breaks system in cars

2. Swedish College of Engineering &
Technology, Wah Cantt.
Prepared By :
M JUNAID MUSHTAQ (UET/SCET-13F-ME-079)
Mechanical Engineering Department
Session 2013-17

3. PROJECT TITLE
“CRUISE CONTROL”

4. TABLE OF CONTANTS
Introduction
History
Adaptive cruise control
Theory of operation
How it works
System Components
Advantages
Disadvantages
conclusion

5. WHAT IS CRUISE CONTROL ?
Cruise control is a system to accurately maintain the driver’s desired
set speed, with out intervention from the driver, by actuating the throttle
accelerator pedal linkage.
Also sometimes known as speed control or auto cruise. The system
takes over the throttle of the car to maintain a steady speed as set by
the driver.
•

6. INTRODUCTION
Cruise control is an invaluable feature on cars. Without cruise
control, long road trips would be more tiring, for the driver at
least, and those of us suffering from lead-foot syndrome would
probably get a lot more speeding tickets.
Cruise control is far more common on American cars than
European cars, because the roads in America are generally
bigger and straighter, and destinations are farther apart.

7. CONT…
With traffic continually increasing, basic cruise control is
becoming less useful, but instead of becoming obsolete,
cruise control systems are adapting to this new reality soon,
cars will be equipped with adaptive cruise control, which
will allow your car to follow the car in front of it while
continually adjusting speed to maintain a safe distance.

8. HISTORY
Speed control with a centrifugal governor was used in
automobile as early as the 1910s.
The technology was invented by James Watt Matthew
Boulton in 1788 to control steam engines. The governor
adjusts the position as the speed of engine changes with
different loads.

9.  Modern cruise control was invented in 1945 by mechanical
engineer Ralph Teetor. His idea was born out of the
frustration of riding in a car driven by his lawyer, who kept
speeding up and slowing down.
 This system calculated ground speed based on drive shaft
rotation and used a solenoid to vary throttle passion as
needed.
 But a 1955 U.S. Patent for a “Constant Speed Regulator”
was filed in by Frank J. Riley.

10. Adaptive cruise control
Adaptive cruise control OR radar cruise control, is an
optional cruise control system for road vehicles that automatically
adjusts the vehicle speed to maintain a safe distance from vehicles
ahead.

11. Adaptive cruise control is similar to conventional cruise control in
that it maintains the vehicle's pre-set speed. However, unlike
conventional cruise control, this new system can automatically
adjust speed in order to maintain a proper distance between vehicles
in the same lane. This is achieved through a radar headway sensor,
digital signal processor and longitudinal controller. If the lead
vehicle slows down, or if another object is detected, the system
sends a signal to the engine or braking system to decelerate. Then,
when the road is clear, the system will re-accelerate the vehicle
back to the set speed.

12. THEORY OF OPERATION
The system pictured below has five buttons: On, Off,
Set/Accel, Resume and Coast. It also has a sixth control,
the brake pedal, and if your car has a manual
transmission the clutch pedal is also hooked up to the
cruise control

14.  The ON and OFF buttons don't actually do much. Hitting the ON
button does not do anything except tell the car that you might be
hitting another button soon. The OFF button turns the cruise control off
even if it is engaged. Some cruise controls don't have these buttons;
instead, they turn off when the driver hits the brakes, and turn on when
the driver hits the set button.
 The SET/ACCEL button tells the car to maintain the speed you are
currently driving. If you hit the set button at 45 mph, the car will
maintain your speed at 45 mph. Holding down the SET / ACCEL butto
n will make the car accelerate; and on this car, tapping it once will make
the car go 1 mph faster. Hit the button five times to go 5 mph faster.

15.  If you recently disengaged the cruise control by hitting the brake
pedal, hitting the RESUME button will command the car to
accelerate back to the most recent speed setting.
 Holding down the COAST button will cause the car to
deaccelerate, just as if you took your foot completely off the gas.
On this car, tapping the coast button once will cause the
car to slow down by 1 mph.
 The brake pedal and clutch pedal each have a switch that
disengages the cruise control as soon as the pedal is
pressed, So you can disengage the cruise control with a
light tap on the brake or clutch.

