Press-fit sleeve for a cylinder head

Abstract

A press-fit sleeve for sealing and cooling a component projecting through a fire deck opening in the cylinder head of an internal combustion engine is described. The press-fit sleeve includes a connecting point at a first end of the press-fit sleeve, said connecting point being designed for press fitting into an indentation at an end of the fire deck opening that faces away from a combustion chamber. Furthermore, the press-fit sleeve includes a radially inwardly protruding step at a second end of the press-fit sleeve lying opposite the first end. Between the first end and the second end, the press-fit sleeve includes a lateral surface which is closed in a fluid-tight manner and is or can be brought into contact with a water jacket surrounding the press-fit sleeve.

Claims

1. A press-fit sleeve for sealing and cooling a component projecting through a fire deck opening in a cylinder head of an internal combustion engine, comprising: a connecting point at a first end of the press-fit sleeve, said connecting point being configured to press fitting into an indentation at an end of the fire deck opening that faces away from a combustion chamber and including a radially inwardly curved collar with a contact surface, said press-fit sleeve not extending continuously over an axial extent of the fire deck as far as the combustion chamber; a radially inwardly protruding step at a second end of the press-fit sleeve lying opposite the first end; and a lateral surface of the press-fit sleeve, said lateral surface being closed fluid-tightly between the first end and the second end and being or being able to be brought into contact with a water jacket surrounding the press-fit sleeve.

2. The press-fit sleeve according to claim 1, wherein the component comprises an injection nozzle and/or a spark plug.

3. The press-fit sleeve according to claim 1, wherein the connecting point comprises a cylindrical pressing surface.

4. The press-fit sleeve according to claim 3, wherein an axial extent of the connecting point is much smaller than an axial length of the press-fit sleeve.

5. The press-fit sleeve according to claim 3, wherein the pressing surface or the contact surface is configured to connecting fluid-tightly to the indentation.

6. The press-fit sleeve according to claim 3, wherein the pressing surface or the contact surface are connected or connectable to the indentation in a force-fitting or integrally bonded manner.

7. The press-fit sleeve according to claim 1, wherein a diameter of the press-fit sleeve at the first end is smaller than a diameter of the press-fit sleeve at the second end.

8. A cylinder head of an internal combustion engine, comprising: a fire deck with a fire deck opening; a press-fit sleeve for sealing and cooling a component projecting through the fire deck opening, the press-fit sleeve including, a connecting point at a first end of the press-fit sleeve, said connecting point being configured to press fitting into an indentation at an end of the fire deck opening that faces away from a combustion chamber and including a radially inwardly curved collar with a contact surface, said press-fit sleeve not extending continuously over an axial extent of the fire deck as far as the combustion chamber; a radially inwardly protruding step at a second end of the press-fit sleeve lying opposite the first end; and a lateral surface of the press-fit sleeve, said lateral surface being closed fluid-tightly between the first end and the second end and being or being able to be brought into contact with a water jacket surrounding the press-fit sleeve; and a cooling water chamber, which is adjacent to the fire deck, for receiving the water jacket which the lateral surface of the press-fit sleeve closes in a fluid-tight manner between the first end and the second end.

9. The cylinder head according to claim 8, wherein the fire deck opening has, between the indentation and an end of the fire deck opening that faces the combustion chamber, an internal thread for a screw connection to the component.

10. The cylinder head according to claim 9, wherein the component holds down a radially inner step of the connecting point with respect to the fire deck opening via the screw connection.

11. The cylinder head according to claim 8 wherein the press-fit sleeve is connected or connectable to the fire deck in a form-fitting manner by means of the component.

12. The cylinder head according to claim 8, wherein the axial extent of the fire deck is greater than an axial extent of the connecting point.

13. The cylinder head according to claim 8, wherein a seal arranged at the second end in an encircling manner between the press-fit sleeve and the cylinder head closes the lateral surface fluid-tightly with respect to the cooling water chamber.

