Household elevators

HOUSEHOLD ELEVATORS 2011

ABSTRACT Hydraulic elevators have dominated the elevator market for 50 years until the beginning of the 21 st century. With the emergence of machine-room-less (MRL) traction elevators in 1995, hydraulic elevators are dealing with increased competition.

Nevertheless, fluid driven systems have their distinct advantages, such as low maintenance cost due to wear free driving components, flexibility of car and machine room design, superior safety features, easy and cost effective installations.

The proclaimed room saving properties of MRLs initially have generated increasing numbers of MRL applications; however this shouldn’t be interpreted as a decreasing market for hydraulic elevators since the facts are that hydraulic control valve production is increasing yearly. As hydraulic elevators and their advantages become better known in the developing countries, the increasing trend to MRLs is expected to level off.

The future of the elevator systems may become certain as their advantages and genuine costs become public.

1

HOUSEHOLD ELEVATORS 2011

PHOTOGRAPHS

PUMP MOTOR

OIL FILLING

SUMP

OUTLINE FILTER

FLOW CONTROL VALVE

DC VALVE

2

HOUSEHOLD ELEVATORS 2011

Fig 1

Fig 2 TOP VIEW OF THE POWER PACK

3

ELECTRICAL CONNECTIONS

HOUSEHOLD ELEVATORS 2011

Fig 3

PRESSURE GAUGE

4

HOUSEHOLD ELEVATORS 2011

Fig 4

DIRECTION & FLOW CONTROL VALVE 5

HOUSEHOLD ELEVATORS 2011

Fig 5

Fig 6

Filter

6

HOUSEHOLD ELEVATORS 2011

Fig 7

PISTON & CYLINDER

7

HOUSEHOLD ELEVATORS 2011

DETAIL IMAGE Fig 8

8

HOUSEHOLD ELEVATORS 2011 TECHNICAL PARAMETERS 

LOAD = 10000N



FLUID USED : SAE 30



FILTER USED :



VALVES USED:

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HOUSEHOLD ELEVATORS 2011

INDEX SR. NO.

PARTICULARS

PAGE NO.

1

ABSTRACT

1

2

PHOTOGRAPHS

2

3

TECHNICAL PARAMETERS

7

4

INTRODUCTION

12

5

HISTORY

13

6

TYPES OF ELEVATORS

17

7

HYDRAULIC ELEVATORS

27

8

DESIGN PARAMETER

39

9

DESGIN OF COMPONENTS

39

10

ASSEMBLY DRAWING

52.1

11

DETAIL DRAWING

52.2

12

BILL OF MATERIAL

53

10

HOUSEHOLD ELEVATORS 2011 13

ESTIMATION

54

14

MANUFACTURING & ASSEMBLY PROCESS

57

15

CONCLUSION

60

16

REFERENCES

53

17

LIST OF SUPPLIERS

54

LIST OF FIGURES AND TABLES FIG NO.

DESCRIPTION

PAGE NO.

1

POWER PACK

2

2

TOP VIEW OF POWER PACK

2

3

ELECTRICAL CONNECTIONS

3

4

PRESSURE GAUGE

3

5

DCV AND FCV

4

6

FILTER

4

7

PISTON & CYLINDER

5

8

DETAILED IMAGE

6

9

SYMBOL OF ELEVATOR

12

OLD ELEVATOR DESIGN BY 10

13 KONRED KEYSER

11

OLD ELEVATOR DESIGN

14

12

CLIMBING ELEVATOR

17

11

HOUSEHOLD ELEVATORS 2011 13

PNUEMATIC ELEVATOR

18

14

TRACTION ELEVATOR

20

GENERAL DESIGN OF 15

21 TRACTION ELEVATOR

16

HYDRAULIC CIRCUIT

28

17

SUMP

28

18

FILTERS

29

19

GEROTOR PUMP

31

20

4/2 DC VALVE

33

21

PRESSURE RELIEF VALVE

34

22

TUBES,PIPES & HOSES

35

23

HYDRAULIC FLUID

36

24

SOLENOID VALVE

38

25

PEDESTAL BEARING

44

26

CHAIN

46

27

DESIGN OF CYLINDER

47 12

HOUSEHOLD ELEVATORS 2011 BENDING MOMENT OF 28

49 SHAFT

29

SPROCKET DESIGN

50

30

BOLT DESIGN

52

31

ASSEMBLY DRAWING

58

32

WINCH

60

TABLES: TABLE NO

DESCRIPTION

PAGE NO.

1

BILL OF MATERIAL

53

2

ESTIMATION

54

3

REFERENCES

61

13

HOUSEHOLD ELEVATORS 2011

INTRODUCTION ELEVATOR  An elevator is a type of vertical transport equipment that efficiently moves people or goods between floors of a building, vessel or other structure.  Elevators are generally powered by electric motors that either drive traction cables or counterweight systems like a hoist, or pump hydraulic fluid to raise a cylindrical piston like a jack.  A modern day lift consists of a cab (also called a "cage" or "car") mounted on a platform within an enclosed space called a shaft or sometimes a "hoist way

SYMBOL OF ELEVATOR

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HOUSEHOLD ELEVATORS 2011

Fig 9

HISTORY

Fig 10

Elevator German rad

design by the engineer Kon Kyeser (1405)

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HOUSEHOLD ELEVATORS 2011  The first reference to an elevator is in the works of the Roman architect Vitruvius, who reported that Archimedes (c. 287 BC – c. 212 BC) built his first elevator probably in 236 BC.  In some literary sources of later historical periods, elevators were mentioned as cabs on a hemp rope and powered by hand or by animals.  It is supposed that elevators of this type were installed in the Sinai monastery of Egypt.  In 1000, the Book of Secrets by Ibn Khalaf al-Muradi in Islamic Spain described the use of an elevator-like lifting device, in order to raise a large battering ram to destroy a fortress.  In the 17th century the prototypes of elevators were located in the palace buildings of England and France.  Ancient and medieval elevators used drive systems based on hoists or winders.  The invention of a system based on the screw driver was perhaps the most important step in elevator technology since ancient times, leading to the creation of modern passenger elevators.  The first screw drive elevator was built by Ivan Kulibin and installed in Winter Palace in 1793.  Several years later another of Kulibin's elevators was installed in Arkhangelskoyenear Moscow.

