EP3333398B1 - Cylinder head - Google Patents

Description

The invention relates to a cylinder head of a liquid-cooled internal combustion engine, the cylinder head having a cooling chamber arrangement which borders on a fire deck and is divided into a fire compartment-side lower partial cooling chamber and an upper partial cooling chamber by an intermediate deck arranged essentially parallel to the fire deck, the upper partial cooling chamber being in one In the direction of a cylinder axis, the side of the intermediate deck facing away from the fire deck is arranged, and the upper partial cooling space and the lower partial cooling space are fluidly connected via at least one overflow opening which extends around the cylinder axis and is preferably arranged on a receiving sleeve. The invention also relates to an internal combustion engine with such a cylinder head.

From the AT 005 939 U1 the applicant is aware of a cylinder head in which the coolant flows from the upper part of the cooling chamber through an annular overflow opening between the intermediate deck and a receiving sleeve for a central component into the lower part of the cooling chamber. From there, the coolant is discharged into the cooling chamber of the crankcase via overflow openings. The valve bridges are flowed through evenly, but without any special directivity, which in certain applications can have disadvantages in terms of the cooling effect. A comparable solution shows the AT 503 182 A2 ,

In the AT 510 857 B1 an inflow channel is provided between an upper and lower partial cooling space, which has a ring or ring segment-shaped inlet opening in a central region. As a result, an adaptation to the local thermal requirements of the subsequent valve bridge passages is sought in order to improve the heat dissipation in the area of the exhaust valve seats and the valve bridges.

JP2866259B discloses another cylinder head.

The known arrangements have the disadvantage that only inadequate adaptation of the cooling of regions of the cylinder head which are subject to high thermal stress is possible, which may prove necessary in certain applications. The flow distribution to the various radial cooling channels can only be adjusted via the size of the overflow openings to the cylinder housing. As a result, the radial cooling channels on the inlet side are cooled as well as on the outlet side, but this is disadvantageous in relation to the temperature distribution on the fire deck. The resulting uneven temperature distribution on the fire deck results in material stresses in the cylinder head. At the same time, the cross-sectional area of the overflow openings can only be expanded to a limited extent for reasons of strength of the cylinder head, so that there is an undersupply of coolant or adverse pressure conditions can come. Furthermore, a specific flow around the receiving sleeve in the lower cooling compartment is not possible due to an annular overflow opening, since the cooling water flows in a vertical direction through the overflow opening onto the fire deck and subsequently into the radial cooling channels.

The object of the invention is to avoid these disadvantages and to ensure optimal cooling of thermally highly stressed areas of the fire deck and the receiving sleeve.

This object is achieved according to the invention by a cylinder head mentioned at the outset in that the overflow opening has at least one ring segment section which extends in the form of an annular segment around the cylinder axis and a bulging section which extends away from the cylinder axis in the radial direction. In other words, the overflow opening has a first section which extends in the form of a segment of a circle around the cylinder axis and from which a second section extends, which is designed as a radial bulge section which points away from the cylinder axis in the radial direction.

A circular ring segment in the sense of the invention is a circular ring section which extends over an angular range of less than 360 °.

In the context of the present disclosure, a cylinder axis is understood to mean a longitudinal center axis of a cylinder, which runs essentially normal to a fire deck or a cylinder head sealing plane.

The limited expansion of the ring segment section and bulge section increases the flow velocities in the transition between the partial cooling rooms and this concentrated flow, in particular due to the bulge section, increases the cooling of thermally highly stressed areas on the fire deck and in the area of valve bridges and thus reduces the temperature.

In a variant of the invention, the ring segment section extends over a first angle around the cylinder axis, which is between 20 ° and 180 °, preferably between 30 ° and 90 ° and particularly preferably 40 ° to 50 °. The bulge section extends over a second angle around the cylinder axis, which is between 5 ° and 45 °, preferably between 5 ° and 20 °. The second angle is advantageously smaller than the first angle.

It is particularly expedient if the overflow opening is arranged to extend from the receiving sleeve in the direction of an outlet channel — preferably between two exhaust valves. As a result, the entire coolant flow in the upper partial cooling space is concentrated on the outlet side and improved cooling of the outlet channel wall and an outlet valve guide is achieved. Furthermore, due to the concentrated flow through the outlet side, the flow through the inlet side is somewhat reduced. This creates a slight temperature rise in the inlet valve bridge, which means that the temperature level on the entire fire deck is very even and the material tensions can be drastically reduced.

A particularly focused flow with a favorable cooling effect can be achieved if the width of the ring segment section running in the radial direction is less than the width of the bulge section running in the circumferential direction. In other words, the width of the ring segment section is defined as its extension in the radial direction while the width of the bulge section is defined as an extension in the circumferential direction around the cylinder axis.

