Technical data

Rexroth IndraDyn H Notes Regarding Application 9-9
DOK-MOTOR*-MBS-H******-PR02-EN-P
Flow rate
The coolant flow required to maintain the rated torque is defined in
chapter 4, “Technical Data”.
The specification of this value is based on a rise of the coolant
temperature by 10 K.
Figures 9-12 and 9-13 are used to determine the necessary coolant flow
for different temperature rises and/or different coolants:
Tc
60000P
Q
co
∆⋅ρ⋅
⋅
=
Q: Required coolant flow in l/min
P
ro
: Removed power loss in W
c: Specific heat capacity of the coolant in J / kg - K
ρ: Density of the coolant in kg/m³
∆T: Coolant temperature rise in K
Fig. 9-4: Coolant flow required for removing a given power loss.
Coolant Specific heat capacity c in J / kg - K
Density ρ
ρρ
ρ in kg/m³
Water 4183 998,3
Thermal oil
(example)
1000 887
Air 1007 1,188
Fig. 9-5: Substance values of different coolants at 20°C
Assuming the same flow rate, you can estimate the reduction of the
allowable motor torque when using coolants other than using formula in
Fig. 9-14.
%100
c
c
k
ww
xx
cred
⋅
ρ⋅
ρ⋅
=
k
cred
: Reduction factor of motor torque in percent relating to water
c
w
: Specific heat capacity of water in J / kg - K
ρ
w
: Density of the coolant in kg/m³
c
x
: Specific heat capacity of used coolant in J / kg - K
ρ
x
: Density of used coolant in kg/m³
Fig. 9-6: Reduction of motor torque when using coolants other than water
Pressure drop
The flow resistance at the pipe walls, curves, and changes of the cross-
section produce a pressure drop along the traversed components (see
Fig. 9-9).
The pressure drop, ∆p, rises as the flow quantity rises (see Fig. 9-15).
Coolant flow to maintain the
rated torque
Reduction of motor torque with
coolants other than water