16. HOW IT WORKS
The cruise control system actually has a lot of functions other than
controlling the speed of your car. For instance, It can accelerate or
decelerate the car by 1 mph with the tap of a button. Hit the button
five times to go 5 mph faster. There are also several important safety
features that, it will disengage as soon as you hit the brake pedal,
and it won't engage at speeds less than 25 mph (40 kph).

17.  Cruise Control Acceleration and Deceleration
The cruise control system controls the speed of your car the
same way you do by adjusting the throttle position. But
cruise control actuates the throttle valve by a cable connected
to an actuator, instead of by pressing a pedal. The throttle
valve controls the power and speed of the engine by limiting
how much air the engine takes in.

18. In the picture, you can see two cables
connected to a pivot that moves the
throttle valve. One cable comes from
the accelerator pedal, and one from the
actuator. When the cruise control is
engaged, the actuator moves the cable
connected to the pivot, which adjusts
the throttle; but it also pulls on the
cable that is connected to the gas pedal
this is why your pedal moves up and
down when the cruise control is
engaged.

19. Controlling the Cruise Control
The brain of a cruise control system is a
small computer that is normally found
under the hood or behind the dashboard. It
connects to the throttle control seen in the
previous slide, as well as several sensors.
The diagram shows the inputs and outputs
of a typical cruise control system.

20. SYSTEM COMPONENTS
Vehicle's Speed Sensor:
The Vehicle Speed Sensor (VSS) is mounted to the transmission and
provides a low voltage AC signal to the Cruise Control Module
(CCM).
The CCM converts the AC signal to a pulse width modulated DC
signal, which is sent to the cruise control module at a rate of 4000
pulses per mile.

21.  Cruise Control Module:
The cruise control module has to do three things:
 First it remembers the speed you set. It stores this set speed until
you change it or turn off the ignition.
 Next it takes the speed signal from the vehicle speed sensor and
compares it to the set speed.
 Lastly it sends pulse signals to the actuator. The actuator will
move the throttle linkage to bring the vehicle up to the set speed
and then modulate vacuum to maintain that speed.

22.  Actuator:
The actuator is what actually moves the throttle linkage. It is most often
vacuum operated although some actuators are electrically controlled
with small stepper type motors.
The actuator moves the linkage as directed by the cruise control module
until the set speed has been achieved. It then maintains this speed by
controlling the amount of vacuum. It actually modulates the vacuum as
the pulses from the control module direct.

23. Brake Switch:
A cruise control release switch and a s op lamp switch, mounted on
the brake pedal bracket disengage the system electrically when the
brake pedal is pressed.
This is accomplished by interrupting the flow of current to the cruise
control module. The cruise speed of the vehicle at brake actuation
will be stored in the cruise control module memory.

24.  Clutch Switch:
In addition to the brake switch, a vehicle with a manual
transmission has a switch very similar to the brake
switch and disengages the cruise control system when
the clutch pedal is depressed.
 Throttle Linkage:
The actual mechanical connection between the cruise
control actuator and the engine throttle.

25. Cruise Control line diagram

26. ADVANTAGES
Its useful for long drives
It reduces driver fatigue
It gives better fuel efficiency.
Some drivers use it to avoid unconsciously violating speed
limits.

27. DISADVANTAGE
In congested traffic conditions, where speeds vary widely, these
systems are no longer effective.
When used during inclement weather or while driving on sno
w or ice-covered roads, the vehicle could go into a skid because
stepping on the brake such as to disengage the cruise control
could result in the driver losing control of the vehicle
Encourages the drivers to become careless.

28. CONCLUSION
The accidents caused by automobiles are injuring hundreds of
people every year. The safety measures starting from air bags and
seat belts have now reached to ACC, SACC, and CACC system.
The researchers of intelligent vehicle initiative in USA and Ertico
program of Europe are working on technologies that may
ultimately lead to vehicles that are wrapped in a cocoon of
sensors with a 360-degree view of their surroundings.