JPH0380999B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to rotary gas machines such as blowers and compressors using damper bearings.

[Conventional technology]

Conventionally, for example, in a turbo compressor, the impeller rotates at high speed by increasing the speed of the electric motor using a speed increasing device. Recently, speeds have been increasing more and more, reaching extremely high speeds of around 30,000 rpm.

In this way, high speeds require high precision in the meshing of gears, so high precision is required in the distance between the shafts, parallelism, etc., and tight tolerances are required in the machining and assembly of gearboxes and bearing parts. .

In order to improve the meshing accuracy of gears, it is necessary to reduce the deflection of the shaft and to prevent shaft resonance. For this reason, in the past, the rigidity of the shaft was increased and the critical speed was selected to be considerably higher than the operating speed.

However, increasing the rigidity of the shaft increases the dimensions and weight of the shaft itself, bearings, and gearbox. A so-called flexible shaft with reduced shaft rigidity is used so that it can be used in conditions exceeding the primary critical speed.

Although the use of flexible shafts reduced the dimensions and weight of each part, it also required the engine to exceed a critical speed when starting up. For this reason, special metal bearings such as tail pads are used as bearings to ensure stable rotation when passing through critical speeds and at steady operating speeds.

[Problems to be Solved by the Invention] However, such conventional bearings have the disadvantage that the metal bearings have a large mechanical loss, and the special metal bearings are not easy to manufacture and are expensive. Therefore, the use of rolling bearings has been desired.

However, when using rolling bearings, strong vibrations occur when passing through critical speeds, and extremely high precision is required in the machining and assembly of bearing holding parts and gearbox support parts, making machining and assembly difficult. It was difficult. In addition, if the gear box is operated with incorrect machining or assembly accuracy and the pinion shaft is rigidly supported, the gears will mesh incorrectly, resulting in vibration, breakage of the pinion shaft, and damage to tooth surfaces.

The present invention solves the above-mentioned problems of conventional rotary gas machines that include a pinion shaft that has an impeller and is a flexible shaft, and a drive shaft that has a gear that meshes with the pinion shaft. This reduces the machining and assembly accuracy, making machining and assembly easier, and makes it possible to apply a rolling bearing to the high-speed pinion shaft bearing, which is a flexible shaft, reducing mechanical loss. The object is to provide a rotary gas machine that is easy to manufacture.

[Means for solving problems]

The present invention provides a rotary gas machine that includes a pinion shaft that has an impeller at the end and is supported by a damper bearing to serve as a flexible shaft, and a drive shaft that has a gear that meshes with the pinion provided on the pinion shaft. In the damper bearing, the inner circumferential ring is held inside a fixed outer circumferential ring with an annular gap between the outer circumferential ring and the inner circumferential ring via a compression coil spring that supports a radial load, and the inner circumferential ring is held between the fixed outer circumferential ring and the annular gap. A radial rolling bearing is provided inside the inner circumferential ring, and a spring seat for adjusting the spring force of the compression coil spring to adjust the annular gap is movably connected to the outer circumference. It is a rotating gas machine characterized by being installed on a ring.

〔Example〕

Embodiments of the present invention will be described using the drawings.

In FIG. 1, an impeller 2 provided in a compressor casing 1 is provided overhanging one end of a pinion shaft 4 having a pinion 3, and the pinion shaft 4 is attached to a gear casing 5 with a damper bearing 6 to be described later. Supported by 13 is a balance weight for balance adjustment.

Reference numeral 14 denotes a thrust transmission collar that contacts and sandwiches both sides of the gear 8 that meshes with the pinion 3, determines the axial position of the pinion shaft 4, and transmits the thrust of the pinion shaft 4 to the gear 8.

The motor 11 has a motor casing 15 and end brackets 16 and 17, and a motor shaft 12 serving as a drive shaft is supported by bearings 18 and 19 within the end brackets 16 and 17. Motor shaft 12
A gear 8 is provided overhanging one end of the gear. 20 is a seal.

A bearing portion 21 supporting the bearing 18 of the end bracket 16 on the gear 8 side protrudes and is fitted into and held by the gear casing 5.

