CN106574525B

CN106574525B - Camshaft adjuster with a pressure-controlled actuator that short-circuits the chambers

Info

Publication number: CN106574525B
Application number: CN201580041880.XA
Authority: CN
Inventors: 托尔斯滕·奇尚
Original assignee: Schaeffler Technologies AG and Co KG
Current assignee: Schaeffler Holding China Co Ltd
Priority date: 2014-08-05
Filing date: 2015-06-11
Publication date: 2020-07-28
Anticipated expiration: 2035-06-11
Also published as: WO2016019955A1; US10385739B2; CN106574525A; US20170211430A1; DE102014215419A1

Abstract

The invention relates to a camshaft adjuster (1) of the vane cell type, comprising a rotor (2) having radially projecting vanes (3), wherein the rotor (2) together with a stator (4) forms vane cells (5) which are each divided by the vanes (3) into two adjustable chambers, wherein the stator accommodates the rotor (2) in a rotatable manner, wherein the chambers are designed to accommodate a hydraulic fluid, wherein a hydraulic fluid control device (12) for guiding the hydraulic fluid is arranged and/or connected between the chambers (6, 7), such that a pressure drop in the chambers (6, 7) is used to open the hydraulic fluid control device (12) in order to pass the fluid, said pressure drop being caused or increased by camshaft alternating torques occurring during operation.

Description

Camshaft adjuster with a pressure-controlled actuator that short-circuits the chambers

Technical Field

The invention relates to a camshaft adjuster of the vane cell type, having a rotor with radially projecting vanes, wherein the rotor forms vane cells together with a stator, which in each case is divided by a vane into two adjustable chambers, which receive the rotor in a rotatable manner and which are provided to receive a hydraulic fluid.

Background

Such camshaft adjusters are used in valve trains of internal combustion engines, which are known, for example, from DE 10239748 a 1. From the prior art, a camshaft adjuster as a valve timing device is also known, for example from US 2008/0173267 a1 or US 7,182,052B 2 or DE 102008000083 a 1. There, the valve timing apparatus controls the valve timing point of an intake/exhaust valve of an internal combustion engine. The device has a housing which is rotated by means of a drive shaft. The housing has a chamber which accommodates a vane rotor which can be rotated to a retard side or a advance side with respect to the housing by a driven shaft by applying hydraulic pressure to the vane rotor in a retard chamber and a advance chamber in the chamber. The filter is provided to remove impurities in a fluid passage extending from a sliding section between the driven shaft and the bearing, through a connecting section between the driven shaft and the vane rotor, to the housing and the vane rotor. The filter is arranged on the side of the housing and the vane rotor with reference to the sliding section.

Camshaft adjusters are also known from the references US 7,245,077B 2, US 7,318,401B 2 and US 7,000,580B 1. A slide valve device for a camshaft adjuster with a check valve is disclosed there.

Disclosure of Invention

The invention relates to the field of having additional control functions in pressure accumulators and switching valves. Therefore, pressure-driven regulators are involved, which are also known as "Oil Pressure Activated (OPA)" regulators.

Nowadays, in the event of excessively large torsional moments, the camshaft adjuster is cyclically exposed to a negative pressure on the pump side. This causes problems in terms of power and also additional air ingress due to suction from the leakage gap and/or degassing of hydraulic fluid, for example hydraulic liquid, for example oil, such as pressure oil and/or engine oil.

The object of the present invention is to avoid the above-mentioned disadvantages and to provide a camshaft adjuster which is particularly power-optimized and eliminates or at least reduces the disadvantages known from the prior art.

The object is achieved according to the invention in such a camshaft adjuster by: in order to conduct hydraulic fluid between the chambers, the hydraulic fluid control device/hydraulic fluid control device is provided and/or connected and/or coupled in such a way that a pressure drop, preferably a pressure drop in the chambers below a predetermined limit pressure, which pressure drop is caused or increased by the camshaft alternating torque occurring during operation, is used to open the hydraulic fluid control device so that fluid can pass through.

The following pressures can be understood as critical pressures which are in certain cases synonymous with the limiting pressure: at which pressure the system starts to suck air or to degas the oil. The limiting pressure is understood to be the pressure which is adjusted via the spring pretension and the effective area of the piston.

