Switchable valve train component for an internal combustion engine

Abstract

Switchable valve train component for an internal combustion engine with two mutually movable components (1, 2) which can be coupled for switching by at least one coupling element (3) which is displaceably arranged in a bore (4) by hydraulic fluid application, characterized in that at least one recess (7) for collecting hydraulic fluid contaminant is provided on the inner diameter of the bore (4), which recess (7) can, on the one hand, be released at least partially on the application side to allow the contaminant to flow in after a predetermined displacement path (L) of the coupling element (3) when hydraulic fluid is applied and, at the same time, be blocked on the outflow side by the coupling element (3), wherein, on the other hand, the recess (7) can be released at least partially on the outflow side to allow the contaminant to flow out by resetting the coupling element (3) and, at the same time, be blocked on the application side by the coupling element (3).

Description

[0001] The invention relates to a switchable valve train component for an internal combustion engine with two components movable relative to each other, which can be coupled for switching by at least one coupling element which is arranged to be displaceable in a bore by hydraulic agent.

[0002] Such a valve train component is known from DE 10 2006 046 573 A1. This patent describes a switchable rocker arm for the valve train of an internal combustion engine, comprising an outer and an inner lever. The outer lever is pivotally arranged relative to the inner lever and encompasses it with its arms. The inner lever has a receptacle for a gas exchange valve at one end and a complementary surface for a support element at the other. The outer and inner levers can be connected to each other via coupling means such that a large valve lift can be generated when coupled and a small or so-called zero valve lift when uncoupled. For coupling, the coupling means can be hydraulically displaced from a bore at the support-side end of the inner lever in the cam base circle, so that it engages under a drive surface of the outer lever.

[0003] A disadvantage of this design is that when hydraulic fluid is applied to switch the coupling agents, this so-called hydraulic fluid contaminate can enter the bore and thus between the contact surfaces due to co-contamination of the hydraulic fluid with abrasive particles, especially metal chips, or other foreign bodies, which can lead to increased wear and jamming of the coupling agents in the bore and consequently to malfunctions up to and including operational failure.

[0004] DE 10 2006 046 573 A1 again shows a valve train component which is designed as a switchable rocker arm with an outer and an inner lever. The coupling element is located on the support side of the inner lever and, in the coupling case, can be displaced longitudinally under an end crossbar of the outer lever by means of hydraulic pressure.

[0005] According to German patent application DE 10 2006 057 895 A1, the technology in question is a switchable rocker arm as a valve train component. The inner rocker arm incorporates a longitudinally extendable coupling element on its support side, which can be moved under a crossbar at the end of the respective outer rocker arm using hydraulic pressure.

[0006] The invention is based on the objective of preventing the ingress of hydraulic fluid contaminants into the bore of the coupling element in a switchable valve train component of the aforementioned type.

[0007] According to the invention, this problem is solved by providing at least one recess on the inner diameter of the bore for collecting hydraulic fluid contaminants, which recess can be opened at least partially on the supply side to allow the contaminants to flow in after a predetermined displacement of the coupling element when hydraulic fluid is applied and can be blocked on the outflow side by the coupling element, wherein the recess can be opened at least partially on the outflow side to allow the contaminants to flow out by resetting the coupling element and can be blocked on the supply side by the coupling element.

[0008] This method allows for easy removal of contaminants from the bore, reliably preventing the coupling element from jamming and causing increased wear on the contact and sealing surfaces. Simultaneously, the required hydraulic pressure for switching the coupling element is maintained in the bore during hydraulic fluid application, ensuring the full functionality of the coupling mechanism. Furthermore, simple flushing of the contaminant from the downstream side is possible without preventing backflow on the supply side.

[0009] In one embodiment of the invention, the recess is designed as an annular groove circumferential to the inner diameter of the bore. This is particularly easy to manufacture and simultaneously ensures the removal of contaminants across the entire inner diameter of the bore.

[0010] Alternatively, several depressions can be arranged, particularly distributed circumferentially around the inner diameter of the bore. For example, one or more arc- or crescent-shaped depressions or grooves can be provided, extending section by section around the inner diameter of the bore. It is particularly advantageous to position such a depression or groove, relative to the direction of gravity, at the lowest point of the bore, where the contaminant can accumulate due to gravity.

