# US 8,751,074 B2 · Control of interconnected trolleys

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- Number: US 8,751,074 B2
- Document ID: US8751074B2
- Status: Granted
- Kind: B2
- Application number: 13/811,557
- Filed: 2011-07-21
- Published: 2013-05-16
- Granted: 2014-06-10
- Earliest claimed: 2010-08-05
- Assignees: Konecranes PLC
- Applicants: Mikko Porma
- Inventors: Mikko Porma
- Web page: https://patentgrep.com/patent/US8751074B2

## CPC

- B66C 13/22: for electric drives (transmitting control pulses B66C13/40; systems or devices of general application H02P)
- B66C 9/14: Trolley or crane travel drives (rope, cable, or chain drives for loads or trolleys B66C11/16; control B66C13/18)
- B66C 13/30: Circuits for braking, traversing, or slewing motors
- B66C: CRANES; LOAD-ENGAGING ELEMENTS OR DEVICES FOR CRANES, CAPSTANS, WINCHES, OR TACKLES ({specially adapted for lifting invalids A61G7/10;} rope, cable, or chain winding mechanisms, braking or detent devices therefor B66D; specially adapted for nuclear reactors G21)

## Abstract

A hoist trolley assembly includes first and second hoist trolleys, electric motors to drive the trolleys and a control system. The control system receives a preliminary speed reference for the trolleys and forms a final speed reference for the first hoist trolley by using initial data including the preliminary speed reference. The control system is adapted to use a hoist trolley coefficient Krb that is calculated by k rb = T A_nom T B_nom · v B_nom v A_nom · m TB + m LB m TA + m LA , wherein TA—nom=the rated torque of the electric motor of the first hoist trolley, TB—nom=the rated torque of the electric motor of the second hoist trolley, vA—nom=nominal speed of the first hoist trolley, vB—nom=nominal speed of the second hoist trolley, mTA=dead weight of the first hoist trolley, mTB=dead weight of the second hoist trolley mLA=load of the first hoist trolley, and mLB=load of the second hoist trolley.

## Claims

### Claim 1

A hoist trolley assembly that comprises a first hoist trolley, drive equipment for the first hoist trolley, a second hoist trolley, drive equipment for the second hoist trolley, and a control system, the first hoist trolley being connected to the second hoist trolley in such a manner that the first hoist trolley and the second hoist trolley are arranged to move at the same speed, both the drive equipment of the first hoist trolley and the drive equipment of the second hoist trolley comprising an electric motor, the control system being adapted to receive a preliminary speed reference for the interconnected first hoist trolley and second hoist trolley and to form a final speed reference for the first hoist trolley by using initial data that comprise the preliminary speed reference, wherein the control system is adapted to use in forming the final speed reference for the first hoist trolley a hoist trolley coefficient krb that is calculated by
k
rb
=
T
A_nom
T
B_nom
·
v
B_nom
v
A_nom
·
m
TB
+
m
LB
m
TA
+
m
LA
,
wherein
TA—nom=the rated torque of the electric motor of the first hoist trolley
TB—nom=the rated torque of the electric motor of the second hoist trolley
vA—nom=nominal speed of the first hoist trolley
vB—nom=nominal speed of the second hoist trolley
mTA=dead weight of the first hoist trolley
mTB=dead weight of the second hoist trolley
mLA=load of the first hoist trolley
mLB=load of the second hoist trolley.

### Claim 2 (depends on 1)

A hoist trolley assembly as claimed in claim 1, wherein the control system comprises a programmable logic controller and a first restriction block, the programmable logic controller being adapted to form a preliminary speed reference nrefA for the first hoist trolley by using the following equation
n
refA
=
min
⁡
(
v
A
,
v
B
)
v
A
·
n
ref
,
the first restriction block being adapted to form a restricted speed reference nrampA for the first hoist trolley by restricting the first time derivative of the preliminary speed reference nrefA of the first hoist trolley at its maximum to an acceleration value arampA of the first restriction block.

