WO2016019955A1

WO2016019955A1 - Camshaft adjuster comprising a chamber-shortcircuiting pressure-controlled control unit

Info

Publication number: WO2016019955A1
Application number: PCT/DE2015/200356
Authority: WO
Inventors: Torsten Zschieschang
Original assignee: Schaeffler Technologies AG & Co. KG
Priority date: 2014-08-05
Filing date: 2015-06-11
Publication date: 2016-02-11
Also published as: US10385739B2; DE102014215419A1; CN106574525A; CN106574525B; US20170211430A1

Abstract

The invention relates to a vane-type camshaft adjuster (1) comprising a rotor (2) which has radially projecting vanes (3) and forms vane cells (5) along with a stator (4) rotatably accommodating the rotor (2), each vane cell (5) being subdividable by a vane (3) into two adjustable chambers provided for holding hydraulic fluid; a hydraulic fluid-controlling device (12) for conducting hydraulic fluid is disposed and/or connected between the chambers (6, 7) in such a way that a drop in pressure in the chambers (6, 7) caused or reinforced by camshaft switching moments occurring during operation is used to open the hydraulic fluid-controlling device (12) such that fluid flows therethrough.

Description

Camshaft adjuster with short-circuiting pressure-controlled actuating unit

The invention relates to a camshaft adjuster of the vane type, with a rotor having radially projecting wings, wherein the rotor, together with a rotor rotatably receiving the stator, vane formed, each of which is divided by a wing in two adjustable, prepared for hydraulic fluid chambers.

Such camshaft adjusters are used in valve trains of internal combustion engines, as they are known, for example, from DE 102 39 748 A1. From the prior art, such as the US 2008/0173267 A1 or US 7,182,052 B2 or DE 10 2008 000 083 A1 and camshaft adjuster are known as valve timing devices. There, a valve timing controller controls a valve timing of an intake / exhaust valve of an internal combustion engine. The device has a housing which is rotated by a drive shaft. The housing has a chamber space receiving a paddle rotatable with a driven shaft to a delay and a Voreilseite relative to the housing by being acted upon by a hydraulic pressure in a delay and Voreilkammer in the chamber space. A filter is provided for removing contaminants in a fluid passage extending from a sliding portion between the driven shaft and a bearing to both the housing and the paddle rotor through a connected portion between the driven shaft and the paddle rotor. The filter is provided on the side of both the housing and the blade rotor with respect to the sliding portion.

Camshaft adjusters are also known from documents US Pat. No. 7,245,077 B2, US Pat. No. 7,318,401 B2 and US Pat. No. 7,000,580 B1. There are disclosed slide valve devices for a camshaft adjuster with integrated check valves. The invention is in the field with pressure accumulators and additional control functions in the switching valve. Thus, pressure-driven stages, which are also known as "oil pressure activated (OPA)" adjusters, are involved In the event of torsional moments that are too large, a camshaft adjuster is periodically put under negative pressure on the pump side, which leads to dynamic problems and additional air suction It is the object of the present invention to avoid these disadvantages, to provide a particularly dynamically optimized camshaft adjuster, and to make available from the state of the art, from leakage gaps and / or degassing of a hydraulic fluid such as a hydraulic fluid, eg oil This object is achieved in a generic camshaft adjuster according to the invention in that a hydraulic fluid control device /

Hydraulikfluidreguliervorrichtung arranged for hydraulic fluid conduction between the chambers and / or interconnected / connected, that a pressure drop, preferably below a predetermined limit pressure in the chambers, which is caused or amplified by operating camshaft alternating torques, is inserted for fluid-permeable opening of the hydraulic fluid control device.

Critical pressure, in certain situations equivalent to a limit pressure, can be understood as the pressure at which the system begins to suck air or oil begins to degas. A limiting pressure is understood to be the pressure which is the pressure set via the spring preload and piston effective area.