Fig 11

Elisha Otis' elevator patent drawing, 15 January 1861.  In the middle 1800s, there were many types of crude elevators that carried freight.

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HOUSEHOLD ELEVATORS 2011  Most of them ran hydraulically.  The first hydraulic elevators used a plunger below the car to raise or lower the elevator.  A pump applied water pressure to a steel column inside a vertical cylinder.  Increasing the pressure caused the elevator to ascend.  The elevator also used a system of counter-balancing so that the plunger did not have to lift the entire weight of the elevator and its load.  The plunger, however, was not practical for tall buildings, because it required a pit as deep below the building as the building was tall.  Later, a rope-geared elevator with multiple pulleys was developed.  Henry Waterman of New York is credited with inventing the "standing rope control" for an elevator in 1850. In 1852, Elisha Otis introduced the safety elevator, which prevented the fall of the cab if the cable broke.  The design of the Otis safety elevator is somewhat similar to one type still used today.  A governor device engages knurled roller(s); locking the elevator to its guides should the elevator descend at excessive speed.  He demonstrated it at the New York exposition in the Crystal Palace in a dramatic, death-defying presentation in 1854.  On March 23, 1857 the first Otis passenger elevator was installed at 488 Broadway in New York City.  The first elevator shaft preceded the first elevator by four years.

Construction for Peter Cooper's Cooper Union Foundation building in New York began in 1853.

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HOUSEHOLD ELEVATORS 2011  An elevator shaft was included in the design, because Cooper was confident that a safe passenger elevator would soon be invented.  The shaft was cylindrical because Cooper felt it was the most efficient design. Later, Otis designed a special elevator for the building.  Today the Otis Elevator Company, now a subsidiary of United Technologies Corporation, is the world's largest manufacturer of vertical transport systems.  The first electric elevator was built by Werner von Siemens in 1880. The safety and speed of electric elevators were significantly enhanced by Frank Sprague.  The inventor Anton Freissler developed the ideas of von Siemens and built up a successful enterprise in Austria-Hungary.  The development of elevators was led by the need for movement of raw materials including coal and lumber from hillsides.  It constructed a network of high pressure mains on both sides of the Thames which, ultimately, extended to 184 miles and powered some 8,000 machines, predominantly lifts (elevators) and cranes.

TYPES OF ELEVATORS  CLIMBING ELEVATOR 18

HOUSEHOLD ELEVATORS 2011

Fig 12

 A climbing elevator is a self-ascending elevator with its own propulsion.  The propulsion can be done by an electric or a combustion engine.  Climbing elevators are used in guyed masts or towers, in order to make easy access to parts of these constructions, such as flight safety lamps for maintenance.  An example would be the Moonlight towers in Austin, Texas, where the elevator holds only one person and equipment for maintenance.  The Glasgow Tower - an observation tower in Glasgow, Scotland also makes use of two climbing elevators.

 PNEUMATIC VACUUM ELEVATORS

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HOUSEHOLD ELEVATORS 2011

Fig 13

 Pneumatic Vacuum Elevators operate without cables or pistons and can be installed more easily and quickly than their alternatives since their housing is composed of prefabricated sections which are considerably narrower than conventional lift shafts.  These sections are transparent and afford the passenger a near 360° view. Other notable features of the vacuum elevator are as follows...  No pit excavation, hoist way, or machine room needed.  Installation within one to two days.

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HOUSEHOLD ELEVATORS 2011  Two to four stops for residential, marine, and stage use (35 ft total rise)  Ideal for new and existing homes due to the minimal space needed to fit the elevator.  Self-supporting structure: the elevator can rest on any existing ground floor “Green Elevator”: minimal energy consumption used during ascent and no energy used during descent.  Minimal maintenance: no oils or lubrication required for the elevator  Absolute safety in case of a power failure since the moving car automatically descends to the lowest level and the electro-mechanical door will open to let the passenger out.  Elevator runs on 220Volts and cabin electric circuits are 24 volts, eliminating the risk of shock.

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HOUSEHOLD ELEVATORS 2011



TRACTION ELEVATOR

Fig 14

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HOUSEHOLD ELEVATORS 2011

Fig 15

ď ś Geared traction machines are driven by AC or DC electric motors.

Geared machines use worm gears to control mechanical movement of elevator cars by "rolling" steel hoist ropes over a drive sheave which is attached to a gearbox driven by a high speed motor.

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HOUSEHOLD ELEVATORS 2011  These machines are generally the best option for basement or overhead traction use for speeds up to 500 ft/min (2.5 m/s).  In order to allow accurate speed control of the motor, to allow accurate levelling and for passenger comfort, a DC hoist motor powered by an AC-DC motor-generator (MG) set was the preferred solution in high-traffic elevator installations for many decades.  The MG set also typically powered the relay controller of the elevator, which has the added advantage of electrically isolating the elevators from the rest of a building's electrical system - eliminating the transient power spikes in the building's electrical supply caused by the motors starting and stopping (causing lighting to dim every time the elevators are used for example), as well as interference to other electrical equipment caused by the arcing of the relay contactors in the control system.  Contemporary cheaper installations, such as those in residential buildings and low-traffic commercial applications generally used a single or two speed AC hoist machine.  The widespread availability of cheap solid state AC drives has allowed infinitely variable speed AC motors to be used universally, bringing with it the advantages of the older motor-generator based systems, without the penalties in terms of efficiency and complexity.  The older MG-based installations are gradually being replaced in older buildings due to their poor energy efficiency.  Gearless traction machines are low speed (low RPM), high torque electric motors powered either by AC or DC.  In this case, the drive sheave is directly attached to the end of the motor. Gearless traction elevators can reach speeds of up to 2,000 ft/min (10 m/s), or even higher.  A brake is mounted between the motor and drive sheave (or gearbox) to hold the elevator stationary at a floor.