14. A vehicle comprising: an internal combustion engine; a cylinder head connected to the internal combustion head, the cylinder head including, a fire deck with a fire deck opening; a press-fit sleeve for sealing and cooling a component projecting through the fire deck opening, the press-fit sleeve including, a connecting point at a first end of the press-fit sleeve, said connecting point being configured to press fitting into an indentation at an end of the fire deck opening that faces away from a combustion chamber and including a radially inwardly curved collar with a contact surface, said press-fit sleeve not extending continuously over an axial extent of the fire deck as far as the combustion chamber; a radially inwardly protruding step at a second end of the press-fit sleeve lying opposite the first end; and a lateral surface of the press-fit sleeve, said lateral surface being closed fluid-tightly between the first end and the second end and being or being able to be brought into contact with a water jacket surrounding the press-fit sleeve; and a cooling water chamber, which is adjacent to the fire deck, for receiving the water jacket which the lateral surface of the press-fit sleeve closes in a fluid-tight manner between the first end and the second end.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Further features and advantages of the disclosure are described below with reference to the attached drawings, in which:

(2) FIG. 1 shows a schematic perspective sectional illustration along a longitudinal axis of an exemplary embodiment of the press-fit sleeve in an exemplary cylinder head; and

(3) FIG. 2 shows a schematic perspective section of the exemplary embodiment of FIG. 1 with a perspective illustration of an exemplary component arranged therein.

DETAILED DESCRIPTION

(4) FIG. 1 schematically shows a section of an exemplary embodiment of a press-fit sleeve, which is denoted in general by reference number 100, for sealing and cooling a component 106 projecting through a fire deck opening 102 in the cylinder head 104 of an internal combustion engine.

(5) The press-fit sleeve 100 comprises a connecting point 108 at a first end 110 of the press-fit sleeve 100. The connecting point 108 is designed for press fitting into an indentation 112 at an end of the fire deck opening that faces away from the combustion chamber 114.

(6) The press-fit sleeve 100 comprises a radially inwardly protruding step 116 at a second end 118 of the press-fit sleeve 100 lying opposite the first end 110 and a lateral surface 120 which is closed fluid-tightly between the first end 110 and the second end 118 and is or can be brought into heat exchange with a water jacket 122 surrounding the press-fit sleeve 100.

(7) The press-fit sleeve 100 can be pulled out of the indentation 112 by means of the radially inwardly protruding step 116. Furthermore, for electric and/or fluidic feed lines, the component 106 projects through an opening at the second end, said opening surrounded by the inwardly protruding step 116. In the exemplary embodiment shown in FIG. 1, the component 106 comprises a spark plug.

(8) In the press-fitting state within the fire deck opening 102 in the fire deck 124, the press-fit sleeve 100 is arranged at the first end 110 in a force-fitting manner by means of the connecting point 108 in the indentation 112. An inner surface of the fire deck opening 102 interacts directly with the component 106 (for example in a force-fitting and/or form-fitting manner). As a result, an inner diameter of the fire deck opening 102, more precisely an inner diameter of the fire deck opening at an end of the fire deck opening 102 that faces the combustion chamber 114, is smaller than in the case of conventional sleeves which extend over the entire length of the fire deck opening 102 in the fire deck 124 and are screwed, for example with an external thread of the sleeve, in the fire deck opening.

(9) The term of fire deck opening 102 can relate here to a lowermost portion (i.e. the fire deck portion) of a cylinder head passage. The cylinder head passage can overall comprise a plurality of coaxial bores (for example stepped in diameter) throughout the cylinder head 104.

(10) The fire deck 124 is bordered by a cooling water chamber 126 for receiving the water jacket 122. Since the press-fit sleeve 100 makes direct contact with the component 106 at the first end 110, and the lateral surface 120 of the press-fit sleeve 100 is in extensive heat exchange with the water jacket 122, effective cooling of the component 106 is ensured.

(11) The connecting point 108 comprises an encircling, for example cylindrical, pressing surface 128. In the press-fitting state, the pressing surface 128 interacts in a frictionally locking manner with the indentation 112 by means of radial compressive forces. This interference fit of the pressing surface 128 in the indentation 112 extends parallel to a longitudinal axis of the pressing sleeve 100 over an axial extent 130 of the connecting point 108. That is to say, the axial extent 130 of the connecting point 108 is in the direction of the longitudinal axis the overlap between the pressing surface 128 and a cylindrical inner surface of the indentation 112 in the fire deck 124.

(12) The axial extent 130 of the connecting point 108 is much smaller (i.e. a fraction significantly smaller than half) than an axial length 134 of the press-fit sleeve 100. The axial length 134 here is the overall length of the press-fit sleeve from the first end 100 as far as the second end 118 along the longitudinal axis of the press-fit sleeve 100.

