Sharp R-267LST Bedienungsanleitung PDF herunterladen (Seite 14)

4,309,917

11

one

of

throttle

and

steer

request

cams

188,

189,

calling

for

the

higher

set

speed,

and

power

pressure

in

chamber

181

will

not

move

piston

177

away

from

abutting

rela

tion

with

control

cylinder

179

to

increase

the

bias

force

of

spring

173,

unless

the

power

pressure

calls

for

a

higher

set

speed.

Thus,

the

set

speed

will

be

the

highest

set

speed

called

for

by

one

of

these

control

function

s—but-not

higher

because

these

control

functions

forces

on

spring

173

are

not

added.

I

The

throttle

control,

on

movement

from

its

minimum

to

maximum

position,

will

increase

the

set

speed

from

idle

speed

to

a

high

or

maximum

set

speed,

e.g.,

full

power

or

maximum

engine

speed.

Then,

after

a

time

delay

as

engine

power

increases

to

a

maximum,

the

engine

power

signal

supplied

by

compressor

discharge

pressure

will

increase

the

set

speed

to

the

maximum

engine

speed.

This

arrangement

provides

ratio

change

in

response

to

torque

demand

shortly

before

the

resul

tant

change

of

engine

torque

and

power

during

engine

acceleration,

and

ratio

change

in

response

to

actual

engine torque

and

power

during

deceleration.

The

steer

request

cam

189, as

steer

request

varies

in

the

full

range

(zero

to

maximum),

controls the

set

speed

in

a

wide

speed range

(e.g.,

idle

to

80%

of

maximum

speed),

to

maintain

engine

speed

at

higher

values

rela

tive

to

propulsion

output

speed

to

maximize

steer

opera

tion—even

though

the

operator

decreases

throttle

de

mand.

At

higher

engine

speeds,

steer

drive

14,

with

the

same

steer

ratio

will

provide

a

greater

speed

difference

between

the

right

and

left

output

drives

16

and

17,

and

thus

the

output

shafts

36

and

36’

have

a

larger

differen

tial

speed

for

tighter

or

smaller

radius

turns.

When

steering,

the

vehicle

operator

often

reduces

the

throttle

to

reduce

propulsion

power,

but

this

steer

request

con

trol

prevents

a

fully

proportional

reduction

of

steer

capability

and

maintains

a higher proportion of

maxi

mum

steer

capability.

Normally

when

the

vehicle

service

brake

system

141

is

applied

for

vehicle

braking,

the

throttle

194

is

re

turned

to

Idle

and

the

power

pressure

signal,

based

on

compressor

discharge

pressure,

will

then

return

to

Idle.

Thus,

during

braking—as

the

engine

power

pressure

signal

decreases

and

vehicle

brake apply

pressure

in

creases—the

power

signal shuttle

valve

186

connects

the

higher

of

these

pressures

via

power

signal

line

183

to

chamber

181

of

ratio

governor

162

to

maintain

the

set

speed

and

thus

engine

speed

at

higher

values,

thus

main

taining

higher

engine

braking

and

higher

steer

capabil

ity

during

vehicle

braking.

RETURN

DEMAND

CONTROL

Return

demand

control

206

employs

an

advance

cut

off

valve

122

controlled

by

return

demand

valve

124

which

is

controlled

by

a

return

demand

signal

supplied

by

return

demand

signal

line

227 which,

in

turn,

is

sup

plied

by

2-3

overpressure

cut-off

valve

431

or

low

charge

signal

valve

631,

as

explained

below.

ADVANCE

CUT-OFF

VALVE

The

advance

cut-off

valve

122

has

a

spool

208

having

three

equal-diameter

lands

a,

b,

and

c,

slidable

in

a

bore

209.

Operating

pressure,

which

normally

is

supplied

by

operating

line

211

to

closed

operating

chamber

212

at

one

end

of bore

209,

moves

spool

208

against

spring

213

to

engage

stop

215

in

the

connecting

position

shown

in’

FIG.

3C. Spring 213

is

located

in

spring

chamber

214

which

is

located

at

the

opposite

end

of

bore

209

and

is

vented

by

an

exhaust

216.

