WO2016110285A1

WO2016110285A1 - Cam shaft adjuster having centrifugally controlled shift element between working chambers of a pressure chamber

Info

Publication number: WO2016110285A1
Application number: PCT/DE2015/200538
Authority: WO
Inventors: Olaf Boese; Jochen Thielen
Original assignee: Schaeffler Technologies AG & Co. KG
Priority date: 2015-01-08
Filing date: 2015-12-14
Publication date: 2016-07-14
Also published as: DE102015200147B4; DE102015200147A1

Abstract

The invention relates to a hydraulic cam shaft adjuster (1), formed as a vane adjuster, comprising a stator (2) that is connected to a crank shaft of the internal combustion engine, and a rotor (4) that is rotatably mounted in the stator (2) and connected to a cam shaft. The cam shaft adjuster (1) also comprises a conducting system that supplies or discharges hydraulic medium to/from at least two pressure chambers (7) with the interposition of a hydraulic valve in association with pressure medium lines, each pressure chamber being divided, by a vane (6) secured to the rotor, into separate counter-operating working chambers (8, 9), whereby a phase position of the cam shaft can be changed in a targeted manner or held relative to the crank shaft Each vane (6) includes a control device (13) which permits a selective releasing and interrupting of a flow connection (10) between the working chambers (8, 9), and which prevents a relative movement between the rotor (4) and the stator (2), according to demand, wherein the cooperating working chambers (8, 9) preferably have a consistent volume. The control device (13) comprises a centrifugally controlled shift element (11), which is assigned a spring (24) for centrifugal force-dependent resetting.

Description

Camshaft adjuster with centrifugal force-controlled switching element between working chambers of a pressure chamber

The invention relates to a hydraulic camshaft adjuster for an internal combustion engine, constructed as a Flügelzellenversteller with the features of the preamble of claim 1.

Camshaft adjusters are used to change the opening and closing times of the gas exchange valves of an internal combustion engine in order to improve the fuel consumption and the operating behavior of the internal combustion engine. A vane phaser constructed as a vane phaser constitutes a proven system in which a rotor having radially extending vanes is disposed in a stator and divides vents in the stator into two opposing cooperating working chambers, respectively, with the vanes. The working chambers are acted upon via a hydraulic system with a pressure medium, wherein when pressure is applied to a working chamber, the pressure medium is displaced from the opposite working chamber. Depending on the pressurization of the working chambers, the rotor is then adjusted relative to the stator in one direction of rotation. Since the rotor is connected to the camshaft and the stator to the crankshaft, the angle of rotation of the camshaft relative to the crankshaft also changes.

For example, DE 10 2006 045 005 A1 and DE 10 2009 015 882 A1 disclose camshaft adjusters with which the angular position of a camshaft relative to a crankshaft can be adjusted. The described camshaft adjusting device has a hydraulic system with a multi-way valve for pressurizing a plurality of working chambers, in which the working chambers are differently pressurized depending on the position of the valve body in the multi-way valve and the camshaft is then adjustable in different directions of rotation relative to the crankshaft , Further, in the valve body of the multi-way valve, a two-way check valve is provided with two spring-loaded closure bodies through which in certain positions of the Valve body is provided a flow connection between the working men. Due to the proposed check valve in conjunction with the multi-way valve, both external pressurization of the working chambers and pressure equalization between the working chambers are possible in certain positions of the valve body.

The object of the invention is to provide a simple camshaft adjuster, with which the oil volume in the control system can be reduced and ensures a secure function of the center lock.

This object is achieved by a camshaft adjuster with the features of claim 1. Further preferred embodiments of the invention can be taken from the subclaims, the figures and the associated description.

According to the basic idea of the invention, it is proposed to achieve the object that the control device associated with each wing comprises a centrifugally controlled switching element, also designated as a control pin, which is assigned a spring for the centrifugal force-dependent return.