(13) In the exemplary embodiment shown in FIG. 1, the fire deck opening 102 comprises, between the indentation 112 and an end of the fire deck opening 102 that faces the combustion chamber 114, an internal thread 136 for the direct screw connection between the fire deck 124 and the component 106. The component 106 comprises a protrusion (for example closed in an encircling manner) above an external thread which is designed for interaction with the internal thread 136. The protrusion of the component 106 lies within the press-fit sleeve 100 against a step 144 of the connecting point 108 or can be brought into contact with the step 144.

(14) In the press-fitting state, the connecting point 108 at the first end 110 of the press-fit sleeve 100 is arranged between the component 106 (more precisely the protrusion of the component 106) and the fire deck 124 (more precisely the indentation 112 in the fire deck 124). As a result, the component 106 holds the connecting point 108 in a form-fitting manner in the indentation 112 of the fire deck 124 via the screw connection to the internal thread 136 of the fire deck opening 102 and the contact against the radially inner step 144 of the press-fit sleeve 100.

(15) The press-fit sleeve does not extend through the entire fire deck 124. For a particularly compact constructional form of the press-fit sleeve 100 and high oscillation strength (in particular flexural fatigue strength and/or endurance strength) of the fire deck 124, the axial extent 130 of the connecting point 108 is smaller, for example much smaller, than an axial extent 142 of the fire deck 124 between the indentation 112 and the combustion chamber 114. Furthermore, the distance between combustion chamber 114 and press-fit sleeve 100 in accordance with the axial extent 142 can prevent a thermal short circuit between combustion chamber 114 and water jacket 122.

(16) FIG. 2 schematically shows a three-dimensional sectional illustration with a sectional plane between the cylinder head 104 and the press-fit sleeve 100 arranged therein. The longitudinal axis of the press-fit sleeve 100 is within the sectional plane (in the vertical direction in FIG. 2). A spark plug as an example of the component 106 in the press-fit sleeve 100 is arranged coaxially with respect to the longitudinal axis of the press-fit sleeve 100.

(17) A spanner width 140 of the component 106 is smaller than an inner diameter 138 of the opening of the sleeve 100 at the second end 118. A spanner, for example a hexagon socket spanner, can be inserted through the opening of the sleeve 100 at the radially inwardly protruding step 116 via the component 106, which is mounted within the press-fit sleeve 100, in order to unscrew the component 106. Unlike in the case of a component 106 screwed to a conventional sleeve, during the unscrewing a torque will not be transmitted here to the press-fit sleeve 100, as a result of which, even after the unscrewing, the latter remains fastened because of the press fitting at the first end 110.

(18) Furthermore, a seal 146 is arranged at the second end 118 in an encircling manner between the press-fit sleeve 100 and the filter head 104, the seal closing the lateral surface 120 fluid-tightly with respect to the cooling water chamber 126 at the second end 118. In the exemplary embodiment shown in FIGS. 1 and 2, an encircling groove is provided for this purpose above the cooling water chamber 126 (i.e. on the side facing away from the combustion chamber 114) in the cylinder head 104 in order to receive an O ring.

(19) In addition to the press fitting, the press-fit sleeve 100 is optionally adhesively bonded at the connecting point 108. Alternatively or additionally, a seal, for example an O ring, can be arranged in an O ring groove (on the press-fit sleeve 100 or the fire deck 124) between the pressing surface 128 and the inner surface of the indentation 112 and/or on the end side on the contact surface 132 of the press-fit sleeve 100 in order to seal the cooling water chamber 126 from the combustion chamber 114 at the first end 110.

(20) Whereas, in the above exemplary embodiment, the press-fit sleeve 100 is described for sealing and cooling a spark plug as an example of the component 106, the press-fit sleeve 100 and the functions thereof can be realised by further exemplary embodiments for each component 106 protruding through the fire deck opening 102 in the cylinder head 104 of the internal combustion engine. In particular, each component 106 tapering toward the combustion chamber 114, for example an injection nozzle for diesel fuel, can be sealed and cooled by an exemplary embodiment of the press-fit sleeve 100.

(21) The internal thread 136 between the indentation 112 and the combustion chamber 114 can be dispensed with, depending on the component 106. For example, an injection nozzle can be fastened as a component 106 by means of an interference fit in the fire deck opening 102.