[0011] The invention is advantageously usable in a switchable rocker arm for a valve train of an internal combustion engine. Here, the first component forms a so-called primary rocker arm, and the second component forms a so-called secondary rocker arm of the switchable rocker arm, which is pivotally supported on the primary rocker arm. Preferably, the primary rocker arm is pivotally supported at a support-side end section, wherein the bore receiving the coupling element is integrated as a through-hole into the support-side end section of the primary rocker arm. At a downstream end of the through-hole, hydraulic fluid and contaminants can be discharged into the environment, while at a coupling-side end of the through-hole, the coupling element can be extended with its coupling-side end to couple the primary and secondary rocker arms and attached to the latter.

[0012] The coupling element can be switched in one direction of movement by applying hydraulic fluid. During switching, while the recess is being released on the hydraulic side, the recess can be blocked on the downstream side by the coupling element. Conversely, while the downstream side is being released, the recess can be blocked on the hydraulic side by the coupling element by resetting it. In this way, the recess and coupling element interact similarly to a sluice gate, where, by moving the coupling element back and forth, the contaminant can be introduced into the recess on the hydraulic side and discharged from it on the downstream side, while simultaneously ensuring the required switching pressure.

[0013] In one embodiment of the invention, the coupling element can be positioned against a stop in the bore in its initial position. This stop is penetrated by the hydraulic fluid inlet opening. The stop can be simply designed as an annular shoulder formed by a recess on the inner diameter of the bore. Preferably, the recess is designed as a relief groove on the inner edge of the stop formed on the inner diameter of the bore. In this way, when hydraulic fluid is supplied from the hydraulic fluid inlet opening, an optimized, and in particular complete, flow around the effective surface of the coupling element with improved pressure is achieved at the relief groove, without requiring any additional machining of the bore and / or the coupling element.

[0014] For the application of hydraulic fluid, a hydraulic fluid inlet opening is preferably provided on the inner diameter of the bore, which is connected to a hydraulic fluid supply at the support-side lever end area. This enables the supply of hydraulic fluid from the support's hydraulic fluid supply, particularly for lubricating the support and the rocker arm.

[0015] For switching, the coupling element is preferably movable from a starting position that couples the first and second components to a switching position that decouples them by applying hydraulic fluid. This eliminates the need for hydraulic fluid to switch to and maintain the coupling starting position, thus avoiding additional energy expenditure. Preferably, the coupling element is reset from the switching position to the starting position by means of a compression spring, preferably a simple cylindrical compression spring.

[0016] Preferably, the coupling element has a particularly easy-to-manufacture annular shoulder formed by a recess on the outer diameter, on the actuation side. This shoulder allows the recess to be opened on the actuation side with a predetermined gap width in the displacement direction. The gap width depends in particular on the length of the recess in the displacement direction and on the length of the available displacement path of the coupling element in the bore.

[0017] Preferably, the aforementioned step forms an annular working surface against which the coupling element can be actuated with hydraulic fluid. The coupling element, preferably in a decoupled initial position, can be pressed against a stop corresponding to the inner diameter of the bore with its working surface.

[0018] It is also advantageous if the coupling element can be applied on the actuation side to a stop formed on the inner diameter of the bore in the direction of displacement, which is penetrated by a hydraulic medium inlet opening for the hydraulic medium actuation of the bore.

[0019] The stop can be easily formed on a shoulder created by a recess on the inner diameter of the bore, which forms a corresponding annular contact surface for the contact surface of the coupling element. Preferably, the coupling element is located in its initial position with its contact surface directly opposite the hydraulic fluid inlet opening for hydraulic fluid application. Preferably, the contact surface of the stop is perforated by the hydraulic fluid inlet opening for hydraulic fluid application in the bore.

[0020] Preferably, by returning the coupling element to its initial position at the downstream end, the recess can be released downstream with a predetermined gap width in the direction of displacement.

[0021] Preferably, the coupling element, in the switching position, can be abutted with its downstream end against a stop arranged in the bore. This stop is preferably formed by a spring support arranged downstream in the bore, against which compression spring elements are supported, allowing the coupling element to be returned from the switching position to its initial position. The spring support is particularly easy to manufacture as a sheet metal part, especially by stamping and bending, and preferably has one or more circumferentially distributed through-holes through which hydraulic fluid and contaminants can flow.