The construction according to the invention has the effect that, at low camshaft speeds, the cooperating working chambers of a pressure chamber are short-circuited, ie connected to one another. This is done by a spring, the spring force at low speed level exceeds the centrifugal force of the centrifugal force-controlled switching element and the flow connection between the working chambers is therefore open. At high speeds, the switching element is adjusted by the centrifugal force against the force of the spring radially outward, thereby closing the flow connection between the working chambers. The cooperating with the centrifugal force-controlled switching element according to the invention flow connection can be further combined with a check valve or one-way valve known construction and arrangement. In previous Mittenverriegelungskonzepten made the short circuit between the cooperating working chambers via control piston or control pins, which are connected via a control channel (also called C-channel). The hydraulic or central valve can either be connected to a pressure source or to the tank via the C channel and thus switched to zero pressure. The disadvantage here are long flow paths of the hydraulic fluid, the oil in the C channel. This results in a high flow resistance in the C channel, which leads to long discharge times. The volume of oil moved through the C channel is determined by the two locking pins and by the control pins assigned to the pressure chambers and is correspondingly large. Especially at low oil temperatures, there are large discharge times due to the long distances and the moving oil volume, which have a negative effect on the operation of the center lock at engine stop.

Due to the inventive concept in which the control device in the wing includes a centrifugal force-controlled switching element over which the working chambers are short-circuited or disconnected, the previously integrated in the wings, hydraulically controlled control pins of the control device can be omitted. The structure according to the invention restricts the C-channel in the hydraulic-fluid-guidance system to the activation of the locking pin intended for the center-locking of the camshaft adjuster, as a result of which the distances shortening the flow paths in the C-channel. At the same time, the moving volume of oil or hydraulic fluid in the C channel is significantly reduced, which, in conjunction with the shortened distances, advantageously results in a deliberate, faster pressure relief of the C channel. Due to the elimination of the control pins previously used in the wings and the supply lines can be provided by the invention, a component optimized camshaft adjuster, which is still inexpensive to produce, since the locking concept according to the invention can be realized by means of easily implementable measures. Furthermore, the inventive centrifugally controlled switching element ensures optimum control of the working chambers to achieve a desired higher adjustment speed, combined with a functionally reliable center lock, which is ensured even at low temperatures at engine stop. Advantageously, the centrifugal force-controlled switching element according to the invention with a check valve known construction and arrangement are combined, which is associated with the flow connection.

According to one embodiment of the invention, it is provided to use a centrifugal force-controlled switching element comprising a displaceably guided in the wing, interacting with a free space piston, which is associated with a spring which is inserted between a radially outer, positioned in the wing cartridge and the piston. Preference is given to a pot-like piston is provided, in which engages an axially projecting approach of the cartridge. This constructive design ensures optimum reception and guidance of the compression spring used between these components.

On the side facing away from the spring, a free space is formed by the piston and by a blind hole in the blade or in the rotor, which can be filled with oil by leakage, which can flow back into a reservoir or tank through a vent hole in the rotor , This ensures that the piston is displaceable by spring force almost without resistance at low speeds of the camshaft adjuster. Alternatively or in addition to a vent hole in the rotor, a through hole can be introduced in the piston.

A further embodiment according to the invention provides, as a centrifugal force-controlled switching element, a piston with a rectangular cross-sectional profile. The in a piston with the outer contour corresponding, preferably frontal recess of the wing or the rotor guided piston can be combined with a spring which is mutually supported to the piston without a cartridge directly on the rotor.

Furthermore, it makes sense to use a spring-loaded sealing plate as a centrifugal force-controlled switching element. The sealing plate is used and guided in a corresponding groove or recess of the rotor. For the function of the sealing plate, it is advantageous if it has a passage or a passage which cooperates with the flow connection between the working chambers. It offers itself to associate with the passage of a check valve, which is fixed in position force, shape or cohesively directly to the sealing plate, whereby the check valve follows a caused by the centrifugal adjusting movement of the sealing plate. Alternatively, the switching element designed as a sealing plate can be combined with a separately arranged check valve, which is advantageously supported in the radial direction on the rotor. Consequently, the sealing plate moves in the radial direction relative to the check valve, so that the check valve is always stationary relative to the rotor.

