UNIT 5
DIESEL FUEL INJECTION
TEXT A
Overview of Diesel Fuel Injection
PROFESSIONAL ENGLISH
UNIT 5
DIESEL FUEL INJECTION
TEXT A
Overview of Diesel Fuel Injection
Overall Diesel Fuel System
Injector Pump Types
Diesel Injector Types
Glow Plug and Intake Air Heaters
本次课学习内容本次课学习目标
掌握柴油机喷油系统的组成
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 — 省略
NEW WORDS
schematic [ski'm?tik] a.示意性的
alert [?'l?:t] v.向 … 发出警报；
clog [kl?g] v.&n.阻塞，堵塞
nozzle ['n?z(?)l] n.喷嘴
jam [m] v.&n.堵塞，拥挤
trap [tr?p] n.圈套，陷阱，捕集器
plunger ['pl?n] n.柱塞，活塞
rack [r?k] n.齿条
barrel['b?r(?)l] n.桶； v.装入桶内
helix ['hi:liks] n.螺旋，螺旋状物
cutaway ['k?twei] a.切去一部分的，剖面的
instantly ['inst?ntli] ad.立即地，即刻地
variation [ve?ri'ei∫?n]n.变化，变更，变种，变调
protrude [pr?'tru:d] v.突出，伸出
dull [d?l] v.变迟钝； a.迟钝的，不鲜明的，无光泽的
readily ['redili] ad.容易，欣然，乐意地
water separator （油）水分离器
inline injector pump 直列式喷油泵
delivery valve 出油阀
segment gear 扇形齿轮
transfer pump 输送泵，输油泵
inline fuel pump 管路串接式燃油泵
inward opening injector 孔式喷油器
outward opening injector 轴针式喷油器
glow plug 预热塞
pumping chamber 预压缩室（腔）
wire mesh （金属、钢、塑料）丝网，线网
PHRASES AND EXPRESSIONS
Overview of Diesel Fuel Injection
Diesel engines are used on some cars and light trucks,The
diesel engine uses the heat of compression,instead of a spark
plug,to ignite the fuel,Diesel fuel injection is similar to gasoline
injection,but requires higher injection pressures,Air is drawn into
the cylinder and highly compressed,The compression is so high
that the compressed air will reach temperatures of
1000℉ (538.2℃ ),At the precise time the piston has completed
the compression stroke,diesel fuel is sprayed into the
combustion chamber,or an offset prechamber,The intense heat
of the compressed air ignites the fuel,and the power stroke
follows.
Overall Diesel Fuel System
A schematic of a diesel fuel system layout is shown in Fig.5-1,
Typical diesel system components include the tank,fuel pump,
filter,injection pump,injectors,and the necessary fuel lines,The
system in Fig.5-1 is typical of newer systems that utilize a
computer-controlled electronic fuel injection pump.
Fig.5-1,An overall view of one particular diesel fuel
injection system as used with a V-8 engine,
Water In Fuel Sensor
Some vehicles are equipped with a water in fuel sensor that
will alert the driver to the fact that water is present in the fuel
[1],The water may then be drawn off through a valve in the
bottom of a water separator,Water is extremely damaging to
the injection system.
Fuel Filter
Diesel fuel must be kept clean to avoid injector system
trouble,Very small particles are enough to clog injector
nozzles or jam the injector,Diesel fuel systems typically use
one or more filters to trap dirt and other deposits,
Diesel Injection Pump
Diesel fuel is injected directly into the cylinder at the top of
the compression stroke,Due to the high compression (around
22:1) used in diesel engines,the diesel injection pump must be
capable of producing high pressures,Injector pump pressures
vary greatly depending on the pump and engine,Pressures
can range from 3000-15,000 psi (20 685-103 425 kPa),
How the Injector Pump Produces Pressure
By using a plunger operating in a cylinder,the pump traps fuel
ahead of the plunger,When the plunger is forced up,it builds
pressure on the fuel,Pressure will be increased to the point at
which the injector will open and spray fuel into the engine,
Pumps can use a single plunger for each injector or a single
pump (often consisting of two or more opposing plungers) to
serve all injectors[2].