[0022] The invention can be used not only in switchable rocker arms but also in other switchable valve train components, such as in particular switchable roller or bucket tappets or switchable support elements with two mutually movable components, which can be coupled for switching by at least one coupling element that is displaceably arranged in a bore by hydraulic agent.

[0023] Regarding the drawing: Fig. Figure 1 shows a cutaway partial view of a valve train component according to the invention for an internal combustion engine in a first embodiment in a first operating state and Fig. Figure 2 shows a cutaway partial view of the valve train component in a second operating state.

[0024] The Fig. 1 and Fig. Figure 2 shows a first embodiment of a switchable valve train component according to the invention for an internal combustion engine. The valve train component is formed here by a switchable rocker arm, which is Fig. 1 and Fig. 2 is shown only partially at a support-side lever end area in a view cut in the longitudinal direction of the lever. The first component 1 is designed as the so-called primary lever and the second component 2 as the so-called secondary lever of the switchable rocker arm, pivotally supported on the primary lever. The primary and secondary levers are shown in the section plane of Fig. 1 and Fig. 2 pivotably arranged. The first component 1, forming the primary lever, is pivotably supported at a support-side lever end region by a spherical contact surface 12 on a support element (not shown). For switching the trailing arm, the primary and secondary levers can be coupled by the coupling element 3, which is slidably guided in a bore 4 at the support-side lever end region of the primary lever. The coupling element 3 is moved from a primary and secondary lever coupling initial position by hydraulic fluid being applied in the bore 4 according to Fig. 1 into a primary and secondary lever decoupling switching position according to Fig. 2. The bore 4 is integrated into the support-side end area of ​​the primary lever as a central through-bore extending in the longitudinal direction of the lever, starting from the lever end. In the illustrated fixed initial position, the primary and secondary levers can be coupled. In the coupling case, the coupling element 3 can be pushed out of the coupling-side inner end of the bore 4 in the initial position, which faces the second component 2 forming the secondary lever, and can be placed against a corresponding contact or drive surface of the secondary lever ( Fig. 1) This is located on the underside of the lever at the free end of the secondary lever opposite the coupling in the illustrated coupling case. The coupling element 3 engages the free end of the secondary lever with its coupling-side end. To decouple, the coupling element 3 can be fully pushed back into the bore 4 by applying hydraulic fluid to the switching position ( Fig. 2) For the application of hydraulic fluid, a hydraulic fluid inlet opening 5 is provided on the inner diameter of the bore 4.

[0025] The bore 4 is open at its outflow-side outer end to allow contaminants and hydraulic fluid to drain into the environment. It is widened at an annular shoulder 6 formed on the inner diameter of its outflow-side end section. On the supply side of the bore 4, a stop 11 is provided, formed by a recess on the inner diameter. The coupling element 3, with a shoulder 8 formed by a recess on the outer diameter, can be pressed against this stop in its initial position in the direction of movement. The shoulder 6 and the stop 11 define a supply-side guide section on the inner diameter of the bore 4, in which the coupling element 3 is guided at its outer diameter against the inner diameter of the bore 4.