As a measure for reducing the component circumference, a control device designed as an integral component can be used according to the invention. This includes a centrifugal force-controlled switching element including check valve and a sealing strip of the wing, which are combined to form a structural unit. The integrated in each rotor blade sealing strip is comparable to the previous known camshaft adjusters each pressed by a spring sealingly against the inner diameter of the stator, so that a short circuit between the cooperating working chambers is prevented.

The integral component preferably embodied as a rectangular disk body comprises a passage, wherein the check valve and mutually the centrifugal force-controlled switching element are assigned to the integral component on one side for controlling a volume flow between the working chambers. When the passage is opened by the centrifugal force-controlled switching element and the working chambers are short-circuited with each other, the oil or hydraulic fluid can flow through the integral component only in one direction, since a counterflow is blocked by the check valve.

The integral component is preferably assigned a disk-like, centrifugal force-controlled switching element which can be pivoted about an axis of rotation positioned offset relative to the passage of the integral component. The switching element is acted upon by a spring, which counteracts the centrifugal force and which is designed, for example, as a spring arm connected in one piece with the switching element. Alternatively, the switching element can be acted upon by a separate spring. As a check valve is preferably a spring steel strip, which is arranged laterally on the integral component, with one end offset relative to the passage position fixed. The further end of the spring steel strip, which is also referred to as a sheet metal tab, locks the passage in a closed position separating the working chambers from one another and is supported on an abutment surface in an open end position.

According to a further embodiment of the invention, it is provided to arrange the centrifugally controlled switching element including the associated return spring within a cavity of the integral component. This results in an encapsulated position of the switching element, which is guided like a slide on an inner side of the integral component, depending on the centrifugal force opens or closes the passage. This construction with the protected position of the switching element simplifies the assembly of the integral component, which can be used for example in a recess of the wing.

The invention will be explained in more detail with reference to preferred embodiments, wherein the figures do not include all components of the camshaft adjuster. The invention is not limited to these illustrations. For simplicity, the same reference numerals are used in the figures for matching components. They show in detail:

Fig. 1 is a front view of a camshaft adjuster with the front cover removed, wherein each wing is associated with a centrifugal force-controlled switching element as a control device;

Fig. 2 shows the detail Z of Figure 1 on an enlarged scale, showing the centrifugal force-controlled switching element in a locked position.

Fig. 3 parts of the centrifugal force-controlled switching element of Figure 1 on an enlarged scale. FIG. 4 shows a representation comparable to the detail Z according to FIG. 1, which shows enlarged the centrifugally controlled switching element in the short-circuited position;

FIG. 5 shows a representation comparable to the detail Z according to FIG. 1, showing in an enlarged view the centrifugal force-controlled switching element whose piston forms a rectangular cross-sectional profile;

6 shows a camshaft adjuster in perspective with the front cover removed, wherein each wing includes a sealing plate as a centrifugal force-controlled switching element;

7 shows the detail Y according to FIG. 6 on an enlarged scale, which includes a sealing plate as a switching element;

8 shows the sealing plate and a separate non-return valve of the centrifugally controlled switching element according to FIG. 7;

9 shows the sealing plate with associated check valve as a structural unit of the centrifugally controlled switching element according to FIG. 7;

10 is a front view of a camshaft adjuster with the front cover removed, wherein each wing is associated with an integral component, consisting of centrifugal force-controlled switching element and sealing strip;

Fig. 1 1, the integral component of Figure 10 with a representation of the centrifugal force-controlled switching element. FIG. 12 shows the integral component according to FIG. 10 with a representation of the check valve; FIG.