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HOUSEHOLD ELEVATORS 2011  This brake is usually an external drum type and is actuated by spring force and held open electrically; a power failure will cause the brake to engage and prevent the elevator from falling.  In each case, cables are attached to a hitch plate on top of the cab or may be "under slung" below a cab, and then looped over the drive sheave to a counterweight attached to the opposite end of the cables which reduces the amount of power needed to move the cab.  The counterweight is located in the hoist-way and rides a separate railway system; as the car goes up, the counterweight goes down, and vice versa.  This action is powered by the traction machine which is directed by the controller, typically a relay logic or computerized device that directs starting, acceleration, deceleration and stopping of the elevator cab.  The weight of the counterweight is typically equal to the weight of the elevator cab plus 40-50% of the capacity of the elevator.  The grooves in the drive sheave are specially designed to prevent the cables from slipping.  Traction is provided to the ropes by the grip of the grooves in the sheave, thereby the name.  As the ropes age and the traction grooves wear, some traction is lost and the ropes must be replaced and the sheave repaired or replaced.  Sheave and rope wear may be significantly reduced by ensuring that all ropes have equal tension, thus sharing the load evenly.  Rope tension equalization may be achieved using a rope tension gauge, and is a simple way to extend the lifetime of the sheaves and ropes.

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HOUSEHOLD ELEVATORS 2011  Elevators with more than 100' (30 m) of travel have a system called compensation. This is a separate set of cables or a chain attached to the bottom of the counterweight and the bottom of the elevator cab.  This makes it easier to control the elevator, as it compensates for the differing weight of cable between the hoist and the cab.  If the elevator cab is at the top of the hoist-way, there is a short length of hoist cable above the car and a long length of compensating cable below the car and vice versa for the counterweight.  If the compensation system uses cables, there will be an additional sheave in the pit below the elevator, to guide the cables.  If the compensation system uses chains, the chain is guided by a bar mounted between the counterweight railway lines.



HYDRAULIC ELEVATOR (Available in the market)

Fig 16

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HOUSEHOLD ELEVATORS 2011  The concept of an elevator is incredibly simple. It's just a compartment attached to a lifting system.  Tie a piece of rope to a box, and you've got a basic elevator.  Of course, modern passenger and freight elevators are a lot more elaborate than this.  They need advanced mechanical systems to handle the substantial weight of the elevator car and its cargo.  Additionally, they need control mechanisms so passengers can operate the elevator, and they need safety devices to keep everything running smoothly.  There are two major elevator designs in common use today: hydraulic elevators and roped elevators.  Hydraulic elevator systems lift a car using a hydraulic ram, a fluid-driven piston mounted inside a cylinder.  The cylinder is connected to a fluid-pumping system (typically, hydraulic systems like this use oil, but other incompressible fluids would also work).

The hydraulic system has three parts: o A tank (the fluid reservoir) o A pump, powered by an electric motor o A valve between the cylinder and the reservoir  The pump forces fluid from the tank into a pipe leading to the cylinder.  When the valve is opened, the pressurized fluid will take the path of least resistance and return to the fluid reservoir.  But when the valve is closed, the pressurized fluid has nowhere to go except into the cylinder.  As the fluid collects in the cylinder, it pushes the piston up, lifting the elevator car.  When the car approaches the correct floor, the control system sends a signal to the electric motor to gradually shut off the pump.

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HOUSEHOLD ELEVATORS 2011  With the pump off, there is no more fluid flowing into the cylinder, but the fluid that is already in the cylinder cannot escape (it can't flow backward through the pump, and the valve is still closed).  The piston rests on the fluid, and the car stays where it is.  To lower the car, the elevator control system sends a signal to the valve.  The valve is operated electrically by a basic solenoid switch (check out How Electromagnets Work for information on solenoids).  When the solenoid opens the valve, the fluid that has collected in the cylinder can flow out into the fluid reservoir.  The weight of the car and the cargo pushes down on the piston, which drives the fluid into the reservoir.  The car gradually descends. To stop the car at a lower floor, the control system closes the valve again.  This system is incredibly simple and highly effective, but it does have some drawbacks.

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HOUSEHOLD ELEVATORS 2011

HYDRAULIC ELEVATOR (We have developed) We have developed a elevator for bungalows, row houses, pent houses considering the following factors:  No structural Damage  Minimal electricity consumption  Operation is noiseless  No vibrations  User friendly  Economical

Construction:  It consists of following components:•

Sprocket

•

Piston & Cylinder

•

Open chain

•

Car Unit

•

Pedestal Bearing

•

Shaft

 There are two sprockets used & both are joined by a common shaft.

29

HOUSEHOLD ELEVATORS 2011  A pedestal bearing is used to support the shaft  One side of the chain is attached to fixed plate while the other side of the chain is attached to a car unit.  A fixed plate is attached to cylinder while a movable plate is attached to piston.

Working:  When the up button is pressed, the signal is electrically given to DC valve.  The flow of oil takes place.  When the piston moves in upward direction, due to the tension provided in one side of the chain the sprockets rotates in the anticlockwise direction & hence the car moves up.  When the down button is pressed, the piston moves in downward direction.  Due to the piston moving in downward direction, the sprockets move in clockwise direction as the chain connected to it is in tension on one side.  Hence as the sprocket rotates in clockwise direction the car comes down.

