Patent Application
20160076479
The present invention relates to a cylinder head cover for a cylinder head of a piston engine. The invention also relates to a piston engine equipped with such a cylinder head cover.
A piston engine usually consists of an engine block, in which cylinders are formed, in which pistons of the piston engine are arranged in a stroke-adjustable manner. Underneath the engine block, a crankcase is generally adjoined, in which a crankshaft is rotatably mounted, which is drive-connected to the pistons via connecting rods. An oil sump is generally adjoined to the bottom of the crankcase. A cylinder head is generally adjoined to the top of the engine block and covers the individual cylinders at the top and contains inlet and outlet ducts that communicate with the cylinders. Charge exchange valves are usually arranged on the cylinder head. Camshafts are also usually mounted on the cylinder head to actuate the charge exchange valves. A cylinder head cover is adjoined to the top of the cylinder head, said cylinder head cover covering the cylinder head and the components arranged thereon. Fuel injectors can be attached to the cylinder head cover, which fuel injectors can inject fuel into the cylinders through the cylinder head cover and through the cylinder head.
Such a cylinder head cover is expediently provided with a certain pressure stability, for example in order to be able to safely absorb an increased internal pressure that can arise in an inner space enclosed between the cylinder head cover and the cylinder head, for example as a result of “blow-by gas”. Blow-by gas is produced during operation of the piston engine when leaks can enter the crankcase from the respective cylinder past piston seals during the explosions inside the combustion chambers and increase the pressure in the crankcase. The crankcase is usually fluidically connected to the above-mentioned inner space through the engine block and through the cylinder head, so the pressure can increase in said inner space too. Furthermore, a certain stability can be necessary for a cylinder head cover if additional parts are to be mounted on the cylinder head cover, such as fuel injectors or a fuel pump or the like.
It is known from DE 10 2005 062 546 A1 to produce a cylinder head cover in composite form, a skeleton assuming the load-bearing function and said skeleton being enclosed by a shell structure. The skeleton can be produced from a high-strength plastic, in particular a fibreglass-reinforced polyamide. In contrast to this, the shell structure can be produced from a simple, inexpensive plastic. The problem with such a composite design is the material mixture that arises as a result, which makes it more difficult to recycle the cylinder head cover. In particular, the different plastics must first be separated in order then to be able to recycle them.
The present invention is concerned with the problem of specifying an improved embodiment for a cylinder head cover and for a piston engine equipped therewith, which in particular has a high level of stability of the cylinder head cover, so that the cylinder head cover is particularly suitable for the attachment of further components. Furthermore, subsequent recycling of the cylinder head cover should at the same time be made easier. It should also be simple to produce.
This problem is solved according to the invention by the subject matter of the independent claim(s). Advantageous embodiments form the subject matter of the dependent claims.
The invention is based on the general concept of equipping the cylinder head cover with a cover body and with a separate securing bridge, both the cover body and the securing bridge each being provided for mounting on the cylinder head. The cover body is equipped with an outer cover seal for sealing off the cover body from the cylinder head, said outer cover seal completely running around along an outer edge of the cover body. This means that a sealing function of the cylinder head cover is assumed exclusively by the cover body in conjunction with the outer cover seal, so that the securing bridge makes no contribution to the sealing off of the inner space enclosed between the cylinder head and the cylinder head cover or cover body in the mounted state. The securing bridge, which for its part can be fastened to the cylinder head separately from the cover body, can be optimised for additional functions, for example, to be able to attach additional components to the cylinder head cover. To be able to support the securing bridge stably and securely on the cylinder head, the securing bridge fits over the cover body on an outer side along a cover body section from a first longitudinal side edge of the cover body to an opposite second longitudinal side edge of the cover body. Since the securing bridge thus fits over or bridges the cover body in the respective cover body section, forces acting on the securing bridge can be transmitted directly to the cylinder head without the cover body being loaded.
An inner side of the securing bridge that faces the cover body is expediently shaped in a complementary manner to the outer side of the cover body in the cover body section in such a manner that the securing bridge is in contact with the cover body in the cover body section. As a result, the cover body can at the same time be supported outwardly on the securing bridge. A pressure stability of the cover body for example can be improved thereby. According to another advantageous embodiment, it can be provided for the securing bridge to press the cover body in the cover body section against the cylinder head when in the mounted state. A certain prestress for the cover body can thereby be realised with the aid of the securing bridge, which in particular improves the pressure stability of the cover body.
