Toyota Camry Hybrid AHV40 Manual page 227

Knock Sensor (Flat Type)
1) General
In the conventional type knock sensor (resonant type), a vibration plate, which has the same resonance
point as the knocking frequency of the engine, is built in and can detect the vibration in this frequency
band.
On the other hand, a flat type knock sensor (non-resonant type) has the ability to detect vibration in a
wider frequency band from about 6 kHz to 15 kHz, and has the following features:
D The engine knocking frequency will change a bit depending on the engine speed. The flat type knock
sensor can detect vibration even when the engine knocking frequency is changed. Thus the vibration
detection ability is increased compared to the conventional type knock sensor, and a more precise
ignition timing control is possible.
: Conventional Type
: Flat Type
2) Construction
D The flat type knock sensor is installed on the engine through the stud bolt installed on the cylinder
block. For this reason, a hole for the stud bolt is running through in the center of the sensor.
D Inside of the sensor, a steel weight is located on the upper portion and a piezoelectric element is located
under the weight through the insulator.
D The open/short circuit detection resistor is integrated.
Steel Weight
Insulator
Piezoelectric
Element
Flat Type Knock Sensor
(Non-Resonant Type)
ENGINE - 2AZ-FXE ENGINE
(V)
Voltage
Frequency
Characteristic of Knock Sensor
Open Circuit
Detection Resistor
214CE01
A: Detection Band of
A
Conventional Type
B: Detection Band of
Flat Type
B
(Hz)
Conventional Type Knock Sensor
(Resonant Type)
EG-39
214CE04
Piezoelectric
Element
Vibration Plate
214CE02