DESCRIPTION OF HYDRAULIC CIRCUIT

Hydraulic

Sump:

30

HOUSEHOLD ELEVATORS 2011

Fig 17

 The hydraulic fluid reservoir holds excess hydraulic fluid to accommodate volume changes from: cylinder extension and contraction, temperature driven expansion and contraction, and leaks.  The reservoir is also designed to aid in separation of air from the fluid and also work as a heat accumulator to cover losses in the system when peak power is used.  Design engineers are always pressured to reduce the size of hydraulic reservoirs, while equipment operators always appreciate larger reservoirs.  Reservoirs can also help separate dirt and other particulate from the oil, as the particulate will generally settle to the bottom of the tank.  In this project, the capacity of the reservoir is 40 liters.

31

HOUSEHOLD ELEVATORS 2011 Filters:

Fig 18

 Filters are an important part of hydraulic systems.  Metal particles are continually produced by mechanical components and need to be removed along with other contaminants.  Filters may be positioned in many locations.  The filter may be located between the reservoir and the pump intake.  Blockage of the filter will cause cavitation and possibly failure of the pump. Sometimes the filter is located between the pump and the control valves.  This arrangement is more expensive, since the filter housing is pressurized, but eliminates cavitation problems and protects the control valve from pump failures.  The third common filter location is just before the return line enters the reservoir.  This location is relatively insensitive to blockage and does not require a pressurized housing, but contaminants that enter the reservoir 32

HOUSEHOLD ELEVATORS 2011 from external sources are not filtered until passing through the system at least once.

Hydraulic Pump  Hydraulic pumps supply fluid to the components in the system.  Pressure in the system develops in reaction to the load.  Hence, a pump rated for 5,000 psi is capable of maintaining flow against a load of 5,000 psi.  Pumps have a power density about ten times greater than an electric motor (by volume).  They are powered by an electric motor or an engine, connected through gears, belts, or a flexible elastomeric coupling to reduce vibration

Gerotor pump

Fig 19  A gerotor is a positive displacement pumping unit.  The name gerotor is derived from "Generated Rotor".  A gerotor unit consists of an inner and outer rotor. The inner rotor has N teeth, and the outer rotor has N+1 teeth.

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HOUSEHOLD ELEVATORS 2011  The inner rotor is located off-center and both rotors rotate.  The geometry of the two rotors partitions the volume between them into N different dynamically-changing volumes.  During the assembly's rotation cycle, each of these volumes changes continuously, so any given volume first increases, and then decreases.  An increase creates a vacuum.  This vacuum creates suction, and hence, this part of the cycle is where the intake is located.  As a volume decreases compression occurs.  During this compression period, fluids compressed (if they are gaseous fluids).

can

be

pumped,

or

 Gerotor pumps are generally designed using a trochoidal inner rotor and an outer rotor formed by a circle with intersecting circular arcs.  A gerotor can also function as a piston less rotary engine.  High pressure gas enters the intake area and pushes against the inner and outer rotors, causing both to rotate as the area between the inner and outer rotor increases.  During the compression period, the exhaust is pumped out.  A single phase AC Induction motor of 1HP is used to drive the pump.

Control valves  Directional control valves route the fluid to the desired actuator. 

They usually consist of a spool inside a cast iron or steel housing.



The spool slides to different positions in the housing, intersecting grooves and channels route the fluid based on the spool's position.



The spool has a central (neutral) position maintained with springs; in this position the supply fluid is blocked, or returned to tank.



Sliding the spool to one side routes the hydraulic fluid to an actuator and provides a return path from the actuator to tank.



When the spool is moved to the opposite direction the supply and return paths are switched.



When the spool is allowed to return to neutral (center) position the actuator fluid paths are blocked, locking it in position.

34

HOUSEHOLD ELEVATORS 2011 

Directional control valves are usually designed to be stackable, with one valve for each hydraulic cylinder, and one fluid input supplying all the valves in the stack.



Tolerances are very tight in order to handle the high pressure and avoid leaking; spools typically have a clearance with the housing of less than a thousandth of an inch (25 µm).



The valve block will be mounted to the machine's frame with a three point pattern to avoid distorting the valve block and jamming the valve's sensitive components.



The spool position may be actuated by mechanical levers, hydraulic pilot pressure, or solenoids which push the spool left or right.



A seal allows part of the spool to protrude outside the housing, where it is accessible to the actuator.



The main valve block is usually a stack of off the shelf directional control valves chosen by flow capacity and performance.



Some valves are designed to be proportional (flow rate proportional to valve position), while others may be simply on-off.



The control valve is one of the most expensive and sensitive parts of a hydraulic circuit

4/2 DC VALVE (Solenoid Operated):

35

HOUSEHOLD ELEVATORS 2011

Fig 20

 4 ways 2 position valve has four connections to it and two valve positions one of them is normally open.  These valves make use of electromechanical Solenoid for sliding of the spool, electrical power is readily available and these valves are extensively used but electrical solenoid cannot generate large forces unless supplied with larger electrical energy which makes there use limited to low actuating forces.  Heat generation poses the threat to use of these valves when held in one position longer.  In practice combination of these actuators such as low power solenoid valve is used to operate the other hydraulic valve.  Here solenoid valve starts the flow of fluid which in turn operates hydraulic valve.

36

HOUSEHOLD ELEVATORS 2011 Pressure relief valve:

Fig 21

 Pressure relief valves are used in several places in hydraulic machinery; on the return circuit to maintain a small amount of pressure for brakes, pilot lines, etc.  On hydraulic cylinders, to prevent overloading and hydraulic line/seal rupture.  On the hydraulic reservoir, to maintain a small positive pressure that excludes moisture and contamination.

Tubes, Pipes and Hoses:

37

HOUSEHOLD ELEVATORS 2011

Fig 22 

Hydraulic

tubes

are

seamless

steel

precision

pipes,

specially

manufactured for hydraulics. 

The tubes have standard sizes for different pressure ranges, with standard diameters up to 100 mm.



The tubes are supplied by manufacturers in lengths of 6 m, cleaned, oiled and plugged.



The tubes are interconnected by different types of flanges (especially for the larger sizes and pressures), welding cones/nipples (with o-ring seal) and several types of flare connection and by cut-rings.



In larger sizes, hydraulic pipes are used.