The cover body can expediently be produced uniformly from one plastic material. In particular, the cover body can be injection-moulded from plastic in one piece. The securing bridge can likewise be produced from a plastic, in this case however a composite material also being considered, to provide the securing bridge with greater strength. For example, a fibre-reinforced plastic can be used to produce the securing bridge. Alternatively, the securing bridge can also be designed as a metal component. In particular, the securing bridge is a single-piece injection-moulded part. Recycling of the cylinder head cover is made easier, because the cylinder head and the securing bridge form separate parts and are each formed in a materially uniform manner.
It is of particular significance that the securing bridge represents a separate part from the cover body, so these parts can be separated easily from each other for recycling. In particular, there is no permanent connection between the cover body and the securing bridge.
The outer cover seal is expediently designed as an axial seal, which therefore bears in a sealing manner against the cover body and the cylinder head in the direction in which the cover body is also fastened to the cylinder head.
The securing bridge is expediently formed in such a manner that it is connected to the cylinder head outside the outer cover seal when in the mounted state. In other words, the outer cover seal runs inside the securing bridge in the cover body section.
According to an advantageous embodiment, the cover body can have a cover opening in the cover body section, while the securing bridge has a pump console for mounting a fuel pump. Said pump console can then have a bridge opening inside the cover opening, which bridge opening passes through the securing bridge and through which a pump drive for driving the fuel pump can interact with a drive cam of a camshaft of the cylinder head, which is covered by the cover body, when the cylinder head cover is in the mounted state. In this case, the securing bridge is thus used to mount a fuel pump, which is drive-coupled to a camshaft of the cylinder head during operation. In such a drive, relatively large drive forces are transmitted, which must ultimately be absorbed by the pump console. Since the pump console is situated on the securing bridge and the latter is supported on the cylinder head independently of the cover body, said large drive forces do not act on the cover body.
According to an advantageous development, a bridge seal can be provided to seal off the cover body from the securing bridge, said bridge seal running around in a closed manner along an inner edge, which encloses the cover opening, of the cover body. The sealing function of the cover body can thereby also be ensured in the region of the cover opening. The bridge seal is expediently also designed as an axial seal, so that it bears in a sealing manner against the cover body and against the securing bridge in the direction in which the securing bridge is placed onto the cover body.
The pump console can have a duct, which surrounds the bridge opening and which passes through the cover opening into the inner space enclosed between the cover body and the cylinder head. The drive connection between the drive cam and the fuel pump is made through this duct. The bridge opening is expediently provided with a round, in particular circular cross section, which makes production of the pump console and thus of the securing bridge simpler. In contrast, the cover opening is expediently provided with an angular, in particular rectangular opening cross section, which can also be stepped in longitudinal section. If the securing bridge bridges or fits over the cover body in an arc-like manner, a sealing direction that is oriented in an inclined manner to the mounting direction can result in the region of the cover opening, which can be problematic. The angular and/or stepped shape of the cover opening means that the bridge seal can be laid particularly simply such that contacting of the bridge seal takes place through the securing bridge and cover body largely parallel to the mounting direction.
In another advantageous embodiment, the securing bridge can have bridge fastening points, which allow direct contact and direct connection to the cylinder head outside the outer edge of the securing body. The securing body can thus be fixed to the cylinder head completely independently of the cover body. In this manner, all forces that act on the securing bridge can be transmitted to the cylinder head without interaction with the cover body.
In another embodiment, the cover body can have at least one positioning element, which interacts in a form-fitting manner with a counter positioning element, which is complementary thereto and is formed on the securing bridge, to position the securing bridge relative to the cover body. This measure simplifies mounting of the cylinder head cover.
According to a further advantageous embodiment, the cover body can have at least one injector mounting point for attaching a fuel injector, at least in the cover body section. The securing bridge can then have an injector cut-out for the respective injector mounting point, through which cut-out the respective injector mounting point for attaching the respective fuel injector is accessible. In this manner, the attachment of fuel injectors is not impaired by the presence of the securing bridge, which makes the mounting of the cylinder head cover on the cylinder head simpler. In particular, the respective injector mounting point can be completely enclosed by the securing bridge, that is, such that it runs around in a closed manner.
