Patent Grant
11536220
The present disclosure relates generally to cooling an igniter in a cylinder head, and more particularly to passive cooling of an igniter without direct feed of coolant.
Internal combustion engines are applied for diverse purposes throughout the world, in applications ranging from vehicle propulsion to electrical power generation to operation of gas and liquid compressors and pumps. Burning a combustible fuel with air in combustion cylinders in the engine produces a rapid pressure and temperature rise exploited to produce power but also subjecting components of the engine to mechanical and thermal stresses and strains. In most instances active cooling by way of a liquid coolant conveyed through parts of the engine is required.
A great many different water jacket and related coolant plumbing structures have been proposed over the years in an effort to optimally manage engine temperatures. In many engines an igniter such as a sparkplug, or a prechamber ignition device, is supported in a cylinder head. These igniters tend to be sensitive to excessive temperatures. Engine head configurations can nevertheless create challenges in optimally cooling an igniter with liquid coolant. Ignition problems, structural failures, and thermal fatigue cracks and the like are common signs of inadequate cooling.
Increased engineering resources have been directed at optimizing cooling of igniters in an engine head in recent years. Optimized coolant flow and geometric arrangements of coolant passages can provide operating benefits as well as increased engine power density. U.S. Pat. No. 10,385,800 employs cross-drilled coolant passages to feed coolant directly to a cooling moat, enabling a pumped positive flow of coolant to dissipate heat of components of an igniter. While the concept disclosed in the '800 patent may have various advantages, there is always room for improvement and development of alternative strategies in relation to igniter cooling and manufacturability of the various components.
In one aspect, a cylinder head includes a cylinder head casting having an upper deck, a fire deck, four gas exchange conduits extending to four gas exchange openings in the fire deck, a coolant cavity formed between the upper deck and the fire deck and extending peripherally around the four gas exchange conduits, and an igniter bore defining a bore center axis and extending downwardly through the upper deck to the coolant cavity. The cylinder head casting further includes an igniter socket having a radially inward igniter post, a radially outward sleeve step that is circumferential of the bore center axis, and a cooling moat formed between the igniter post and the sleeve step. The coolant cavity includes a valve bridge through-channel extending to the igniter socket and formed between two of the four gas exchange conduits, and a valve bridge part-way channel extending from the igniter socket and formed between two of the four gas exchange conduits.
In another aspect, a cylinder head assembly includes a cylinder head having formed therein an igniter bore extending downwardly from an upper deck to a coolant cavity and defining a bore center axis, and an igniter socket including an igniter post extending upwardly from a fire deck in a direction of the coolant cavity. The cylinder head assembly further includes an igniter sleeve having a first axial sleeve end within the igniter bore, a second axial sleeve end interference-fitted with the igniter post, and a plurality of stop surfaces located between the first axial sleeve end and the second axial sleeve end. The igniter socket further includes a sleeve step extending continuously circumferentially around the bore center axis and contacted by the plurality of stop surfaces, and a cooling moat formed between the sleeve step and the igniter post and receiving the second axial sleeve end. A plurality of coolant openings are defined between the igniter sleeve and the sleeve step at locations angularly between the plurality of stop surfaces, circumferentially around the bore center axis, and coolant flow between the coolant cavity and the cooling moat is confined to the plurality of coolant openings.
In still another aspect, a method of cooling an igniter in a cylinder head assembly includes conveying coolant through a first valve bridge channel of a coolant cavity to an igniter socket in a cylinder head, and conveying the coolant through a cooling moat of the igniter socket receiving an igniter sleeve for the igniter. The method further includes exchanging heat between the coolant and the igniter sleeve within the cooling moat, conveying the coolant from the igniter socket to a second valve bridge channel of the coolant cavity, and limiting a flow of the coolant between the cooling moat and the coolant cavity to a finite number of coolant openings defined between the igniter sleeve and the igniter socket.
Referring to the drawings generally, but focusing on
Engine valves 22 are supported in a cylinder head 24 in a cylinder head assembly 26. Cylinder head 24 may include a one-piece cylinder head casting 28. In the illustrated embodiment cylinder head 24 is a so-called slab cylinder head where a one-piece casting is associated with multiple cylinders 16, and potentially all cylinders 16 in engine 12. In other embodiments cylinder head 24 could include multiple separate castings each associated with one cylinder 16. Cylinder head 24 and cylinder head casting 28 are terms used herein, at times, interchangeably. A liquid coolant, such as conventional liquid engine coolant, may be conveyed between cylinder block 14 and cylinder head 24 and circulated through a heat exchanger such as a conventional radiator according to well-known practices.
Engine system 10 may also include a plurality of igniters 56, hereinafter referred to at times in the singular, each associated with one of cylinders 16.