Direct joining of tubes by welding is not acceptable since the interior cannot be inspected.



Hydraulic pipe is used in case standard hydraulic tubes are not available. Generally these are used for low pressure.



They can be connected by threaded connections, but usually by welds.



Because of the larger diameters the pipe can usually be inspected internally after welding.



Black pipe is non-galvanized and suitable for welding.



Hydraulic hose is graded by pressure, temperature, and fluid compatibility.

38

HOUSEHOLD ELEVATORS 2011 

Hoses are used when pipes or tubes cannot be used, usually to provide flexibility for machine operation or maintenance.



The hose is built up with rubber and steel layers.



A rubber interior is surrounded by multiple layers of woven wire and rubber.



The exterior is designed for abrasion resistance.



The bend radius of hydraulic hose is carefully designed into the machine, since hose failures can be deadly, and violating the hose's minimum bend radius will cause failure.



Hydraulic hoses generally have steel fittings swaged on the ends.



The weakest part of the high pressure hose is the connection of the hose to the fitting.



Another disadvantage of hoses is the shorter life of rubber which requires periodic replacement, usually at five to seven year intervals.



Tubes and pipes for hydraulic applications are internally oiled before the system is commissioned.

Hydraulic fluid:

Fig 23 

Also known as tractor fluid, hydraulic fluid is the life of the hydraulic circuit.



It is usually petroleum oil with various additives.

39

HOUSEHOLD ELEVATORS 2011 

Some hydraulic machines require fire resistant fluids, depending on their applications.



In some factories where food is prepared, either an edible oil or water is used as a working fluid for health and safety reasons.



In addition to transferring energy, hydraulic fluid needs to lubricate components, suspend contaminants and metal filings for transport to the filter, and to function well to several hundred degrees Fahrenheit or Celsius.

The following characteristics and properties are important for hydraulic oils:

•

Low temperature sensitivity of viscosity

•

Thermal and chemical stability

•

Low compressibility

•

Good lubrication (anti-wear and anti-stick properties, low coefficient of friction)

•

Hydrolytic stability (ability to retain properties in the high humidity environment)

•

Low pour point (the lowest temperature, at which the oil may flow);

•

Water emulsifying ability

•

Filterability

•

Rust and oxidation protection properties

•

Low flash point(the lowest temperature, at which the oil vapours are ignitable)

•

Resistance to cavitations.

•

Low foaming

•

Compatibility with sealant materials.

The oil used in our project is SAE 30.

SOLENOID VALVES PRESSURE RELIEF CONDUIT

40

HOUSEHOLD ELEVATORS 2011 SOLENOID

PRESSURE CHAMBER

DIAPHRAGM OUTPUT SIDE INPUT SIDE

Fig 24

 A solenoid valve is an electromechanical valve for use with liquid or gas.  The valve is controlled by an electric current through a solenoid coil.  Solenoid valves may have two or more ports: in the case of a twoport valve the flow is switched on or off; in the case of a three-port valve, the outflow is switched between the two outlet ports.  A solenoid valve has two main parts: the solenoid and the valve.

41

HOUSEHOLD ELEVATORS 2011 ď ś The solenoid converts electrical energy into mechanical energy which, in turn, opens or closes the valve mechanically.

DESIGN OF COMPONENTS SELECTION OF HYDRAULIC CYLINDER Hydraulic cylinders are defined by their ability to exert a linear force and hold it at any specified position indefinitely. The parameters relate to the selection of hydraulic cylinders are discussed here.

Purpose: The purpose of the actuator describes the type of cylinder. The cylinder may move the load in one direction only, to move in both directions or to have equal velocities as it travels in both direction. Single acting cylinders with a gravity or spring type are used to move the load in one direction. Double acting cylinders move the load in both directions under pressure. Cylinders with double end rod provide equal velocity in both directions because of equal areas on both sides of the piston. Tandem cylinders exert twice the force available from single piston cylinders by providing twice the effective piston area in two chambered spaces.

Stroke requirement: The cylinder stroke determines the length of the cylinder. The stroke length is the difference between the fully extended and fully retracted length. For a simple cylinder, the stroke should be less than the barrel length, for a given bore size, stoke also determines the amount of fluid required for a specified cylinder velocity. If the length of the cylinder is restricted and the stroke requirement is more, telescoping cylinders are preferable.

Thrust: The output thrust required from a hydraulic cylinder and hydraulic pressure available for the purpose determines the area and bore diameter of the cylinder. In dynamic applications, the dynamic thrust is taken into account. Dynamic thrust is less than the static thrust due to seal friction, fluid friction, piston inertia etc. As a first approximation dynamic thrust can be taken as 0.9 times the static thrust.

Speed: The maximum speed of the piston is limited by the rate of fluid flow in and out of the cylinder and the ability of the cylinder to withstand the impact forces which occur when the piston movement is arrested. In an uncushioned cylinder, it is normal to limit the piston velocity to 8m/min.

This value is increased to12m/min for a cushioned cylinder and 45m/min is permissible with high speed cylinders.

Acceleration and deceleration: The additional forces being imparted, when a body being accelerated or decelerated must be considered.

Hydraulic shocks to the cylinder are minimised by slowing down the piston.

Cushioning devices are provided for this.

During cushioning, high pressures will develop within the cylinder cushion. The pressure generated 42

HOUSEHOLD ELEVATORS 2011 on cushion side must be considered. Since too much pressure would rupture the cylinder.

Cylinder mountings: Various types of cylinder mountings are available.

The cylinder mounting is determined by the application. Fixed centreline mounts are used for thrusts that can occur linearly or in centreline with the cylinder. Fixed non-centreline mounts are used when heavy linear thrusts are encountered. Pivoted centreline mounts are suitable. If the attached load travels in a curved path.

Special seal requirement: The working pressure as well as the temperature affect the selection of material used for seals, packings and rod wipers. Special materials are required when the working pressure and temperature are high. High pressure require stiffer materials. Metallic, asbestos or dissimilar synthetic materials have received widespread high temperature applications.

