Patent Application
20090205605
The present disclosure relates to engine bracket assemblies, and more specifically to controlling loads applied between engine components due to varying thermal growth between the components.
The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
Engine assemblies include a variety of components that are fixed to an engine structure such as an engine block or a cylinder head. During engine operation, the thermal loads applied to the components and engine structure may result in different rates of thermal expansion between the parts. For example, when a bracket assembly is fixed to a cylinder head of the engine at two or more points, expansion of the bracket assembly at a greater rate than the cylinder head may result in an increased stress on the cylinder head. The increased stress may result in cracking of the cylinder head. The different rates of thermal expansion experienced between the engine structure and components may result from different thermal loads applied to each part or may result from each part having material properties, such as thermal expansion rates, that are different from one another.
An engine bracket assembly may include a first mounting portion, a second mounting portion, and a support member. The first mounting portion may fix a first end of the bracket assembly to the engine and the second mounting portion may fix a second end of the bracket assembly to the engine. The support member may support an engine component and may be disposed between and coupled to the first and second mounting portions. The coupling between the first and second mounting portions and the support member may provide relative displacement between the first mounting portion and the support member in a longitudinal direction extending from one of the first and second mounting portions toward the other of the first and second mounting portions during thermal expansion of the bracket assembly.
An engine assembly may include an engine structure, an engine component, and a bracket assembly. The bracket assembly may include a first mounting portion that fixes a first end of the bracket assembly to the engine structure, a second mounting portion that fixes a second end of the bracket assembly to the engine structure, and a support member that supports the engine component, the support member may be disposed between and coupled to the first and second mounting portions. The coupling between the first and second mounting portions and the support member may provide relative displacement between the first mounting portion and the support member in a longitudinal direction generally extending from one of the first and second mounting portions toward the other of the first and second mounting portions during thermal expansion of the bracket assembly.
Further areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.
The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way.
The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features.
Referring to
With reference to
The support member 42 may include a flange portion 58 having an airflow communication member 60 fixed thereto. The flange portion 58 may include a first end portion 62 adjacent to the second end of the first mounting member 38 and a second end portion 64 adjacent to the second end of the second mounting member 40. The first end portion 62 may include cylindrical recesses 66 generally aligned with the cylindrical recesses 50 in the first mounting member 38 and the second end portion 64 may include cylindrical recesses (not shown) generally similar to the cylindrical recesses 66 and aligned with the cylindrical recesses 56 in the second mounting member 40.
In the present example, the airflow communication member 60 may be integrally formed with the flange portion 58. Therefore, the flange portion 58 and the airflow communication member 60 may be fixed relative to one another. The airflow communication member 60 may include first and second passages 70, 72 therein. The first passage 70 may extend through an upper surface 78 of the airflow communication member 60 and may be in communication with the second passage 72. The second passage 72 may extend through the first and second sides 80, 82 of the airflow communication member 60.
The coupling members 44 may each have a generally cylindrical body that generally conforms to the recesses 50, 56, 66 in the first and second mounting members 38, 40 and the flange portion 58. In the present example, the coupling members 44 may be in the form of slotted dowel pins. The coupling members 44 may therefore each include a generally hollow cylindrical body 84 having an axially extending slot 86 that extends the entire length of the cylindrical body 84 and allows radially inward and outward displacement of the cylindrical body 84. The coupling members 44 may be disposed within the recesses 50, 56, 66 in the first and second mounting members 38, 40 and the flange portion 58 and may couple the support member 42 to the first and second mounting members 38, 40 to provide a spacing (D), or air gap, between the support member 42 and each of the first and second mounting members 38, 40. While the spacing (D) is only shown between the support member 42 and the second mounting member 40 in
The first and second mounting members 38, 40 may be fixed to the engine 12. For example, as seen in
In operation, the thermal expansion rate of the bracket assembly 32, and more specifically, the thermal expansion rate of the first and second mounting members 38, 40, may be different than the thermal expansion rate of the portion of the engine 12 that the bracket assembly 32 is fixed to. The different rates of thermal expansion between the bracket assembly 32 and the portion of the engine 12 that the bracket assembly 32 is fixed to may be caused by differing material properties between the components or differing thermal loads experienced by the components.
In the present example, the first and second mounting members 38, 40 may experience a rate of thermal expansion that is greater than the thermal expansion rate of the cylinder head 90 due to the coupling between the bracket assembly 32 and the first and second conduits 36, 37. The communication between the first and second conduits 36, 37 and the exhaust gas may provide a thermal load on the bracket assembly 32 that is greater than a thermal load on the cylinder head 90 at the mounting location. As a result, the cylinder head 90 may experience thermal growth at a rate that is less than the thermal growth experienced by the bracket assembly 32.
In the present example, the initial spacing (D), or air gap, between the support member 42 and the first and second mounting members 38, 40 may provide for expansion of the first and second mounting members 38, 40 relative to one another in a longitudinal direction along an axis (A) extending between the first and second mounting portions 46, 52 without applying a load on the cylinder head 90. Rather than applying an expansion load to the cylinder head 90 along axis (A), the first and second mounting members 38, 40 may thermally grow inwardly toward one another along axis (A) and may extend further along coupling members 44, reducing the spacing (D), or air gap, therebetween.
The initial spacing (D), or air gap, may additionally inhibit the transfer of heat to the first and second mounting members 38, 40 from the first and second conduits 36, 37. The relative expansion of the first and second mounting members 38, 40 relative to one another and relative to the support member 42 may additionally prevent displacement, or bending, of the first and second conduits 36, 37 along axis (A).
