UNIT 6
ENGINE ELECTRICAL SYSTEMS
TEXT B
Direct Ignition Systems and Electronic
Triggering Devices
PROFESSIONAL ENGLISH
UNIT 6
ENGINE ELECTRICAL SYSTEMS
TEXT B
Direct Ignition Systems and Electronic
Triggering Devices
Direct Ignition System
Electronic Triggering Devices
本次课学习内容本次课学习目标
掌握直接点火系统的组成
掌握主要部件的型式及原理
掌握有关的专业名词与术语
了解翻译技巧 — 增词
NEW WORDS
coil-on-plug a.点火线圈在火花塞上的
saturation [?s? t∫?'rei∫?n] n.饱和 (状态 ),浸润,浸透，饱和度
intermittent [?int? (:) 'mit?nt] a.间歇的,断断续续的
misfire ['mis'fai?] v.不发火，缺火
confirmation [?k?nf?'mei∫?n] n.证实,确认,批准
verify ['verifai] v.检验,校验,查证,核实
command [k?'mɑ:nd] n.命令,掌握,司令部； v.命令,指挥，
支配
recommend [rek?'mend] vt.推荐,介绍,劝告,使受欢迎
swap [sw?p] v.交换； n.交换
expectancy [ik'spekt?nsi] n.期待,期望
wafer ['weif?] n.晶片,圆片,薄饼
tab [t? b] n.标签,制表符,短小突出部
shutter ['∫?t?] n.关闭者,百叶窗,快门
slit [slit] n.裂缝,狭长切口； v.切开,撕裂
incidence [‘insid?ns] n.发生，影响，发生率
PHRASES AND EXPRESSIONS
曲轴位置传感器crank position sensor
将 M与 N比较compare M to N
点火顺序firing order
断续性缺火intermittent misfire
（磁）饱和时间saturation time
独立点火系统independent ignition
system
变速器换档离合器transmission clutch
跨接线jumper wire
安装板mounting plate
隔热板,挡热板heat shield
auto shut down relay 自动关闭继电器
life expectancy 预期寿命，预计使用期限
magnetic pickup 电磁式传感器
trigger wheel 磁阻轮
air gap 气隙
reluctor wheel 磁阻轮
Hall-effect switch 霍尔效应开关
optical sensor 光电式传感器
rotor plate 遮光板
light emitting diode 发光二极管 (LED)
photo sensitive diode 光电二极管，光敏二极管
photo diode 光电二极管
Direct Ignition Systems and Electronic
Triggering Devices
Direct Ignition System
Some engines use a distributorless ignition system that
eliminates the need for spark plug wires,The direct ignition
system (DIS) utilizes a coil tower that is installed onto a cover
plate and plug boots that fit directly onto the spark plugs,The
ignition module and coils are installed under the coil tower,
The spark is transmitted to the plug boots through secondary
conductors located in the tower,This system operates using
the same principles as the distributorless ignition system.
Electronic Ignition Systems
with Coils Connected Directly to the Spark Plugs
These EI systems have the same reluctor ring and magnetic
sensor as other electronic injection (EI) systems,However,on
these EI systems,the spark plug wires are eliminated and the
coil secondary terminals are connected directly to the spark
plugs,
Since the spark plug wires are eliminated,the chance of
high-voltage leaks is reduced,The coil module and coils are
mounted under a plate that is positioned between the cam covers
on top of the engine (Fig.6-3),Each coil is connected to a pair of
spark plugs,and the spark plug pairs are 1-4 and 2-3,Since the
coil module contacts the mounting plate,this plate acts as a heat
shield,The mounting plate must be grounded to the engine to
provide ignition operation,Remote spark plug wires may be
connected between the spark plugs and the coil secondary
terminals for test purposes,but the coil mounting cover must be
grounded with a jumper wire during this test procedure.
The operation and electrical connections (Fig.6-4) for these
EI systems are similar to the EI system explained previously,The
PCM reduces the spark advance for a few milliseconds during
transmission shifting to lower the engine torque load on the
transmission clutches.
Fig,6-3 Ignition systems with coils connected
directly to the spark plugs
Fig,6-4 A distributorless ignition system circuit
Independent Ignition System
(Coil-On-Plug or Coil-Near-Plug)
The independent ignition system is also known as a coil-on-
plug system or coil-near-plug and uses one coil for each
cylinder,The independent ignition system mounts an ignition
coil as an assembly directly to a spark plug or near the spark
plug with a very short secondary ignition wire.
