Fluid Power Symbols

(1)

9. Hydraulic Circuit Design & Analysis

Description of the operation of hydraulic circuits

drawn using graphical symbols for all components

d d l d i i i f i li d

speeds and load-carrying capacities of regenerative cylinders mechanical-hydraulic servo systems

Troubleshoot hydraulic circuits

to determine causes of malfunctions

Analysis of hydraulic circuits

to evaluate the safety of operation to evaluate the safety of operation to perform a desired function

including the effects of frictional losses the speed control of hydraulic cylinders

Fluid Power Symbols

- 1 - Fluid Power 유압공학

Fluid Power Symbols

(2)

유압 시스템 기본 구성

(3)

9.1 Introduction

Hydraulic circuit

a group of components such as pumps, actuators, control valves, and conductors arranged so that will perform a useful task

Three important considerations

Safety of operationy p

Performance of desired function Efficiency of operation

(4)

유압 회로도

(5)

Hydraulic Circuit of Hydrostatic Transmission

(6)

Control of Hydraulic Cylinders

Control of single acting hydraulic cylinder

Control of double acting hydraulic cylinder

(7)

Regenerative Cylinder Circuit

(8)

Regenerative Cylinder

Cylinder extending speed Ratio of extending &

retracting speeds

Q

_T

= Q

_P

+ Q

_R

Q = Q + Q

P T R

Q = Q − Q

^ret

P P

P r

v Q

A A

= −

( )

ext ext

P P P r P

A v A A v

= − −

Q

/

/( )

Pext P r

v Q A

v = Q A A

−

ext

P P

r

v Q

= A ^/( ⁾

Pret P P r

P r

v Q A A

A A A

−

= −

Load-carrying capacity during extension

A

r

1

Pext P

v = A −

extension

1

Pret r

v A

loadext r

F = pA

(9)

Drilling Machine Application

The spring-centered position gives rapid spindle advance

spindle advance (extension)

The left envelope mode gives slow feed

(extension) when the

drill starts to cut into the workpiece

The right envelope

mode retracts the piston mode retracts the piston

(10)

Pump-unloading Circuit

(11)

Double-pump Hydraulic System

(12)

Counterbalance Valve Application

(13)

Hydraulic Cylinder Sequence Circuit

(14)

Automatic Cylinder Reciprocating System

(15)

Locked Cylinder using Pilot Check Valves

(16)

Cylinder Synchronizing Circuits

Cylinder Connected in Parallel

Cylinder Connected in Series

(17)

Analysis of Cylinders hooked in Series

continuity equation

( 1) ( 2)

out cyl in cyl

Q

₍ _y ₎

= Q

₍ _y ₎

1 2

( ) ( )

( )

eff cyl eff cyl

A v A v

A A v A v

=

− =

for synchronization ( )

1 1 1 2 2

( A

_P

− A

_R

) v = A v

_P

P R P

A − A = A ^v

¹

⁼ ^v

²

summing force on cylinder 1

1 1 2

P R P

1 1 1

1 _P 2

(

_P _R

)

1

p A − p A − A = F

summing force on cylinder 2

2 2 2

2 _P 3

(

_P _R

)

2

p A − p A − A = F

desired result

1 P 1 2

p A = F + F

1 P1 1 2

p

(18)

Fail-Safe Circuits

Fail-safe circuit

Fail-safe circuit with overload protection

p

(19)

Two-Handed Safety Circuit

(20)

Meter-in Speed Control of Hydraulic Cylinder

(21)

Meter-out Speed Control of Hydraulic Cylinder

(22)

Analysis of Extending Speed Control

flow-rate to the cylinder

cyl pump PRV

Q = Q − Q

flow-rate through the flow control valve (FCV)

y p p

1 2

p p p

Δ −

pressure p

₂

1 2

FCV v v

p p p

Q C C

SG SG

= Δ =

pressure p

₂

extending speed of the cylinder

2 piston load

p A = F p

2

= F

_load

/ A

_piston

extending speed of the cylinder

/ /

cyl cyl piston FCV piston

v = Q A = Q A

PRV load

/

piston v

cyl

piston

p F A

v C

A SG

= −

piston

(23)

Speed Control of Hydraulic Motor

(24)

Hydraulic Motor Braking System

(25)

Closed-circuit One-direction HST

(26)

Closed-circuit Reversible-direction HST

(27)

Air-over-oil Circuit

(28)

Example: Analysis of Hydraulic System

(29)

Mechanical-hydraulic Servo System

(30)

9.A Fluid Power Symbols

Line & Line Functions

Pumps Motors Cylinders

Miscellaneous Units

Basic Valve Symbols Valve Examples

Valve Examples

Methods of Operation

(31)

Lines & Line Functions

(32)

Pumps, Motors & Cylinders

(33)

Miscellaneous Units

(34)

Basic Valve Symbols

(35)

Valve Examples

(36)

Methods of Operation

(37)

㉿ 한국공업규격

유압용어: KS B 0119

유압.공기압 도면 기호: KS B 0054

Report #9

KS 유공압관련 규격 찾아 볼 것

(38)

Report

Text Problems

9-16 9-28 9-45

Fluid Power Symbols

9. Hydraulic Circuit Design & Analysis

Description of the operation of hydraulic circuits

Troubleshoot hydraulic circuits

Analysis of hydraulic circuits

Fluid Power Symbols

Fluid Power Symbols

유압 시스템 기본 구성

9.1 Introduction

Hydraulic circuit

Three important considerations

유압 회로도

Hydraulic Circuit of Hydrostatic Transmission

Control of Hydraulic Cylinders

Regenerative Cylinder Circuit

Regenerative Cylinder

Q

= Q

+ Q

Q = Q + Q

Q = Q − Q

v Q

A A

= −

( )

A v A A v

= − −

Q

/

/( )

v Q A

v = Q A A

−

v Q

= A /( )

v Q A A

A A A

−

= −

A

1

v = A −

1

v A

F = pA

Drilling Machine Application

Pump-unloading Circuit

Double-pump Hydraulic System

Counterbalance Valve Application

Hydraulic Cylinder Sequence Circuit

Automatic Cylinder Reciprocating System

Locked Cylinder using Pilot Check Valves

Cylinder Synchronizing Circuits

Analysis of Cylinders hooked in Series

Q

= Q

( ) ( )

( )

A v A v

A A v A v

=

− =

( A

− A

) v = A v

A − A = A v

= v

(

)

p A − p A − A = F

(

)

p A − p A − A = F

p A = F + F

p

Fail-Safe Circuits

Two-Handed Safety Circuit

Meter-in Speed Control of Hydraulic Cylinder

Meter-out Speed Control of Hydraulic Cylinder

Analysis of Extending Speed Control

= A ^/( ⁾

A − A = A ^v

⁼ ^v