FIG. 13 shows the integral component according to FIG. 10 with an alternative representation of FIG

centrifugally controlled switching element;

FIG. 14 shows the integral component according to FIG. 10 with an alternative representation of FIG

centrifugally controlled switching element; and

Fig. 15, the integral component of FIG. 14 in a different perspective.

Fig. 1 shows a camshaft adjuster 1, which is intended for adjusting a camshaft (not shown) relative to a crankshaft, not shown, of an internal combustion engine. The camshaft adjuster 1, which is constructed as a known type of vane, is acted upon by a hydraulic medium, preferably the oil of the internal combustion engine. The camshaft adjuster 1 depicted in FIG. 1 without an end cover comprises a stator 2 which can be driven by the crankshaft via a traction mechanism drive (not shown), which is preferably designed as a chain drive, and which includes an external toothing 3 for this purpose. In the stator 2, a limited relatively rotatable rotor 4 is integrated, which is fixed against rotation on the camshaft. The annular stator 2 forms a plurality of radially inwardly directed separating elements 5, whose bores are intended for a screw connection (not shown) with which in particular cover elements are fastened. According to a known construction according to the vane cell principle, the rotor 4 comprises a plurality of radially aligned vanes 6, seen in the circumferential direction of the camshaft adjuster 1 between the separating elements 5 of the stator 2 engage in a pressure chamber 7 and divide them into pairs working chambers 8,9. For adjusting the rotational angle of the camshaft 1 relative to the crankshaft, for example, hydraulic fluid or oil can act on the working chambers 8 via a corresponding setting of a switching valve in conjunction with hydraulic lines (not shown), thereby increasing their volume in groups, while at the same time displacing the hydraulic fluid from the working chambers 9 and is returned via hydraulic lines in a tank. This volume change of the working chambers 8, 9 leads to a relative rotation of the rotor 4 relative to the stator 2 in the direction of the arrow, in order to achieve a center locking position of the camshaft adjuster 1, in particular when the internal combustion engine is stopped. During this rotational angle adjustment for center locking, flow connections 10 between the working chambers 8, 9 of a control device 13 in the wings 6 are closed. For opposite adjustment of the camshaft 1, the working chambers 9 are acted upon in accordance with hydraulic means.

In Fig. 1, all flow connections 10 of the wings 6 are shown in an open position, which automatically adjusts itself at a low speed level of the internal combustion engine via a centrifugal force-controlled, as a control pin to be designated switching element 1 1. The switching element 1 1 comprises a piston 12 which is acted upon by a spring 24 on the outside. For this purpose, the spring 24 is designed so that its spring force exceeds a centrifugal force of the piston 12 up to a defined speed of the internal combustion engine, whereby the piston 12 each remain in a basic position releasing the flow connections 10.

FIGS. 2 to 4 show further details of the centrifugal force-controlled switching element 11 of the control device 13, the piston 12 of which is guided in a receptacle 14 of the rotor 4 designed as a blind hole. In the pot-like piston 12, the spring 24 is used as a compression spring which mutually surrounds a projection 15 of a cartridge 16 positioned in the wing 6. In the operating state of the piston 12 is acted upon by two forces, a radially outwardly directed centrifugal or centrifugal force, which counteracts a direction of rotation 17 of the camshaft adjuster 1 directed spring force of the spring 24. 2, the piston 12 is supported directly on the cartridge 16, whereby the flow connection 10 is interrupted between the working chambers 8,9. This piston position results at a speed of the internal combustion engine in which the centrifugal force of the piston 12 exceeds the spring force of the spring 24. On the side facing away from the spring 24, the piston 12, together with the receptacle 14 in the rotor 4, defines a free space 18 which ensures unimpeded setting movement of the piston 12 and which, in the operating state of the internal combustion engine, can be used. Leakage oil is determined, which flows back through a vent hole 19 in a reservoir or a tank. Furthermore, the free space 18 ensures that the piston at low speeds of the camshaft adjuster 1 by spring force almost without resistance in the basic position is displaced. As an alternative or in addition to a vent bore 19 in the rotor 4, the piston 12 with a through-bore 20 is shown in FIG. 4.

