Design Considerations for a More Efficient Power Unit Circuit

Design Considerations for a More Efficient

Power Unit Circuit

Tom Shickel

Manager – Marine & Offshore

Bosch Rexroth Corporation

Tele: 610/ 694-8552

Hydraulic Drive System Advantages

Reliability

Power Density

Component Longevity

Maintenance

System Noise

Cost of Construction

…..If properly sized, flushed, and

commissioned!

Pump Motor Group on

Top of Tank - Horizontal

Low Noise

Fair

Accessibility

Good

Overall Size

Excellent

Suction

Characteristics

Mounted Pump Group

on Top of Tank- Vertical

Low Noise

Excellent

Accessibility

Fair

Overall Size

Excellent

Suction

Characteristics

Pump Motor Below the

Tank (Overhead Design)

Low Noise

Good

Accessibility

Good

Overall Size

Excellent

Suction

Characteristics

Motor Pump Group on

Side of Tank (L-shape)

Excellent

Suction

Characteristics

Fair

Overall Size

Excellent

Accessibility

Good

Low Noise

Design & Procedure Considerations:

1. Electric Motor Sizing

2. Pump Selection

3. Pump Controllers

4. Heat Exchangers

5. Temperature Settings

Don‘t oversize the electric motor

ƒ

Some OEM‘s specify motors sized 20% max requirement

ƒ

High throttling losses caused by

proportional valves

ƒ

High motor heating caused by current

flow.

ƒ

High leakage losses caused by high

speed.

ƒ

Full motor speed during part-load

operation.

ƒ

High Energy losses caused by

releasing pressure overshoot to tank

Î

No energy saving potential used in

classic (fixed displacement/ speed)

hydraulic solutions

Energy Saving Potential

A10VO

Parts

Distributor Plate

Piston Shoe

Retainer Plate

Retainer Ball

Piston

Swash Plate

Cylinder Barrel

Hydrostatic Bearing

Mechanical Pretension

Spring force

A10VO/VSO Control Summary

DR pressure compensation control

DRG remote pressure control

DFR load sensing control

DRT offsettable pressure control

DFLR torque control (series 31)

DFSR summation torque control (series 31)

FHD hydraulic pilot flow control (series 31)

DFE electronic pressure/flow control

(series 31)

ED electronic pressure control

Variable Displacement Pump Controls:

1. Constant Pressure Control (DR)

2. Load Sensing (DFR)

3. Horse Power Control (DFLR)

4. Integrated Electronic Control (DFEE)

Pump Control Options Tailored for Specific

Operations

Oil Reservoir - Size of Tank

1.

Minimum 3x total flowrate per minute

2.

Baffle recommended

3. Sufficient time for cooling, settling of particles

and aeration

Filtration Guidelines

1. Cleanliness level determined by the most

sensitive component

2. Pressure and return filters sized sufficiently

3. Breather to be lowest micron filter in system

4. Kidney loop filters

Filter/Cooler Module

ƒ

MFC3, MFN3, MNC3

ƒ

4-19 HP Removal

ƒ

Pump Flow 3-13 GPM

ƒ

Motor 1500/1800 RPM

ƒ

RA 50127

Rear Mounted Heat Exchangers

ƒ

Mounts directly to the

back of the main electric

motor

ƒ

1-2 HP Removal

ƒ

Pump Flow 2-3 GPM

Hydraulic Fluid - Temperature

1. Suitable viscosity for ambient temperatures and duty cycle

2. Heat exchanger approach temperature is critical for energy

conservation

3. Life span of fluid is halved every additional 18 degrees F

over 160 degrees F

4. Pumps’ ideal range of 80 to 170 SUS

Viscosity range for Shell Tellus 32

Temperature (Degrees F)

Viscosity (SUS)

210

44

160

60

140

78

120

105

100

167

80

230

60

400

Avoid Air Entrainment and Cavitation Design Traps

ƒ

Place air bleed valves at high points of the circuit

ƒ

Optimize pump suction line characteristics

ƒ

Avoid suction strainers when possible

ƒ

Size reservoir adequate for the fluid to settle and deaerate.

ƒ

Use a reservoir baffle design

ƒ

Mount suction lines sufficiently well below lowest level fluid

level

Pressure Drop in Transmission Lines

We recommend the following oil velocities for noise sensitive

applications:

ƒ

Suction lines:

Not to exceed 3 ft/sec

ƒ

Return lines:

Not to exceed 6 ft/sec

ƒ

Pressure lines:

ƒ

0-400 psi: Not to exceed 9 ft/sec

ƒ

800 psi:

Not to exceed 13 ft/sec

ƒ

1500 psi:

Not to exceed 15 ft/sec

Manifold Advantages

Manifold Mounted Components

1. Elimination of leak points

2. Compact size enable shorter runs

between valves and less pressure

drop

3. Flexibility for future changes

4. Ease of maintenance

After commissioning, all systems will

vary efficiency degradation over time

depending on fluid and operating

conditions are maintained.

