achieved.

The short-circuit device can selectively or alternately act in both possible adjustment directions of the camshaft adjuster or the camshaft to be adjusted, namely in the direction of "early" in which the intake and / or exhaust valves of the internal combustion engine open earlier, in particular before top dead center (TDC) , and in the direction of "late", in which open the intake and / or exhaust valves of the internal combustion engine later, in particular after top dead center (TDC).

The locking device for locking the rotor and the stator in the center can be effected, for example, by one or more locking pistons or locking pins, which can be brought into mechanical engagement with a locking counterpart. For example, the locking pistons or locking pins may be pressurized by a hydraulic control line or a hydraulic control channel during normal operation of the camshaft adjuster or the internal combustion engine in a non-locked (switching) position. Furthermore, they can be actuated or switched, for example, by a spring force into a locked (switching) position. For example, the one or more locking pistons or locking pins can be designed as a hydraulic 2/2-way valves.

So it is for the simplest possible structural design and for the lowest possible hydraulic losses of the camshaft adjuster advantageous if the Kurschlusseinrichtung is integrated in a hydraulic central valve of the camshaft adjuster. In this case, the integration of the short-circuiting device can be embodied, for example, in the form of a hydraulic circulation arranged in or on the central valve. The connection or activation of the hydraulic circulation can take place in dependence of the respective switching position of the central valve.

Advantageous embodiments are claimed in the subclaims and are explained in more detail below.

Such a hydraulic, possibly electromagnetically actuated and / or spring-biased central valve is provided in a camshaft adjuster to control, for example, the pressurization of the hydraulic chambers formed in the camshaft adjuster via two (switchable) hydraulic connections and / or to regulate. Such a hydraulic valve may have a hydraulic connection for a hydraulic pump for conveying the hydraulic fluid and a (switchable) hydraulic tank connection to the hydraulic fluid reservoir. For example, the hydraulic central valve can be designed as a hydraulic actuator in the form of a designed depending on the purpose directional control valve, for example, a 4 / 4-, or a 5/4-way valve. It is also possible that more or fewer switching positions and a lower or higher number of terminals are provided.

For example, a switching position of the hydraulic central valve, a short-circuit position, in which the first and second chambers are fluid-transmitting connected, and a further switching position to be a blocking position, in which the first and the second chamber not at all or only on the in the at least one rotor blade provided bypass fluid-communicating with each other.

It may therefore be advantageously provided that the short-circuiting device according to the invention is integrated into the possibly present anyway hydraulic central valve. This offers the advantage that little or no constructive measures must be taken to integrate the invention, further (to) switchable short-circuit device in the camshaft adjuster.

The direct integration into the central valve, it is also possible that already an exchange of hydraulic fluid between the (not supporting) short-circuiting hydraulic chambers takes place before the bypass is released in the at least one rotor blade via a hydraulic actuator or a control pin of the bypass. A further advantageous effect is that no hydraulic fluid is conducted or pressed through a connection to the hydraulic supply in the camshaft adjuster. Thus, it can be prevented, in particular with cold hydraulic fluid and / or outside temperatures, that the bypasses arranged in the rotor blades are additionally stressed by the hydraulic pressure still present in the camshaft adjuster.

It is also advantageous if the short-circuit device is automatically switchable between a short-circuited position and a blocking position as a function of a hydraulic pressure prevailing in the camshaft adjuster. For example, a prevailing in a control channel hydraulic pressure for the switching back and forth of the short-circuiting device are used, so that no additional control device must be provided. A switch back to the other position, for example, by a correspondingly directed spring preload, for example, a compression spring, the short-circuiting device.

In order to automatically switch the short-circuit device into its short-circuit position, for example when the engine is stopped, it is advantageous if the short-circuit device connects the first and the second hydraulic chamber in a fluid-transmitting manner when and / or falls below a certain hydraulic pressure threshold value. Thus, if the hydraulic pressure prevailing in the camshaft adjuster during operation of the internal combustion engine drops due to an engine stop initiated and an associated speed reduction of an oil pump, the short-circuiting device can automatically be switched into the short-circuited position.

