Mazda CX-5 Service & Repair Manual: Variable Valve Timing Mechanism
Outline
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Achieves optimum valve timing according to the driving conditions by the variable valve timing mechanism changing the phases of the camshaft.
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An electric type variable valve timing mechanism on the intake side and a hydraulic pressure type on the exhaust side has been adopted. The expansion of the valve opening angle and the accuracy of the intake and exhaust controls have been improved.
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The electric variable valve timing mechanism obtains higher response than the hydraulic variable valve timing mechanism. As a result, expansion of overlap and the closing timing of the intake valve are achieved.
Structural View
Structure
|
Part name |
Function |
|
Hydraulic variable valve timing actuator |
The hydraulic variable valve timing actuator operates according to the hydraulic pressure and changes the phases of the exhaust camshaft. |
|
Electric variable valve timing actuator |
The electric variable valve timing actuator changes the phases of the intake camshaft. |
|
Electric variable valve timing motor/driver |
Operates the electric variable valve timing actuator based on the signals from the PCM. |
|
OCV |
Operated by current (duty signal) from the PCM. Controls the hydraulic oil passages to the hydraulic variable valve timing actuator. |
|
Intake camshaft position sensor |
Sends the intake camshaft position signal to the PCM. |
|
Exhaust camshaft position sensor |
Sends the exhaust camshaft position signal to the PCM. |
|
Crankshaft position sensor |
Sends the crankshaft position signal to the PCM. |
Operation
At engine start
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Engine startability has been improved by utilizing the features of the operable electric VVT even under the engine stop condition and controlling the optimal timing according to engine conditions.
Light/medium load range
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Pumping loss* is reduced by properly controlling the timing of intake and exhaust, improving the fuel consumption rate.
High load range
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By properly controlling the timing of the intake and exhaust and using the effect of scavenging residual gas in the cylinder and the inertia charging effect, the volumetric efficiency and the output are improved.
Valve Mechanism
Outline
A DOHC type valve system has been adopted and consists of four valves (two
intake valves and two exhaust valves) per cylinder for a total of 16 valves
operated by two camshafts.
...
Other materials:
Main Fuse
Purpose
If electric current of the specified value or more flows to each fuse, the
fuse melts due to heat generation to protect the systems and parts downstream
of the fuse.
Function
If electric current to each fuse is the specified value or more, the fuse
melts due to h ...
Throttle Position (TP) Sensor
Purpose/Function
Detects the throttle valve opening/closing condition, which operates in accordance
with the accelerator pedal operation, as basic information for mainly determining
the fuel injection amount.
Detects the throttle valve opening/closing condition, which operates i ...
Heater Core Inspection
1. Inspect the heater core for damage, cracks, and water leakage.
If there is any malfunction, replace the heater core.
2. Visually inspect the fins for bending.
If there is any bending, use the end of a flathead screwdriver to straighten
the fins.
3. Visually inspect ...