Valves - Wilmink

Valves
Wahler – Solutions in Partnership.
Products for Exhaust Gas and Temperature Management.
EGR Components
Key components for clean engine power
C EGR pipe
3
EGR cooler
B EGR pipe (cold)
2
D Bypass flap
Engine control unit
E
A Throttle flap with
mixing chamber
1
2 3
Air filter
5
Engine
EGR valve
F
EGR pipe (hot)
4
Exhaust system
Entwicklung
Development
der Euro-Normen
of Euro standards
und derand
Wahler-AGR-Komponenten
Wahler EGR components
Elektrisches
Electric EGR flap
AGR-Klappenventil
valve with
mit
electronics
Elektronik
Electric
Elektrisches
EGR
AGR-Ventil
valve with
mitelectronics
Elektronik
Pneumatisches
Pneumatic
AGR-Ventil
EGR valve
Elektrisches
Electric rotary
AGR-Drehventil
EGR valve with
mit
electronics
Elektronik
Electric
Elektrische
throttle
Drosselklappe
flap with
mitelectronics
Elektronik
Elektrisches
Electric EGR
AGR-Ventil
valve without
ohne
electronics
Elektronik
Elektrisches
Electric EGR
AGR-Ventil
valve with
mit
DC actuator
DC-Antrieb
EGR Systems
The combustion under differing operating
conditions of the engine is always kept
1992
1993
1994
1995
1996
Euro I
1997
1998
2001
2002
2003
2004
Euro III
500
800
180
PM
2000
Euro II
1000
NOx
1999
80 / 100*
50
2005
2006
2007
2008
2009
Euro IV
250
2010
within the optimum working range via
unit and the implementation of EGR
180
25
Values
Werte in mg/km
respective functions of the engine control
Euro V
systems.
5
* mit
* With
Direkteinspritzung
direct injection
The EGR valve enables the quantity of the
recirculated exhaust gas to be regulated.
Depending on the engine temperature, the
exhaust gas can be conducted through
sucked-in ambient air. This leads to a
the bypass flap via the EGR cooler, or to
lower oxygen concentration in the air/fuel
the mixing chamber, uncooled. The throttle
The demands made on driving comfort
mixture for the same load quantity in the
flap in the intake channel allows the
and engine power are constantly
combustion chamber, and thus to slower
differential pressure to rise and thereby
increasing. At the same time a growing
combustion. The subsequently achieved
the EGR quantity to increase.
awareness of the environment and more
reduction in the peak combustion
stringent exhaust gas limit values
temperatures results in the reduced
The figure on the left shows all the EGR
world-wide demand reduced emissions
formation of nitric oxide.
components that complement each
The reduced combustion temperature
with the engine manufacturers to form a
leads to an increase in the particle
perfectly adapted EGR system. The
EGR for reducing NOx
distribution in diesel engines. Post-oxida-
implementation of EGR systems in the
The most effective method for reducing
tion of the particles and their complete
engines of the future will continue to
the share of nitric oxides (NOx) is
burn-out would only take place at high
increase, in order to adhere to the
achieved by exhaust gas return (EGR).
temperatures. A conflict of objectives with
emission standards that are continually
Here, the exhaust gas is mixed with the
the technical term ‘Trade-Off’.
becoming more and more stringent.
of hazardous substances, particularly of
nitric oxide and particle distributions.
other due to Wahler's close collaboration
Durchsatzkennlinien
Mass
flow characteristics
Partikel, uncooled
Particle,
ungekühlt
NOx, uncooled
ungekühlt
Q [kg/h]
bei100
at
100hPa
hPa
>200
Klappenventil
Flap
valve
Drehventil
Rotary
valve
Partikel, cooled
Particle,
gekühlt
Emission
NOx, cooled
gekühlt
0
10
20
30
40
50
60
70
EGR rate in
AGR-Rate
in [%]
[%]
‘Trade-Off’ – NOx versus particle emission
Hubventil
Poppet
valve
120
0
0
Hubventil
Poppet
valve
Flap/Rotary
valve
Klappen-/Drehventil
max Hub
max.
stroke
90°
s [mm]
ϕ[ ]
Mass flow characteristics of the different valves
EGR Poppet Valves
Proven in the past and still up-to-date
Features of the EGR poppet valves
• Application for small to medium EGR rates (passenger cars,
approx. 130 kg/h at 100 hPa and 20°C gas temperatur)
• Continuously variable control of the EGR mass flow rate
• Tight closure of the EGR channel during full-load operation
• Fail-safe function in the case of an actuator failure
• Pneumatic or electric actuator
• On-board diagnosis possible with position sensor
• Option – with or without controller
• With/without cooling for use on hot/cold side
4 5
Proven a millionfold
In the case of the poppet valve, the valve
seat is integrated in the housing. It is
closed by a poppet disc with a closely
fitting geometry and thereby has very low
leakage values. The poppet disc itself is
connected to the actuator by a shaft.