5, the centrifugal force-controlled switching element 21 is shown, which comprises a piston 22 having a rectangular cross-sectional profile which is guided in an end-side recess 23 of the rotor 4.

FIGS. 6 to 9 show the camshaft adjuster 1 or details thereof, in which the control device 33 includes a centrifugal force-controlled switching element 31 designed as a sealing plate 38, which is inserted and guided in a corresponding recess 32 of the rotor 4. The externally acted upon by a spring 37 sealing plate 38 has a communicating with the flow connection 10 in the wing 6 passage 34 or a passage. On the side facing the working chamber 8, the switching element 31 designed as a sealing plate 38 is provided with a non-return valve 35 which is in operative connection with the passage 34. By virtue of the non-positive, positive or materially fixed position non-return valve 35 directly on the sealing plate 38, this follows the adjusting movement of the sealing plate 38 caused by the centrifugal force. Alternatively, the sealing plate 38 can be combined with a separately arranged non-return valve 36, as shown in FIG be supported in the radial direction on the rotor 4. Consequently, the sealing plate 38 moves in the radial direction relative to the check valve 36, so that the check valve is always positioned relative to the rotor stationary.

FIGS. 10 to 15 show a further variant of a camshaft adjuster 1 or details thereof, in which the control device 43 of the vanes 6 is designed as an integral component 42, which includes a centrifugal force-controlled switching element 41 and a check valve 45. Furthermore, the integral component 42 also performs the function of a sealing strip. The integrated in each rotor blade, designed as an integral component 42 formed sealing strip is similar to the previous known Nockenwellenverstel- learning each by a spring 44 sealingly pressed against an inner diameter 46 of the stator 2, so that a short circuit between the cooperating working chambers 8,9 is prevented.

As FIGS. 11 to 13 make clear, the integral component 42 forms a rectangular body which encloses a passage 47. In order to control a volume flow between the working chambers 8, 9, the check valve 45 and mutually the centrifugal force-controlled switching element 41 is assigned to the integral component 42 on one side. If the passage 47 are short-circuited to each other by the switching element 41 and the working chambers 8.9, the oil or hydraulic fluid can flow through the integral component 42 only in one direction, since a counterflow is blocked by the check valve 45. The disc-shaped, centrifugal force-controlled switching element 41 is pivotable about a rotational axis 48 which is offset relative to the passage 47 of the integral component 42. In this case, the switching element 41 shown in FIG. 1 1 is acted upon by an integrally connected with the switching element 41, designed as a spring 49 spring. Deviating from this, FIG. 13 shows a separate spring 50 which counteracts the centrifugal force counteracting the centrifugal force-controlled switching element 41. The check valve 45 is arranged mutually to the switching element 41 laterally on the integral component 42 and fixed in position at one end to the passage 47. The further end of the check valve 45 locks the passage 47 in a closed position separating the working chambers 8, 9.

FIGS. 14 and 15 show the centrifugally controlled switching element 51, which prevents the check valve 45 from opening when the centrifugal force exceeds a force of the spring 52. The opening is interrupted because the switching element 51 is pressed by the centrifugal force against a stop 53 and a lower, designed as a hook 54 part of the switching element 51, the check valve 45 is closed. Thus, the flow connection 10 is interrupted between the working chamber 8,9. If the centrifugal force acting on the switching element 51 is smaller than the force of the spring 52, the switching element 51 is pressed into the position shown in FIGS. 14 and 15. Thus, the check valve 45 can open and the passage 10th between the working cans 8,9 release. In order to limit the opening travel of the check valve 45, the upper part of the hook 54 is used by the switching element 51 as a stop.

