GB2270541A - I. c. engine exhaust poppet valve. - Google Patents

I. c. engine exhaust poppet valve. Download PDF

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Publication number
GB2270541A
GB2270541A GB9219360A GB9219360A GB2270541A GB 2270541 A GB2270541 A GB 2270541A GB 9219360 A GB9219360 A GB 9219360A GB 9219360 A GB9219360 A GB 9219360A GB 2270541 A GB2270541 A GB 2270541A
Authority
GB
United Kingdom
Prior art keywords
valve
region
stem
poppet valve
port
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
GB9219360A
Other versions
GB9219360D0 (en
Inventor
Thomas Tsoi-Hei Ma
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Ford Motor Co
Original Assignee
Ford Motor Co
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Ford Motor Co filed Critical Ford Motor Co
Priority to GB9219360A priority Critical patent/GB2270541A/en
Publication of GB9219360D0 publication Critical patent/GB9219360D0/en
Publication of GB2270541A publication Critical patent/GB2270541A/en
Withdrawn legal-status Critical Current

Links

Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
    • F01L3/00—Lift-valve, i.e. cut-off apparatus with closure members having at least a component of their opening and closing motion perpendicular to the closing faces; Parts or accessories thereof
    • F01L3/02—Selecting particular materials for valve-members or valve-seats; Valve-members or valve-seats composed of two or more materials
    • F01L3/04—Coated valve members or valve-seats

Abstract

The poppet valve 16 comprises a valve head 16b for sealing against a valve seat 12 in the engine when the port is closed and an elongate stem having a guided region 16a which lies within a valve guide 14 in the engine when the port is closed. An unsupported region 16c connecting the guided region 16a to the valve head 12b, is surrounded by a separately formed heat shield 18 for preventing the unsupported region of the stem from being heated by gases in the port. Insulating material is located between the shield 18 and the stem region 16c. <IMAGE>

Description

POPPET VALVE Field of the invention The present invention relates to a poppet valve for an use as an exhaust valve in an internal combustion engine.
Object of the invention The invention seeks to reduce the temperature at which the poppet valves, especially the exhaust poppet valves, of an engine operate in order to reduce the risk of pre-ignition.
Summary of the invention According to the present invention, there is provided a poppet valve for closing an exhaust port in an internal combustion engine, which comprises a valve skirt for sealing against a valve seat in the engine when the port is closed and an elongate stem having a guided region which lies within a valve guide in the engine when the port is closed, and an unsupported region connecting the guided region to the valve skirt, wherein the unsupported region of the poppet valve is surrounded by a separately formed heat shield for preventing the unsupported region of the stem from being heated by gases in the port.
Preferably, the heat shield is formed of a metal sleeve of larger inner diameter than the outer diameter of the unsupported region of the valve stem. For improved insulation, a fibrous or particulate insulating material may be used to fill the space between the sleeve and the valve stem.
Conveniently, the valve stem is stepped between the guided and the unsupported regions and the end of the sleeve remote from the valve skirt abuts the step to prevent movement of the heat shield relative to the valve stem.
If exhaust valves are allowed to become too hot, they risk causing pre-ignition. The valves are cooled by heat rejection at their points of contact with the cylinder head.
Heat flows from the rim of the valve skirt to the valve seat when the valve is closed and at all times from the valve stem to the valve guide. The valve seat and the valve guide are in turn cooled by the coolant flowing in cooling channels in the cylinder head.
It is normally assumed that the only significant source of heat flowing into the valve is the burning charge within the combustion chamber. This invention is however based on the discovery that the normally exposed unsupported region of the valve stem is heated significantly by the hot exhaust gases in the exhaust port. Contrary to conventional belief, there is a net transfer of heat into this region of the valve stem rather than out of it. By shielding this region of the valve, the invention allows an engine to run with a reduced exhaust valve temperature and thereby reduces the risk of pre-ignition.
Brief description of the drawing The invention will now be described further, by way of example, with reference to the accompanying drawing, which is a section through an exhaust port fitted with a poppet valve of the present invention.
Description of the preferred embodiment The drawing shows an exhaust port 10 having a valve seat 12 and a valve guide 14 for a poppet valve 16. The valve 16 has a guided stem region 16a received within the valve guide 14 and a valve skirt 16b which seals against the valve seat 12 when the valve is closed.
The valve 16 also has an unsupported stem region 16c which lies between the valve seat 16b and the valve guide 14 when the port is closed. It is conventionally assumed that heat from the poppet valve escapes to the exhaust gases from this unsupported region but it has been found that in practice that the contact with the hot exhaust gases in this region helps to raise rather than lower the temperature of the poppet valve.
For this reason, in the present invention, a heat shield is placed around this unsupported region 16c of the poppet valve. The heat shield comprises a metal sleeve 18 which contacts the stem of the poppet valve only at its upper and lower edges leaving a space 20 between it and the valve stem which is filled with a fibrous of particulate heat insulating material, such as rock wool. In this way, the poppet valve is shielded from the heat of the exhaust gases and the area of heat input into the valve is restricted to the head of the valve which is in contact with the burning charge in the combustion chamber.
In order to retain the heat shield 18 on the valve, a step 16d is formed in the valve stem 16 and the end of the metal sleeve 18 abuts this step after it has been fitted over the end of the poppet valve 16.
It is important to note that the valve stem is not hollow as it is important to provide a heat flow path from the valve skirt to the guided region of the valve stem. The invention does not remove this heat flow path but merely provides a heat shield around it to prevent additional heat from entering the poppet valve through this region.