Injector Pump Types
There are a number of injector pump designs,The most
commonly used automobile and light truck diesel injector pumps
are classified as inline or distributor,Both are mechanical
pumps that pressurize the fuel and deliver it to the cylinders at
the proper time for each.
Inline Injector Pump
Inline Injector Pump
The inline injector pump uses a separate cylinder plunger-
cam for each cylinder,They are contained in a straight row in a
common housing,The cams are part of a common camshaft
driven by the engine at one-half engine speed,Drive may be
by chain,belt,or gear,Fuel from the fuel pump is fed to all of
the plunger assemblies,As the camshaft rotates,each of the
plungers is moved up and down in their cylinders.
A single control rack or rail with gear teeth along one side is
meshed with each plunger assembly,By moving the control
rack,the effective pump action (amount of fuel pumped) of all
plungers can be adjusted,
Inline Injector Pump Metering Control
Each plunger operates in a separate cylinder or barrel,The
top section of the plunger has a wide band or groove cut away,
One edge of the cut forms a helix (spiral shape),The plunger
also has a vertical slot reaching from the top of the plunger
down into the cutaway area,
The bottom of the plunger is connected,by means of a flange,to
the toothed control sleeve that meshes with the control rack teeth,
When the control rack is moved back and forth,the plunger will
rotate in the cylinder,so the effective pump action,or stroke,will
be changed.
Injector Pump Delivery Valve
Fuel flowing from the pump cylinder is forced through a delivery
valve on its way to the injector,The fuel flow forces the delivery
valve from its seat,When the helix uncovers the cylinder ports,fuel
pressure in the pump cylinder drops instantly,This causes the
delivery valve plunger to quickly return to its seat,In so doing,the
volume in the delivery line (injector housing,line to injector and
delivery valve spring chamber) is suddenly increased by the
amount of the delivery valve plunger travel,This increase in
volume causes a sudden reduction in delivery line pressure that
allows the injector nozzle valve to snap shut quickly and cleanly
without dripping [3],A delivery valve is used on both inline and
distributor type pumps,
Figure 5-2,Pump plunger construction,When the control
rack is moved,the plunger will be forced to rotate by the
segmented gear sleeve acting on the plunger flange.
Distributor Type Injection Pump(自学）
The distributor injection pump is shown in Figure 5-3,You
will note that a single,double-plunger type pump serves all
injector outlets,A single delivery valve is located in the rotor,
Pump Charging Cycle
Fuel enters the transfer pump from the inline fuel pump,
From the transfer pump,fuel moves through the rotor
passages into the pumping chamber and fuel metering valve
area,Excess fuel flows through the transfer pump pressure
regulator back to the inlet side.
For fuel to flow through the rotor passages,the rotor must
turn far enough to align the rotor passages with the fuel
charging ports,The cam ring is positioned to permit the pump
plungers to be forced apart by the fuel entering the chamber,
The distance the pump plungers move apart determines how
much fuel is delivered [4],The distance the plungers move
apart is controlled by the governor operated metering valve [5].
Pump Discharge Cycle
When the angled inlet passages no longer line up with
the charging ports,fuel is trapped in the pumping chamber,
The cam ring rollers have been squeezed inward,forcing
the two plungers toward each other,As the plungers are
forced together,the trapped fuel is forced past the delivery
valve,into the injector line which opens the injector nozzle,
spraying fuel into the cylinder.
Pump Fuel Return Circuit
Transfer pump pressure forces fuel through a vent
passage in the hydraulic head,Flow through the passage is
partially blocked by a wire to prevent excessive flow and
pressure loss,Any air from the transfer pump flows,with
some fuel,through the vent into the governor linkage
compartment and then back to the fuel tank.
Electrical Fuel Shutoff
An electrical fuel shutoff,Fig.5-4,is used on diesel
engines to stop the engine,it rotates the metering valve to
the closed position when the shutoff solenoid is de-
energized,This stops fuel flow.
Fig.5-3 Cutaway view of a distributor type injection pump,This
pump creates pressure and distributes fuel from a single rotary
pump to all injectors.