The coil on plug design allows for increased coil saturation
time between cylinder firing,Coil saturation time is the period
when current flows through the primary windings,increasing
the magnetic field generated,and thereby increasing the
secondary voltage when required [1],Misfires are more likely
to occur under higher engine speeds and increased load
conditions,The ability to increase firing voltage when required
lowers the risk of intermittent misfires,
The coil on plug independent ignition system either uses one
ignition module to control the primary circuit of all coils (Fig,6-5)
or integrates the ignition module into each coil assembly (Fig.6-6)
or integrates the ignition module into the PCM (CHRYSLER),
The ignition module is controlled by the PCM,The PCM supplies
an ignition timing signal to the ignition module,Next,the ignition
module commands the transistors in the driver circuit to turn on
the primary circuit in the independent coil circuit,The ignition
module sends a confirmation signal back to the PCM to verify the
command,The coil assembly uses a high-voltage diode in the
secondary circuit (Fig.6-7) for rapid cutoff of the secondary
ignition voltage,If the ignition module is not integrated into the
coil assembly,both the primary and secondary circuits may be
checked using a conventional digital ohmmeter for circuit
integrity,Always compare readings to manufacturer
specifications,It is generally recommended to swap coils when
testing for a faulty ignition coil since all coils are the same on the
engine,
Fig,6-5 A independent ignition system that uses one ignition
module to control the primary circuit of all coils
Fig,6-6 A independent ignition system that integrates
the ignition module into each coil assembly
The independent ignition system with integrated ignition
modules into each coil assembly typically use four wires
connected to the primary side of the assembly (Fig.6-6),The
four wires consist of battery positive,ground,ignition timing
signal,and ignition confirmation signal,The PCM uses the
ignition confirmation signal to determine if a coil is not
operating,The primary circuits of these coils cannot be tested
with an ohmmeter.
Some engines do not have the physical space to integrate
the coil-on-plug design,In these situations,manufacturers
have placed the individual coil assemblies as close to the
spark plugs as possible,typically on top of the valve cover,
and integrated short plug wires from each of the coils to their
respective spark plugs.
Fig.6-7 The coil assembly uses a high-voltage diode in the
secondary circuit
The independent ignition system offers greater reliability and
a lower incidence of cylinder misfires compared to past ignition
systems,The coil-on-plug system eliminates the spark plug
wires,which have been a common source of shorts in the past
[3],The independent ignition system has become the preferred
ignition system by most vehicle manufacturers.
The coil-on-plug system,sometimes referred to as a coil-
over-plug ignition system,is subject to the same problems as
previous systems,such as faulty spark plugs,misfire,hard start,
and no-start conditions,If the crank position sensor signal is
lost,the ignition system will shut down,
Electronic Triggering Devices
Some systems also include an auto shut down relay
controlled by the PCM,which supplies battery power to both
the ignition coils and the fuel injectors [4],[2],When the starter
motor armature begins to turn,the starter gear moves out and
engages the ring gear,which spins the crankshaft,When the
engine starts,the driver breaks the starter electrical circuit by
releasing the ignition key switch,This causes the starter gear
to move out of mesh with the ring gear [3].
Electronic triggering devices send a signal current to the
ignition module,which then breaks the primary circuit,The
parts of the triggering device do not wear,which gives them a
much longer life expectancy than contact points,Since the
triggering device does not wear,engine timing does not
change,This improves engine performance,emissions output,
and reliability,There are three types of triggering devices
currently in use,magnetic,Hall effect and optical.
Most of the triggering devices are operated by rotation of the
distributor shaft,Some triggering devices are installed into or on
the engine block and are operated by the rotation of the
crankshaft and/or camshaft.
Magnetic Pickup
The magnetic pickup shown in Fig.6-8 is mounted in the
distributor and reacts to distributor speed,which is one half of
crankshaft speed,This sensor generates alternating current,
The current produced is small (about 250 millivolts),but can be
read easily by the ignition module,The rotating tooth assembly
is called a reluctor,or trigger wheel,The stationary assembly is
called the pickup coil or stator.
Fig,6-8 A magnetic crankshaft position sensor
Some sensors are mounted near the crankshaft,A reluctor
wheel is part of the crankshaft and is placed at its midpoint,An
air gap also exists between this sensor and the reluctor,When
the sensor is in the middle of each slot,the transistor is turned
off and interrupts current flow to the ignition coil,causing a
spark plug to fire,The air gap is critical on all magnetic sensors
and must be set to specifications.