Pneumatic poppet valves have a vacuum
actuator with a membrane that controls
valve ensures short positioning times
the poppet disc. If the vacuum pressure
and high positioning accuracy of less
system should fail, a return spring
than 0.1 mm. The actuation via a rotary
ensures that the ‘fail-safe’ position ‘valve
solenoid or a DC actuator enables direct
closed’ comes into effect. It similarly
access of the engine control unit.
produces a counteracting force and
thereby ensures a linear course of the
Intelligence of its own
characteristic.
A sensor for detecting the valve position
Modern actuator
the case of the rotary solenoid either via
The introduction of the electronic control
the engine control unit – like also in the
units (ECU) for engines gave rise to the
case of the DC actuator – or via the own
enables real control. This takes place in
requirement for enabling the EGR valves
intelligence of the valve. In this case the
to be controlled by the engine software.
engine control unit sends a set value via
An electro-pneumatic transducer
a powerless connection, that the valve
Wahler was one of the first to realise the
therefore converts the control signals of
holds independently, even in the case of
significance of exhaust gas return and
the ECU to pneumatic pressure signals.
variable differential pressure on the
played a decisive role in its development.
As a result, the link was established
poppet.
Since 1994 we have been producing pneu-
between mechanics and electronics.
matic EGR valves in series and the figures
In addition, the sensor enables the
speak for themselves. Over 10 million
Following the requirements of modern
increasingly important OBD function.
poppet valves have since been regulating
combustion engines, Wahler fitted his
Diagnostic data can be recorded by the
the flow of exhaust gas in the engines of
successful poppet valves with an electric
control unit and stored for later error
the most varying manufacturers.
actuator in 1999. The electric poppet
diagnosis.
Vergleich
Comparison
Aktuatortypen
of actuator types
stroke
elektrisch
electric
pneumatisch
pneumatic
temperature
Pneumatic EGR valve with
throttle flap
Hysteresis-free control for the electric
poppet valve
Poppet valve with DC actuator
EGR Rotary and Flap Valves
Continuously variable from low to high mass flow rates
EGR flap valves at a glance
• Application for high EGR rates (medium and
large-sized engines for commercial vehicles)
• Continuously variable control of the
EGR mass flow rate
• Closure of the EGR channel during
full-load operation
• Fail-safe function in the case of an
actuator failure
• On-board diagnosis with position sensor
6 7
Electric rotary valve
For engines with a displacement of
2.5 - 9 litres (large passengers cars to
medium-sized commercial vehicles) the
rotary valve takes over both the exact
and continuously variable control of small
exhaust gas flows during full-load
oper­ation as well as the throughput of
large flow rates during partial load
operation.
In this case, the valve disc does not
operate against the exhaust pressure like
the poppet valve but, in a rotary movement, clears the window openings for the
exhaust gas to flow through. The special
contour of these openings enables the
said requirements for controlling the
exhaust gas flow to be fulfilled.
With the increasing complexity of modern
combustion engines, the demands made
Electric flap valve
on EGR components change. Due to the
The flap valve fulfils the requirement for
differing laws on emissions, different
high exhaust gas return rates. These are
requirements result world-wide. New
required for large volume engines in
valves have been developed as a result
heavy commercial vehicles. This valve is
of increasing exhaust counter pressure
outstanding due to its short positioning
and variable differential pressure on the
times and its exact and continuously
valve, the demand for continuously
variable regulation of large flow rates.
variable control of large flow rates and an
Appropriately adapted housing and flap
exact control of small quantities of
geometries also ensure low leakage
exhaust gas.
values.
Electric EGR rotary valve
Short introduction of the EGR rotary valves
• Application for medium EGR rates (passenger
cars and medium-sized commercial vehicles)
• Continuously variable control of the EGR mass flow rate
• Exact control of low return rates
• Closure of the EGR channel during full-load operation
• Fail-safe function in the case of an actuator failure
• On-board diagnosis possible with position sensor
• Option – with or without electronics
Cross-section: electric
EGR flap valve
Cross-section: electric
EGR rotary valve
• Option – with or without cooling
EGR Bypass Flap and Actuator
Pneumatics with a groundbreaking task
Features of the EGR bypass flap
• Conducts exhaust gas through
the EGR cooler or bypass channel
• Installation possible before or after
the EGR cooler
• Drive via pneumatic actuator
• Fail-safe function in the case of an
actuator failure
• On-board diagnosis with position sensor
• Option – with or without cooling
8 9
installation circumstances, the mechanics of these bypass flaps has to be
protected by a suitable liquid cooling.