The ring segment section has a greater extent in the circumferential direction around the cylinder axis (hereinafter referred to as the length of the ring segment section) than in the radial direction (extent in the radial direction hereinafter referred to as the width of the ring segment section). In contrast, the bulge section has a greater extent in the radial direction (hereinafter referred to as the length of the bulge section) than in the circumferential direction around the cylinder axis (this extent in the circumferential direction is hereinafter referred to as the width of the bulge section). An arrangement which is favorable for the flow conditions results when the overflow opening extends in the circumferential direction around the cylinder axis essentially between two connecting lines extending from the cylinder axis to one valve axis each of two different valves, preferably between connecting lines from the cylinder axis to the exhaust valve axes of the two exhaust valves. In a variant of the invention, the bulge section extends along a valve symmetry plane that runs normal to the fire deck between two valve axes, preferably the valve axes of the exhaust valves. The extension of the bulge section advantageously ends in the radial direction in front of a connecting plane between the two valve axes. This results in a favorable balance between the cooling effect and the strength of the cylinder head.

It is advantageous if the bulge section extends in the direction leading away from the cylinder axis over a radial cooling channel running through an exhaust valve bridge. As a result, the region of the exhaust valve bridge which is subject to high thermal stress can be cooled particularly effectively.

For good cooling, it is also advantageous if the overflow opening is flow-connected in the lower partial cooling space via a distribution ring arranged in the lower partial cooling space around the receiving sleeve with cooling channels leading radially away from the distribution ring. This allows specific flow around the receiving sleeve in the lower part of the cooling chamber.

The object of the invention is also achieved by an internal combustion engine with a cylinder head according to one of the variants described above.

Fig.1

eine schematische Darstellung eines erfindungsgemäßen Zylinderkopfs in einem Schnitt gemäß der Linie I-I in Fig. 2;

Fig. 2

den Zylinderkopf aus Fig. 1 in einem Schnitt im Bereich eines oberen Teilkühlraumes gemäß der Linie II-II in Fig. 1; und

Fig. 3

den Zylinderkopf aus Fig. 1 in einem Schnitt im Bereich eines unteren Teilkühlraumes gemäß der Linie III-III in Fig. 1.

The invention is explained in more detail below on the basis of a non-restrictive exemplary embodiment, which is shown in the figures. In it show:

Fig.1

is a schematic representation of a cylinder head according to the invention in a section along the line II in Fig. 2 ;

Fig. 2

the cylinder head Fig. 1 in a section in the area of an upper sub-refrigerator according to line II-II in Fig. 1 ; and

Fig. 3

the cylinder head Fig. 1 in a section in the area of a lower partial cold room according to the line III-III in Fig. 1 ,

Fig. 1 shows in a section of an internal combustion engine 100 a liquid-cooled cylinder head 1 with at least one cylinder, not shown, which is arranged along a cylinder axis 2. The cylinder head 1 has a fire deck 3 in the direction of a combustion chamber of the cylinder. An intermediate deck 4 divides a cooling space arrangement 5 into a lower partial cooling space 5a near the fire deck 3 and an upper partial cooling space 5b adjoining in the direction of the cylinder axis 2.

The intermediate deck 4 has at least one overflow opening 6 for the flow connection between the upper partial cooling chamber 5b and the lower partial cooling chamber 5a, which is formed between the intermediate deck 4 and a receiving sleeve 7. The receiving sleeve 7 serves, for example, to receive a fuel injection device or a spark plug and is arranged essentially concentrically with the cylinder axis 2. According to Fig. 2 connects the overflow opening 6 starting from the cylinder axis 2 in the radial direction to the receiving sleeve 7 and, according to the invention, has an annular segment section 6a which extends at least partially around the cylinder axis 2 or the receiving sleeve 7, with an additional bulging section 6b running in the radial direction. In the case of top-down cooling, that is, when the coolant flows from the upper 5b into the lower partial cooling space 5a, a favorable distribution of the coolant and cooling, in particular of the thermally highly stressed areas, can thus be achieved.

The ring segment section 6a has the shape of a circular ring segment and extends in the circumferential direction over a first angle α about the cylinder axis 2 or the receiving sleeve 7. The first angle α is between 20 ° and 180 °, an angle of approximately 65 in the exemplary embodiment shown ° is realized. The substantially radially extending bulge section 6b extends in the circumferential direction over a second angle β, which is between 5 ° and 45 °, with approximately 16 ° being implemented in the exemplary embodiment shown.