In another advantageous embodiment, the securing bridge can have two longitudinal webs, which extend along the two longitudinal side edges of the cover body, the securing bridge having at least two transverse webs, which extend from one longitudinal web via the cover body section to the other longitudinal web. The securing bridge obtains a comparatively stable structure thereby. While the longitudinal webs expediently extend in a straight line, the transverse webs can preferably extend in an arc-shaped manner, in particular in such a manner that they are concave on the inner side facing the cover body. This arc shape allows for example pressure forces acting on the securing bridge from the outside to be transmitted in a particularly favourable manner from the transverse webs to the longitudinal webs and from the latter to the cylinder head. If three or more transverse webs are present, at least one transverse web can extend between two adjacent injector mounting points of the above-mentioned type.
In another embodiment, the securing bridge can be supported on the cover body section by means of at least one elastomer body. For example, vibrations can be damped with the aid of such an elastomer body. Also, such an elastomer body can be used to realise a certain prestress between the securing bridge and the cover body. Finally, the elastomer body can be used to compensate a play that can arise for example owing to production tolerances between the cover body and the securing bridge. At least one such elastomer body can be arranged substantially centrally. For example, such an elastomer body can be positioned on one of the transverse webs, for instance centrally between the two longitudinal webs.
In a preferred embodiment, such an elastomer body can be ring-shaped. In particular, the ring-shaped elastomer body can have an H-shaped cross-sectional profile in the circumferential direction thereof.
In another advantageous embodiment, the securing bridge can have an engine bearing point for supporting an engine bearing. Engine bearings are used to be able to support oscillations and vibrations of the piston engine on a frame structure of the vehicle equipped therewith. Thanks to the proposal according to the invention, it is now possible to arrange such an engine bearing on the cylinder head cover, so the piston engine can also be supported on the frame structure in the region of the cylinder head cover. For example, such an engine bearing can be realised by means of an engine bearing strut, a first end of which is supported on the engine bearing point of the securing bridge and a second end of which is supported on said frame structure of the vehicle. Said engine bearing strut can have at its first end and/or at its second end an elastomer bearing, in order to be able to achieve the desired elastic support for the piston engine on the frame structure.
According to another advantageous embodiment, the securing bridge can have at least one securing bolt for fastening an attachment part. For example, it can be desirable to conceal the piston engine with the aid of a decorative cover. Such a decorative cover can be fastened to the securing bridge by means of such a securing bolt. The cylinder head cover thus has a further additional function to the attachment of additional components.
According to another advantageous embodiment, the securing body can have a blow-by gas outlet outside the securing bridge, through which outlet blow-by gas can be discharged out of the inner space enclosed between cylinder head cover and cylinder head, for example in order to supply the blow-by gas to a fresh air tract of the piston engine. The blow-by gas generally entrains oil, which should remain in the piston engine. To this end, an oil separation device is usually arranged in a blow-by gas return line, so that only de-oiled blow-by gas is ultimately supplied to the fresh air tract, while the separated oil is fed back to the piston engine or remains in the piston engine. Particularly expedient is an embodiment in which such an oil separation device is arranged on an inner side of the cover body that faces the cylinder head, for example in the form of a cyclone separator or labyrinth separator or impactor.
According to a preferred embodiment, it can be provided for the securing bridge to press the cover body against the cylinder head in the region of the first longitudinal side edge and/or in the region of the second longitudinal side edge when the cylinder head cover is in the mounted state. The securing bridge thus supports the fixing and sealing off of the cover body on the cylinder head. Other separate fastening points of the cover body can thereby be relieved and in particular at least some of them can be omitted in the region of the securing bridge. According to an advantageous development, the securing bridge can form a shoulder in the region of the respective longitudinal side edge, which shoulder acts as a holding-down device and in particular makes direct contact with a complementary step formed on the cover body.
In another embodiment, it can be provided for the securing bridge to be adhesively bonded to the cover body. In this manner, an easy-to-handle unit of cover body and securing bridge can be formed, which makes mounting easier.