It is therefore advantageous: the hydraulic fluid regulating device has at least one bypass line closing device or preferably two bypass line closing devices. In this way, hydraulic fluid can be introduced from one chamber into the other chamber in the event of a pressure drop, but also from the other chamber into this one chamber. Optimization in both adjustment directions of the camshaft adjuster can thus be achieved.

If two bypass line closures are arranged parallel to one another to be able to conduct the fluid, the reaction time can be kept small.

A particularly effective optimization of the camshaft adjuster is achieved when the bypass line closing device comprises a valve, for example a two-position two-way valve, and a spring acting on the valve, for example a compression spring or a tension spring. It is then also possible to provide two on/off valves on and/or in the camshaft adjuster, which are actuated when the pressure in the first chamber drops. The actuated valve then opens the passage to enable oil to flow from the other chamber to the first chamber.

When the spring pretensions the valve into a position blocking the flow of hydraulic fluid, a complex actuation can be achieved by simple means.

Therefore, a hydraulic fluid control unit is proposed which is lower than the pressure (p) set via the regulator/switch only in one chamber_krit) Only then are the chambers a and B, i.e. the first and second chambers, connected. Thus, pressure equalization between the chambers is performed. In this case, the pressure drop between the chambers, which is always caused by the alternating torque (of the camshaft), is used.

The associated regulator/switch is responsible for isolating the short circuit between the chambers as long as the pressure in the associated chamber is above the critical pressure (limit pressure). Each path a or B with respectively associated chambers requires a separate control unit, which controls the respective pathThe element changes the pressure in the respective path or, below a critical pressure in one chamber, opens a bypass to the other chamber. Here, the pressure difference between the chambers is not important. Additionally, it is possible to implement: when the pressure drops below a level set via the control unit (limit pressure), the bypass line is opened. Thus, overflow is generated through the bypass line

In this case, the pressure level is not "equalized", but the camshaft adjuster now receives the oil additionally supplied to it (i.e., "oil available to the camshaft adjuster"), and is thus in its adjusting movement more quickly.

It is desirable that: the bypass line closing device is preset so as to be lower than the limit pressure (p) in the first chamber of the chambers_krit) When the bypass line closing device is forced into an open position in which hydraulic fluid passes through the bypass line from the further second chamber into the first chamber.

It is advantageous that: spring for limiting pressure and/or pressure (p) set via regulator_krit) The setting is performed. The limit pressure is set precisely by means of a spring, an area ratio and/or an effective area at the piston.

It is also advantageous: the hydraulic fluid device is integrated or built into the blade. In this way, an extremely compact camshaft adjuster can be achieved.

It is advantageous here that: the bypass line closing device has an actuating line which establishes a connection between the first chamber and the closing element, said connection acting to transmit pressure, wherein the spring in its basic position presses the closing element into the bypass line connecting the two chambers in order to prevent the hydraulic fluid from flowing through, and in the activated position opens the bypass line when the limit pressure in the first chamber is reached and/or falls below.

An advantageous embodiment is also characterized in that: two pistons which can be moved toward and away from one another are arranged in the channel, wherein the pistons are arranged such that they are controlled only by the actuation line associated therewith. The two pistons can therefore be controlled hydraulically separately from one another. It should therefore be possible to maintain a pressure-tight separation in the channels, which can be constituted according to the type of drilling. In this way, embodiments can be used in the blade as insert elements with two separate cavities and pistons and/or cups. The insertion element can be provided with two sections with a bore in the sleeve. The spring-loaded piston or cup closes the bore in the interior in the basic position, wherein the pressure in the two chambers is above the critical pressure. If the pressure in one of the two chambers is below the critical pressure, the piston on the side of this chamber moves, whereby the piston opens the bore and, by means of the lower pressure, an overflow from the other chamber to this chamber takes place via the bypass line.

Such a camshaft adjuster can also be improved in the following manner: the switching region is a region of the common actuating line which ensures a connection through which hydraulic fluid can flow between the two bypass lines when one of the pistons is displaced as a function of the pressure difference/pressure drop.

It should be noted that it is possible to: depending on the critical pressure level to be set, at which the slide is to be deflected from its initial position (closed without pressure), the springs at the two slide valves are designed with a tension or pressure pretension, or they can be omitted altogether. Thus, for example, if the slide valve should open below 0bar, no spring is required, wherein the negative pressure in the chambers coupled at the respective ports "pulls" the slide valve.