The second angle β is preferably small compared to the first angle α. This allows the coolant to be directed specifically to the areas of the valve axes that are particularly thermally highly stressed on the outlet side.

In addition to the above-mentioned angular ranges in the circumferential direction around the cylinder axis 2, the extensions in the radial direction, starting from the cylinder axis 2, must also be taken into account: the ring segment section 6a has a larger extent in the circumferential direction than in the radial direction in all design variants. The extent in the radial direction is the width of the ring segment section 6a. The bulge section 6b can be designed differently depending on the design variant: the width of the bulge section 6b, i.e. its extent in the circumferential direction around the cylinder axis 2, can either be smaller, the same size or greater than the extent of the bulge section 6b in the radial direction (starting from the cylinder axis 2). In the illustrated embodiment according to Fig. 2 and Fig. 3 the width of the bulge section 6b is essentially equal to the length, that is to say to extend in the radial direction. A favorable coolant distribution when flowing through the overflow opening 6 can be achieved if - as implemented in the exemplary embodiment shown - the width of the ring segment section 6a running in the radial direction is smaller than the width of the bulge section 6b running around the cylinder axis 2 in the circumferential direction.

In order to achieve the best possible balance between the pressure loss when flowing through the overflow opening 6 and the cooling effect in the area of the thermally highly stressed areas such as the receiving sleeve 7 and valve bridges, the dimensioning of the overflow opening 6 is selected as follows: The overflow opening 6, in particular the ring segment section 6a, is between two connecting lines A extending from the cylinder axis 2 to one valve axis 8a, 8b each from two different valves are arranged. Basically, these can be the exhaust valve axes 8a and the intake valve axes 8b, or each a connecting line A to an exhaust valve axis 8a and an intake valve axis 8b run, in the illustrated embodiment according to Fig. 2 however, the connecting lines A are arranged between the cylinder axis 2 and the exhaust valve axes 8a. This is advantageous because the highest thermal loads occur during operation on the outlet side. The connecting line A connects as a valve axis 8a, 8b to the cylinder axis 2. At the same time, the bulge section 6b extends along a valve symmetry plane Z running between two valve axes 8a, 8b - in the exemplary embodiment shown between the exhaust valve axes 8a - normal to the fire deck 3. The valve symmetry plane Z runs normal to the fire deck 3 or to the cylinder head sealing plane and parallel to the valve axes 8a, 8b through the cylinder axis 2. The extension of the overflow opening 6, in particular the bulge section 6b, ends in the radial direction in front of a connecting line between the two valve axes 8a assigned to the valve symmetry plane Z. , 8b - in the exemplary embodiment shown, these are the exhaust valve axes 8a.

Using the arrows P, the figures show the flow of a coolant in a cylinder head 1 according to the invention. According to the arrows P in Fig. 1 the coolant passes from a pressure source (not shown), for example a coolant pump, through a coolant inlet into the upper partial cooling space 5b, flows through the overflow opening 6 in the vertical direction into the lower partial cooling space 5a, where it strikes the fire deck 3 directly and cools it.

As in Fig. 3 The coolant is shown in the lower partial cooling space 5a via a distribution ring 10 on, for example, four radial cooling channels 9a, 9b, 9c, 9d and flows further through openings 11a, 11b, 11c, 11d into a crankcase. Of course, fewer radial cooling channels and fewer openings can also be provided.

A targeted flow around and thus cooling of the receiving sleeve 7 is made possible via the distribution ring 10. The radial cooling channels 9a, 9b, 9c, 9d are arranged in particular in the region of valve bridges - due to the design of the overflow opening 6 with ring segment section 6a and bulge section 6b, the coolant flow is directed and in particular the outlet valve bridge 90, i.e. the first radial cooling channel 9a between the outlet channels 8, efficiently cooled. How from Fig. 2 together with Fig. 3 As can be seen, the bulge section 6b runs in a direction leading radially away from the cylinder axis 2 over the first radial cooling channel 9a running through an exhaust valve bridge 90. The positioning “above” is to be understood here in a direction leading away from the fire deck 3 along the cylinder axis 2. The first radial cooling duct 9a is part of the lower partial cooling space 5a and the bulge section 6b is carried out in the area of the intermediate deck 4. On the one hand, a larger amount of water is supplied to this first cooling duct 9a, on the other hand, the outlet valve bridge 90 is additionally cooled in the area of the intermediate deck 4.

This steering effect is reinforced by the positioning of the openings 11a, 11b, 11c, 11d, through which the coolant flows out of the cylinder head 1 into the crankcase.