Makes Commercial Vehicles Up to 25 Percent

More Economical

Components of the HRB

ƒ

A4VSO Axial Piston Unit + Gearbox

ƒ

Hydraulic Accumulator

ƒ

Pressure Relief Valve

ƒ

Valve Control Block HIC

ƒ

High vehicle mass

ƒ

Strong, active deceleration for storing much energy in a short time

ƒ

Frequent accelerating and braking

P

T

L

DR

M

3

≈

DR

M

3

≈

m

RAHC -

R

otativ

A

ctive

H

eave

C

ompensation

based on BR secondary control technology

System Description Linear AHC

Reduced installed power:

LAHCS175: 175 t @ +/- 3.0 m heave & 8 sec period

ƒ

Theoretical net peak power : 3900 kW

AHC solution:

ƒ

Passive part compensates the static external load, stores and

regenerates energy

ƒ

Active part compensates dynamic effects and losses

ƒ

Installed power : 600 kW

V

ariable

S

peed

P

umps (

VSP

)

Variable Displacement <=> Variable Speed

Slide title

VSP

–

variable speed

pump

Improved diagnostic capability

(SW + sensors)

Potential

Energy savings

High accuracy and performance

Significant noise reduction

Easy and flexible integration in control system

Easy commissioning

(Indraworks engineering tool)

high

performance

basic

performance

high

performance

advanced

performance

FcP

DFEn

SvP

Sytronix

energy efficient variable speed pump drives

Sytronix Systems

ƒ

No throttling losses caused by

proportional valves

ƒ

40-70 % speed reduction during

part-load operation.

ƒ

Reduction of motor heating caused by

reduced current flow.

ƒ

Reduced leakage losses due to lower

average speed.

ƒ

Additional inverter losses

Î

Saving potential up to 80% compared

to classic hydraulic solutions

Energy Saving Potential

Energy Saving – Injection Molding Machine

100 %

Energy

consumption

M

3~

P

_EL

p Q

Classic solution

60 %

Energy

consumption

M

3~

P

_EL

p Q

Variable displacement

30 %

Energy

consumption

M

3~

P

_EL

p Q

Variable Speed Pump

System Components

Fixed Displacement Pump

IndraDrive Fc

Electric asynchronous motor

with external fan

FCS01

Today: Siemens

PGF1/2/3

Pressure

sensor

HM17

Quadrant Operation / Control Functionalities

Control Functionalities

ƒ

Open loop:

ƒ

Flow control

ƒ

Closed loop:

ƒ

Pressure control

1 Quadrant Operation

+n

+p

-n

internal gear

pump

Pump operation

M

open loop operation

-p

IndraDrive Fc

Frequency Converters

Servo Drive

IndraDrive Fc

Type

FCS01

Power

1,5 – 7,5 kW

Supply Voltage

3 AC 380 – 480V

Input frequency

47 – 63 Hz

Max. current

8 – 32 A

Nom. Current

4 – 16 A

Nominal current input

5,6 – 22,4 A

ambient temperature

0 to +40°C

(Derating up to 50°C)

ƒ

Communication interface

ƒ

analog

ƒ

field bus

ƒ

Compact design

ƒ

High availability

E-Motor

Name

Low-Voltage Motor

Motor Type

Asynchronous motor

Protection Class

IP55

Housing Material

Aluminum

Cooling

Integrated

Number of pole

pairs

4

Power

50 Hz: 4kW – 11kW

60 Hz: 4,6kW – 12,6 kW

ƒ

Standard asynchronous motor

ƒ

Integrated ventilation / cooling

ƒ

Integrated frequency converter

ƒ

supports Retrofit

ƒ

no changes in control

cabinet necessary

PP

PPV

FCP

DFE

n

SVP

Product Name

Machine Tool

2.6 kW

Energy saving

24.1 %

-

Series-production

-

2.175s cycle time

Energy consumption:

_{3.4 kW}

Former solution:

Constant rotation system

(5.5kW motor) with variable

displacement pump

2.6 kW

New solution:

Variable-speed pump drive

Sytronix FcP

Energy saving

24.1 %

Lathe Machine

-

Series-production

-

45s cycle time

Energy consumption:

_{3.7 kW}

Former solution:

Constant rotation system

(5.5kW motor) with variable

displacement pump

Energy saving

40.5 %

2.2 kW

New solution:

Variable-speed pump drive

Sytronix FcP

Advantages of Variable Speed Drives:

¾

Energy saving due to variable input speed = Energy on Demand

¾

Lower noise level over cycle

¾

Lower overall cost of hydraulic equipment (smaller pump, less valves, less

or no cooling, smaller reservoir)

¾

Higher efficiency requires less installed power and smaller e-motor

¾

Commissioning similar to electro mechanical drive (Indraworks)

Benefits in efficiency and noise strongly depend on the load cycle of

the machine !!!