(22) Installation of the component 106 by means of an exemplary embodiment of the press-fit sleeve 100 can comprise a step of pressing the press-fit sleeve 100 against a pressing device with a certain pressing force, and a subsequent step of screwing or pressing in the component 106. Alternatively, the press-fit sleeve 100 can be pressed in during the screwing or pressing of the component 106 into the indentation 112, i.e. simultaneously with the installation of the component 106. In the latter case, the component 106 (for example by means of its protrusion) presses the press-fit sleeve 100 into the indentation 112.

(23) Removal of the press-fit sleeve 100 on the cylinder head 104 can comprise the step of pulling off or unscrewing the component 106 and the subsequent step of pulling off the press-fit sleeve from the radially inwardly protruding step 116. The connection between press-fit sleeve 100 and cylinder head 104 thus remains releasable and repairable.

(24) The press-fit sleeve 100 permits a more favourable production of the cylinder head 104, in particular an automated installation of the press-fit sleeve 100 and/or of the component 106. The cutting of an additional thread in the fire deck opening for fastening a conventional sleeve can be dispensed with.

(25) With reference to the above exemplary embodiments, the advantages, associated with the exemplary embodiments, of the press-fit sleeve 100 are apparent to a person skilled in the art. An indentation 112 for the interference fit of the press-fit sleeve 100 is provided in the fire deck 124, said press-fit sleeve 100 not extending continuously over the axial extent 142 of the fire deck 124 as far as the combustion chamber 114. For example, the axial extent 130 of the connecting point 108 is 5 mm or less. An internal thread 136 for the component 106 (for example a spark plug) can be cut into the fire deck 124, or a simple bore for the component 106 (for example a diesel injection nozzle) can be drilled therein. By contrast, in the case of a conventional sleeve, for example for an M18 spark plug, at least one M24 internal thread has to be cut in the fire deck in order to receive the conventional sleeve. The press-fit sleeve 100 therefore permits a diameter of the fire deck opening 102 toward the combustion chamber 114, which diameter is limited to the outer diameter of the respective component 106. Owing to the smaller opening, which is tailored to the outer diameter of the component 106, at that end of the fire deck opening 102 which faces the combustion chamber 114, a higher strength of the fire deck can be achieved.

(26) The press-fit sleeve 100 is pressed and optionally adhesively bonded into the fire deck 124. The component 106 additionally keeps the press-fit sleeve 100 in position. The press-fit sleeve 100 is held down in the fire deck 124 in a force- and form-fitting and optionally integrally bonded manner. By means of the adhesive bonding of the press fitting (i.e. of the interference fit between the connecting point 108 and the indentation 112), the tightness at the first end 110 is ensured.

(27) Since the component does not engage with its external thread in an internal thread of the sleeve, an unintentional twisting of the sleeve during the installation or during the removal of the component is ruled out.

(28) Although the disclosure has been described with respect to exemplary embodiments, it is apparent to a person skilled in the art that various modifications may be undertaken and equivalents may be used in their place. Furthermore, a multiplicity of modifications can be undertaken in order to adapt a certain situation or a certain material to the teaching of the disclosure. Consequently, the disclosure is not restricted to the disclosed exemplary embodiments, but rather comprises all of the exemplary embodiments.

LIST OF REFERENCE SIGNS

(29) 100 Press-fit sleeve 102 Fire deck opening 104 Cylinder head of an internal combustion engine 106 Component 108 Connecting point of the press-fit sleeve 110 First end of the press-fit sleeve 112 Indentation at the fire deck opening 114 Combustion chamber of the internal combustion engine 116 Radially inwardly protruding step of the press-fit sleeve 118 Second end of the press-fit sleeve 120 Lateral surface of the press-fit sleeve 122 Water jacket 124 Fire deck of the internal combustion engine 126 Cooling water chamber for water jacket 128 Pressing surface of the connecting point 130 Axial extent of the connecting point 132 Contact surface of the connecting point 134 Axial length of the press-fit sleeve 136 Internal thread of the fire deck opening 138 Inner diameter of the press-fit sleeve at the second end 140 Spanner width of the component 142 Axial extent of the fire deck 144 Radially inner step of the connecting point 146 Seal at the second end