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

Thus, it is advantageous if the hydraulic fluid control device has at least one bypass line closure device or preferably two bypass line closure devices. In this way, both hydraulic fluid from the one Kamner in the other Kannnner be spent in pressure drop, but also from the other Kannnner in a Kannnner. An optimization in both adjustment of the camshaft adjuster is then reached. If the two bypass line closing devices are arranged in parallel to one another in a fluid-conducting manner, the reaction times can be kept low.

Particularly efficient camshaft phaser optimization is achieved when the bypass line closure device includes a valve, such as a 2/2-way valve, and a spring acting thereon, such as a compression or tension spring. It can then be arranged on / in the camshaft adjuster two open / close valves, which are actuated when the pressure in the first chamber decreases. The actuated valve then opens a channel to allow oil flow from the other chamber to the first chamber.

When the spring biases the valve into a hydraulic fluid flow preventing position, complex actuation can be facilitated by simple means.

Thus, a hydraulic fluid control unit is proposed which connects chambers A and B, ie a first chamber and a second chamber, only when the pressure set by a regulator / switch (p _kr it) is _fallen below in a chamber. Then a pressure equalization between the chambers can take place. Here, the already caused by the (camshaft) alternating moments pressure gradient between the chambers is utilized.

As long as the pressure in the relevant chamber is above the critical pressure (limit pressure), the relevant controller / switch ensures that the short circuit between the chambers is blocked. Each path A or B with the respectively connected chambers each requires a separate control unit, which changes the pressure in the corresponding path or opens the bypass to the other chamber when the critical pressure in one of the chambers is undershot. The differential pressure between the chambers does not matter. In addition, it can be explained that a bypass / a bypass line is opened when the pressure is lower than the control unit set level decreases (limit pressure). Then it comes to overflow through this bypass line. The pressure level is not "compensated", but the camshaft adjuster now takes the oil additionally available to it (ie the oil "what he can get") and thus becomes faster in its adjustment movement.

It is desirable if the bypass line closing device is preset so that when a limit pressure (p _kr it) is fallen below in a first of the chambers, a switching position of the bypass line closing device is forced, in / by the hydraulic fluid through a bypass line of the other, second chamber enters the one, first chamber.

It is advantageous if the spring is adjusted to the limit pressure / pressure set by the regulator (pcrit). With the help of the spring, the area ratios and / or the effective areas on the piston exactly this limit pressure is set.

It is also advantageous if the Hydraulikfluidleitvornchtung is integrated or installed in a wing. In this way, a very compact camshaft adjuster can be achieved.

It is advantageous if the bypass line closure device has a pilot line which produces a pressure-transmitting connection between the first chamber and a closure element, wherein the spring in its basic position, the closure element hydraulicfluidflussunterbindend in those connecting the two chambers bypass line urges and in an activation position, when reaching and / or falling below the limit pressure in the first chamber, opens the bypass line.

An advantageous embodiment is also characterized in that two mutually movable toward and away from each other piston are arranged in a channel, wherein the pistons are arranged so that they are driven only by the associated pilot line. The two pistons are therefore hydraulically separated from each other controllable. So it should be a pressure-tight separation in the channel, the be designed in the manner of a bore, be held. In this way, an embodiment in a wing as a male element with two separate chambers and piston / cups can be used. The male member may be provided with two sections with holes in a sleeve. On the inside, the spring-loaded pistons or cups seal the holes in a basic position, whereby the pressure in both chambers is above the critical pressure. If, in one of the two chambers, the pressure falls below the critical pressure, the piston located on this chamber side moves, whereby the piston releases a bore and an overflow from the other chamber into that chamber takes place with the lower pressure via the bypass line ,

Such a camshaft adjuster can also be further developed by virtue of the fact that the shift range is that region of the common pilot line which ensures a hydraulic fluid-permeable connection between the two bypass lines in the case of pressure-dependent / pressure-drop-dependent displacement of one of the pistons.