23 is an air-cooling fan, 24 is an air-cooled oil cooler, and 25 is an oil pump.

Details of the damper bearing 6 are shown in FIG.

26 is a fixed ring fixed to the gear casing 5, and an outer peripheral ring 27 is fitted therein. Inside the outer ring 27, there is an inner ring 29 with an annular gap 28 in between.
is held via a spring 30 that supports the load in the radial direction. Reference numeral 31 denotes a spring seat, which has an oil passage 32 as an introduction path for introducing liquid into the gap 28, and is adapted to adjust and set the gap 28 with a screw.

A radial rolling bearing 33, such as a deep groove ball bearing, is held inside the inner ring 29.

Reference numeral 34 denotes an oil passage, from which lubricating oil is guided to and fills the gap 28.

The damper bearing 6 configured in this way has an inner circumferential ring 2.
Even if 9 is subjected to vibration, the damping effect due to the squeezing effect of the oil film in the gap 28 acts as a damper, reducing and absorbing the vibration.

According to many experiments conducted by the inventors, the strength of the spring 30 of the damper bearing 6 is the same as that of the pinion 3 and the gear 8.
It is preferable to select such a value that the inner circumferential ring 29 will not become eccentric and come into solid contact with the outer circumferential ring 27 due to the tangential force generated by the torque transmission between the inner circumferential ring 29 and the outer circumferential ring 27.

Further, for elastic support, it is preferable to perform appropriate modification work such as crowning on the tooth surface so that the tooth contact does not worsen even if the pinion shaft 4 moves and tilts.

By doing this, the gap 28 during assembly
Even if the distance between the pinion shaft 4 and the motor shaft 12 is inappropriate due to non-uniformity or machining errors, and the gears do not mesh well, the pinion shaft 4 is elastically supported by the damper bearing 6. Gap 28
Within this range, the pinion shaft 4 moves to an appropriate position, eliminating unreasonable forces such as pinching force applied to the gears due to poor meshing, and allowing normal operation. Furthermore, the damping effect of the damper bearing 6 also helps to ensure stable normal operation.

In FIG. 1, a pinion shaft 4 provided with an impeller 2 of a turbo blower, compressor, etc. receives thrust force from the impeller 2 and, if the pinion 3 and gear 8 are helical gears, a thrust force based on the torsion angle. If this thrust force is to be supported by the damper bearing 6, the thrust force will be supported by a flange as shown at 36 in FIG. However, in this case, contact friction caused by the thrust force prevents free movement of the inner circumferential ring 29 in the radial direction, making it impossible to obtain a sufficient damping effect.

It is also possible to increase the area of the surface that receives the thrust force, supply lubricating oil at high pressure, and form an oil film between the contact surfaces, but this would require a larger bearing body and require a large amount of lubricating oil to be circulated. This causes the problem that there is

Further, as shown in FIG. 3, the outer peripheral ring 27 is a fixed ring 26
The inner circumferential ring 29 is elastically supported by a thin cylindrical spring 35, and has a structure in which it performs a vibration damping action by the squeezing action of oil introduced into the gap 28, and at the same time receives a thrust load. Yes, but
An axial length l is required to provide a sufficient damping effect, which inevitably increases the distance between the bearings and increases the size of the casing.

The thrust transmission collars 14 provided on both sides of the pinion 3 are used to solve these problems.The thrust transmission collars 14 transmit the thrust force received by the pinion shaft 4 to the gear 8, and further transmit the thrust force received by the pinion shaft 4 to the gear 8. It is supported by a bearing 18 fixed to.

With this structure, the damper bearing 6 does not receive thrust load, so the inner ring 29 and the outer ring 2
The facing surface 7 can be a simple cylindrical surface, making it easy to manufacture, and just forming an oil film in the gap 28 reduces the amount of oil. Even if the pinion shaft 4 receives thrust force, sufficient damping action can be obtained in the damper bearing 6 without interfering with the movement of the inner ring 29 in the axis-perpendicular direction, and the axial length can be shortened. The whole can be made smaller.

