Mazda 6. Manual — part 10

VALVE MECHANISM

B–29

B

Construction

•

The variable valve timing mechanism consists of a variable valve timing actuator, oil control valve (OCV), CKP
sensor, CMP sensor, and the PCM.

.

AME2211N015

1

CKP sensor

2

CMP sensor

3

PCM

4

Oil control valve (OCV)

5

Variable valve timing actuator

6

Electric signal

7

Hydraulic pressure

B–30

VALVE MECHANISM

Hydraulic Pressure Flow Diagram

.

Component and function

AME2211N016

1

Oil pan

2

Oil pump

3

Oil pipe

4

Oil filter

5

Oil control valve (OCV)

6

Oil control valve (OCV) adapter

7

Camshaft

8

Variable valve timing actuator

9

Cylinder block

Variable valve timing actuator

•

Continuously modifies the phases of the intake camshaft and crankshaft at the forward
end of the intake camshaft using hydraulic pressure from the oil control valve (OCV).

Oil control valve (OCV)

•

Operated by current (duty signal) from the PCM. Switches the hydraulic oil passages
to the variable valve timing actuator.

CKP sensor

•

Inputs engine revolution signal to the PCM.

CMP sensor

•

Inputs cylinder identification signal to the PCM.

PCM

•

Controls the oil control valve (OCV) so that optimum valve timing is obtained according
to engine operation conditions.

VALVE MECHANISM

B–31

B

Operation outline

•

The variable valve timing actuator has two hydraulic chambers: a valve timing advance chamber and a valve
timing retard chamber. They are located between the integrated housing of the camshaft sprocket and the
camshaft integrated rotor. The oil pump supplies engine oil. to each chamber. Hydraulic pressure applied to
each chamber is controlled by the oil control valve (OCV) and the relative phases of the camshaft sprocket and
the camshaft are modified to obtain optimum valve timing according to engine operation conditions.

At engine start

•

When the stopper pin in the variable valve timing actuator engages with the rotor, which is at the position of
maximum valve timing retard due to spring force, the camshaft sprocket and the camshaft rotate as one unit.
When the oil pump pressure rises and the stopper pin is disengaged, it becomes possible to modify the relative
angles of the camshaft sprocket and the camshaft.

Advancing valve timing

•

When the spool valve in the oil control valve (OCV) moves to the left according to the PCM signal, hydraulic
pressure, from the oil pump, feeds into the valve timing advance passage and finally to the valve timing
advance chamber in the variable valve timing actuator. Then, the rotor integrated with the camshaft rotates in
the valve timing advance direction, against the housing driven by the crankshaft, and the valve timing is
advanced.

.

Retarding valve timing

•

When the spool valve in the oil control valve (OCV) moves to the right according to the PCM signal, hydraulic
pressure, from the oil pump, feeds into the valve timing retard passage and finally to the valve timing retard
chamber in the variable valve timing actuator. Then, the rotor integrated with the camshaft rotates in the valve
timing retard direction, against the housing driven by the crankshaft, and valve timing is retarded.

AME2211N017

1

PCM

2

Oil control valve (OCV)

3

Spool valve

4

Oil pump

5

Camshaft

6

Variable valve timing actuator

7

Rotor

8

Housing

9

Oil pan

10

To valve timing advance chamber

11

Valve timing advance chamber

12

From valve timing retard chamber

13

Hydraulic pressure flow

B–32

VALVE MECHANISM

.

Maintaining intermediate valve timing

•

The spool valve in the oil control valve (OCV) is located near the middle of the valve timing advance and retard
positions. Because of this, hydraulic pressures are maintained in both valve timing advance and retard
chambers of the variable valve timing actuator. At the same time, relative angles of the rotor and the housing
are fixed and maintained, resulting in fixed valve timing.

.

AME2211N018

1

PCM

2

Oil control valve (OCV)

3

Spool valve

4

Oil pump

5

Camshaft

6

Variable valve timing actuator

7

Rotor

8

Housing

9

Oil pan

10

To valve timing retard chamber

11

Valve timing retard chamber

12

From valve timing advance chamber

13

Hydraulic pressure flow

AME2211N019

1

PCM

2

Oil control valve (OCV)

3

Oil pump

4

To valve timing advance chamber

5

To valve timing retard chamber

6

Hydraulic pressure flow