• 1 einen schematisch dargestellten hydraulischen Schaltplan eines ersten Ausführungsbeispiels eines Nockenwellenverstellers mit einer Kurzschlusseinrichtung, wobei sich der Nockenwellenversteller im Normalbetrieb und die Kurzschlusseinrichtung in einer Sperrstellung befinden,
• 2 einen schematisch dargestellten hydraulischen Schaltplan eines ersten Ausführungsbeispiels eines Nockenwellenverstellers mit einer Kurzschlusseinrichtung, wobei sich der Nockenwellenversteller in eine Mittenverriegelungsposition bewegt und sich die Kurzschlusseinrichtung in einer Kurzschlussstellung befindet,
• 3 einen schematisch dargestellten hydraulischen Schaltplan eines ersten Ausführungsbeispiels eines Nockenwellenverstellers mit einer Kurzschlusseinrichtung, wobei sich der Nockenwellenversteller in eine Mittenverriegelungsposition bewegt und sich die Kurzschlusseinrichtung in einer Kurzschlussstellung befindet,

The invention will be explained in more detail with the aid of a drawing. In this case, a first and a second embodiment are shown. Show it:

• 1 a schematically illustrated hydraulic circuit diagram of a first embodiment of a camshaft adjuster with a short-circuiting device, wherein the camshaft adjuster in normal operation and the short-circuiting device are in a blocking position,
• 2 a schematically illustrated hydraulic circuit diagram of a first embodiment of a camshaft adjuster with a short-circuiting device, wherein the camshaft adjuster moves into a center locking position and the short-circuiting device is in a short-circuited position,
• 3 a schematically illustrated hydraulic circuit diagram of a first embodiment of a camshaft adjuster with a short-circuiting device, wherein the camshaft adjuster moves into a center locking position and the short-circuiting device is in a short-circuited position,

The figures are merely schematic in nature and are only for the understanding of the invention. The same elements are provided with the same reference numerals. Features of the individual embodiments can be interchanged.

The 1 to 3 show in each case a schematically illustrated hydraulic circuit diagram, a first embodiment of a camshaft adjuster 1 , which is provided for the controlled / controlled adjustment of a camshaft of an internal combustion engine of a motor vehicle.

According to 1 has the camshaft adjuster 1 a stator 2 with a variety of dividers 3 on, each in the radial direction of the stator 2 extend inwards and those in 1 a total of five are shown. In addition, the camshaft adjuster has 1 over a rotor 4 that is inside the stator 2 is added relative to this rotatably mounted.

The rotor 4 has a plurality of rotor blades 5 on, which are arranged evenly distributed over its circumference and of which in 1 a total of four are shown. The rotor blades 5 extend inside the stator 2 and its dividers 3 such that the volume space between two adjacent separating webs 3 through one of the rotor blades 5 is separated at least approximately fluid-tight. This will be through the stator 2 and the rotor 4 a plurality of each of a first hydraulic chamber 6 and a second hydraulic chamber 7 trained, of which in 1 a total of four are shown.

Every first hydraulic chamber 6 is with a possibly designed as an annular channel, the first hydraulic channel 8th fluidly connected or connected to this, via the respective first hydraulic chamber 6 a possibly pressurized hydraulic fluid can be supplied or can be discharged therefrom. In addition, every second hydraulic chamber is 7 with a possibly designed as an annular channel, the second hydraulic channel 9 fluidly connected, via the respective second hydraulic chamber 7 a possibly pressurized hydraulic fluid can be supplied or can be discharged therefrom.

The first Hydraülikkanal 8th and the second hydraulic channel 7 are by a hydraulic actuator in the form of a hydraulic central valve 10 adjustable / controllable. According to 1 has the here as electromagnetically actuated 5/4-way valve designed central valve 10 via a switchable first hydraulic connection 11 and a switchable second hydraulic port 12 , Thus, the supply or discharge of a hydraulic fluid and possibly in the hydraulic channels 8th . 9 as well as in the first and second hydraulic chambers 6 . 7 prevailing hydraulic pressure controllable / controllable. The hydraulic central valve 10 also has a switchable, third hydraulic connection 13 for connection to a hydraulic pump 14 for conveying the hydraulic fluid and a switchable fourth hydraulic connection 15 for connecting a hydraulic fluid reservoir 16 on.