For a high temperature-resistant variant
without a liquid cooling, investment
casting or steel casting is used. More
recent developments use deep-draw
housings made of stainless steel.
Universal actuator
After the quantity of exhaust gas actually
The bypass flap is commonly activated
needed has branched off via the EGR
via a pneumatic actuator. These versatile
valve and has been conducted into the
actuators fulfil various other functions on
recirculation system, the further path of
different engine components. Here, the
the EGR flow has to be determined, this
membrane of a vacuum actuator is
depending on the engine and exhaust
directly linked to a driving rod that can
gas temperature. A bypass flap deter-
operate flaps for sound modulation in
mines whether it should flow through the
turbocharger applications, or for diesel
EGR cooler or through the bypass
particle filter regeneration (DPF) etc.
channel.
Fitted with a position sensor, the
Each flap is different
tions where it is necessary to detect the
The design of the flap has to be adapted
stroke of the actuator (e.g. sound flap,
to the respective cooler used and thus
turbocharger).
actuator can also be used for applica-
there are different designs and housing
materials. For reasons of weight, the
These mechanical components with their
housing of a conventional bypass flap, is
versatile applications are integrated with
mostly made of aluminium die-cast.
electronic control circuits by the use of
Depending on the application and
an electro-pneumatic transducer.
Pneumatic actuator
Profile of the pneumatic actuator
• Takes over different adjustment
functions on the engine
• Membrane produces a lifting movement
• High actuating force in proportion to
weight and installation space
• Fail-safe function in the case of a
pressure system failure
Cross-section of bypass flap
Driving rod of the actuator
Throttle Flap
The gateway from the intake channel to the engine
Functions of the throttle flap
• Mostly integrated in the mixing chamber
• In connection with the EGR valve, it controls the
EGR rate by setting a defined differential pressure
• Controls the mass flow in the regeneration mode of
the diesel particle filter
• Tight closure prevents the shut-down stroke when
the engine is switched off
• On-board diagnosis with position sensor
• Fail-safe function in the case of an actuator failure
10 11
Performance
Fitting accuracy
High performance requires a progressive
Today’s diesel engines however, have to
flow characteristic shortly before the
be operated with a defined air/fuel
throttle flap is in the closing position. If
mixture, similar to gasoline engines. The
the angle for the closed flap is chosen
modern throttle flaps take over important
at almost 90°, the flow characteristic is
functions, e.g. the control of the inco-
flat, as required. At smaller angles the
ming amount of air in the mode of the
characteristic is steeper and the control
diesel particle filter regeneration. Com-
precision is reduced, as shown in the
plete closure of the throttle flap enables
figure below.
the temperature in the particle filter to
As a rule, the throttle flap is mostly inte-
increase until burn-off. The tight closure
Stable positioning
grated in the mixing chamber. Originally
of the throttle flap is also beneficial when
Besides integrating the algorithms for
controlling the flap position completely
its scope of application was restricted to
turning off the diesel engine. By inter-
throttling the intake air in diesel engines
rupting the air-mass flow the engine only
with the engine electronics, the throttle
and – by increasing the differential pres-
sucks in air at a very low density and
flap can also be fitted with its own
sure – thereby increasing the amount of
stops without juddering. This contributes
intelligence. This means the set value
the returned exhaust gas. The demands
towards improving comfort, especially
given by the engine control unit can be
for control precision and manipulating
where large-volume engines in commer-
maintained even at variable differential
speed were comparably low.
cial vehicles are concerned.
pressures on the flap.
