DE102019131752A1 - Camshaft adjustment system with different damping characteristics - Google Patents

Abstract

The invention relates to a camshaft adjustment system (1) with a hydraulic camshaft adjuster (3) having at least one working chamber (2), the at least one working chamber (2) having a first partial chamber (4a) and a second partial chamber (4a) acting against the first partial chamber (4a) Partial chamber (4b) and with a control valve (5) operatively connected to the camshaft adjuster (3), the control valve (5) being designed such that in its first switching position the first partial chamber (4a) is connected to a pump connection (6) , while the second sub-chamber (4b) is connected to a tank connection (7), in its second switching position the second sub-chamber (4b) is connected to the pump connection (6), while the first sub-chamber (4a) is connected to the tank connection (7) is, and in its holding position both the first sub-chamber (4a) and the second sub-chamber (4b) are connected to the pump connection (6), wherein the control valve (5) further a It is designed that it has an independently selectable damping position, in which damping position the two sub-chambers (4a, 4b) are connected to one another and can be connected to the pump connection (6) to compensate for hydraulic fluid losses.

Description

The invention relates to a camshaft adjustment system, preferably for an internal combustion engine of a motor vehicle, with a hydraulic camshaft adjuster having at least one working chamber, the at least one working chamber having a first sub-chamber and a second sub-chamber acting against the first sub-chamber, as well as one that is operatively connected to the camshaft adjuster Control valve, the control valve being designed in such a way that in its first switching position the first sub-chamber is connected to a pump connection (of the control valve), while the second sub-chamber is connected to a tank connection (of the control valve), and in its second switching position the second sub-chamber is connected to the Pump connection is connected, while the first subchamber is connected to the tank connection, and in its holding position both the first subchamber and the second subchamber are connected to the pump connection (as well as from the tank connection are separated).

Generic camshaft adjustment systems are already sufficiently known from the prior art. In this regard, the US 7 214 153 B2 a spool that is in a damping state and is moved back and forth in its center position "trembling" in order to achieve a desired leakage and to dampen vibrations in the timing drive.

It is therefore already known to convert kinetic energy of the control drive into thermal energy by damping work in order to ensure sufficient damping. A fundamental problem, however, is in principle that the existing damping units are not directly coupled to the oscillatable mass, but are connected to the mass via an endless traction device. The damping unit is thus connected in series with an elastic component in the form of the endless traction means, which inevitably results in a phase shift between the movement of the mass and the internal relative movement of the damping unit. In addition, the hydraulic camshaft adjuster withdraws kinetic energy from the system, which, however, decreases with increasing speed. The camshaft adjuster is therefore less available as a damping component in the significant resonance ranges.

It is therefore the object of the present invention to eliminate the disadvantages known from the prior art and to provide a camshaft adjustment system by means of which more kinetic energy is to be extracted in an increased speed range without inadmissibly increasing an oscillation angle in the lower speed range. A speed-dependent regulation should therefore be carried out, whereby the engine load is not taken into account.

This is achieved according to the invention in that the control valve is also designed such that it has an independently selectable damping position, in which damping position the two sub-chambers are connected to one another and can be connected to the pump connection to compensate for hydraulic fluid losses.

A fourth position is thus created which is independent of the holding position and the two first and second switching positions, in which the camshaft adjuster serves as a damping element if required. In addition to reducing the loads in the timing gear, relocating the damping function from the tensioning unit of the timing gear to the camshaft adjuster makes it possible to design the tensioning unit in a more simplified manner, preferably as a pure (mechanical) spring tensioner. This also results in advantages with regard to the cost of manufacturing the timing drive.

Further advantageous designs are claimed with the subclaims and explained in more detail below.

Accordingly, it is advantageous if, in the damping position, a check valve (within the control valve) is inserted between the pump connection and two working connections (of the control valve) connected to the two sub-chambers that a return flow of hydraulic medium from the respective sub-chamber to the pump connection / via the Pump connection is blocked. This keeps the structure of the control valve as simple as possible.

The hydraulic damping is designed as effectively as possible if at least one throttle device is used in a connecting channel (of the control valve) connecting the sub-chambers in the damping position.