List of Reference Numbers Camshaft adjuster

stator

external teeth

rotor

separating element

wing

pressure chamber

working chamber

flow connection

switching element

piston

control device

admission

approach

cartridge

axis of rotation

free space

vent hole

Through Hole

switching element

piston

recess

feather

switching element

recess

control device

passage

check valve

feather sealing plate

Switching element Integral component Control device Spring

Check valve internal diameter passage

axis of rotation

feather

Switching element spring

attack

hook

Claims

claims

Hydraulic camshaft adjuster (1), constructed as a vane-cell adjuster, with a stator (2) which is connected to a crankshaft of the internal combustion engine and a rotor (4) rotatably mounted in the stator (2) and connected to a camshaft and a control system , the hydraulic fluid with the interposition of a hydraulic valve in conjunction with pressure medium lines at least one pressure chamber (7) supplies or dissipates, each of a rotor fixed wing (6) into separate, counteracting working chambers (8,9) is divided, whereby a phase angle of the camshaft relative held to the crankshaft or can be selectively changed and the wing (6) a control device (13,33,43) is introduced, which allows selective release and interruption of a flow connection (10) between the working chambers (8,9) and demand-dependent relative movement between the rotor (4) and the stator (2) prevents, characterized in that the control device (13, 33, 43) assigned to each vane (6) has a centrifugal force-controlled switching element (11, 31, 41, 51) to which a spring (24, 37, 49, 50, 53) is assigned for the centrifugal force-dependent return.

2. Hydraulic camshaft adjuster (1) according to claim 1, characterized in that as a switching element (1 1) in a wing (6) or rotor (4) displaceable piston (12) is provided, which is associated with a spring (24) between a radially outer, in the wing (6) positioned cartridge (16) and the piston (12) is inserted.

3. Hydraulic camshaft adjuster (1) according to any one of the preceding claims, characterized in that the switching element (1 1) includes a piston (22) having a rectangular cross-sectional profile in a corresponding recess (23) of the wing (6) and the rotor (4) guided and acted upon by a spring.

4. Hydraulic camshaft adjuster (1) according to one of the preceding claims, characterized in that a spring-loaded sealing plate (38) is provided as a switching element (31) in a corresponding recess (32) of the wing (6) and the rotor ( 4) and which includes a passage (34).

5. Hydraulic camshaft adjuster (1) according to claim 4, characterized in that the passage (34) of the sealing plate (38) formed switching element (31) directly with a check valve (35) or indirectly with a separately arranged check valve (36) cooperates.

6. Hydraulic camshaft adjuster (1) according to one of the preceding claims, characterized in that the control device (43) is designed as an integral component (42) and a centrifugal force-controlled switching element (41) and at the same time the function of a sealing strip of the wing (6 ) takes over.

7. Hydraulic camshaft adjuster (1) according to one of the preceding claims, characterized in that the integral component (42) has a passage (47) and the centrifugal force-controlled switching element (41) and mutually a non-return valve (45) is assigned on one side.

8. Hydraulic camshaft adjuster (1) according to one of the preceding claims, characterized in that a disk-like designed, centrifugal force-controlled switching element (41) about an offset to the passage (47) of the integral component (42) positioned pivot axis (48) pivotally and by one of Centrifugal force opposing spring (49,50) is acted upon.

9. Hydraulic camshaft adjuster (1) according to one of the preceding claims, characterized in that the check valve (45) by a passage (47) closing spring plate is formed, which with a End offset from the passage (47) on the integral component (42) is fixed in position and the other end in a closed position, the passage (47) blocks and is supported in an open end position on a stop surface (51).

Hydraulic camshaft adjuster (1) according to one of the preceding claims, characterized in that within the integral component (42), the centrifugal force-controlled switching element (51) including the centrifugal force-dependent provision specific spring (52) is introduced.