Fuel supply control device
A fuel supply control device ( 10 ) is configured to generate an operation amount used for feedback-controlling rotation of a gear pump ( 3 ) based on a deviation of a detected fuel flow rate with respect to a target flow rate, wherein the fuel supply control device generates the operation amount such that a rotation speed of the gear pump is equal to or greater than a predetermined lower limit rotation speed Nmin so as to protect a bearing of the gear pump.
1. A fuel supply control device configured to generate an operation amount used for feedback-controlling rotation of a gear pump based on a deviation of a detected flow rate of a fuel with respect to a target flow rate,
wherein the fuel supply control device generates the operation amount such that a rotation speed of the gear pump is equal to or greater than a lower limit rotation speed Nmin so as to protect a bearing of the gear pump,
wherein the fuel supply control device comprises:
a lower limit value calculator configured to calculate the lower limit rotation speed Nmin using a viscosity coefficient of a lubricant of the bearing calculated based on a fuel temperature of the gear pump, a pressure-boosted amount of the gear pump, a shaft diameter and a minimum gap of the bearing, and a Sommerfeld number,
an operation amount calculator configured to calculate an operating rotation speed N based on the deviation; and
a comparator configured to output larger one of the lower limit rotation speed Nmin and the operating rotation speed N as the operation amount of an actual rotation speed, and
wherein the lower limit rotation speed Nmin is given by the following Equation (1) constituted by a viscosity coefficient μ of the lubricant of the bearing calculated based on the fuel temperature of the gear pump, the pressure-boosted amount P of the gear pump, a shaft diameter r, the minimum gap of the bearing cmin, and the Sommerfeld number S:
N
min
=
P
μ
S
[
c
min
r
]
2
(
1
)
2. The fuel supply control device according to claim 1 , comprising:
a pressure-boosted amount calculator configured to calculate a pressure-boosted amount of the gear pump based on the actual rotation speed, a discharge pressure and the fuel temperature of the gear pump.
3. The fuel supply control device according to claim 1 , wherein the gear pump is a high pressure pump configured to further boost a pressure of the fuel pressurized by a low pressure pump and to supply the fuel boosted by the high pressure pump to an engine.
4. The fuel supply control device according to claim 1 , wherein the gear pump is driven by a motor, and
the operation amount is used for operating the motor.