Hall-Effect Switch
The Hall-effect switch can be mounted in the distributor or at
the crankshaft,Fig,6-9,The Hall-effect sensor is a thin wafer of
semiconductor material with voltage applied to it constantly,A
magnet is located opposite the sensor,There is an air gap
between the sensor and magnet (Fig.6-9 a).
The magnetic field acts on the sensor until a metal tab,
usually called a shutter,is placed between the sensor and
magnet (Fig.6-9 b),This metal tab does not touch the
magnet or sensor,When contact between the magnetic field
and sensor is interrupted,it causes its output voltage to be
reduced,This signals the ignition module to turn the power
transistor off,This interrupts primary current to the ignition
coil,causing it to fire.
Optical Sensor
The optical sensor is usually located in the distributor,as
shown in Fig,6-10a,The rotor plate,Fig,6-10b,has many slits
in it through which light passes from the light emitting diode
(LED) to the photo sensitive diode (light receiving) [5],As the
rotor plate turns,it interrupts the light beam from the LED) to
the photo diode,When the photo diode does not detect light,it
sends a voltage signal to the ignition module,causing it to fire
the coil,The coil fires,the spark exits one terminal,travels
through the plug wire to fire the plug,and returns to the other
coil terminal through the engine block,the other spark plug,
and the other plug wire,In effect,the coil fires both spark plugs
at the same time,see Fig,6-4.
The coil wires are arranged so that the coil fires one plug
on the top of the compression stroke and the other plug on
the top of the exhaust stroke,The plug firing on the top of
the exhaust stroke has no effect on the operation of the
engine and is often called a waste spark,Since it takes
very little voltage to jump the spark plug gap on the exhaust
stroke,the coil is powerful enough to fire both plugs.
Fig,6-10 A optical crankshaft
position sensor
小结
Direct Ignition System
Electronic Ignition Systems with Coils Connected
Directly to the Spark Plugs
Independent Ignition System (Coil-On-Plug or
Coil-Near-Plug)
Electronic Triggering Devices
Magnetic Pickup
Hall-Effect Switch
Optical Sensor
作业
熟记相关专业词汇
P150 EXERCIES Ⅰ & Ⅱ
ENGINE ELECTRICAL SYSTEMS
TEXT B
Direct Ignition Systems and Electronic
Triggering Devices
PROFESSIONAL ENGLISH
UNIT 6
ENGINE ELECTRICAL SYSTEMS
TEXT B
Direct Ignition Systems and Electronic
Triggering Devices
Direct Ignition System
Electronic Triggering Devices
本次课学习内容本次课学习目标
掌握直接点火系统的组成
掌握主要部件的型式及原理
掌握有关的专业名词与术语
了解翻译技巧 — 增词
NEW WORDS
coil-on-plug a.点火线圈在火花塞上的
saturation [?s? t∫?'rei∫?n] n.饱和 (状态 ),浸润,浸透，饱和度
intermittent [?int? (:) 'mit?nt] a.间歇的,断断续续的
misfire ['mis'fai?] v.不发火，缺火
confirmation [?k?nf?'mei∫?n] n.证实,确认,批准
verify ['verifai] v.检验,校验,查证,核实
command [k?'mɑ:nd] n.命令,掌握,司令部； v.命令,指挥，
支配
recommend [rek?'mend] vt.推荐,介绍,劝告,使受欢迎
swap [sw?p] v.交换； n.交换
expectancy [ik'spekt?nsi] n.期待,期望
wafer ['weif?] n.晶片,圆片,薄饼
tab [t? b] n.标签,制表符,短小突出部
shutter ['∫?t?] n.关闭者,百叶窗,快门
slit [slit] n.裂缝,狭长切口； v.切开,撕裂
incidence [‘insid?ns] n.发生，影响，发生率
PHRASES AND EXPRESSIONS
曲轴位置传感器crank position sensor
将 M与 N比较compare M to N
点火顺序firing order
断续性缺火intermittent misfire
（磁）饱和时间saturation time
独立点火系统independent ignition
system
变速器换档离合器transmission clutch
跨接线jumper wire
安装板mounting plate
隔热板,挡热板heat shield
auto shut down relay 自动关闭继电器
life expectancy 预期寿命，预计使用期限
magnetic pickup 电磁式传感器
trigger wheel 磁阻轮
air gap 气隙
reluctor wheel 磁阻轮
Hall-effect switch 霍尔效应开关
optical sensor 光电式传感器
rotor plate 遮光板
light emitting diode 发光二极管 (LED)
photo sensitive diode 光电二极管，光敏二极管
photo diode 光电二极管
Direct Ignition Systems and Electronic
Triggering Devices
Direct Ignition System
Some engines use a distributorless ignition system that
eliminates the need for spark plug wires,The direct ignition
system (DIS) utilizes a coil tower that is installed onto a cover
plate and plug boots that fit directly onto the spark plugs,The
ignition module and coils are installed under the coil tower,
The spark is transmitted to the plug boots through secondary
conductors located in the tower,This system operates using
the same principles as the distributorless ignition system.