Next goes out 1 apparent that the hydraulic central valve 10 a switchable fifth hydraulic connection 17 for a connection to a control channel 18 having:

The possibly executed as a ring channel control channel 18 is on the one hand with a locking device 19 for center locking of the stator 2 and the rotor 4 fluidly connected.

This locking device 19 has a plurality of locking pins, designed as hydraulic actuators, of which in 1 a first and a second locking pin 20 . 21 are shown. These are axially displaceable in the rotor 4 stored. According to 1 are the locking pins 20 . 21 designed as (pressure) spring-biased hydraulic actuators in the form of a 2/2-way valve. Here is the first locking pin 20 with the first hydraulic channel 8th hydraulically connected and is thus with each of the first hydraulic chambers 6 connectable. The second locking pin 21 is with the second hydraulic channel 9 hydraulically connected and thus is also with each one of the second hydraulic chambers 7 connectable.

Furthermore, the locking device has 19 via a locking link 22 of the stator 2 with which the locking pins 20 . 21 in a center locking position of the rotor 4 opposite the stator 2 optionally be brought into mechanical engagement and detachable from it. Here are the locking pins 20 . 21 then in mechanical engagement with the locking link 22 brought or brought, if in the control channel 18 prevailing hydraulic pressure is lower than the spring preload of the locking pins 20 . 21 , If the in the control channel 18 prevailing hydraulic pressure, however, is higher than the spring preload of the locking pins 20 . 21 , these are as in 1 shown, from the mechanical engagement with the locking link 22 solvable or solved.

The control channel 18 on the other hand with a variety of hydraulic bypasses 23 fluidly connected, one of which in each of the plurality of rotor blades 5 of the rotor 4 is arranged. According to 1 is the multitude of bypasses 23 each designed as a spring-biased hydraulic actuator in the form of a 2/2-way valve. In the in 1 shown, first switching position of the respective bypass 23 are the respective first hydraulic chamber 6 and the respective second hydraulic chamber 7 separated from each other at least approximately fluid-tight, that is, the fluid-transmitting connection is shut off. In a second switching position of the respective bypass 23 are the respective first hydraulic chamber 6 and the respective second hydraulic chamber 7 at least in a flow direction fluidly connected to each other. There is every hydraulic bypass 23 then in the in 1 shown, first switching position brought or brought, if the in the control channel 18 prevailing hydraulic pressure is higher than the spring preload of each hydraulic bypass 23 , Is the spring preload of the respective hydraulic bypass 23 but higher than the control channel 18 prevailing hydraulic pressure, is every hydraulic bypass 23 can be brought or brought into the fluid-conducting, second switching position.

In addition, the camshaft adjuster points 1 one to the variety of hydraulic bypasses 23 additional, that is another switchable short-circuit device 24 for fluid-conducting connection of the first hydraulic chambers 6 and the second hydraulic chambers 7 on.

In the in the 1 to 3 The first embodiment shown is the short-circuiting device 24 as a hydraulic circuit 25 in the hydraulic central valve 10 integrated. It can be seen that there is a switching position of the hydraulic central valve 10 there, namely the in 1 extremely left, in the first hydraulic channel 8th and the second hydraulic channel 9 over the hydraulic circuit 25 are fluidly connected to each other. Consequently, the respective first and second hydraulic chambers are also 6 . 7 by means of the short-circuiting device 24 or the hydraulic circulation 25 if necessary, fluid-conductively connected to one another. In the remaining, here altogether three switching positions of the hydraulic central valve 10 are the first hydraulic channel 8th and the second hydraulic channel 9 and thus the respective first and second hydraulic chambers 6 . 7 separated from each other at least approximately fluid-tight.

The operation of the camshaft adjuster 1 and the short-circuit device 24 According to the first embodiment can as follows using the 1 to 3 explained expire.

1 shows the camshaft adjuster 1 and as a hydraulic circuit 25 trained short-circuit device 24 in their normal operating state. This means that the internal combustion engine equipped with it is in normal operation, wherein the phaser 1 while a load- and / or speed-dependent controlled / controlled adjustment of the camshaft makes. In this normal operating state is the short-circuit device 24 in a blocking position, in which the first hydraulic channel 8th and the second hydraulic channel 9 and hence the respective first and second hydraulic chambers 6 . 7 are separated approximately fluid-tight from each other. In particular, the hydraulic circuit 25 not switched or deactivated in this operating state.