It should be noted that it is possible to design the springs on the two slide valves with tensile or compressive prestressing or to omit them altogether, depending on how the critical pressure level is to be set, at which the slide is out of its initial position (pressurelessly closed). should be deflected. Thus, for example, no spring is necessary if the slide valve is to open at below 0 bar, the negative pressure in the chamber connected to the corresponding port "raises" the slide valve For example, at a pilot pressure of -0.1 bar, theoretically, a tensile prestress is also conceivable if the slide is to open the bypass even if the pressure falls below a certain positive pressure, for example above 0 bar However, this design is risky, because at the start of the internal combustion engine, both valves are on "let-through", ie are open without pressure, and can thus generate an unwanted short circuit via both slide valves. One can try that the condition is intercepted by additional switching elements. This interpretation is still technically very critical, since at each torque zero crossing / change moment the risk that the bypass unintentionally opens, or is open anyway, and a backflow of the fluid takes place. The variant without spring is critical, since the indifferent position of the cups / pistons / slide can cause that also the wrong bypass opens unintentionally. It is technically so the variant with spring preload useful and preferred because this allows a defined basic position of the valve and thus can take place a secure sealing against the chamber pressures. The invention will be explained in more detail below with the aid of a drawing in which four exemplary embodiments are shown. Show it:

Fig. 1 is a circuit diagram for a first embodiment of an inventive

Camshaft adjuster, wherein a first chamber A is supplied via a pump with hydraulic fluid, the pressure in the first chamber A is above the critical pressure, the torsional moments are not critical, the system functions as an OPA system, and a short-circuited AB to a main valve / 1, in the situation in which the pressure in the first chamber A drops below the critical pressure p _kr it, ie there is a suction phase, the torsional moments dominating the behavior of the camshaft adjuster, driving it Furthermore, the pressure supply from the pump is no longer sufficient, with a Hydraulikfluidregelvorrich- / pressure regulating unit releases a short circuit via a bypass line from the second chamber B to the first chamber A, so long as the system pressure-equalizing from the second chamber to the first chamber and hydraulikfluidnachführend ensures that the pressure again on the crit 1, wherein the second chamber B is supplied with hydraulic fluid by the pump, but the pressure in the chamber B is above the critical pressure, the Torsionsmomente are uncritical, the adjustment of the camshaft adjuster opposite to the adjustment of the embodiment of FIGS. 1 and 2, but also the short circuit AB is closed, Fig. 4 shows the situation in the adjustment direction, as in Fig. 3, but the pressure in the second chamber B drops below the critical pressure (suction phase), the torsional moments drivingly dominate the behavior of the camshaft adjuster, the pressure regulator / hydraulic fluid control device releasing the short circuit / bypass line from chamber A to chamber B, the system being so long from the chamber A to the chamber B pressure-compensating and hydraulikfluidnachführend acts until the pressure in the chamber B is again above the critical pressure,

5 shows a further embodiment in which two valves are integrated in a rotor blade and spring-loaded cups / pistons are used,

Fig. 6 shows the embodiment of FIG. 5 but with bypass line opener

Switching position, Fig. 7 shows a further embodiment for positioning the valves in the wing, wherein the pilot hole can also be centered to the piston or cup axis, so that the bypass line must not be discontinued, but can also be drilled in one go, if the piston or the cup in a blocking position sufficiently shuts off the opposite chamber and, in an open position, releases sufficient passage for the flow,

8 shows a further embodiment in a bypass-line-locked position, and FIG. 9 shows the embodiment of FIG. 8 in the bypass-line-opened position.

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

FIG. 1 shows a first embodiment of a camshaft adjuster 1 according to the invention. This camshaft adjuster 1 is provided for use in a valve train on an internal combustion engine. This camshaft adjuster

I has a rotor 2, the radially projecting wing 3 has. Usually, three or more wings 3 are used. Particularly preferred are four wings 3. The rotor 2 is rotatably arranged in a stator 4, which can be connected, for example. Via a gear with a continuous traction means such as a chain. The rotor 2 and the stator 4 form vane 5, which are each divided by a wing 3 in a first chamber 6 and a second chamber 7. The first chamber may also be referred to as chamber A and the second chamber as chamber B or vice versa. In a line system 8, a main shut-off / change-over valve 9 is provided. This Hauptabsperr- / Umschaltventil 9 is between a pump (P) 10 and a tank (T)

I I arranged. In addition, a hydraulic fluid control device 12 is provided.