Electronic Ignition Systems
with Coils Connected Directly to the Spark Plugs
These EI systems have the same reluctor ring and magnetic
sensor as other electronic injection (EI) systems,However,on
these EI systems,the spark plug wires are eliminated and the
coil secondary terminals are connected directly to the spark
plugs,
Since the spark plug wires are eliminated,the chance of
high-voltage leaks is reduced,The coil module and coils are
mounted under a plate that is positioned between the cam covers
on top of the engine (Fig.6-3),Each coil is connected to a pair of
spark plugs,and the spark plug pairs are 1-4 and 2-3,Since the
coil module contacts the mounting plate,this plate acts as a heat
shield,The mounting plate must be grounded to the engine to
provide ignition operation,Remote spark plug wires may be
connected between the spark plugs and the coil secondary
terminals for test purposes,but the coil mounting cover must be
grounded with a jumper wire during this test procedure.
The operation and electrical connections (Fig.6-4) for these
EI systems are similar to the EI system explained previously,The
PCM reduces the spark advance for a few milliseconds during
transmission shifting to lower the engine torque load on the
transmission clutches.
Fig,6-3 Ignition systems with coils connected
directly to the spark plugs
Fig,6-4 A distributorless ignition system circuit
Independent Ignition System
(Coil-On-Plug or Coil-Near-Plug)
The independent ignition system is also known as a coil-on-
plug system or coil-near-plug and uses one coil for each
cylinder,The independent ignition system mounts an ignition
coil as an assembly directly to a spark plug or near the spark
plug with a very short secondary ignition wire.
The coil on plug design allows for increased coil saturation
time between cylinder firing,Coil saturation time is the period
when current flows through the primary windings,increasing
the magnetic field generated,and thereby increasing the
secondary voltage when required [1],Misfires are more likely
to occur under higher engine speeds and increased load
conditions,The ability to increase firing voltage when required
lowers the risk of intermittent misfires,
The coil on plug independent ignition system either uses one
ignition module to control the primary circuit of all coils (Fig,6-5)
or integrates the ignition module into each coil assembly (Fig.6-6)
or integrates the ignition module into the PCM (CHRYSLER),
The ignition module is controlled by the PCM,The PCM supplies
an ignition timing signal to the ignition module,Next,the ignition
module commands the transistors in the driver circuit to turn on
the primary circuit in the independent coil circuit,The ignition
module sends a confirmation signal back to the PCM to verify the
command,The coil assembly uses a high-voltage diode in the
secondary circuit (Fig.6-7) for rapid cutoff of the secondary
ignition voltage,If the ignition module is not integrated into the
coil assembly,both the primary and secondary circuits may be
checked using a conventional digital ohmmeter for circuit
integrity,Always compare readings to manufacturer
specifications,It is generally recommended to swap coils when
testing for a faulty ignition coil since all coils are the same on the
engine,
Fig,6-5 A independent ignition system that uses one ignition
module to control the primary circuit of all coils
Fig,6-6 A independent ignition system that integrates
the ignition module into each coil assembly
The independent ignition system with integrated ignition
modules into each coil assembly typically use four wires
connected to the primary side of the assembly (Fig.6-6),The
four wires consist of battery positive,ground,ignition timing
signal,and ignition confirmation signal,The PCM uses the
ignition confirmation signal to determine if a coil is not
operating,The primary circuits of these coils cannot be tested
with an ohmmeter.
Some engines do not have the physical space to integrate
the coil-on-plug design,In these situations,manufacturers
have placed the individual coil assemblies as close to the
spark plugs as possible,typically on top of the valve cover,
and integrated short plug wires from each of the coils to their
respective spark plugs.
