ISO 6621-1:2018 内燃機関 — ピストンリング — Part 1: 語彙 | ページ 6

3.1.1

piston ring

outward expanding annular ferrous spring, fitting into a piston groove, sealing against pressure differential of gases or liquids between the peripheral and side faces of the ring and the bore and piston groove respectively

3.1.2

single-piece ring

piston ring (3.1.1) formed from only one part that is intended for installation in a single ring groove

3.1.3

multi-piece ring

piston ring (3.1.1) comprising two or more component parts that are intended for installation in a single ring groove

3.1.4

compression ring

piston ring (3.1.1) whose primary purpose is to prevent leakage of gas past the piston

3.1.5

oil control ring

piston ring (3.1.1) with oil return slots or an equivalent whose primary purpose is to scrape oil from the cylinder wall

3.1.6

rectangular ring

compression ring (3.1.4) with a rectangular cross-section whose geometrically simple form provides an adequate seal under normal engine operating conditions

3.1.7

keystone ring

compression ring (3.1.4) with both sides tapered

Note 1 to entry: The keystone ring is used in those cases when the ring sticking can be expected. Due to its wedge shape, any radial movement of the ring will alter its axial clearance and thus minimize the build-up of combustion residues.

3.1.8

half keystone ring

compression ring (3.1.4) with one side face tapered

Note 1 to entry: Usually, the tapered side face is the one that faces the combustion chamber.

3.1.9

scraper ring

ring with a rectangular shaped step on the lower peripheral edge to scrape oil from the cylinder wall

Note 1 to entry: It can also act as a lower compression ring (3.1.4) .

3.1.10

Napier ring

scraper ring (3.1.9) with a radiused undercut step

3.1.11

slotted oil control ring

oil control ring (3.1.5) with parallel side faces and two contact lands

Note 1 to entry: Due to the narrow lands of this type of ring, a high unit pressure is achieved.

3.1.12

bevelled-edge oil control ring

slotted oil control ring (3.1.11) with lands that are chamfered on their outer edges

Note 1 to entry: The peripheral edges of both lands are chamfered in order to achieve a further increase in unit pressure and thereby a better oil scraping effect.

3.1.13

double-bevelled oil control ring

slotted oil control ring (3.1.11) with lands that are chamfered on their upward facing edges

Note 1 to entry: By chamfering the edges of both lands in the same direction, the oil scraping effect is even further improved.

3.1.14

coil-spring-loaded slotted oil control ring

slotted oil control ring (3.1.11) whose radial pressure is increased by means of a cylindrical coil spring

Note 1 to entry: This spring acts equally in all directions against the inside of the ring.

3.1.15

coil-spring-loaded bevelled-edge oil control ring

coil-spring-loaded slotted oil control ring (3.1.14) with lands that are chamfered on their outer edges

3.1.16

coil-spring-loaded double-bevelled oil control ring

coil-spring-loaded slotted oil control ring (3.1.14) with lands that are chamfered on their upward facing edges

3.1.17

coil-spring-loaded bevelled-edge chromium-plated oil control ring

coil-spring-loaded slotted oil control ring (3.1.14) with lands that are chromium-plated and chamfered on their inner and outer edges

Note 1 to entry: May or may not be profile ground.

3.1.18

expander/segment oil control ring

multi-piece (3.1.3) oil control ring comprised of an expander-spacer and two segments

Note 1 to entry: Expander-spacer design will vary with manufacturer.

3.2.1

nominal ring diameter

nominal diameter, d₁, identical to the nominal cylinder bore, in accordance with ISO 286-1

3.2.2

witness line

narrow continuous line of contact lapped on the peripheral surface of the ring which can be seen around the circumference with normal vision

3.2.3

joint

location on a piston ring (3.1.1) where the butt ends come together

3.2.4

butting

touching of the two ring gap faces

3.2.5

effective free gap

free gap, m, minus the measured closed gap, s₁

Note 1 to entry: See Figure 2 for m; see Figure 3 for s₁.

Note 2 to entry: Free gap used in the formulae for calculation of E value, tangential force, F_t, diametral force, F_d, and stresses.

3.2.6

pressure pattern

contact pressure distribution around the circumference of the ring when closed in its nominal cylinder bore

3.2.7

contact pressure

pressure that a ring exerts radially against the cylinder wall

Note 1 to entry: Pressure is expressed in N/mm².

3.2.8

pin point

burry light

intermittent pinpoints of bright light or hazy light, but not bright direct light, observed in the test for light-tightness

3.3.1

ring groove

groove in the piston in which the piston ring (3.1.1) is fitted

3.4.1

ring gauge

solid annular gauge having an inside diameter of the nominal cylinder bore

3.4.2

reference plane (datum surface)

plane on which the piston ring (3.1.1) is placed for measurements, except where otherwise specified