intake
Frischluftdurchsatz
air throughput[kg/h]
[kg/h]
500
Endwinkel
75°
End
angle 75°
Klappe
beihPa
10 hPa
Flap
B atB 10
Endwinkel
70°
End
angle 70°
Klappe
beihPa
10 hPa
Flap
A atA 10
400
300
200
100
0
0°
10°
20°
30°
40°
50°
60°
70°
80°
opening angle [ °]
Öffnungswinkel
Cross-section – throttle flap
Adapted throttle flap with mixing chamber
Mass flow characteristics of different flaps
EGR Systems
Function and form – perfectly combined
Profile of the EGR system
• Consists of co-ordinated components
• Reduces the peak combustion temperature
for reducing exhaust emissions
• The most effective method for reducing
the NOx emission
• More complex engines and more stringent
environmental laws increase the demands
• One engineering partner – less co-ordination
effort as well as lower prices
12 13
Bypass flap
(drop-in)
Support housing
EGR valves
Competent development partner
The mere supply of isolated products is
increasingly giving way to the joint development of sophisticated EGR components. Wahler is a long-standing, competent development partner for many
automobile manufacturers and is in daily
contact with the engine developers. Due
Actuator
to this close co-operation, well-adapted
and efficient solutions result and signify
a continuous improvement in engine
System solution including various
components for exhaust gas return
technology.
The actuators of the future for example,
will have a considerably smaller overall
Tradition and innovation
dimension for the same, or higher power
The development of new solutions is based
density. EGR components are being
on experience gained from previous
fitted with sensors to an increasing extent
projects. The development in the engine
and thus have an analogue or digital in-
sector is progressing ever faster and
The engine concepts and thus also the
terface that enables them to be integra-
Wahler is paving the way by modularising
concepts for exhaust gas return are
ted in the engine control.
its products. New, decisive components for
Only in this way shall we, together with
successful mix of tradition and innovation.
undergoing continual further development. The individual components have
exhaust gas return thus develop from a
to be adapted mutually in an optimum
our customers, be able to face the
This reduces the time spent on develop-
way, in order to fulfil the high demands
demands of the current engine develop-
ment and provides new solutions based on
for control precision and speed.
ment and the future legal requirements.
proven concepts.
Pressure stress on the
housing screw connections
Specialists with one aim –
customer satisfaction
Compact EGR system
Continuous Improvements
Experience gained today are basis for the requirements of tomorrow
Research and development at Wahler
• A competent development partner for
our customers
• Modern development methods
• Serial testing of all the components inhouse
• Continued development of automobile
technology through innovation
14 15
Modern methods
The product development implements
Outlook
established methods and tools such as
In the future, exhaust gas return in diesel
Finite Element Method (FEM), Computa-
engines will also be taking place during
tional Fluid Dynamics (CFD), Failure
full-load operation and will thus involve
Modes and Effects Analysis (FMEA) and
the entire operating range of the engine.
prototype construction. Particularly in the
In the same way, the reduction of the
last point, Wahler is a convincing partner
NOx emissions on a stratified-charge
with its short response times and its fast
direct fuel injected gasoline engine calls
availability of prototypes. The high
for external EGR rates. As a result, the
flexibility of our medium-sized company
requirements for temperature resistance
helps to reduce the overall development
and solidity of the EGR components will
time considerably.
rise. At the same time, the exhaust gas
At Wahler the product engineering
flow rate to be controlled will increase.
process is determined by the quality
At our company's own test benches the
This trend will demand new solutions for
assurance specifications of the automo-
prototypes are put to the acid test and
the housings, components and gaskets
tive industry (VDA standards, QS 9000,
at our engine test bench, for example,
of the EGR components.
DIN ISO 16949) and based on the
they can prove their suitability for daily
progressive methods of APQP (Advan-
use.
ced Process Quality Planning).
Fast, accurate and yet low-cost actuators will make their entrance, just as the
Once a product has reached the readi-
assembly of individual components in a
Different aspects
ness stage for serial production, it is
single unit makes up for the increasingly
A process-oriented structural organisati-
produced at modern, interlinked
restricted installation conditions.
on accompanies the development
production lines. During production each
process from the initial idea through to
valve is assigned a profile in which the
The growth in the application of EGR
the readiness for series production.
origin and the testing parameters of
systems will be promoted by new engine
Specialists from the Development,
each finally assembled product are
concepts and more stringent emission
Production, Quality Assurance, Purcha-
recorded. This enables complete
standards. With its wide experience
sing, Sales and Logistics already
retracing of possible faults and ensures a
gained over many years, its motivated
contribute their experience at an early
consistent feedback of information from
and highly qualified employees and its
phase in the new product’s develop-
the quality assurance to the further
modern equipment, Wahler is optimally
ment.
product development.
geared to this trend.
Visualisation of flow and
temperature distribution
Examination of vibration stress
Test under real conditions at the
engine test bench
Gustav Wahler GmbH u. Co. KG
Hindenburgstrasse 146
73730 Esslingen
Germany
Phone: +49 711 3152-0
Fax: +49 711 3152-210
Email: [email protected]
Internet:www.wahler.de