Fig.6-7 The coil assembly uses a high-voltage diode in the
secondary circuit
The independent ignition system offers greater reliability and
a lower incidence of cylinder misfires compared to past ignition
systems,The coil-on-plug system eliminates the spark plug
wires,which have been a common source of shorts in the past
[3],The independent ignition system has become the preferred
ignition system by most vehicle manufacturers.
The coil-on-plug system,sometimes referred to as a coil-
over-plug ignition system,is subject to the same problems as
previous systems,such as faulty spark plugs,misfire,hard start,
and no-start conditions,If the crank position sensor signal is
lost,the ignition system will shut down,
Electronic Triggering Devices
Some systems also include an auto shut down relay
controlled by the PCM,which supplies battery power to both
the ignition coils and the fuel injectors [4],[2],When the starter
motor armature begins to turn,the starter gear moves out and
engages the ring gear,which spins the crankshaft,When the
engine starts,the driver breaks the starter electrical circuit by
releasing the ignition key switch,This causes the starter gear
to move out of mesh with the ring gear [3].
Electronic triggering devices send a signal current to the
ignition module,which then breaks the primary circuit,The
parts of the triggering device do not wear,which gives them a
much longer life expectancy than contact points,Since the
triggering device does not wear,engine timing does not
change,This improves engine performance,emissions output,
and reliability,There are three types of triggering devices
currently in use,magnetic,Hall effect and optical.
Most of the triggering devices are operated by rotation of the
distributor shaft,Some triggering devices are installed into or on
the engine block and are operated by the rotation of the
crankshaft and/or camshaft.
Magnetic Pickup
The magnetic pickup shown in Fig.6-8 is mounted in the
distributor and reacts to distributor speed,which is one half of
crankshaft speed,This sensor generates alternating current,
The current produced is small (about 250 millivolts),but can be
read easily by the ignition module,The rotating tooth assembly
is called a reluctor,or trigger wheel,The stationary assembly is
called the pickup coil or stator.
Fig,6-8 A magnetic crankshaft position sensor
Some sensors are mounted near the crankshaft,A reluctor
wheel is part of the crankshaft and is placed at its midpoint,An
air gap also exists between this sensor and the reluctor,When
the sensor is in the middle of each slot,the transistor is turned
off and interrupts current flow to the ignition coil,causing a
spark plug to fire,The air gap is critical on all magnetic sensors
and must be set to specifications.
Hall-Effect Switch
The Hall-effect switch can be mounted in the distributor or at
the crankshaft,Fig,6-9,The Hall-effect sensor is a thin wafer of
semiconductor material with voltage applied to it constantly,A
magnet is located opposite the sensor,There is an air gap
between the sensor and magnet (Fig.6-9 a).
The magnetic field acts on the sensor until a metal tab,
usually called a shutter,is placed between the sensor and
magnet (Fig.6-9 b),This metal tab does not touch the
magnet or sensor,When contact between the magnetic field
and sensor is interrupted,it causes its output voltage to be
reduced,This signals the ignition module to turn the power
transistor off,This interrupts primary current to the ignition
coil,causing it to fire.
Optical Sensor
The optical sensor is usually located in the distributor,as
shown in Fig,6-10a,The rotor plate,Fig,6-10b,has many slits
in it through which light passes from the light emitting diode
(LED) to the photo sensitive diode (light receiving) [5],As the
rotor plate turns,it interrupts the light beam from the LED) to
the photo diode,When the photo diode does not detect light,it
sends a voltage signal to the ignition module,causing it to fire
the coil,The coil fires,the spark exits one terminal,travels
through the plug wire to fire the plug,and returns to the other
coil terminal through the engine block,the other spark plug,
and the other plug wire,In effect,the coil fires both spark plugs
at the same time,see Fig,6-4.
The coil wires are arranged so that the coil fires one plug
on the top of the compression stroke and the other plug on
the top of the exhaust stroke,The plug firing on the top of
the exhaust stroke has no effect on the operation of the
engine and is often called a waste spark,Since it takes
very little voltage to jump the spark plug gap on the exhaust
stroke,the coil is powerful enough to fire both plugs.
Fig,6-10 A optical crankshaft
position sensor
小结
Direct Ignition System
Electronic Ignition Systems with Coils Connected
Directly to the Spark Plugs
Independent Ignition System (Coil-On-Plug or
Coil-Near-Plug)
Electronic Triggering Devices
Magnetic Pickup
Hall-Effect Switch
Optical Sensor
作业
熟记相关专业词汇
P150 EXERCIES Ⅰ & Ⅱ