### Claim 3 (depends on 2)

A hoist trolley assembly as claimed in claim 2, wherein the programmable logic controller is also adapted to form a preliminary speed reference nrefB for the second hoist trolley by using the following equation
n
refB
=
min
⁡
(
v
A
,
v
B
)
v
B
·
n
ref
,
and
the control system also comprises a second restriction block that is adapted to form a restricted speed reference nrampB for the second hoist trolley by restricting the first time derivative of the preliminary speed reference nrefB of the second hoist trolley at its maximum to an acceleration value arampB of the second restriction block.

### Claim 4 (depends on 3)

A hoist trolley assembly as claimed in claim 3, wherein the acceleration value arampA of the first restriction block is substantially equal to the acceleration value arampB of the second restriction block.

### Claim 5 (depends on 2)

A hoist trolley assembly as claimed in claim 2, wherein the control system is adapted to form a final speed reference nref—A—fin for the first hoist trolley by using the equation
nref—A—fin=nrampA−krb·KB·TA, wherein
nrampA=restricted speed reference of the first hoist trolley
krb=hoist trolley coefficient
KB=load flex coefficient of the second hoist trolley
TA=actual value of the first hoist trolley electric motor torque.

### Claim 6 (depends on 2)

A hoist trolley assembly as claimed in claim 2, wherein the control system is adapted to form a final speed reference nref—A—fin for the first hoist trolley by using the equation
nref—A—fin=nrampA−krb·sB·TA, wherein
nrampA=restricted speed reference of the first hoist trolley
krb=hoist trolley coefficient
sB=nominal slip of the second hoist trolley short-circuit motor as a relative value
TA=actual value of the first hoist trolley electric motor torque.

### Claim 7 (depends on 1)

A hoist trolley assembly as claimed in claim 1, wherein the hoist trolley assembly also comprises a position measurement sensor that is connected to at least one wheel of the first hoist trolley and adapted to transmit data on the position of the interconnected hoist trolleys to the control system.

### Claim 8 (depends on 1)

A hoist trolley assembly as claimed in claim 1, wherein the lifting capacity of the first hoist trolley is substantially higher than that of the second hoist trolley.

### Claim 9

A hoist trolley assembly that comprises a first hoist trolley, drive equipment for the first hoist trolley, a second hoist trolley, drive equipment for the second hoist trolley, and a control system, the first hoist trolley being connected to the second hoist trolley in such a manner that the first hoist trolley and the second hoist trolley are arranged to move at the same speed, both the drive equipment of the first hoist trolley and the drive equipment of the second hoist trolley comprising an electric motor, the control system being adapted to receive a preliminary speed reference for the interconnected first hoist trolley and second hoist trolley and to form a final speed reference for the first hoist trolley by using initial data that comprise the preliminary speed reference, wherein the control system is adapted to use in forming the final speed reference for the first hoist trolley a hoist trolley coefficient krb that is obtainable by an equation
k
rb
=
T
A_nom
T
B_nom
·
v
B_nom
v
A_nom
·
m
TB
+
m
LB
m
TA
+
m
LA
,
wherein
TA—nom=the rated torque of the electric motor of the first hoist trolley
TB—nom=the rated torque of the electric motor of the second hoist trolley
vA—nom=nominal speed of the first hoist trolley
vB—nom=nominal speed of the second hoist trolley
mTA=dead weight of the first hoist trolley
mTB=dead weight of the second hoist trolley
mLA=load of the first hoist trolley
mLB=load of the second hoist trolley,
and the control system comprises a programmable logic controller and a first restriction block, the programmable logic controller being adapted to form a preliminary speed reference nrefA for the first hoist trolley, the preliminary speed reference being obtainable by an equation
n
refA
=
min
⁡
(
v
A
,
v
B
)
v
A
·
n
ref
,
the first restriction block being adapted to form a restricted speed reference nrampA for the first hoist trolley by restricting the first time derivative of the preliminary speed reference nrefA of the first hoist trolley at its maximum to an acceleration value arampA of the first restriction block.