[0026] On the actuation-side guide section, a recess 7 is formed in a central area between shoulder 6 and stop 11 on the inner diameter of bore 4 as a circumferential annular groove for collecting hydraulic fluid contaminants. This recess is arranged coaxially to the displacement direction of the coupling element 3 and has two annular limiting walls opposite each other in the displacement direction: an actuation-side limiting wall facing the hydraulic fluid inlet opening 5 and an outflow-side limiting wall facing the outflow-side end of bore 4. The recess 7 can be completely covered by the coupling element 3 with its outer diameter and can thus be locked on both the actuation-side and outflow-side sides. On the actuation-side, it is in the initial position that couples components 1, 2 or the primary and secondary levers ( Fig. 1) lockable by the coupling element 3 and, during the hydraulic medium application, only after a predetermined displacement L of the coupling element 3, can be released and actuated with hydraulic medium on the actuation side at the annular shoulder 8 formed on its outer diameter by a recess in the displacement direction ( Fig. 2) The recess 7 is opened on the actuation side by an annular gap S1 in the displacement direction between the shoulder 8 of the coupling element 3 and the actuation-side boundary wall of the recess 7. Hydraulic fluid and contaminants can flow into the recess 7 through the gap S1 at the inner diameter of the bore 4. Since the recess 7 can be blocked on the outflow side (i.e., on the side facing away from the hydraulic fluid inlet opening 5) by the coupling element 3 during the actuation-side release, the contaminants cannot flow out and collect in the annular recess 7. Preferably, the actuation-side release of the recess 7 by the coupling element 3 only occurs when the first and second components are decoupled. The displacement L of the coupling element 3, or the distance of the actuation-side boundary wall of the recess 7 to the stop 11 in the displacement direction, is predetermined accordingly.This distance determines the displacement L of the coupling element 3 during hydraulic fluid application in the initial position until the recess 7 is released on the application side. This ensures that, during hydraulic fluid application for switching the rocker arm, the recess 7 is only released by the coupling element 3 and can be pressurized with hydraulic fluid once the primary and secondary levers are decoupled. However, it is also possible to adjust the displacement L of the coupling element 3 so that the recess 7 is released on the application side before the switching position is reached or the primary and secondary levers are decoupled.

[0027] In the primary and secondary lever decoupling switching position, the coupling element 3 rests with its downstream end against a spring support 9 arranged in the downstream end section of the bore 4, which is designed as a simple spring support plate against which compression spring elements 10 are supported in the bore 4. In this decoupling switching position, bore 4 and coupling element 3 are constantly pressurized with hydraulic fluid.

[0028] By ceasing the hydraulic fluid supply, the coupling element 3 is removed from the switching position ( Fig. 2) by the spring force of the pre-tensioned compression spring means 10, here a simple cylindrical compression spring, into the starting position ( Fig. 1) Releasable and restorable against the stop 11 formed on the actuation side of the bore 4. The recess 7 is designed with a corresponding distance in the direction of movement from the stop 11 on the actuation side. During hydraulic actuation, this distance determines the displacement L of the coupling element 3 from the initial position until the recess is released on the actuation side, and simultaneously, in the initial position, the length of the seal in the direction of movement at the leakage gap between the outer diameter of the coupling element 3 and the inner diameter of the bore 4.

[0029] Upon return to the initial position, after a predetermined displacement, the downstream end of the coupling element 3 comes opposite the recess 7, whereby this recess can be released on the downstream side in the initial position through an annular gap S2 in the displacement direction between the downstream end of the coupling element 3 and the downstream boundary wall of the recess 7 ( Fig. 1) This allows the contaminant to exit the recess 7 through the gap S2 on the outflow side and be flushed out of the bore 4 on the outflow side during the next switching operation with the leakage flow. The recess 7 can be blocked on the supply side by the coupling element 3, thus reliably preventing backflow of the contaminant in this direction. The annular gaps S1 and S2 allow contaminant to flow in and out uniformly around the entire circumference of the recess 7.

[0030] The coupling element 3 is formed by a cylindrical coupling piston, which is manufactured in one piece and has two inwardly tapered sections on its outer diameter. Its outer diameter is slidably guided and sealed on the correspondingly tapered guide section on the inner diameter of the bore 4 of the first component 1. At the shoulder 8, the coupling element 3 forms an annular contact surface on its end face for the application of hydraulic fluid. At its tapered end section on the coupling side, the coupling element 3 has a flattened section where it forms a flat coupling surface for contact with a corresponding contact or drive surface on the second component 2 for coupling. Fig. 1) The coupling element 3 is guided on the flat surface by a pin arranged transversely in the bore 4 to prevent rotation. This anti-rotation feature ensures precise positioning and alignment of the flat surface with the coupling surface relative to the contact or drive surface on the second component 2 when coupled. It is also conceivable to design the coupling element 3 as a multi-part assembly.