2 shows the camshaft adjuster 1 in an operating condition in which the rotor 4 in its center locking position for activating the locking device 19 should be brought. The operating state may be, for example, an engine stop of the internal combustion engine. This requires the rotor 4 from a rather "late" adjustment direction into an in 2 right side, rather "early" adjustment brought or twisted so that the locking pins 20 . 21 in a position suitable for locking with respect to the locking link 22 are located. Due to the (residual) pressure in the first and second hydraulic chambers 6 . 7 must this rotation of the rotor 4 take place in its center locking position against a certain adjustment.

In 2 it can be seen that the hydraulic bypasses 23 due to the hydraulic pressure in the control channel, which gradually dissipates in this operating state 18 and in contrast, the spring preload increasing in each case in the fluid-transmitting, first switching position. Accordingly, there is a fluid transfer between the first hydraulic chambers 6 and the second hydraulic chambers 7 possible, allowing for a rotation of the rotor 4 to be overcome adjusting resistance is reduced.

Since this adjustment is still comparatively high; is additionally the short-circuit device 24 in the form of hydraulic circulation 25 switched or activated and is located as in 2 recognizable, in a short-circuited position, in which the first hydraulic channel 8th and the second hydraulic channel 9 and hence the respective first and second hydraulic chambers 6 . 7 over the hydraulic circuit 25 are fluidly connected to each other. Through this additionally created exchange of hydraulic fluid between the hydraulic chambers 6 . 7 the displacement resistance is further reduced, so that the rotor 4 comparatively smooth and swiftly rotatable in the center locking position.

3 shows that by means of 2 already described functional principle with activated short-circuit device 24 or activated hydraulic circulation 25 in the opposite direction of adjustment. That means that the rotor 4 in 3 from a rather "early" adjustment of the camshaft adjuster 1 is twisted in a rather "late" adjustment, the resistance to be overcome for this is comparatively low.

LIST OF REFERENCE NUMBERS

1

Phaser

2

stator

3

Variety of dividers

4

rotor

5

Variety of rotor blades

6

Variety of first hydraulic chambers

7

Variety of second hydraulic chambers

8th

first hydraulic channel

9

second hydraulic channel

10

hydraulic central valve

11

first hydraulic connection

12

second hydraulic connection

13

third hydraulic connection

14

hydraulic pump

15

fourth hydraulic connection

16

Hydraulic fluid reservoir

17

fifth hydraulic connection

18

control channel

19

locking device

20

locking pin

21

locking pin

22

locking link

23

hydraulic bypass

24

Short-circuit device

25

hydraulic circulation

26

circuit pin

Claims (3)

Camshaft adjuster (1) for an internal combustion engine of a motor vehicle, with a stator (2) and with a rotor (4) which is accommodated within the stator (2) rotatably mounted relative to this and at least one rotor blade (5), which between the Stator (2) and the rotor (4) a first hydraulic chamber (6) and a second hydraulic chamber (7) is formed, which are hydraulically connected to one hydraulic line (8 and 9) and pressurized via this, and with a locking device (19 ) for causing a central locking of the rotor (4) relative to the stator (2), wherein in the at least one rotor blade (5) a hydraulic bypass (23) between the first and the second hydraulic chamber (6 and 7) for fluid transmission is provided is selectively releasable for reaching the center locking position, wherein the first and the second hydraulic chamber (6 and 7) via a further switchable Kurzschlusseinricht ung (24) are fluid-communicable with each other, characterized in that the further switchable Kurschlusseinrichtung (24) in a hydraulic central valve (10) of the camshaft adjuster (1) is integrated Camshaft adjuster (1) to Claim 1 , characterized in that the short-circuiting device (24) is switchable back and forth between a short-circuited position and a blocking position as a function of a hydraulic pressure prevailing in the camshaft adjuster (1). Camshaft adjuster (1) according to any one of the preceding claims, characterized in that the short-circuiting device (24) at and / or falls below a certain hydraulic pressure threshold, the first and the second hydraulic chamber (6 and 7) connects to transmit fluid.

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