Claims (5)

1. A poppet valve for closing an exhaust port in an internal combustion engine, which comprises a valve skirt for sealing against a valve seat in the engine when the port is closed and an elongate stem having a guided region which lies within a valve guide in the engine when the port is closed, and an unsupported region connecting the guided region to the valve skirt, wherein the unsupported region of the poppet valve is surrounded by a separately formed heat shield for preventing the unsupported region of the stem from being heated by gases in the port.
2. A poppet valve as claimed in claim 1, wherein the heat shield is formed of a metal sleeve of larger inner diameter than the outer diameter of the unsupported region of the valve stem.
3. A poppet valve as claimed in claim 2, wherein a fibrous or particulate insulating material is arranged in the space between the sleeve and the valve stem.
4. A poppet valve as claimed in any preceding claim, wherein the valve stem is stepped between the guided and the unsupported regions and the end of the sleeve remote from the valve skirt abuts the step to prevent movement of the heat shield relative to the valve stem.
5. A poppet valve constructed arranged and adapted to operate substantially as herein described with reference to and as illustrated in the accompanying drawing.
GB9219360A 1992-09-12 1992-09-12 I. c. engine exhaust poppet valve. Withdrawn GB2270541A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB9219360A GB2270541A (en) 1992-09-12 1992-09-12 I. c. engine exhaust poppet valve.

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB9219360A GB2270541A (en) 1992-09-12 1992-09-12 I. c. engine exhaust poppet valve.

Publications (2)

Publication Number Publication Date
GB9219360D0 GB9219360D0 (en) 1992-10-28
GB2270541A true GB2270541A (en) 1994-03-16

Family

ID=10721833

Family Applications (1)

Application Number Title Priority Date Filing Date
GB9219360A Withdrawn GB2270541A (en) 1992-09-12 1992-09-12 I. c. engine exhaust poppet valve.

Country Status (1)

Country Link
GB (1) GB2270541A (en)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6675757B2 (en) * 2001-01-31 2004-01-13 Trw Deutschland Gmbh Intake valve for an internal combustion machine
CN103925028A (en) * 2013-12-25 2014-07-16 马勒技术投资(中国）有限公司 Partially-coated valve
CN107939470A (en) * 2017-04-17 2018-04-20 赵毛兴 A kind of engine valve for preventing high temperature failure with collet
WO2018191951A1 (en) * 2017-04-17 2018-10-25 赵毛兴 Engine valve with heat insulation sleeve for preventing high temperature failures

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB234283A (en) * 1924-05-27 1925-05-28 Maschf Augsburg Nuernberg Ag Improvements in or relating to methods of and means for reducing the loss of heat from the waste gases of combustion engines
GB470934A (en) * 1936-03-19 1937-08-25 Standard Valves Ltd Improvements in or relating to internal combustion engine valves
EP0048333A1 (en) * 1980-09-22 1982-03-31 Eaton Corporation Shielded valve

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB234283A (en) * 1924-05-27 1925-05-28 Maschf Augsburg Nuernberg Ag Improvements in or relating to methods of and means for reducing the loss of heat from the waste gases of combustion engines
GB470934A (en) * 1936-03-19 1937-08-25 Standard Valves Ltd Improvements in or relating to internal combustion engine valves
EP0048333A1 (en) * 1980-09-22 1982-03-31 Eaton Corporation Shielded valve

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6675757B2 (en) * 2001-01-31 2004-01-13 Trw Deutschland Gmbh Intake valve for an internal combustion machine
CN103925028A (en) * 2013-12-25 2014-07-16 马勒技术投资(中国）有限公司 Partially-coated valve
CN107939470A (en) * 2017-04-17 2018-04-20 赵毛兴 A kind of engine valve for preventing high temperature failure with collet
WO2018191951A1 (en) * 2017-04-17 2018-10-25 赵毛兴 Engine valve with heat insulation sleeve for preventing high temperature failures

Also Published As

Publication number Publication date
GB9219360D0 (en) 1992-10-28

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Legal Events

Date Code Title Description
WAP Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1)