Распределитель Линдэ LSC System

7/23/2019 LSC System

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LSC SYSTEM

FUNCTIONAL DESCRIPTION


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Function of the LSC system explained by a simplified schematic with three functions

Fig. 1: All three spools are in neutral position, engine is on.

Stand by pressure of the HPR pump is in front of the three spools. Theoretically the

pressure under this condition would correspond to the spring in the load sensing regulator

(e.g. p= 20 bar).

The stand by pressure that really ensues is higher, due to the backlash forces of the pump

(some 30 bar, depending on the spring setting).

Fig. 2: Only the function 1 spool is opened. Compensator 1 opens up completely, and function 1 pressure p1 is signalled to the LSC

control via LS line and LS connection port. At the metering orifice of spool 1 the LS control

maintains a p that correspondens to the spring setting of the LS control (e.g. p=20 bar).

So the pump flow Q demanded in terms of orifice area A stays always the same, even though

the function pressure may vary.

Fig. 3: In addition to high load function 1, low load function 2 is activated.

The pressure difference between function 1 and 2 pushes the shuttle to the opposite side. As a result pressure of function 1 (= LS pressure) is now available on the left hand side of the

compensator of function 2. Hence compensator 2 maintains at the metering orifice of spool 2

the same p as at metering orifice 1. The residual difference between pressure of function 1

and 2 is throttled off by compensator 2.

Important:

Pressure fluctuations at function 1 (LS pressure) are corrected by the LS control of the pump;

Pressure fluctuations at function 2 are corrected by compensator 2.

Qges. = Q1 + Q2

Qges. = (A1 ) + (A2 ) Qges. = (A1 + A2)

This equation applies as long as the pump can meet the flow demand by A1 and A2.

If e.g. the power limiter reduces flow while cross section A = A1 + A2 remains unchanged p will

drop to a smaller value.

The configuration of fig. 3 shows that pdrops by the same amaunt at each orifice. This is why

the individual flows change proportionally - the great advantage of the LSC system.

Should pressure at function 2 rise over that of function 1, then function 2 becomes leader function,

and now it is its pressure that is signalled to the LS control.

In the case of three functions and more the procedure is still the same. At all spools it is the same

pwhich has to be kept stable.

Q = pA^

p p^

^

p

Linde - Synchron - Control - System

simplified schematic

04 / 00

1 / 6

Date:

Page:

M. Zivkovic

Department HK 1

Description:

LINDE AG

Industrial Trucks and Hydraulics Division.

Schweinheimer Strae 34, 63743 Aschaffenburg, Telephone: 0 60 21 / 99 15 66

Hanauer Landstrae 100, 63796 Kahl / Main, Telephone: 0 61 88 / 4 16 09

Hydraulic

Service Training


3/8

2 / 6

L

P

U

T

P-sup

plyline

Controlspool

LS-s

ignalline

Compensator

Function1

L

S

HPRpumpwith

LScontrol

PV

X

Basic

circuitdiagram

Linde

-Synchron-

Control-

System

(Exam

plewith3functions)

Fig.1:

Allspoolsareinneutralposition(closecenter),

Engineisrunning.

Shuttle

Shuttle

Sh

uttle

Function3

Function2

Compensator

Compensator

Controlspool

Controlspool

LS-signalline

PCO

PV=pumpvalve(60bar)

PCO=pressurecutoffvalve

Date:

Page:

M. Zivkovic

Department HK 1

Description:

LINDE AG




Hydraulic

Service Training

04 / 00




4/8

L

P

U

T

Basicc

ircuitdiagram

Linde-

Synchron-

Control-

System

(Examplewith3functions)

Fig.

2:

Function1isactive.

P-supplyline

Controlspool

LS-signalline

Compensator

Function1

LS

HPRpumpwith

LScontrol

PV

Shuttle

Shuttle

Shuttle

Function3

Fun

ction2

Compensator

Compensator

Controlspool

Controlspool

LS-signalline

PCO

PV=pumpvalve(60bar)


Date:

Page:

M. Zivkovic

Department HK 1

Description:

LINDE AG




Hydraulic

Service Training

3 / 6

04 / 00




5/8

L

P

U

T

PV

Basic

circuitdiagram

Linde-

Synchron-

Control-

System

(Exam

plewith3functions)

Fig.3

:

Function1isunderhighload,

Function2isunderlowloadand

Function3isnotactive.

P-sup

plyline

Controlspool

LS-s

ignalline

Compensator

Function1

L

S

HPRpumpwith

LScontrol

Shuttle

Shuttle

Sh

uttle

Function3

Function2

Compensator

Compensator

Controlspool

Controlspool

LS-signalline

PCO

PV=pumpvalve(60bar)


Date:

Page:

M. Zivkovic

Department HK 1

Description:

LINDE AG




Hydraulic

Service Training

4 / 6

04 / 00




6/8

Functional description: control valve operation for one load

Control valve is shown in neutral

Control valve starts tomove

Control valve is shown in full actuating operation.

Q = pAK^


Date:

Page:

M. Zivkovic

Department HK 1

Description:

LINDE AG




Hydraulic

Service Training

5 / 6

04 / 00

LST A P

LST A P

p

AP

LS

T A P


7/8

Q = pAK^

Functional description: control valve combined

operations and different loads

Date:

Page:

M. Zivkovic

Department HK 1

Description:

LINDE AG




Hydraulic

Service Training

6 / 6

04 / 00


LST A P

LST A P

LST A P

LST A P

V1

V2

V1

V2

Control valve V1 is shown in full actuating operation.

Control valve V2, withlowest

work port pressure, is shown in

full actuating operation.

Control valve V1, with highestwork port

pressure, is shown in full actuating operation.

Control valve V2 is shown in neutral.


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Requirement

Q1

Requirement

Q3

Requirement

Q2

PumpQtotal = 270 l/min

(100%)

Q1 =100%

100%+30%+20%* 100% =

Q1 =270 l/min

150%* 100% =

67% 180 l/min

Q2 = 30%100%+30%+20%

* 100% =

Q2 =270 l/min

150%* 30% =

20%

54 l/min

Q3 =20%

100%+30%+20%* 100% =

Q3 =270 l/min

150%* 20% =

13%

36 l/min

100%

270 l/min

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Calculation of flow split-up

Linde - Synchron - Control - System1 / 1

Example:

Qtotal = 270 l/min = 100 %

Q1 + Q2 + Q 3 = Qtotal

100 % + 30 % + 20 % = 150 %} Requirement

Date:

Page:

M. Zivkovic

Department HK 1

Description:

LINDE AG




Hydraulic

Service Training

Распределитель Линдэ LSC System

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