A spring with a pressure preload is expedient if the slide is to be displaced from a specific negative pressure, for example in the case of an actuating pressure of-0.1 bar. In principle, the tensile pretension can also be taken into account if the slide is to open the bypass even at a positive pressure below a predetermined positive pressure, for example a positive pressure above 0 bar. Thus, an operating pressure of, for example, 0.1bar can be determined. However, this design is risky because the two slides open "let through", i.e. without pressure, when the internal combustion engine is started, and an undesired short circuit can occur via the two slide valves. An attempt is made to intercept this state by means of an additional switching element. Nevertheless, this design is technically very disadvantageous, since the following risks are present at each moment zero crossing/moment alternation: the bypass is undesirably open, or is always open, and fluid backflow occurs. The variant without spring is also disadvantageous, since the random (indexed) position of the cup/piston/slide can give rise to: also undesirably opening the wrong bypass. The variant with spring pretension is therefore meaningful and preferred from a technical point of view, since it enables a defined basic position of the valve and thus a reliable sealing against the chamber pressure.

Drawings

The invention is explained in detail below with the aid of the drawing, in which four embodiments are shown. The figures show:

fig. 1 shows a circuit diagram of a first embodiment of a camshaft adjuster according to the invention, in which a first chamber a is supplied with hydraulic fluid via a pump, the pressure in the first chamber a is above a critical pressure, the torque moment is not critical, the system acts as an OPA system, and a short circuit a-B at the main valve is closed/closed,

fig. 2 shows the following for the camshaft adjuster in fig. 1: wherein the pressure in the first chamber a drops below the critical pressure p_kritI.e. there is a pumping phase in which the torsional moment dominates its performance in such a way that the camshaft adjuster is driven, and in which, furthermore, the pressure supply by the pump is no longer sufficient, wherein the hydraulic fluid regulating device/pressure regulating unit opens a short circuit from the second chamber B to the first chamber a via a bypass line as soon as the system causes the pressure to rise again above the critical pressure in the first chamber in such a way that the pressure is equalized and the hydraulic fluid is redirected from the second chamber B to the first chamber a,

fig. 3 shows another view of the camshaft adjuster of fig. 1 and 2, in which a second chamber B is supplied with hydraulic fluid by a pump, but the pressure in chamber B is above a critical pressure, in which the torsional moment is not critical, the adjustment direction of the camshaft adjuster being opposite to that of the embodiment of fig. 1 and 2, but also closing the short-circuit a-B,

fig. 4 shows the case of the adjustment direction as in fig. 3, however, in which the pressure in the second chamber B falls below the critical pressure (suction phase), the torsional moment dominates the performance of the camshaft adjuster in such a way that it is driven, in which the pressure regulating unit/hydraulic fluid regulating device/short-circuit/bypass line from chamber a to chamber B is opened, in which the system acts in such a way that the pressure is equalized and the hydraulic fluid is redirected from chamber a to chamber B until the pressure in chamber B is again above the critical pressure,

fig. 5 shows another embodiment, in which two valves are integrated in the rotor blade, and a spring-loaded cup/piston is used,

fig. 6 shows the embodiment of fig. 5, however with the on position opening the bypass line,

fig. 7 shows a further embodiment of the positioning of the valve in the vane, in which the actuating bore can also be realized concentrically to the piston axis or the cup axis, so that the bypass line does not have to be interrupted, but rather drilling can take place without interruption even when the piston or the cup sufficiently isolates the opposing chambers in the blocking position and sufficiently opens the passage for throughflow in the open position,

FIG. 8 shows another embodiment in a position closing the bypass line, an

Fig. 9 shows the embodiment of fig. 8 in a position in which the bypass line is open.

Detailed Description

The drawings are only schematic in form and serve only for understanding the invention. Like elements are provided with like reference numerals. The features of the various embodiments can also be interchanged with one another.

Fig. 1 shows a first embodiment of a camshaft adjusting device 1 according to the invention. The camshaft adjuster 1 is provided for use in a valve drive of an internal combustion engine. The camshaft adjuster 1 has a rotor 2 with radially projecting blades 3. Typically, three or more blades 3 are used. Particularly preferred are four blades 3.