As can be seen in the detailed enlargement of
As also illustrated in
Focusing now on
It will be recalled igniter sleeve 68 may be interference-fitted upon igniter post 78. Igniter sleeve 68 may further include a plurality of stop surfaces 84 formed, for example, on protruding stop feet (not numbered), located between first axial sleeve end 70 and second axial sleeve end 72. When igniter sleeve 68 is installed in cylinder head 28 igniter sleeve 68 may be pressed downwardly into interference-fit engagement with igniter post 78, and stopped by contact between stop surfaces 84 and radially outward sleeve step 80. A plurality of coolant openings 90 are defined between igniter sleeve 68 and sleeve step 80 at locations angularly between stop surfaces 84, circumferentially around bore center axis 54, such that coolant flow between coolant cavity 50 and cooling moat 82 is confined to coolant openings 90. Put differently, no coolant flows into or out of cooling moat 82 but by way of openings 90 in at least some embodiments, the significance of which will be further apparent from the following description. Stop surfaces 84 and coolant openings 90 may each number 3 or 4 in some embodiments.
It will be recalled cylinder head 24 includes four gas exchange conduits 34, 36, 38, 40. Where implemented as a slab cylinder head, cylinder head casting 28 may include four gas exchange conduits for each of a plurality of cylinders. Cylinder head 24 further includes four valve bridges 92, 94, 96, 98 in an alternating arrangement with the four gas exchange conduits 34, 36, 38, 40, circumferentially around bore center axis 54. Coolant cavity 50 further includes a first valve bridge through-channel 100 and a second valve bridge through-channel 102 extending to igniter socket 76 and formed in two of the four valve bridges, valve bridges 92 and 96 in the illustrated embodiment. Coolant cavity 50 also includes a first valve bridge part-way channel 104 and a second valve bridge part-way channel 106 formed in a different two of the four valve bridges, and in the illustrated embodiment valve bridges 94 and 98. It can be noted the first and the second valve bridge through-channels 100 and 102 are in an alternating arrangement with the first and the second valve bridge part-way channels 104 and 106, circumferentially around bore center axis 54.
With focus now on
Making cylinder head assembly 26 can include casting material, such as an iron or iron alloy material, to form a unitary body of sufficient size and configuration generally for installation and service associated with a desired number of cylinders in an engine. Some of the surfaces of the casting may be left as-cast, while others may be machined. According to the present disclosure, each valve bridge through-channel 100 and 102 and each valve bridge part-way channel 104 and 106 may be formed by an as-cast surface 112. Features of igniter socket 76, however, may be machined using one or more machining tools and/or passes, such that peripheral wall surface 88, upward facing step surface 86, and surfaces forming cooling moat 82 and igniter post 78 are machined. In an implementation, and as can be seen in
Operating engine system 10 will include combusting fuel and air in cylinder 16 as noted above. During operation igniter 56 will tend to heat in response to elevated temperatures in cylinder 16 as well as in prechamber 62. Coolant can be pumped through cylinder head 24, and into coolant cavity 50 such that coolant is conveyed through a first valve bridge channel of coolant cavity 50, including one or both of valve bridge through-channels 100 and 102, to igniter socket 76. The coolant may be conveyed from valve bridge through-channels 100 and 102 through cooling moat 82 of igniter socket 76 receiving igniter sleeve 68. Coolant conveyed through cooling moat 82 will enable exchanging heat between the coolant and igniter sleeve 28 within cooling moat 82. Coolant conveyed through cooling moat 82 can be conveyed from igniter socket 76 to a second valve bridge channel of coolant cavity 50, including one or both of valve bridge part-way channels 104 and 106. As discussed herein a flow of coolant between cooling moat 82 and coolant cavity 50 is limited to coolant openings 90. Coolant openings 90 are finite in number, including for example 3 or 4, and are defined between igniter sleeve 68 and igniter socket 76. More particularly, cylinder openings 90 may be defined at locations between stop surfaces 84, circumferentially around bore center axis 54, between igniter sleeve 68 and sleeve step 80.
The present description is for illustrative purposes only, and should not be construed to narrow the breadth of the present disclosure in any way. Thus, those skilled in the art will appreciate that various modifications might be made to the presently disclosed embodiments without departing from the full and fair scope and spirit of the present disclosure. Other aspects, features and advantages will be apparent upon an examination of the attached drawings and appended claims. As used herein, the articles “a” and “an” are intended to include one or more items, and may be used interchangeably with “one or more.” Where only one item is intended, the term “one” or similar language is used. Also, as used herein, the terms “has,” “have,” “having,” or the like are intended to be open-ended terms. Further, the phrase “based on” is intended to mean “based, at least in part, on” unless explicitly stated otherwise.
| Number | Name | Date | Kind |
|---|---|---|---|
| 10385800 | Hyde et al. | Aug 2019 | B2 |
| 20060054112 | Paul | Mar 2006 | A1 |
| 20160273481 | Ickinger | Sep 2016 | A1 |
| 20190284985 | Perr | Sep 2019 | A1 |
| Number | Date | Country |
|---|---|---|
| 111075591 | Apr 2020 | CN |
| 10248663 | May 2004 | DE |
| 10321035 | Jan 2005 | DE |
| 102007062347 | Jun 2009 | DE |
| 3004761 | Oct 2014 | FR |
| 2020051607 | Mar 2020 | WO |