Fig.5-4 A distributor type fuel injection pump showing the location
of one particular fuel shutoff solenoid,This solenoid is controlled
by the powertrain control module (PCM),When energized,it is
designed to completely stop the fuel flow into the injection pump.
Other Pump Features
The pump can also offer a viscosity compensating valve
that tends to keep the injector pump functioning the same with
either light or heavy (or cold) fuels,Fuel delivery timing can be
automatically advanced or retarded to compensate for engine
speed and/or load changes,A fuel automatic delivery advance
mechanism is shown in Fig.5-3.
Diesel Injector Types
Fuel pressure,fuel viscosity,nozzle design,and nozzle
condition must all be correct so that a proper spray pattern is
formed,There are many different injector designs,but all are a
variation of two basic types-inward opening and outward
opening,Diesel spray patterns will vary depending upon
engine design.
Glow Plug and Intake Air Heaters
To aid in igniting the compressed air-fuel mix during cold
starting,diesel engines use glow plugs and intake air heaters.
The glow plug is an electrically operated device that
protrudes into the precombustion chamber,When energized,
the glow plug tip heats to a dull red,The swirling,highly
compressed air-fuel mixture is heated by the glow plug tip,
This additional heat helps the engine to start by causing the
mixture to ignite more readily.
On older vehicles,the glow plugs must be turned on by the
vehicle operator and allowed to heat the combustion chamber
for several seconds before the engine can be started,On later
engines,the glow plugs are turned on and off automatically,
Under most starting conditions,the plugs are energized for a
very short period,The engine can be started in seconds after
the key is turned on,The glow plugs may still be energized for
a very short while following engine startup.
Intake air heaters warm the air as it passes through on its
way to the intake manifold,The heater element is a wire mesh
that is electrically heated,The computer energizes the heater
element before cranking.
小结
Overall Diesel Fuel System
Injector Pump Types
Diesel Injector Types
Glow Plug and Intake Air Heaters
作业
熟记相关专业词汇
P112 EXERCIES Ⅰ & Ⅱ
DIESEL FUEL INJECTION
TEXT A
Overview of Diesel Fuel Injection
PROFESSIONAL ENGLISH
UNIT 5
DIESEL FUEL INJECTION
TEXT A
Overview of Diesel Fuel Injection
Overall Diesel Fuel System
Injector Pump Types
Diesel Injector Types
Glow Plug and Intake Air Heaters
本次课学习内容本次课学习目标
掌握柴油机喷油系统的组成
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 — 省略
NEW WORDS
schematic [ski'm?tik] a.示意性的
alert [?'l?:t] v.向 … 发出警报；
clog [kl?g] v.&n.阻塞，堵塞
nozzle ['n?z(?)l] n.喷嘴
jam [m] v.&n.堵塞，拥挤
trap [tr?p] n.圈套，陷阱，捕集器
plunger ['pl?n] n.柱塞，活塞
rack [r?k] n.齿条
barrel['b?r(?)l] n.桶； v.装入桶内
helix ['hi:liks] n.螺旋，螺旋状物
cutaway ['k?twei] a.切去一部分的，剖面的
instantly ['inst?ntli] ad.立即地，即刻地
variation [ve?ri'ei∫?n]n.变化，变更，变种，变调
protrude [pr?'tru:d] v.突出，伸出
dull [d?l] v.变迟钝； a.迟钝的，不鲜明的，无光泽的
readily ['redili] ad.容易，欣然，乐意地
water separator （油）水分离器
inline injector pump 直列式喷油泵
delivery valve 出油阀
segment gear 扇形齿轮
transfer pump 输送泵，输油泵
inline fuel pump 管路串接式燃油泵
inward opening injector 孔式喷油器
outward opening injector 轴针式喷油器
glow plug 预热塞
pumping chamber 预压缩室（腔）
wire mesh （金属、钢、塑料）丝网，线网
PHRASES AND EXPRESSIONS
Overview of Diesel Fuel Injection
Diesel engines are used on some cars and light trucks,The
diesel engine uses the heat of compression,instead of a spark
plug,to ignite the fuel,Diesel fuel injection is similar to gasoline
injection,but requires higher injection pressures,Air is drawn into
the cylinder and highly compressed,The compression is so high
that the compressed air will reach temperatures of
1000℉ (538.2℃ ),At the precise time the piston has completed
the compression stroke,diesel fuel is sprayed into the
combustion chamber,or an offset prechamber,The intense heat
of the compressed air ignites the fuel,and the power stroke
follows.