The hydraulic fluid control device 12 preferably has two bypass line closing devices 13. Both bypass

Line closing devices 13 have a valve 14, such as a 2/2 way valve 15. This valve 14, which can also be referred to as a slide / slide valve, is biased by a spring 16. The bypass line closing devices 13 are arranged in each case in a bypass line 17 or arranged in a common bypass line 17. However, there is also a pilot line 18 for each bypass line closing device 13. Via the pilot line 18, if the limit pressure / critical pressure falls below the limiting pressure / critical pressure p _kr it in the first chamber 6, one of the two 2/2-way valves 15 is opened, so that, as shown in Fig. 2, for example, hydraulic fluid, such as oil, passes from the second chamber 7 via the bypass line 17 into the first chamber 6. The bypass line 17 is opened by the right-hand valve 14 in the figure as long as the pressure P in the first chamber 6 drops below the critical pressure p _kr it. The adjustment direction of the rotor 2 relative to the stator 4 is symbolized by the arrow 19.

A modified representation of this, in the reverse adjustment direction 19 of the rotor 2 relative to the stator 4 is shown in Figs. 3 and 4 reproduced.

A variant of the embodiments shown in FIGS. 1 to 4, however, is shown in FIGS. 5 and 6. In Fig. 5, both a first bypass line 17, and a second bypass line 17 is closed, whereas due to the pressure transmission from the first chamber 6 because of a biased by the spring 16 closure element 20, a bypass line 17 is open, so that hydraulic fluid can pass from the second chamber 7 into the first chamber 6.

The two separate bypass line closing devices 13 are mutually mounted in the wing 3. Each bypass line closure device 13 has a pilot line 18 to the respectively associated first or second chamber 6 or 7, which allows in coordination with the acting spring 16 opening and closing of the respective associated bypass / bypass line 17. The pilot line 18 may also be referred to as a pilot channel.

The arrangement is chosen so that the first and second chambers are hydraulically separated from each other in a basic valve position, that is, when the pilot pressure is above the critical pressure. Neither the (over) pressure in the first chamber 6, nor the pressure in the second chamber 7 can bring the closure element 12, in the manner of a piston or a cup, for opening, nor a pressure gradient between the two chambers 6 and 7.

A suitable undercut, in the sense of a depression for the frontal reception of the closure element 20, can assist the secure closing of the closure element / the valve body / the cup / the piston. In both chambers, as shown in Fig. 5, the pressure is above the critical pressure. The valves are in their normal position, whereby the bypass / the bypass line 17 is closed. In contrast, in FIG. 6 the pressure in the first chamber 6 has fallen below the critical pressure. The Torsionsmomente but tearing the camshaft adjuster 1, in particular the rotor 2 with. The volume flow supply by the pump 10 is then no longer guaranteed sufficient. As a result, in the chamber A, so the first chamber 6, a pressure that drops below the critical pressure. The closure element 20 is then pulled out of its seat or undercut by the "negative pressure" in the first chamber 6 against the illustrated spring 16. The short circuit from the second chamber 7 into the first chamber 6 is thus opened is also hydraulically assisted by acting on the now released end face of the closure element 20 chamber pressure in the second chamber. 7

If there is pressure equalization between the two chambers 6 and 7, the valve / closure element 20 falls back into the seat and closes the bypass / the bypass line 17. A slight undercut for receiving the closure element 20 ensures a secure seal against a laterally acting pressure from the chambers 6 and 7.

The system works as long as a traditional phaser in pure OPA mode until the pressure in a chamber 6 or 7 as a result of the applied alternating moments and the way of the spring 16, and an effective area of the closing element inside or piston area set critical pressure P _cr it decreases. Until then, the system is operated with oil pressure control and is not dependent on the "pumping" between the chambers, which has an advantageous effect on the adjustment speed or the adjustment behavior with small torsional torques In the case of increasing moments, the adjustment is additionally supported by the pumping between the chambers , in the sense of a CTA adjustment, ie a "cam torque actuation". The pressure drop between the chambers 6 and 7 additionally helps in achieving higher adjustment speeds. The potential for Sucking air or outgassing from the oil is minimized. Of course, this also depends on the set pilot pressure.