In this context, it has also been found to be expedient if two throttle devices are used in the connecting channel.

More preferably, the throttle devices differ from one another in terms of their cross-section / flow cross-section.

In a preferred embodiment, there is a first throttle device between a first working connection (of the control valve) connected to the first subchamber and the pump connection, and a second throttle device inserted between a second working connection connected to the second partial chamber and the pump connection.

It is also expedient, preferably when only one throttle device is provided in the damping position, if the two sub-chambers / working connections are permanently separated from the tank connection in the damping position.

As an alternative to this, it is also advantageous, preferably when both throttle devices are provided in the damping position, when the two sub-chambers / working connections are connected to the tank connection.

The damping position can also be controlled as simply as possible if it is supported by a valve piston of the control valve resting against an end stop (preferably against the spring force of a spring supporting the valve piston). This makes it possible to decouple other influences, such as the friction in the magnet or the fluctuations in the magnetic field strength or the voltage supply, from the damping function.

The control valve is preferably implemented as a 4/4 way valve.

In other words, a camshaft adjuster with different damping characteristics is thus implemented.

The invention will now be explained in more detail below with reference to figures, in which context various exemplary embodiments are also shown.

• 1 eine schematische Darstellung eines erfindungsgemäßen Nockenwellenverstellsystems nach einem ersten Ausführungsbeispiel, wobei neben einem stark vereinfacht dargestellten Nockenwellenversteller ein Steuerventil hinsichtlich seiner unterschiedlichen Schaltstellungen detailliert zu erkennen ist, sowie
• 2 eine schematische Darstellung eines erfindungsgemäßen Nockenwellenverstellsystems nach einem zweiten Ausführungsbeispiel, in dem eine Dämpfungsstellung des Steuerventils im Gegensatz zu dem ersten Ausführungsbeispiel nicht nur mit einer, sondern mit zwei Drosseleinrichtungen ausgestattet ist.

Show it:

• 1 a schematic representation of a camshaft adjustment system according to the invention according to a first embodiment, in addition to a greatly simplified camshaft adjuster, a control valve can be seen in detail with regard to its different switching positions, and
• 2 a schematic representation of a camshaft adjustment system according to the invention according to a second embodiment, in which a damping position of the control valve, in contrast to the first embodiment, is equipped not only with one, but with two throttle devices.

The figures are merely of a schematic nature and serve exclusively for the understanding of the invention. The same elements are provided with the same reference symbols.

In 1 is a camshaft adjustment system according to the invention 1 recognizable in its basic structure. In this regard, it should be noted that the second embodiment according to 2 is implemented largely in accordance with this first embodiment, so that only the differences between these two embodiments are described below for the sake of brevity.

The camshaft adjustment system 1 the 1 has a hydraulic camshaft adjuster, shown in a simplified manner 3rd on. The camshaft adjuster 3rd is typically implemented as a vane type camshaft adjuster. The camshaft adjuster 3rd thus has a stator, not shown here for the sake of clarity, and a rotor which can be hydraulically adjusted relative to this stator in a specific angle of rotation range. The adjustment of the rotor relative to the stator takes place via a pressure change by means of a hydraulic medium within various sub-chambers 4a , 4b several working chambers distributed in the circumferential direction 2 how they are arranged between the rotor and the stator. A first sub-chamber 4a , in the 1 is marked with A, acts against a second sub-chamber 4b , in the 1 marked with B. Each sub-chamber 4a , 4b is with a working connection 13a , 13b (A, B) of a central control valve 5 connected.

The central control valve 5 that controls the camshaft adjuster 3rd serves, is implemented according to the invention as a 4/4-way valve. In 1 there is a valve piston 11 of the control valve 5 , which is displaceable along a longitudinal axis, in a first switching position in which the first sub-chamber 4a via the first working connection 13a with a pump connection 6th (P) is connected while the second sub-chamber 4b via the second working connection 13b with a tank connection 7th (T) is connected. This first switching position is thus implemented in the usual way to move the rotor by enlarging the first sub-chamber 4a and at the same time reducing the size of the second sub-chamber 4b to be adjusted in a first direction of rotation relative to the stator.