[0031] The coupling element 3 is for switching between an output coupled to the second component 2 ( Fig. 1) and a switching position decoupled from this ( Fig. 2) is movable back and forth in bore 4. By applying hydraulic fluid via the hydraulic fluid inlet opening 5 of bore 4, the coupling element 3 can be moved from its initial position to the switching position against the spring force of the compression spring elements 10. Hydraulic fluid then passes through a small leakage gap between the inner diameter of bore 4 and the outer diameter of the coupling element 3 to the outflow end of the coupling element 3, which is furthest away from the hydraulic fluid inlet opening 5, and can be discharged into the environment at the outflow end of bore 4.

[0032] In its initial position, the coupling element 3, with its effective surface formed at the shoulder 8, rests against the actuation-side stop 11 in the direction of movement. The bore 4 on the stop 11 is radially recessed inwards in a ring shape, corresponding to the diameter of the shoulder 8. The stop 11 forms an annular contact surface corresponding to the effective surface of the shoulder 8, which is perforated by the hydraulic fluid inlet opening 5. In this way, the effective surface of the coupling element 3 can be directly actuated with hydraulic fluid from the hydraulic fluid inlet opening 5 at the stop 11. The coupling element 3 has a chamfer on the outer diameter of the effective surface at the shoulder 8, ensuring a continuous flow and optimized pressure application to the effective surface of the coupling element 3 in its initial position when hydraulic fluid is supplied from the hydraulic fluid inlet opening 5.

[0033] In the starting position according to Fig. 1. The coupling element 3, with its coupling-side end pushed out of the bore 4 by the spring force of the compression spring means 10, is positioned for coupling to the second component 2. The displacement path of the coupling element 3 is limited on the actuated side by the stop 11 in the bore 4. In the Fig. In the switching position shown in Figure 2, the coupling element 3 is fully retracted into the bore 4 by hydraulic fluid pressure, against the spring force of the compression spring elements 10, thus decoupling it. The compression spring elements 10 are guided in a central blind bore extending from the downstream end of the coupling element 3 and are supported on one side in this bore and on the other side by the spring support 9, here a simple spring support plate, which is fixed downstream in the bore 4 by a retaining ring. This spring support plate also forms a downstream stop, against which the downstream displacement of the coupling element 3 is limited in the switching position. The hydraulic fluid exiting downstream from the leakage gap between the coupling element 3 and the bore 4 as a leakage flow can flow through through holes in the spring support 9 and discharge into the environment at the downstream end of the bore 4.

[0034] The first component 1, forming the primary lever, has at least one valve contact surface on the underside of the lever at its valve-side end region (not shown), which faces away from the support-side lever end region. This valve contact surface allows the primary lever to be applied to at least one gas exchange valve of the internal combustion engine for actuation. A housing-like section is provided at the support-side lever end region, into which the coupling mechanism with the bore 4 and the coupling element 3, which is slidably arranged therein, is integrated. Fig. 1 and Fig. 2) On the underside of the lever of this section, the dome-shaped contact surface 12 is formed, on which the first component 1 can be pivotally supported by a support element (not shown). The hydraulic fluid inlet opening 5 is in direct hydraulic fluid communication with the contact surface 12 via a branch channel, the branch channel of which can be supplied with hydraulic fluid from a hydraulic fluid reservoir (not shown) via the support element acting on the contact surface 12. The hydraulic fluid is typically pressurized oil from the engine oil circuit of the internal combustion engine.

[0035] In the switching position, the coupling element 3 is decoupled from the second component 2 forming the secondary lever ( Fig. 2) For illustration, the flow of contaminant and hydraulic fluid is indicated by arrows at the primary lever when hydraulic fluid is applied to bore 4. Starting from the contact surface 12 of the support, contaminant and hydraulic fluid flow through the hydraulic fluid connection between contact surface 12 and hydraulic fluid inlet opening 5 into bore 4 and, through the gap S1 on the inner diameter of this bore 4, which is opened on the application side by the coupling element 3 at the shoulder 8, into the recess 7 and collect there, as this recess is blocked on the outflow side by the outer diameter of the coupling element 3. Upon return to the initial position ( Fig. 1) The coupling element 3 releases the recess 7 at its downstream end in the downstream gap S2, so that contaminant and hydraulic fluid can escape into the downstream end section of the bore 4 and flow through the through holes of the spring support element 9 and escape into the environment at the downstream end of the bore 4.