Piston Rod Buckling: The piston rod in a hydraulic cylinder will act as a strut when it is subjected to a compressive load or when it exerts a thrust.

Therefore the rod must be of sufficient diameter to prevent buckling.

SELECTION OF CONTROL VALVES: Various hydraulic valves are used for controlling the hydraulic system.

They are used to control the flow rate, the direction of flow and the pressure of the fluid. The valves are selected based on the application.

SELECTION OF RELIEF VALVES: The rule of thumb for the main relief valve in a circuit is to be at 10-20% above the maximum required working pressure, taking into account the type of valve, its position relative to the actuator and pressure losses in the system. For any particular model, varieties of pressure setting ranges are available.

The pressure at which the relief valve opens is called the cracking pressure.

The pressure at which the rated flow passes through the valve is termed as flow pressure. The pressure at which the opened valve closes is the reset pressure. Considerable care should be taken in the selection of relief valve for a particular application and in selecting the pressure at which it should crack. A higher cracking pressure is advantageous, because once the relief valve cracks the flow is lost over the relief valve even the system has not yet achieved the maximum system pressure. For the same pressure setting two stage type has a higher cracking pressure than direct acting valve.

The pressure override is the difference between the cracking pressure and full flow pressure at given relief valve setting. The pressure override charecteristics are important. Pressure override curves are provided for multiple pressure settings for any particular model.

Direct pressure relief valves have high pressure override characteristics which make them unsuitable for systems with widely varying flows. But two stage valves give good pressure regulation over a wide range of flows with low pressure override. The reset pressure must also be considered.

This may be as low as 50% of the opening pressure. Two stage valves have 43

HOUSEHOLD ELEVATORS 2011 a close tolerance between the opening and resetting pressures. Response time may be the most important criterion in specific applications. Direct acting valves have rapid response time typically 25ms.

SELECTION OF FLOW CONTROL VALVE The flow control valve is used to regulate the fluid rate by varying the area of an orifice. Flow through the control orifice is usually considered to be turbulent and the quantity of a fluid flowing can be given by q = c.a Where, q is the quantity flowing, a is the orifice area, p is the pressure drop over the orifice and c is a constant which may include functions such as orifice characteristics, viscosity of fluid and Reynolds number.

The flow through the orifice will vary as the square root of the pressure drop. So non-pressure compensated flow control valves are used if the pressure drop and the fluid temperature are reasonably constant and minor variations in flow rate are acceptable. Pressure compensated flow controls must be used when accurate speed control at varying supplies or load pressures is required.

Then selection of best type of flow control valve depends on the design parameters of the application. The general selection guidelines, based on common application characteristics, are: i)

if load on the actuator and supply pressure both are constant and accuracy is 5%, a non-compensated flow control valve is selected.

ii)

if load on the actuator and supply pressure or both undergo change and accuracy is 3-5% pressure compensated flow control valve is selected,

iii)

if load on the actuator and supply pressure or both undergo change, fluid temperature varying 17 C and accuracy is 3-5% pressure and temperature compensated flow control valve is selected.

In any precision flow control valve application, it is essential to have well filtered fluid (better that 10 um absolute) to promote efficient control. The smaller the flow to be controlled, the finer the filtration accuracy.

SELECTION OF DIRECTION CONTROL VALVE A vast majority of the direction control valves are of the sliding spool type.

The valves are selected based on their center condition to suit a particular application. The most frequently used center conditions. Notched and tapered spools are used to smoothen the switching action and reduce pressure shocks during changeover.

The other parameters for the selection of direction control valve are maximum pressure, flow capacity and pressure drop. The flow capacity of a direction control valve depends on the valve size. If the valve is too small for the flow, excessive pressure drop causes power loss. If the valve is too 44

HOUSEHOLD ELEVATORS 2011 large for a given flow it adds excessive cost and more size and weight to the circuit.

Pressure drop data are available from the manufacturer. They provide graphs that relate pressure to flow rare through the vale. They are measured at a specific viscosity and temperature and when used under other circumstances the figures must be adjusted accordingly. Separate curves are given for the different port-to-port connections.

SELECTION OF FILTERS The manufacturer will provide information in the catalog relating to particle size sensitivity. If not, the following rule of thumb may be applied.

(1) With standard vane and gear pump operating at 70 bar or less, 74 um filtration can be selected.

(2)

Circuits operating upto 135 bar should be equipped with 40 um filtration.

(3)

For circuits operating above 135 bare, 25 um filtration should be selected.

Most manufacturers give recommended flow rate for their filters but these are for fluids having a certain specific gravity and viscosity at a particular temperature. So depending upon the fluid being used, they have to be adjusted keeping in mind the minimum operating temperatures. A general rule of thumb is that the filter capacity per minute should be at least twice the pumps rated flow per minute or one third the reservoir’s capacity in litres, whichever is greater.

Filter elements are available in a wide variety of materials ranging from paper to woven wire mesh. The Table 11.3 lists some of the common materials together with the ratings available with each medium.

SELECTION OF HYDRAULIC CONDUITS The fluid in a hydraulic system is generally conveyed through either semirigid tubing or hoses. The correct specification of these conduits and in practice their connections are as important as the rest of the parts of the system.

Tubing Tubing constructed of cold drawn steel has become the accepted standard in hydraulics where high pressures are encountered. But tubing is also made from other materials like copper, brass, aluminium, titanium and stainless steel depending on the applications.

Tubing size is indicated by the outside diameter with a range of wall thickness for the various working pressures. But the designer is interested in the inside diameter which has to be suitable for the flow rate. The choice of wall thickness is based on the strength and flow rate.

Other considerations such as the safety factor, pressure loss, temperature may be included.

45

HOUSEHOLD ELEVATORS 2011 It is desirable to keep the fluid flow to be laminar and for pressure drops to be minimal. This can be achieved by keeping the fluid velocities low. The suitable velocity range for suction and return lines is 0.6-1.2 m/s and for pressure lines it is 2.1 to 4.6 m/s.