Overall Diesel Fuel System
A schematic of a diesel fuel system layout is shown in Fig.5-1,
Typical diesel system components include the tank,fuel pump,
filter,injection pump,injectors,and the necessary fuel lines,The
system in Fig.5-1 is typical of newer systems that utilize a
computer-controlled electronic fuel injection pump.
Fig.5-1,An overall view of one particular diesel fuel
injection system as used with a V-8 engine,
Water In Fuel Sensor
Some vehicles are equipped with a water in fuel sensor that
will alert the driver to the fact that water is present in the fuel
[1],The water may then be drawn off through a valve in the
bottom of a water separator,Water is extremely damaging to
the injection system.
Fuel Filter
Diesel fuel must be kept clean to avoid injector system
trouble,Very small particles are enough to clog injector
nozzles or jam the injector,Diesel fuel systems typically use
one or more filters to trap dirt and other deposits,
Diesel Injection Pump
Diesel fuel is injected directly into the cylinder at the top of
the compression stroke,Due to the high compression (around
22:1) used in diesel engines,the diesel injection pump must be
capable of producing high pressures,Injector pump pressures
vary greatly depending on the pump and engine,Pressures
can range from 3000-15,000 psi (20 685-103 425 kPa),
How the Injector Pump Produces Pressure
By using a plunger operating in a cylinder,the pump traps fuel
ahead of the plunger,When the plunger is forced up,it builds
pressure on the fuel,Pressure will be increased to the point at
which the injector will open and spray fuel into the engine,
Pumps can use a single plunger for each injector or a single
pump (often consisting of two or more opposing plungers) to
serve all injectors[2].
Injector Pump Types
There are a number of injector pump designs,The most
commonly used automobile and light truck diesel injector pumps
are classified as inline or distributor,Both are mechanical
pumps that pressurize the fuel and deliver it to the cylinders at
the proper time for each.
Inline Injector Pump
Inline Injector Pump
The inline injector pump uses a separate cylinder plunger-
cam for each cylinder,They are contained in a straight row in a
common housing,The cams are part of a common camshaft
driven by the engine at one-half engine speed,Drive may be
by chain,belt,or gear,Fuel from the fuel pump is fed to all of
the plunger assemblies,As the camshaft rotates,each of the
plungers is moved up and down in their cylinders.
A single control rack or rail with gear teeth along one side is
meshed with each plunger assembly,By moving the control
rack,the effective pump action (amount of fuel pumped) of all
plungers can be adjusted,
Inline Injector Pump Metering Control
Each plunger operates in a separate cylinder or barrel,The
top section of the plunger has a wide band or groove cut away,
One edge of the cut forms a helix (spiral shape),The plunger
also has a vertical slot reaching from the top of the plunger
down into the cutaway area,
The bottom of the plunger is connected,by means of a flange,to
the toothed control sleeve that meshes with the control rack teeth,
When the control rack is moved back and forth,the plunger will
rotate in the cylinder,so the effective pump action,or stroke,will
be changed.
Injector Pump Delivery Valve
Fuel flowing from the pump cylinder is forced through a delivery
valve on its way to the injector,The fuel flow forces the delivery
valve from its seat,When the helix uncovers the cylinder ports,fuel
pressure in the pump cylinder drops instantly,This causes the
delivery valve plunger to quickly return to its seat,In so doing,the
volume in the delivery line (injector housing,line to injector and
delivery valve spring chamber) is suddenly increased by the
amount of the delivery valve plunger travel,This increase in
volume causes a sudden reduction in delivery line pressure that
allows the injector nozzle valve to snap shut quickly and cleanly
without dripping [3],A delivery valve is used on both inline and
distributor type pumps,
Figure 5-2,Pump plunger construction,When the control
rack is moved,the plunger will be forced to rotate by the
segmented gear sleeve acting on the plunger flange.