In

this

normal

connecting

40

45

55

60

65

12

position

of

advance

cut-off

valve

122,

advance

and

return

feed

lines

201

and'

202

are

respectively

con

nected,

between

lands

a

and

b

and

lands

b

and

c

of

spool

208,

to

advance

and

return

connecting

lines

217

and

218.

When

operating

line

211v

is

exhausted,

spring

213

moves

spool

208

to

the

cut-off

position

so

advance

cut-off

valve

122

functions

so

that

lands

a

and

b

of

spool

208

respectively

block

advance

and

return

feed

lines

201

and

202,

advance

connecting

lines

217

is

connected

between

lands

a

and

b

of

spool

208

to

exhaust

219,

and

mainline

112

is

connected

between

lands

b

and

c

of

spool

208

to

return

connecting

line

218.

'

RETURN

DEMAND

VALVE

Return

demand

valve

124

has

a

spool

221 having

two

equal-diameter

lands

a

and

b

slidable

in

a

bore

222.

Spool

221

is

biased

by

spring

223

to

the

normal

connect

ing

position

shown

(FIG.

3C),

blocking

exhaust

226

and

connecting

mainline

112

to

operating

line

211.

Spring

223

is

located

in

one

end

of

bore

222

which

is

vented

by

exhaust

224.

The

return

demand

signal

line

227

is

con

nected

to

chamber

228

to

move

spool

221

against

spring

223

to

the

cut-off

position,

blocking

mainline

112

and

connecting

operating

line

211

to

exhaust

226

permitting

advance

cut-off

valve

122

to

be

moved

by

its

spring

213

to

the

advance

cut-off

position.

A

timing or

restriction

and

check

valve

device

229

having

restriction

231

and

check

valve

232

is

placed

in

operating

line

211

for

de

layed

flow

only

through

the

restriction

231

to

operating

chamber

212

to

delay

movement

of

advance

cut-off

valve

122

to

the

normal

connecting

position

and

rapid

exhaust

flow

from

operating

chamber

212

through

both

the

restriction

231

and

check

valve

232

for

rapid

move

ment

of

advance

cut-off

valve

122

to

the

cut-off

position

for

rapid

cut-off

of

advance

pressure

and

supply

of

return

pressure

and

delayed

return

to

normal

position

for

connection of

advance

and

return

pressures

as

sup

plied

by

ratio

governor

162.

RATE

OF

RATIO

CHANGE

CONTROLS

To

provide,

in

the

advance

return

signal

system

160,

governor

stability

and

smooth

ratio

change,

rate

of

ratio

change

controls

203,

between

the

advance

and

return

feed

lines

201

and

202

and

advance

and

return

lines

204

and

205,

provide

a

high

rate

of

?ow

and

pressure

in

crease

of

return

pressure

to

return

line

205

for

rapid

response

to

a

request

for

reduction

of

drive

ratio

and

a

lower

rate

of

flow

and

pressure

increase

of

advance

pressure

to

advance

line

204

for

slower

response

to

a

request

for

an

increase

of

drive

ratio.

The

advance

connecting

line

217

is

connected

by

a

restriction

and

check

valve

device

233

and

lst

range

advance

control

valve

123

to

advance

line

204.

The

lst

range

advance

control

valve

123

has

a

spool

234

having

equal-diameter

lands

a

and

b

slidable

in

a

bore

236.

Spring

237,

in

one end

of

bore 236

vented

by

exhaust

238,

biases

spool

234

to

the

higher

range

position

shown

in

FIG.

3C.

The

lst

apply

pressure,

which

is

supplied

by

lst

apply

line

239

to

operating

chamber

241

located

at

the

opposite

end

of

bore

236,

moves

spool

234

against

spring

237

to

the

low

or

lst

range

position.

When

ad

vance

pressure

is

supplied

from

advance

connecting

line

217

to

restriction

and

check

valve

device

233,

the

check

valved

line

242

is

closed

and

blocks?ow,

and

flow

is

only

via

restricted

line

243

to

lst

range

advance

control

valve

123

which,

in

higher

2nd

and

3rd

range

positions,

connects

restricted

line

243

via

its

free-?ow

advance

branchline

244

to

advance

line

204,

and

in

lst

range

1 2 ... 9 10 11 12 13 14 15 16 17 18 19 ... 33 34

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