Hoses Hose is a flexible fluid conductor which can adapt to machine members that move. Hose is made up of three basic elements: inner tube, reinforcement and cover. Inner tube is made up of layers of rubber or thermoplastic. The reinforcement is made up of layers of steel wire or textile braiding. The hose cover is again made with layers of rubber or plastic.

Society of Automotive Engineers (SAE) has recommended standards (SAE J 517) for hydraulic hoses. 100R numbers from R1 to R11 are used to indicate hose construction and performance capabilities. For example, 100 R1 is a rubber hose with one layer of wire braid reinforcement. It is useful for most medium pressure applications. 100 R2 has a heavy wire wrap reinforcement and is used in extremely high pressure systems.

The two important pressures that are related to hoses are maximum working pressure and minimum burst pressure. The working pressure of a particular type of hydraulic hose is different for each bore size. The minimum burst pressure for a hose is generally 4 times the working pressure.

PEDESTAL BEARING

Fig 25 

It is a split type of bearing. This type of bearing is used for higher speeds, heavy loads and large sizes.

 •

The component of the bearing: Cast iron pedestal or block with a sole 46

HOUSEHOLD ELEVATORS 2011 •

Brass or gun-metal or phosphorus-bronze “Brasses”, bushes or steps made in two halves.

•

Cast iron cap.

•

Two mild steel bolts and nuts. 

Care is taken that the brasses do not move axially nor are allowed to rotate.



For preventing this rotation, usually a snug at the bottom fitting inside a recess at the bottom of the pedestal is provided.



This bearing facilitates the placements and removal of the of the shaft from the bearing.



Unlike the solid bearing which are to be inserted end-wise and hence are kept near the ends of the shaft, these can be placed anywhere.



This bearing ensures a perfect adjustment for wear in the brasses by screwing the cap.

SPROCKET

A

sprocket is a profiled wheel with teeth that mesh with a chain,

track or other perforated or indented material.

 The

name 'sprocket' applies generally to any wheel upon which are

radial projections that engage a chain passing over it.

 It

is distinguished from a gear in that sprockets are never meshed

together directly, and differs from a pulley in that sprockets have teeth and pulleys are smooth.

ROLLER CHAIN

47

HOUSEHOLD ELEVATORS 2011  A large number of roller chains are designed to provide a power transmission between two sprockets with minimum/no regular lubrication and under conditions of high levels of contamination.

 Chains rarely fail because they do not have sufficient tensile strength.

 They most often fail in wear or fatigue.  In practice sprocket teeth wear allowing the chains to jump the teeth.

Fig 26

DESIGN OF

HYDRAULIC CYLINDER:

48

HOUSEHOLD ELEVATORS 2011 Fig 27



DIAMETER OF THE CYLINDER P = W/ Π x D2 4 60 x 105 = 10000 x 4 Π x (D)2 D = 50mm

 BUCKLING LOAD F = K/S Where, F = Force K = Buckling Load S = Factor of Safety I = Moment of Inertia E = Modulus of Elasticity Where, •

I = Π /64 x D4 Π/64 x (50)4 I = 3.7 x 10-7 mm4

•

K = Π2 x E x I/l2

Π2 x 2.1 x 1011 x 3.7 x 10-7 / (4)2 K = 47.92 x 103 N

49

HOUSEHOLD ELEVATORS 2011 •

F = 47.92 x 103 /5

F = 9.5 x 103 KN

 BENDING MOMENT OF SHAFT M=

Π/32 x σb x D3 W

W Fig 28 30 We know that, M = W. L = 5000 x 30 M = 15000 N-M

Now, 15000

=

Π/32 x 70 x d3

d = 30mm 

DESIGN

OF

SPROCKET

50

HOUSEHOLD ELEVATORS 2011

Fig 29

D = P/Sin (Π/2)

Where, P = pitch

FROM PSG 7.71 SELECTING ROLLER CHAIN OF R 40 WITH F50101N NUMBER •

Pitch = 12.7mm

•

Bearing area =0.44cm2

•

Weight/meter = 0.69

•

Breaking load = 1410kgs

Ds = 12.7/Sin (180/27) Ds = 110mm

Accordingly selection of chain by refer 7.80 article from PSG the Roller Diameter of chain is 7.75mm.

51

HOUSEHOLD ELEVATORS 2011



DESIGN OF BOLTS

Fig 30

σt = W/ Π/4 x (dc)2

70 = x (dc) 2 Where, dc= core

5000/ Π/4 dc = 10mm diameter of bolt

dc = 0.84 do

Where, dc= core diameter of bolt

dc = 12mm M 20 BOLTS ARE

BILL OF MATERIAL:

SR. NO

PART NAME

USED

QTY

MATERIAL

52

HOUSEHOLD ELEVATORS 2011 1

CYLINDER

1

M.S.

2

PISTON

1

C.I

3

SPROCKET

2

M.S.

4

OPEN CHAIN

2

M.S.

5

CAR UNIT

1

M.S.

6

PEDESTAL BEARING

1

M.S.

7

STUDS

6

C20

8

FIXED PLATE

1

M.S.

9

MOVABLE PLATE

1

M.S.

Table 1

ESTIMATION

SR.NO

PART NAME

53

HOUSEHOLD ELEVATORS 2011 1

PISTON & CYLINDER WITH CHROME PLATING

2

HYDRAULIC POWER PACK

3

CHAIN & SPROCKET

4

CAR UNIT

5

INSTALLATION

TOTAL

2

Table 2

MANUFACTURING PROCESS

54

HOUSEHOLD ELEVATORS 2011 CYLINDER

 The cylinder is the external part of the piston - cylinder assembly and creates the envelopment into which the piston moves.

 The stages of its manufacturing process are similar to the piston stages, excluding the stage of final grinding of the external surface.

