JP4089145B2 - Centrifuge - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a centrifuge having a drive device supported by a vibration isolation mechanism.
[0002]
[Prior art]
A conventional centrifuge includes a driving device, a rotating shaft (shaft) rotated by the driving device, a rotor engaged with the rotating shaft, a rotating chamber that houses the rotor, and a casing that covers the rotating chamber. The rotating chamber is fixed to a part of the casing, and the driving device is attached to the casing via a vibration isolation mechanism. Further, when the rotating shaft is a rigid shaft, the unbalance of the rotor directly becomes the vibration of the driving device, so that a gap is provided in the housing so that the driving device can move. Since the rotor also moves with the driving device, the rotating chamber is sized accordingly. Furthermore, in order to detect an excessive imbalance of the sample accommodated in the rotor, it has a detecting means for measuring the external vibration of the non-rotating driving device and generating an alarm when the vibration exceeds a certain level.
[0003]
[Problems to be solved by the invention]
The centrifuge has a tendency to have a complicated structure because the configuration for attaching the member on the inner surface constituting the rotating chamber and the configuration for attaching the driving device are different configurations. In particular, when the rotor is unbalanced or vibrates at the natural frequency of the vibration system, the drive device moves, so that a space in consideration of that is required around the drive unit. When the rotor is unbalanced, the vibration on the drive unit is often small despite the large vibration on the rotor side. Therefore, vibration sensors (gap sensors), acceleration pickups, etc. are used as sensors for measuring vibration. There is a problem that an expensive sensor must be used.
[0004]
An object of the present invention is to provide a centrifuge that can solve the above problems and reliably perform unbalance detection using an inexpensive detection means.
[0005]
[Means for Solving the Problems]
The above object is achieved by fixing the driving device supported by the vibration isolation mechanism and the bowl on the inner surface of the rotating chamber, and detecting the position of the bowl using an inexpensive member such as a proximity switch.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
The centrifuge in a present Example is demonstrated using FIGS. 1-3. FIG. 1 is a longitudinal side view showing a centrifuge in the present embodiment. A motor 8 is disposed in a lower space of a casing (frame) having a space formed vertically by a center plate, and a center plate is disposed in an upper space. A driving device 7 is fixed together with a stainless steel bowl 5 serving as a rotor chamber on which flange portions are placed on the six vibration isolating portions 6 fixed above. A protector 4 integrated with the frame 9 is disposed outside the bowl 5, and the bowl 5 and the protector 4 block the space between the inside and the outside of the bowl 5 with an expandable bellows 10. A rotor 3 and a door 1 for taking in and out the sample are provided at the upper part of the centrifuge chamber. The rotor 3 is coupled to the upper portion of the drive device 7 via a rigid shaft 11.
[0007]
FIG. 2 is an enlarged cross-sectional view of a portion A shown in FIG. 1 (enlarged cross-sectional view showing the upper end portion of the bowl 5), and ribs 13 are provided on the entire upper end portion of the bowl 5 to increase rigidity. A photoelectric switch 12 for detecting the rib 13 of the bowl 5 is fixed to the upper frame portion of the rib 13. When the rotor 3 rotates, the entire drive device 7 vibrates, but is attenuated by the vibration isolator 6 to prevent transmission to the frame 9. Since the rotation system of the drive device 7 is a rigid shaft, the vibration of the drive device 7 increases in accordance with the unbalance (sample variation) in the rotor 3. In particular, the vibration peaks at the natural frequency of the vibration isolator 6, but the subsequent vibration also increases according to the unbalance amount.
[0008]
FIG. 3 is a state diagram (mode) showing the difference between the unbalance amount and the vibration mode. (A) shows a small unbalance state, and (B) shows a large unbalance state. In general, vibration due to unbalance of the rotor 3 vibrates on the rotor 3 side, and therefore, vibration on the upper side (rotor side) of the driving device increases. However, the lower side is not so large but may be smaller (until the phase with respect to rotation is reversed). Therefore, it is ideal to detect the vibration on the upper side of the drive unit where the relationship between the unbalance amount and the vibration is proportional. The vibration of the driving device 7 is transmitted to the bowl 5 as it is. The upper part of the bowl 5 has an amplitude close to the vibration of the rotor 3. The position of the photoelectric switch 12 is adjusted and fixed in advance to a position that can be detected within an amplitude within a specified range from the relationship between the unbalance amount and the shake of the bowl 5. When the unbalance exceeds the specified value, the shake of the bowl 5 increases and deviates from the detection range of the photoelectric switch 12 (once per rotation). By detecting this switching, it can be determined that there is an imbalance abnormality. In addition, the flow of the wind is interrupted by the bellows 10 so that the heat from the driving device 7 is not drawn into the rotating chamber due to the rotation of the rotor 3.
[0009]
With such a configuration, a centrifuge having a simplified configuration can be provided.
[0010]
【The invention's effect】
According to the present invention, by fixing the bowl serving as the centrifuge chamber to the driving device so that both the members can move integrally, the vibration caused by the unbalance of the rotor or the like can be reliably detected using an inexpensive sensor. Can be detected.
[Brief description of the drawings]
FIG. 1 is a longitudinal side view showing a centrifuge according to the present invention.
FIG. 2 is an enlarged cross-sectional view of a part A shown in FIG.
FIG. 3 is a state diagram showing vibration characteristics of the driving device according to the present invention.
[Explanation of symbols]
1 is a door, 2 is a rotor bucket, 3 is a rotor, 4 is a protector, 5 is a bowl, 6 is a vibration isolator, 7 is a drive unit, 8 is a motor, 9 is a frame, 10 is a bellows, 11 is a rotating shaft, 12 Is a photoelectric switch, and 13 is a bowl rib.

Claims (6)

A driving device; a rigid shaft that transmits rotational power of the driving device; a rotor that engages with the rigid shaft; a ball that accommodates the rotor; and a housing that covers the ball; In the centrifuge provided with a vibration isolating member arranged between the housing,
A centrifuge characterized by detecting the unbalance of the rotor by fixing the ball to the driving device and detecting the vibration and position of the rib at the upper end of the ball by a position detection sensor . The centrifuge according to claim 1, wherein the position detecting sensor is a photoelectric switch. The position detection sensor, centrifuge according to claim 1 wherein characterized in that it is a proximity switch. Wherein when detecting the unbalance of the rotor, centrifuge according to claim 1 wherein characterized in that stopping the rotation of the rotor.   The centrifuge according to claim 1, wherein an outer periphery of the ball and the housing are coupled by a vibration isolating member.   The centrifuge according to claim 1, wherein a bellows, which is a member that can be expanded and contracted, is provided between an outer periphery of the ball and the housing.

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