The geometry shown in the exemplary embodiment in the figures and positioning of the overflow opening 6 on the outlet side results in concentrated cooling of the outlet side both in the upper partial cooling space 5b and in the lower partial cooling space 5a. This ensures optimal cooling of the outlet channel 8 or the outlet channels, of outlet valve guides 7a, 7b (see Fig. 2 ) and subsequently reached the fire deck 3 in the thermally highly stressed area of an exhaust valve bridge 90. This results in a homogeneous temperature level on the entire fire deck 3 and thus lower material stresses occur in the cylinder head 1. The valve bridge or exhaust valve bridge 90 is understood to mean the accumulation of material between the gas exchange valves (not shown) or the exhaust valves. The exhaust valve bridge 90 is very thermally stressed.

In addition to the variant shown in the exemplary embodiment in the figures, other variants are also possible where, for example, the bulge section 6b is arranged in the region of the inlet valve bridge or the inlet-outlet valve bridge or that further ring segment sections are provided, which are each connected or partially connected to bulge sections.

The invention thus permits an increase in the flow velocities in the transition between the partial cooling rooms 5a, 5b, and through this concentrated flow, in particular due to the bulge section 6b, the cooling of thermally highly stressed areas on the fire deck 3 and in the area of valve bridges - especially the exhaust valve bridge 90 - increased and thus the temperature reduced. This prevents thermal stresses and consequent damage to the cylinder heads.

Claims (10)

1. A cylinder head (1) of a liquid-cooled internal combustion engine, wherein the cylinder head (1) has a cooling chamber arrangement (5) which adjoins a fire deck (3) and is divided by an intermediate deck (4) arranged substantially parallel to the fire deck (3) into a lower cooling compartment (5a) on the fire deck side and an upper cooling compartment (5b), wherein the upper cooling compartment (5b) is arranged on a side of the intermediate deck (4) facing away from the fire deck (3) in the direction of a cylinder axis (2), and the upper cooling compartment (5b) and the lower cooling compartment (5a) are flow-connected via at least one overflow opening (6) extending around the cylinder axis (2), which overflow opening (6) is preferably arranged adjacent to a receiving sleeve (7), characterised in that the overflow opening (6) has at least one ring segment section (6a) extending annularly around the cylinder axis (2) and a bulging section (6b) which originates therefrom and faces away from the cylinder axis (2) in the radial direction, wherein the ring segment section (6a) is arranged entirely within two diameters, and these diameters are at least tangent to the ring segment section (6a).
2. A cylinder head (1) according to claim 1, characterised in that the ring segment section (6a) extends over a first angle (α) about the cylinder axis (2), which is between 20° and 180°, preferably between 30° and 90°, and particularly preferably 40° to 50°.
3. A cylinder head (1) according to claim 1 or 2, characterised in that the bulging section (6b) extends over a second angle (β) about the cylinder axis (2), which is between 5° and 45°, preferably between 5° and 20°.
4. A cylinder head (1) according to one of claims 1 to 3, characterised in that the bulging section (6b) extends over a second angle (β) about the cylinder axis (2), which is smaller than the first angle (α).
5. A cylinder head (1) according to one of claims 1 to 4, characterised in that the width of the ring segment section (6a) extending in the radial direction [the direction originating from the cylinder axis (2)] is smaller than the width extending in the circumferential direction of the bulging section (6b).
6. A cylinder head (1) according to one of claims 1 to 5, characterised in that the overflow opening (6) extends in the circumferential direction about the cylinder axis (2) substantially between two connecting lines (A) reaching from the cylinder axis (2) to a respective valve axis (8a, 8b) of two different valves, preferably between the connecting lines (A) from the cylinder axis (2) to the outlet valve axes (8a) of the two outlet valves.
7. A cylinder head (1) according to one of claims 1 to 6, characterised in that the bulging section (6b) extends along a valve symmetry plane (Z) extending between two valve axes (8a, 8b), preferably the outlet valve axes (8a) of the outlet valves, normally to the fire deck (3).
8. A cylinder head (1) according to one of claims 1 to 7, characterised in that the bulging section (6b) extends in the direction away from the cylinder axis (2) via a radial cooling channel (9a, 9b; 9c; 9d) extending through a valve bridge, in particular an outlet valve bridge (90).
9. A cylinder head (1) according to one of claims 1 to 8, characterised in that the overflow opening (6) is flow-connected via a distribution ring (10) arranged in the lower cooling compartment (5a) around the receiving sleeve (7) to cooling channels (9a, 9b, 9c, 9d) leading radially away from the distribution ring (10) in the lower cooling compartment (5a).
10. An internal combustion engine (100) with a cylinder head (1) according to one of claims 1 to 9.

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