The control valve is axially offset from the first switching position 5 typically on the part of its valve piston 11 a second switching position in which the second sub-chamber 4b via the second working connection 13b with the pump connection 6th is connected, while the first sub-chamber 4a via the first working connection 13a with the tank connection 7th connected is. This second switching position is thus implemented in the usual way in order to move the rotor by enlarging the second sub-chamber 4b and at the same time reducing the size of the first sub-chamber 4a in one direction opposite to the first direction of rotation, to adjust the second direction of rotation relative to the stator.

A holding position of the control valve is located between the two switching positions 5 , in which holding position both the first sub-chamber 4a via the first working connection 13a as well as the second sub-chamber 4b via the second working connection 13b with the pump connection 6th are connected while they are from the tank port 7th are separated. This holding position is preferably a neutral position / central position in which the first sub-chamber 4a and the second sub-chamber 4b are essentially the same size.

The control valve 5 is implemented so that between the first working connection 13a and the pump connection 6th in this holding position a (third) throttle device 10c (with throttle cross-section Q _D1 ) arranged / inserted. Between the second working connection 13b and the pump connection 6th is a (fourth) throttle device 10d (with throttle cross-section Q _D2 ) arranged / inserted.

According to the invention, the control valve is in a fourth position, a so-called damping position 5 the first subchamber 4a with the second sub-chamber 4b connected. In the first embodiment according to 1 is in a connecting channel 9 the damping position between the first working connection 13a and the second working connection 13b a (first) throttle device 10a (with throttle cross-section Q _D3 ) are used. The two working connections 13a , 13b / Sub-chambers 4a , 4b are also via a check valve 8th with the pump connection 6th coupled. The check valve 8th is used in such a way that a return flow of hydraulic medium from the sub-chambers 4a , 4b to the pump connection 6th is blocked. One to the pump connection 6th towards (first) junction 14th closes on one of the first working line 13a facing side of the first throttle device 10a to the connection channel 9 / Working connection 13a at.

At the same time, the tank connection is in this first exemplary embodiment 7th of the two sub-chambers 4a , 4b / the two working connections 13a , 13b severed. In addition, it is advantageous if an optional end stop, shown schematically and with dashed lines 12th the damping position secures. A corresponding return spring 15th of the control valve 5 is then preferably maximally compressed in the damping position.

With 2 is finally the second embodiment of the camshaft adjustment system according to the invention 1 shown. The first switching position, the second switching position and the holding position are implemented according to the first exemplary embodiment. Only the damping position differs from the first embodiment. There are now between the two working connections 13a , 13b two throttling devices 10a , 10b used effectively. A first throttle device 10a I am between the first work connection 13a / the first subchamber 4a and the pump connection 6th / the first junction 14th from the connection channel 9 towards the pump connection 6th . A second throttle device 10b (with throttle cross-section Q _D4 ) is located between the second working port 13b / the second sub-chamber 4b and the pump connection 6th / the first junction 14th . The throttle devices 10a , 10b differ in this version in terms of their (minimal) cross-section.

There is also another (second) junction 16 present over which the sub-chambers 4a , 4b permanently with the tank connection during operation 7th are connected. The second turn 16 is preferably located on one of the two working connections 13a , 13b facing away from the throttle devices 10a , 10b towards the tank connection 7th .

In other words, a 4/4-way valve 5 is implemented according to the invention, which comprises the following switching position: 1. Filling chamber A; Drain from chamber B; 2. Filling chamber B; Drain from chamber A; 3. Holding position: filling chambers A and B to compensate for leakage; 4th damping position: In a 4th switching position, a damping function is specifically integrated. This additional damping effect of the camshaft adjuster 3rd During operation, it may be unnecessary for a clamping unit to continue to have a hydraulic damping function. That is, the control drive clamping unit can be designed as a simple spring element.

In the first embodiment according to 1 is in the 4th switching position a throttled connection between chambers A and B (sub-chambers 4a , 4b ) and a connection to the pressure oil supply (P) to compensate for oil losses due to leakage. The connection to the tank (T) is blocked in the 4 switching position. There is a check valve in the connection to the pressure oil supply 8th used to prevent the oil from flowing back from chamber A and / or chamber B into pressure line P.