On the other hand, the thrust load is transmitted through the thrust transmission collar 14.
This is transmitted to the gear 8 and is reliably supported by the fixed bearing 18 of the motor shaft 12, which is a low-speed drive shaft.
The bearing 18 has a sufficiently large allowable thrust load and can easily and reliably support the thrust force of the pinion shaft 4.

Furthermore, since the rolling bearing 33 of the pinion shaft 4 rotates at high speed, it is advantageous in terms of life if it is not subjected to thrust load in this way.

The thrust transmission collar 14 and the side surface of the gear 8 are
If you make contact near the pitch circle of the gear, there will be almost no relative speed and the contact area will be extremely small.
The mechanical loss is significantly smaller than that suffered by thrust metal installed in the gearbox.

〔Effect of the invention〕

The present invention can bring about the following extremely great practical effects.

(a) In a rotary gas machine that has an impeller and a pinion shaft that rotates at high speed by meshing with gears on other shafts, the distance between the two shafts and the accuracy of parallelism are important when machining gearboxes and bearings. Even if there is poor accuracy during assembly, the abnormal force generated between the gears will be buffered by the action of the spring that applies a load in the radial direction, and further damped by the damping effect of the liquid squeezing effect, suppressing vibration. Stable high-speed rotation is maintained without causing any problems.

Therefore, the accuracy of the distance between the two axes of the gearbox and the bearing portion and the degree of parallelism may be lower than that of the conventional ones, and processing and assembly are facilitated.

(b) When the pinion shaft is a flexible shaft, vibration is prevented even when passing through critical speeds by the damping action of the spring and the damping action of the squeezing effect of the liquid.

Therefore, a flexible shaft can be applied, and the device can be made smaller and lighter.

(c) As shown in (a) and (b) above, it has the effect of suppressing vibrations, both for gear meshing problems and for flexible shafts passing through critical speeds, and therefore for gear meshing. It becomes possible to use a radial rolling bearing on the pinion shaft, which is a flexible shaft, which performs the rotation, which reduces mechanical loss and makes it easier to manufacture the bearing part.

(d) Since the spring force of the compression coil spring can be easily adjusted using the spring seat, the annular gap during assembly can be adjusted by taking into consideration the movement of the pinion shaft due to the gear load during operation, and the gap can be made uniform during operation. A uniform oil film can be formed, and vibrations can be reduced by utilizing the damping effect of this oil film's squeezing effect.

[Brief explanation of drawings]

1 and 2 show examples of the present invention, FIG. 1 is a longitudinal sectional view of a compressor, FIG. 2 is a sectional view of a damper bearing, and FIG. 3 is a sectional view of a damper bearing of a comparative example. It is a diagram. 1... Compressor casing, 2... Impeller, 3... Pinion, 4... Pinion shaft, 5...
Gear casing, 6... Damper bearing, 8... Gear, 11... Motor, 12... Motor shaft, 13...
...Balance weight, 14... Thrust transmission collar, 15... Motor casing, 16, 17...
End bracket, 18, 19...Bearing, 20...
... Seal, 21 ... Bearing section, 22 ... Spring, 23
...Juan, 24...Oil cooler, 25...
Oil pump, 26...Fixed ring, 27...Outer ring, 2
8...Gap, 29...Inner peripheral ring, 30...Spring, 3
1... Spring seat, 32... Oil pipe, 33... Radial rolling bearing, 34... Oil pipe, 35... Spring, 36...
...Flange.

Claims (1)

[Claims] 1 A pinion shaft 4 that has an impeller 2 at its end and is supported by a damper bearing 6 to serve as a flexible shaft.
and a drive shaft 12 having a gear 8 that meshes with a pinion 3 provided on the pinion shaft 4, the damper bearing 6 is located inside a fixed outer ring 27, and is connected to the outer ring 27. Circular space 28
The inner circumferential ring 29 is held by a compression coil spring 30 that supports a load in the radial direction, and oil passages 32 and 34 are provided for guiding lubricating oil into the gap 28. The rotating gas is characterized in that a spring seat 31 that holds a radial rolling bearing 33 and adjusts the spring force of the compression coil spring 30 to adjust the annular gap 28 is movably provided on the outer ring 27. machine.