The rotor 2 is rotatably arranged in a stator 4, which can be connected, for example, via a gear wheel to an endless traction means, such as a chain. The rotor 2 and the stator 4 form a vane chamber 5 which is divided by each vane 3 into a first chamber 6 and a second chamber 7. The first chamber can also be referred to as chamber a and the second chamber can also be referred to as chamber B, or vice versa. A main shut-off valve/switching valve 9 is provided in the line system 8. The master cut valve 9 is provided between a pump (P)10 and a tank (T) 11. In addition to this, a hydraulic fluid regulating device 12 is provided.

The hydraulic fluid regulating device 12 preferably has two bypass line closing devices 13. The two bypass line closing devices 13 have valves 14, such as two-position two-way valves 15. The valve 14 is prestressed by means of a spring 16, said valve 14 also being able to be called a slide/slide valve.

The bypass line closures 13 are arranged in each case one bypass line 17 or in a common bypass line 17. But there is also a pilot line 18 for each bypass line closing device 13. Finally, below the limit/critical pressure p in the first chamber 6_kritVia the pilot line 18, one of the two-position, two-way valves 15 is acted upon, so that opening takes place, so that, as shown in fig. 2, for example, hydraulic fluid, for example oil, passes from the second chamber 7 via the bypass line 17 into the first chamber 6. In this case, as soon as the pressure P in the first chamber 6 drops below the critical pressure P_kritThe bypass line 17 is opened by the valve 14 on the right in the figure.

The adjustment direction of the rotor 2 relative to the stator 4 is indicated by means of an arrow 19.

Fig. 3 and 4 show the type of view of the variant of the rotor 2 in the case of an opposite adjustment direction 19 of the rotor relative to the stator 4.

Fig. 5 and 6 show variants with respect to the embodiments shown in fig. 1 to 4. In fig. 5, the first bypass line 17 and the second bypass line 17 are closed, while the bypass line 17 is opened due to the closing element 20, which is prestressed by the spring 16, on account of the pressure transmission from the first chamber 6, so that hydraulic fluid from the second chamber 7 can reach the first chamber 6.

Two bypass line closures 13, which are separate from each other, are alternately mounted in the blade 3. Each bypass line closing device 13 has an actuating line 18 which opens into the respectively associated first or

second chamber

6 or 7 and, in conjunction with the active spring 16, effects the opening and closing of the respectively associated bypass line 17. The pilot line 18 can also be referred to as a pilot channel.

The arrangement is selected such that the first and second chambers are hydraulically separated from each other in the basic valve position when the operating pressure is above the critical pressure. Neither the (over) pressure in the first chamber 6 nor the pressure in the second chamber 7 can cause the closure element 12, which is constructed in the form of a piston or cup, to open, nor the pressure drop between the two

chambers

6 and 7.

A suitable undercut can contribute to a secure closure of the closure element/valve body/cup/piston in the case of a recess for receiving the closure element 20 at the end.

In both chambers, as shown in fig. 5, the pressure is above the critical pressure. The valve is in its basic position, whereby the bypass line 17 is closed.

In contrast, in fig. 6, in the first chamber 6, the pressure drops below the critical pressure. However, the torsional moment drives the camshaft adjuster 1, in particular the rotor 2. The volumetric flow supply by the pump 10 is then no longer sufficiently ensured. As a result, a pressure is present in the chamber a, i.e. in the first chamber 6, which pressure drops below the critical pressure. By this "underpressure" in the first chamber 6, the closure element 20 is now pulled out of its seat or undercut against the spring 16 shown. Thereby, a short circuit from the second chamber 7 into the first chamber 6 is opened. This opening can also be assisted hydraulically by the chamber pressure in the second chamber 7, which acts on the now open end face of the closing element 20.

If a pressure equilibrium between the two

chambers

6 and 7 is reached, the valve/closure element 20 falls back into the seat again and closes the bypass line 17. The small undercut for receiving the closing element 20 serves for a reliable sealing against laterally acting pressure forces from the

chambers

6 and 7.