Distributor Type Injection Pump(自学）
The distributor injection pump is shown in Figure 5-3,You
will note that a single,double-plunger type pump serves all
injector outlets,A single delivery valve is located in the rotor,
Pump Charging Cycle
Fuel enters the transfer pump from the inline fuel pump,
From the transfer pump,fuel moves through the rotor
passages into the pumping chamber and fuel metering valve
area,Excess fuel flows through the transfer pump pressure
regulator back to the inlet side.
For fuel to flow through the rotor passages,the rotor must
turn far enough to align the rotor passages with the fuel
charging ports,The cam ring is positioned to permit the pump
plungers to be forced apart by the fuel entering the chamber,
The distance the pump plungers move apart determines how
much fuel is delivered [4],The distance the plungers move
apart is controlled by the governor operated metering valve [5].
Pump Discharge Cycle
When the angled inlet passages no longer line up with
the charging ports,fuel is trapped in the pumping chamber,
The cam ring rollers have been squeezed inward,forcing
the two plungers toward each other,As the plungers are
forced together,the trapped fuel is forced past the delivery
valve,into the injector line which opens the injector nozzle,
spraying fuel into the cylinder.
Pump Fuel Return Circuit
Transfer pump pressure forces fuel through a vent
passage in the hydraulic head,Flow through the passage is
partially blocked by a wire to prevent excessive flow and
pressure loss,Any air from the transfer pump flows,with
some fuel,through the vent into the governor linkage
compartment and then back to the fuel tank.
Electrical Fuel Shutoff
An electrical fuel shutoff,Fig.5-4,is used on diesel
engines to stop the engine,it rotates the metering valve to
the closed position when the shutoff solenoid is de-
energized,This stops fuel flow.
Fig.5-3 Cutaway view of a distributor type injection pump,This
pump creates pressure and distributes fuel from a single rotary
pump to all injectors.
Fig.5-4 A distributor type fuel injection pump showing the location
of one particular fuel shutoff solenoid,This solenoid is controlled
by the powertrain control module (PCM),When energized,it is
designed to completely stop the fuel flow into the injection pump.
Other Pump Features
The pump can also offer a viscosity compensating valve
that tends to keep the injector pump functioning the same with
either light or heavy (or cold) fuels,Fuel delivery timing can be
automatically advanced or retarded to compensate for engine
speed and/or load changes,A fuel automatic delivery advance
mechanism is shown in Fig.5-3.
Diesel Injector Types
Fuel pressure,fuel viscosity,nozzle design,and nozzle
condition must all be correct so that a proper spray pattern is
formed,There are many different injector designs,but all are a
variation of two basic types-inward opening and outward
opening,Diesel spray patterns will vary depending upon
engine design.
Glow Plug and Intake Air Heaters
To aid in igniting the compressed air-fuel mix during cold
starting,diesel engines use glow plugs and intake air heaters.
The glow plug is an electrically operated device that
protrudes into the precombustion chamber,When energized,
the glow plug tip heats to a dull red,The swirling,highly
compressed air-fuel mixture is heated by the glow plug tip,
This additional heat helps the engine to start by causing the
mixture to ignite more readily.
On older vehicles,the glow plugs must be turned on by the
vehicle operator and allowed to heat the combustion chamber
for several seconds before the engine can be started,On later
engines,the glow plugs are turned on and off automatically,
Under most starting conditions,the plugs are energized for a
very short period,The engine can be started in seconds after
the key is turned on,The glow plugs may still be energized for
a very short while following engine startup.
Intake air heaters warm the air as it passes through on its
way to the intake manifold,The heater element is a wire mesh
that is electrically heated,The computer energizes the heater
element before cranking.
小结
Overall Diesel Fuel System
Injector Pump Types
Diesel Injector Types
Glow Plug and Intake Air Heaters
作业
熟记相关专业词汇
P112 EXERCIES Ⅰ & Ⅱ
