Mazda CX-5 Service & Repair Manual: Piston, Piston Ring, Piston Pin

Purpose, Function

Piston

• The piston in the cylinder of the cylinder block moves reciprocally by the pressure received when the air-fuel mixture combusts.

Piston ring

• The piston ring consists of the compression ring (top ring, second ring) and the oil ring, and has the following function.

• The compression ring prevents leakage of pressure in the cylinder from the piston circumference.

• The oil ring clears off extra engine oil adhered to the cylinder wall.

• The piston ring transmits piston heat to the cylinder wall to cool the piston.

Piston pin

• The reciprocating movement of the piston is transmitted to the connecting rod by the connection of the piston pin to connecting rod.

Construction

Piston

• The high-temperature strength piston is made of aluminum alloy with excellent thermal conductivity.

• The piston has a cavity on the top surface. As a result, the initial combustion flame is prevented from hitting the top surface of the piston to reduce cooling loss.

  

  
  

  

  
  

• The sliding resistance has been reduced by optimizing the piston skirt shape.

• A weight reduction is realized by optimizing the piston shape.

• With the adoption of the offset piston, piston slap is suppressed.

  

  
  

Piston ring

• A barrel-face ring for the top ring and a taper under cut ring for the second ring have been adopted.

• A three-piece oil ring consisting of a side rail and spacer have been adopted for the oil ring.

• Tracking capability to the cylinder wall has been improved by thinning down the piston ring. As a result, a low-tension piston ring has been implemented without increasing the engine oil consumption, and the sliding resistance has been reduced during reciprocating movement.

Piston pin

• The piston is a full-floating type.