Advantageously, the 4th switch position has an end stop, which reduces the tolerance band by the positioning tolerances of at least the magnet. In this way, the damping function can be optimally adjusted to the motor without the influence of the friction in the magnet, the magnetic field strength or the power supply. When the 4th switch position is in the end stop position is the return spring 15th the directional control valve 5 higher preloaded compared to the other switching positions.

Since the acting moments to be damped can be different, it can be advantageous to determine the cross-sections of the leakage openings in chambers A ( 3rd Reference number 10a ) and B ( 3rd Reference number 10b ) to be dimensioned differently. To do this, the excess oil, which cannot be absorbed by the chamber with the smaller leakage opening, must be drained off. This can be done via the tolerance-related leakages in the valve or via a suitable channel to the tank.

The 4th switch position / damping switch position is approached depending on the engine load and the engine speed. In addition, the signal from a pump, which has an effect on the dynamics of the control drive and / or the valve drive, can be used. If an active valve lift change is installed on the engine, the information from this variation option can also be used to approach the damping switch position.

List of reference symbols

1

Camshaft adjustment system

2

Work chamber

3

Camshaft adjuster

4a

first subchamber

4b

second sub-chamber

5

Control valve

6th

Pump connection

7th

Tank connection

8th

check valve

9

Connection channel

10a

first throttle device

10b

second throttle device

10c

third throttle device

10d

fourth throttle device

11

Valve piston

12th

End stop

13a

first working connection

13b

second working connection

14th

first junction

15th

Return spring

16

second junction

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• US 7214153 B2 [0002]

Claims (9)

Camshaft adjustment system (1) with a hydraulic camshaft adjuster (3) having at least one working chamber (2), the at least one working chamber (2) having a first sub-chamber (4a) and a second sub-chamber (4b) acting against the first sub-chamber (4a) and with a control valve (5) operatively connected to the camshaft adjuster (3), the control valve (5) being designed such that in its first switching position the first sub-chamber (4a) is connected to a pump connection (6), while the second Partial chamber (4b) is connected to a tank connection (7), in its second switching position the second part chamber (4b) is connected to the pump connection (6), while the first part chamber (4a) is connected to the tank connection (7), as well as in its holding position, both the first sub-chamber (4a) and the second sub-chamber (4b) are connected to the pump connection (6), characterized in that the control valve (5) furthermore expands in this way It is formed that it has an independently selectable damping position, in which damping position the two sub-chambers (4a, 4b) are connected to one another and can be connected to the pump connection (6) to compensate for hydraulic fluid losses. Camshaft adjustment system (1) Claim 1 , characterized in that in the damping position a check valve (8) is inserted between the pump connection (6) and two working connections (13a, 13b) connected to the sub-chambers (4a, 4b) in such a way that a return flow of hydraulic medium from the respective sub-chamber ( 4a, 4b) to the pump connection (6) is blocked. Camshaft adjustment system (1) Claim 1 or 2 , characterized in that at least one throttle device (10a, 10b) is inserted in the control valve (5) in a connecting channel (9) connecting the sub-chambers (4a, 4b) in the damping position. Camshaft adjustment system (1) Claim 3 , characterized in that two throttle devices (10a, 10b) are used in the connecting channel (9). Camshaft adjustment system (1) Claim 4 , characterized in that the throttle devices (10a, 10b) differ from one another in their cross-section. Camshaft adjustment system (1) Claim 4 or 5 , characterized in that a first throttle device (10a) is inserted between a first working connection (13a) connected to the first sub-chamber (4a) and the pump connection (6), and a second throttle device (10b) is inserted between one connected to the second sub-chamber (4b) connected second working connection (13b) and the pump connection (6) is used. Camshaft adjustment system (1) according to one of the Claims 1 to 6th , characterized in that the two sub-chambers (4a, 4b) are permanently separated from the tank connection (7) in the damping position or are connected to the tank connection (7). Camshaft adjustment system (1) according to one of the Claims 1 to 7th , characterized in that the damping position is supported by a valve piston (11) of the control valve (5) resting against an end stop (12). Camshaft adjustment system (1) according to one of the Claims 1 to 8th , characterized in that the control valve (5) is implemented as a 4/4-way valve.

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