FIG. 7 shows a further embodiment in which there are (orthogonally) pilot lines 18 originating from the two chambers 6 and 7 and acting on adjusting devices 19 / closing elements 20, which are in operative connection with springs 16. The closure elements 20 close oblique bypass lines 17. Two independently movable closure elements 20 in a bore orthogonal to the surface of the wing 3, the two chambers 6 and 7 together, are shown in Figs. 8 and 9. Falls below the limit pressure in the second chamber 7, for example, the closer the second chamber 7 closing element 20, so the corresponding piston to the second chamber 7 sucked / displaced. Thereby, a passage for oil from one section of the bypass line 17 to the other section of the bypass line 17 is enabled, so that according to the arrow direction shown in Fig. 9 in the bypass line 17 hydraulic fluid from the first chamber 6 in the second chamber 7 spent.

LIST OF REFERENCES

Phaser

rotor

wing

stator

vane

first chamber

second chamber

line system

Main shut-off / diverter valve

pump

tank

Hydraulikfluidregelvomchtung

Bypass Leitungsverschließvorrichtung

Valve

2/2 way valve

feather

Bypass line

pilot line

adjustment device

closure element

Claims

claims

1 . Camshaft adjuster (1) of the vane type, comprising a rotor (2) having radially projecting wings (3), the rotor (2) together with a rotor (2) rotatably receiving stator (4) vane (5) forms, the each by a wing (3) into two adjustable, for Hydraulikfluidaufneh- men prepared chambers (6, 7) are divided, characterized in that a hydraulic fluid control device (12) for hydraulic fluid between the chambers (6, 7) is arranged so that a Pressure drop in the chambers (6, 7), which is caused or amplified by occurring during operation Nockenwellenwechselmo- elements, is used for fluid-permeable opening of the hydraulic fluid control device (12).

Second camshaft adjuster (1) according to claim 1, characterized in that the hydraulic fluid control device (12) has at least one bypass Leitungsver closing device (13) or two bypass Leitungsverschließvorrichtungen (13).

3. camshaft adjuster (1) according to claim 2, characterized in that the two bypass line closing devices (13) are arranged fluid-parallel to each other.

4. camshaft adjuster (1) according to claim 2 or 3, characterized in that the bypass line closing device (13) includes a valve (14) and a spring acting thereon (16).

5. camshaft adjuster (1) according to claim 4, characterized in that the spring (16) biases the valve (14) in a hydraulic fluid flow preventing position.

6. camshaft adjuster (1) according to one of claims 2 to 5, characterized in that the bypass line closing device (13) is preset so that falls below a limit pressure in a first of the Chambers (6) a switching position of the bypass line closure device (13) is enforced, passes through the hydraulic fluid through a bypass line (17) from the second chamber (7) in the first chamber (6).

Camshaft adjuster (1) according to claim 6, characterized in that the spring (16) is tuned to the limit pressure.

Camshaft adjuster (1) according to one of claims 1 to 7, characterized in that the Hydraulikfluidleitvorrichtung (12) in the wing (3) is integrated.

Camshaft adjuster (1) according to claim 6, characterized in that the bypass line closure device (13) comprises a pilot line (18) which produces a pressure-transmitting connection between the first chamber (6) and a closure element (20), wherein the spring ( 16) in its basic position, the closure element (20) hydraulikfluidflussunterbindend in those, the two chambers (6, 7) connecting the bypass line (17) urges and in an activation position, upon reaching and / or falling below the limit pressure in the first chamber (6) the bypass line (17) is open.

Camshaft adjuster (1) according to any one of claims 1 to 9, characterized in that two pistons movable towards and away from one another are arranged in a channel / bore, the pistons being arranged so as to be movable only by the pilot line (18 ) are driven.