A piston engine according to the invention has in the usual manner a cylinder head, to which a cylinder head cover of the above-described type is attached.
Further important features and advantages of the invention can be found in the subclaims, the drawings and the associated description of the figures using the drawings.
It is self-evident that the above-mentioned features and those still to be explained below can be used not only in the combination given in each case but also in other combinations or alone without departing from the scope of the present invention.
Preferred exemplary embodiments of the invention are shown in the drawings and are explained in more detail in the description below, the same reference symbols referring to the same or similar or functionally equivalent components.
In the figures,
According to
The cover body 5 is equipped with an outer cover seal 9, which seals off the cover body 5 from the cylinder head 2 when in the mounted state. The outer cover seal 9 runs around completely along an outer edge 10 of the cover body 5, so that the cover body 5 in conjunction with the outer cover seal 9 can seal off an inner space 11, which is enclosed between the cover body 5 and the cylinder head 2 and can be seen in
The securing bridge 6 is arranged on the cover body 5 such that said bridge fits over the cover body 5 on an outer side 13 facing away from the cylinder head 2 along a cover body section 14 in such a manner that the securing bridge 6 extends from a first longitudinal side edge 15 to an opposite second longitudinal side edge 16.
The securing bridge 6 is fastened to the cylinder head 2 outside the outer cover seal 9 when in the mounted state. The outer cover seal 9 thus also runs inside the securing bridge 6 in the cover body section 14.
According to
In order to be able to seal off the cover body 5 from the securing bridge 6 in the region of the cover opening 17, a bridge seal 26 is expediently provided, which runs around in a closed manner along an inner edge 27, which encloses the cover opening 17, of the cover body 5. The cover opening 17 is provided here with a rectangular opening cross section, which is also stepped in the cross section of the cylinder head cover 1 according to
As can be seen in particular in
According to a preferred embodiment, it can be provided according to
According to
According to
The securing bridge 6 here has two longitudinal webs 37, 38 and a plurality of transverse webs 39, 40, 41. The two longitudinal webs 37, 38 each extend along one of the two longitudinal side edges 15, 16 of the cover body 5. The three transverse webs 39, 40, 41 provided here extend from one longitudinal web 37 via the cover body section 14 to the other longitudinal web 38. Whereas the two longitudinal webs 37, 38 run substantially in a straight line, the three transverse webs 39, 40, 41 extend in an arc-shaped manner. The left-hand transverse web 39 and the central transverse web 40 each extend between two adjacent injector mounting points 34, 34′.
The inner side 42 of the securing bridge 6 that faces the cover body 5 can be in direct contact with the outer side 13 of the cover body 5. In particular, the securing bridge 6 can press the cover body 5 against the cylinder head 2 when in the mounted state. However, the embodiment shown, in which the securing bridge 6 is supported on the cover body section 14 by means of at least one elastomer body 43, is preferred. Two such elastomer bodies 43 are shown here. These can expediently have a ring-shaped structure. According to
In the embodiment shown here, an engine bearing point 45 is formed on the securing bridge 6, with the aid of which engine bearing point an engine bearing 46, which can be seen in
In the embodiments shown here, the securing bridge 6 also has a securing bolt 53, with the aid of which an attachment part (not shown here) can be fastened to the securing bridge 6 and thus to the cylinder head cover 1. Such an attachment part is for example a decorative cover of the piston engine 3.
The cylinder head cover 1 shown here has a blow-by gas outlet 54 on the cover body 5 outside the securing bridge 6, to which outlet a return line can be connected to feed blow-by gas back to a fresh air system of the piston engine 3. According to the views of
In
In
In another embodiment, it can be provided for the securing bridge 6 to be adhesively bonded to the cover body 5. In this manner, an easy-to-handle unit of cover body 5 and securing bridge 6 can be formed, which makes mounting easier.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2013 208 231.2 | May 2013 | DE | national |
This application claims priority to German Patent Application No. 10 2013 208 231.2, filed May 6, 2013, and International Patent Application No. PCT/EP2014/058677, filed Apr. 29, 2014, both of which are hereby incorporated by reference in their entirety.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2014/058677 | 4/29/2014 | WO | 00 |