The system isThe system works as a conventional regulator in pure OPA mode until the pressure in the

chamber

6 or 7 is due to the applied alternating torque and the critical pressure p_kritAnd decreases, wherein said critical pressure is set via the effective area of the spring 16 and the inside of the closing element and also the piston area. Until then, the system operates in an oil-pressure-controlled manner and is independent of the "pumping switch" (umpen) between the chambers, which has a favorable effect on the control speed or control behavior with low torsional moments.

Thus, as the torque becomes greater, adjustment can be additionally assisted by the pump switching between chambers, based on CTA adjustment, i.e., "cam torque actuation". In the case of a higher adjustment speed, the pressure drop between the

chambers

6 and 7 additionally helps. The potential for air intake or exhaust from the oil is minimized. This of course also relates to the set operating pressure.

In fig. 7, a further embodiment is shown, in which there is an operating line 18 (vertically) extending from the

chambers

6 and 7, which acts on an adjusting device 19/closing element 20, which is operatively associated with the spring 16. The closing element 20 closes the inclined bypass line 17.

In fig. 8 and 9, two closing elements 20 are shown in bores which are movable independently of one another, are perpendicular relative to the surface of the blade 3, and connect the two

chambers

6 and 7 to one another. For example, below the limit pressure in the second chamber 7, the second chamber 7 sucks/displaces the closer closing element 20, i.e. the respective piston toward the second chamber 7. Thereby, a passage for oil from one section of the bypass line 18 to another section of the bypass line 17 is achieved, so that hydraulic fluid is introduced from the first chamber 6 into the second chamber 7 according to the arrow direction shown in the bypass line 17 in fig. 9.

List of reference numerals

1 camshaft adjuster

2 rotor

3 blade

4 stator

5 vane chamber

6 first chamber

7 second Chamber

8 pipeline system

9 Main cut-off/switch valve

10 Pump

11 case

12 hydraulic fluid regulating apparatus

13 bypass pipeline closing device

14 valve

15 two-position two-way valve

16 spring

17 bypass line

18 operating pipeline

19 adjustment device

20 closure element

Claims

1. Camshaft adjuster (1) of the vane cell type, having a rotor (2) with radially projecting vanes (3), wherein the rotor (2) together with a stator (4) forms vane cells (5) which are each divided by a vane (3) into two adjustable chambers which accommodate the rotor (2) in a rotatable manner and which are provided to accommodate a hydraulic fluid,

characterized in that a hydraulic fluid regulating device (12) for conducting hydraulic fluid is arranged between the chambers (6, 7), so that a pressure drop in the chambers (6, 7), which is caused or intensified by camshaft alternating moments occurring during operation, is used to open the hydraulic fluid regulating device (12) in order to pass fluid.

2. Camshaft adjuster (1) according to claim 1, characterized in that the hydraulic fluid adjusting device (12) has at least one bypass line closing device (13) or two bypass line closing devices (13).

3. Camshaft adjuster (1) according to claim 2, characterized in that the two bypass line closing devices (13) are arranged parallel to one another so as to be able to conduct a fluid.

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

5. Camshaft adjuster (1) according to claim 4, characterized in that the spring (16) pretensions the valve (14) into a position blocking hydraulic fluid.

6. Camshaft adjuster (1) according to claim 5, characterized in that the bypass line closing device (13) is preset such that below a limit pressure in a first one of the chambers (6), the bypass line closing device (13) is forced into an on position in which hydraulic fluid passes from a second chamber (7) through a bypass line (17) into the first chamber (6).

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

8. Camshaft adjuster (1) according to claim 1, characterized in that the hydraulic fluid guiding device (12) is integrated in the vane (3).

9. Camshaft adjuster (1) according to claim 6, characterized in that the bypass line closing device (13) has a control line (18) which establishes a connection between the first chamber (6) and a closing element (20), which connection serves for transmitting pressure, wherein the spring (16) in its basic position presses the closing element (20) into the bypass line (17) connecting the two chambers (6, 7) so that the hydraulic fluid is prevented from flowing through, and in the activated position the bypass line (17) is opened up to and/or below the limit pressure in the first chamber (6).

10. Camshaft adjuster (1) according to claim 9, characterized in that two pistons which can be moved toward and away from one another are arranged in the channel/bore, wherein the pistons are arranged such that they are controlled only by the associated control line (18).