 The head, that carries the tightness and drive components, is adjusted to the upper extremity and is manufactured on CNC lathes.

 The final stage, before the storage, is the assembling of the piston cylinder assembly.

 According to the European lift regulations (ΕΝ 81.2) and the quality control procedures that are defined by the ISO 9001 Quality Assurance System it’s testing in high pressure (80 - 100 bar) is required.

 When the testing is finished, the piston - cylinder assemblies are dyed externally and forwarded to the prefabricated products store.

PISTON  The piston body is the most fundamental part of the piston-cylinder assembly. 

It is the base on which the rest of the components are assembled.



During the operation of the lift, the need for a flawless "cooperation" between the cylinder and the piston body requires high accuracy of its mechanical operation.



This results to the avoiding of leakage and other problems.



The first stage of the engineering of the body is the cutting of the tube at the required length according to each order.

55

HOUSEHOLD ELEVATORS 2011 

The stage of its alignment follows up, being performed into special hydraulic presses, and the welding of the micro-components at its two edges, with an automatically programmed welding machine.



The micro-components of the piston (plug, bottom, bottom ring, etc) are manufactured by massif steel in programmed CNC lathes and state-of-the-art engineering centers, in order to achieve high productivity, perfection in terms of component clearance and their exchangeability.



At the next stage, the most important stage of the manufacturing process, the piston is forwarded to the place of the final grinding of its external surface.



Aiming at the improvement of its flexibility of the manufacturing process and the increase of its production volume, the company has obtained state-of-the--art finishing grinding machines.



The installation of the machines mentioned before, given that it is fully programmed and incorporates automatic feeding, directly resulted in the innovation, increase and improvement of the offered products.



The final engineering is performed by a Honing programmed machine that makes possible the achievement of a perfect roughness of surface (2-3 m), as well as eliminating completely the oval shape.

Chrome plating Chrome plating, often referred to simply as chrome, is a technique of electroplating a thin layer of chromium onto a metal object.  The chromed layer can be decorative, provide corrosion resistance, ease cleaning procedures, or increase surface hardness. 

 A component to be chrome plated will generally go through these different stages: •

Degreasing to remove heavy soiling;

56

HOUSEHOLD ELEVATORS 2011 •

Manual cleaning to remove all residual traces of dirt and surface impurities

•

Various pretreatments depending on the substrate;

•

Placement into the chrome plating vat, where it is allowed to warm to solution temperature; and

•

Application of plating current, under which the component is left for the required time to attain thickness.

 There are many variations to this process depending on the type of substrate being placed upon.  Different etching solutions are used for different substrates.  Hydrochloric, hydrofluoric, and sulfuric acids can be used.  Ferric chloride is also popular for the etching of Nimonic alloys.  Sometimes the component will enter the chrome plating vat electrically live.  Sometimes the component will have a conforming anode either made from lead/tin or platinized titanium.  A typical hard chrome vat will plate at about 25 micrometers (0.00098 in) per hour.  Various Linishing and Buffing processes are used in preparing components for decorative chrome plating.  The overall appearance of decorative chrome plating is only as good as the preparation of the component.

57

HOUSEHOLD ELEVATORS 2011

Fig 31

ASSEMBLY Assembly of Hydraulic Power Pack   

A sump of 40 liters is fitted with filters.

The filters are provided at inlet as well as outlet for a safer & smoother operation.

The power pack consist of: • Motor • Pump • Pressure Relief Valve • Direction Control Valve • Flow Control Valve • Filters

ASSEMBLY OF PISTON & CYLINDER  

The piston & cylinder is assembled after the piston is chrome plated.

A fixed plated is fabricated on the cylinder.

58

HOUSEHOLD ELEVATORS 2011 

A movable plate fabricated on the piston

CONCLUSION 







We conclude that this elevator is very safe in operation.

It operation is very much noiseless.

We have achieved the required results according to our design.

Our future plans are to attach a winch instead of a car for industrial purpose to carry heavy loads.

59

HOUSEHOLD ELEVATORS 2011

Fig 32

REFERENCES

SR.NO

NAME OF BOOK/JOURNAL

NAME OF AUTHOR

1

Hydraulic & Pneumatics

R. Shrinivasan

2

Hydraulic & Pneumatics

Andrew Parr

3

PSG design data book

PSG IAS

60

HOUSEHOLD ELEVATORS 2011 4

Design Data Book

Raghavan

5

Design of Machine Elements

R.S. Khurmi

6

Theory of Machines & Mechanisms

R.S. Khurmi

7

Fluid Mechanics and Hydraulic Machines

Dr. K.K. Bansal

Table 3

LIST OF SUPPLIERS 

Hydrul Engineering Works www.indiamart.com - 16/20, 1/10, Raja Building, Janjikar Street, Nagdevi, Mumbai - 400003 - 09869139408



Bell Hydromatics www.bellhydromatics.com - Bell House, Multani Mansion Lane, Next To Shatranj Tower, M M G S Road, Dadar East, Dadar East, Mumbai - 022 24185069



Fluid Power and Control Corpo www.fluidpowercontrol.com - 37/A, Bombay Timber Mkt., Signal Hill Avenue Road, Reay Road, Mumbai - 022 23712021



Khoday Hydraulics www.khoday.com - 621 Khush Villa, Khareghat Road, Dadar (c.r.), Mumbai - 022 24128787



Preston Hydraulics www.prestonhydraulics.net - A-33 Ansa Industrial Estate, Saki Vihar Road, Saki Naka, Mumbai - 022 28470769



Dantal Hydraulics Private Limited 61

HOUSEHOLD ELEVATORS 2011 www.dantal.in - D-213, Floral Deck Plaza, Cross Road C, Chakala M.i.d.c., M.i.d.c Road, chakala, Mumbai - 022 28236644

ď ś Shantilal C Mehta www.shantilalcmehta.com - 45 Sagar Vihar, Munshi Road, Grant Road, Mumbai - 022 23611109

62