[0036] In a decoupled state ( Fig. 2) The second component 2, which forms the secondary lever, generally performs a lost-motion movement, in which no stroke is transmitted to the secondary lever. The secondary lever can be positioned with its free end at the bottom of the lever towards the lower edge of the image. Fig. 2. Swing through. The return to the depicted unpivoted basic position is achieved by in Fig. 1 and Fig.2 Torsion spring elements, indicated at the support-side end of the primary lever, preload the primary and secondary levers against each other in their home position. The secondary lever can thus be engaged or disengaged by the coupling element 3, enabling valve lift switching or valve / cylinder deactivation. Depending on the design, the rocker arm may be equipped with tap-off elements, in particular cam rollers and / or sliding surfaces, for tapping off a cam lift movement from a camshaft (not shown) on the upper side of the lever.

[0037] The first component 1, forming the primary lever, is designed here as a so-called outer lever, which at least partially encompasses the second component 2 as a so-called inner lever. The primary and secondary levers have parallel, opposing side walls that extend in the longitudinal direction of the lever. It is also conceivable to design the primary lever as an inner lever, which is at least partially encompassed by the secondary lever as an outer lever. Reference symbol list 1 component 2 components 3 coupling element 4 holes 5 Hydraulic fluid inlet opening Paragraph 6 7. Further Study Paragraph 8 9 Spring support 10 compression spring components 11 attacks 12 Contact area L displacement path S1 gap S2 gap

Claims

[1] Switchable valve train component for an internal combustion engine with two components (1, 2) that are movable relative to each other and which can be coupled for switching by at least one coupling element (3) which is arranged to be displaceable in a bore (4) by hydraulic agent, characterized by , that at least one recess (7) for collecting hydraulic fluid contaminant is provided on the inner diameter of the bore (4), which recess (7) is, on the one hand, when hydraulic fluid is applied, after a predetermined displacement path (L) of the coupling element (3), at least partially released on the application side to allow the contaminant to flow in and, at the same time, blocked on the outflow side by the coupling element (3), wherein, on the other hand, the recess (7) is, by resetting the coupling element (3), at least partially released on the outflow side to allow the contaminant to flow out and, at the same time, blocked on the application side by the coupling element (3). [2] Switchable valve train component according to claim 1, characterized by , that the recess (7) is designed as an annular groove circumferential to the inner diameter of the bore (4). [3] Switchable valve train component according to claim 1, characterized by , that the first component (1) is designed as a primary lever and the second component (2) as a secondary lever of a switchable rocker arm for a valve train of an internal combustion engine, which is pivotally supported on the primary lever, wherein the primary lever can be pivotally supported with a support-side lever end area and the bore (4) is integrated into this bore, from which the coupling element (3) can be pushed out with its coupling-side end and can be placed on the secondary lever for coupling. [4] Switchable valve train component according to claim 1 or 3, characterized by, that the coupling element (3) can be moved from an initial position coupling the first and second components (1, 2) into a switching position decoupling the components (1, 2) by applying hydraulic fluid, wherein in this initial position the recess (7) can be blocked on the application side by the coupling element (3) and can be released at least section by moving it into the switching position to allow the contaminant to flow in. [5] Switchable valve train component according to claim 1 or 3, characterized by , that the coupling element (3) has a shoulder (8) formed on the outer diameter by a recess on the actuation side, at which, when hydraulic medium is applied, the recess (7) can be released on the actuation side with a gap width (S1) in the displacement direction through the coupling element (3). [6] Switchable valve train component according to claim 1 or 3, characterized by, that the coupling element (3) has a shoulder (8) formed on the outer diameter by a recess on the actuation side, which forms an effective surface for applying hydraulic fluid, wherein the coupling element (3) can be applied with the effective surface to a stop (11) formed on the inner diameter of the bore (4) on the actuation side in the direction of displacement. [7] Switchable valve train component according to claim 1 or 3, characterized by , that the coupling element (3) can be applied on the actuation side to a stop (11) formed on the inner diameter of the bore (4) in the direction of displacement, which is perforated by a hydraulic medium inlet opening (5) for the hydraulic medium actuation of the bore (4).

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