Shock mounting of a motor in a downhole tool
A downhole tool for use in a subterranean well can include an electric motor, a motor carrier, and a compressed gas chamber. The motor may be axially reciprocably received in the motor carrier. The compressed gas chamber may decrease in volume in response to displacement of the motor in an axial direction relative to the motor carrier. The chamber may be formed radially between the motor and the motor carrier.
1 . A downhole tool for use in a subterranean well, the downhole tool comprising:
an electric motor;
a motor carrier, the motor being axially reciprocably received in the motor carrier;
a compressed gas chamber configured to decrease in volume in response to displacement of the motor in a first axial direction relative to the motor carrier; and
a spring that biases the motor carrier in a second axial direction opposite to the first axial direction.
2 . The downhole tool of claim 1 , in which the chamber biases the motor in the second axial direction.
3 . The downhole tool of claim 1 , further comprising a first seal that seals between the motor and the motor carrier.
4 . The downhole tool of claim 3 , further comprising a second seal axially spaced apart from the first seal, the chamber being isolated between the first and second seals.
5 . The downhole tool of claim 4 , in which the second seal seals between the motor and the motor carrier.
6 . The downhole tool of claim 5 , in which the second seal further seals between the motor and a gearbox.
7 . The downhole tool of claim 6 , in which the gearbox is axially reciprocably received in the motor carrier.
8 . The downhole tool of claim 6 , in which the chamber is formed axially between the gearbox and the motor carrier.
9 . The downhole tool of claim 1 , in which the chamber is formed radially between the motor and the motor carrier.
10 . A downhole tool for use in a subterranean well, the downhole tool comprising:
an electric motor;
a motor carrier, the motor being axially reciprocably received in the motor carrier; and
a compressed gas chamber configured to decrease in volume in response to displacement of the motor in a first axial direction relative to the motor carrier, the entire chamber being formed radially between the motor and the motor carrier, in which pressure within the chamber increases in response to the decrease in volume.
11 . The downhole tool of claim 10 , further comprising a spring that biases the motor carrier in a second axial direction opposite to the first axial direction.
12 . The downhole tool of claim 11 , in which the chamber biases the motor in the second axial direction.
13 . The downhole tool of claim 10 , further comprising a first seal that seals between the motor and the motor carrier.
14 . The downhole tool of claim 13 , further comprising a second seal axially spaced apart from the first seal, the chamber being isolated between the first and second seals.
15 . The downhole tool of claim 14 , in which the second seal seals between the motor and the motor carrier.
16 . The downhole tool of claim 15 , in which the second seal further seals between the motor and a gearbox.
17 . The downhole tool of claim 16 , in which the gearbox is axially reciprocably received in the motor carrier.
18 . The downhole tool of claim 16 , in which the chamber is formed axially between the gearbox and the motor carrier.
19 . The downhole tool of claim 16 , in which an output shaft of the gearbox is configured to transfer torque from the gearbox to an inner mandrel of the downhole tool while the output shaft is axially reciprocable relative to the inner mandrel.