Lightweight articulated piston head and method of making the piston head
First Claim
1. A piston head for an articulated piston assembly including a skirt connected to the head by a pin, comprising:
- a top head portion having an upper wall, a depending outer wall extending from said upper wall, a first inner depending wall positioned a spaced transverse distance from said depending outer wall, a first cooling gallery positioned between said depending outer wall and said first inner depending wall, a second inner depending wall positioned a spaced transverse distance from said first inner depending wall, and a second cooling gallery positioned between said first inner depending wall and said second inner depending wall;
a bottom head portion having a pair of support portions connected to said top head portion and spaced inwardly from said depending outer wall; and
a friction weld connecting said bottom head portion to said first and said second inner depending walls.
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Accused Products
Abstract
A piston head is provided which is lightweight and inexpensive yet capable of handling high mechanical and thermal loading during operation. The piston head generally includes a top head portion and a bottom head portion formed separately and connected by a friction weld. Importantly, the top head portion includes a first cooling gallery formed between the depending outer wall and a first inner depending wall and a second cooling gallery formed between the first inner depending wall and a second inner depending wall. The bottom head portion also includes corresponding first and second upper extending walls connected to the first and second inner depending walls to form the lower portion of each cooling gallery. The inner depending and upper extending walls are formed so that the ratio of the sum of the transverse thickness of the adjacent walls to the outer diameter of the piston head is approximately from 2% to 8%, and preferably 4% to 6%. This ratio optimal reduces piston weight while maintaining sufficient strength to endure mechanical loading during operation and providing improved thermal cooling capacity.
47 Citations
23 Claims
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1. A piston head for an articulated piston assembly including a skirt connected to the head by a pin, comprising:
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a top head portion having an upper wall, a depending outer wall extending from said upper wall, a first inner depending wall positioned a spaced transverse distance from said depending outer wall, a first cooling gallery positioned between said depending outer wall and said first inner depending wall, a second inner depending wall positioned a spaced transverse distance from said first inner depending wall, and a second cooling gallery positioned between said first inner depending wall and said second inner depending wall; a bottom head portion having a pair of support portions connected to said top head portion and spaced inwardly from said depending outer wall; and a friction weld connecting said bottom head portion to said first and said second inner depending walls. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A piston head for an articulated piston assembly including a skirt connected to the head by a pin, comprising:
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a top head portion having an upper wall, a depending outer wall extending from said upper wall, a first inner depending wall positioned a spaced transverse distance from said depending outer wall, a first cooling gallery positioned between said depending outer wall and said first inner depending wall, a second inner depending wall positioned a spaced transverse distance from said first inner depending wall and a second cooling gallery positioned between said first inner depending wall and said second inner depending wall, said top head portion including an outer diameter, said first and said second inner depending walls each including a transverse thickness, wherein a ratio of a sum of said transverse thickness of said first inner depending wall and said transverse thickness of said second inner depending wall to said outer diameter is approximately from 2% to 8%; and a bottom head portion having a pair of support portions connected to said top head portion and spaced inwardly from said outer wall. - View Dependent Claims (9, 10, 11, 12, 13)
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14. A method of making a piston head for an articulated piston assembly, comprising the steps of:
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providing a top head blank; forming a first cooling gallery in said top head blank; forming a second cooling gallery in said top head blank between said first cooling gallery and a central axis of the piston head, said first and said second cooling galleries separated by a first inner depending wall, said central axis and said second cooling gallery separated by a second inner depending wall; providing a bottom head blank; friction welding said bottom head blank to said top head blank to create a friction weld connecting said first and said second inner depending walls to said bottom head blank. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21, 22, 23)
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Specification