JP5354558B1 - Rotor liquid cooling system - Google Patents

Abstract

An outer cover that covers a bearing that supports a rotating shaft has a cooling liquid box that is attached via an adapter and receives a front end portion of the rotating shaft that protrudes outward from the outer cover. Rotor liquid cooling device equipped with a liquid inlet pipe and a liquid drainage passage, which prevents the intrusion of the liquid coolant into the housing by a mechanical seal unit having a sliding ring and a fixed ring. Suppresses the increase in vibration acceleration at the location where the mechanical seal unit is mounted due to the forced external force induced by the number, and also suppresses the increase in vibration acceleration at the location where the mechanical seal unit is mounted due to the amount of bending deformation around the rotation axis And improve durability.
A fixing ring 62 is extrapolated to the peripheral edge of the rear end of the mounting bracket 7, and a sliding ring 61 is directly fitted into a recessed portion 32 formed in a recess on the front surface of an adapter 3, so that the sliding ring is moved forward. A coil spring 35 that is biased toward the inside is built in the adapter.
[Selection] Figure 2

Description

  The present invention relates to a rotor liquid cooling apparatus mainly for cooling a rotor of an electric motor.

  This type of liquid cooling device for a rotor is known from Patent Document 1, for example. This housing accommodates a rotor that is extrapolated to the rotating shaft and a stator that surrounds the rotor, and is closely attached to a housing that supports the rotating shaft and is provided with a pair of front and rear bearings in the axial direction of the rotating shaft. And it has the cooling fluid box which receives the front-end part of the rotating shaft which was attached to the outer cover which covers the front bearing which is a non-transmission side via the adapter, and protruded outward from the outer cover. The cooling liquid box is provided with a liquid inlet pipe inserted into the internal passage of the rotating shaft whose front end is open and a drainage passage communicating with the cooling liquid box. Then, the coolant flows into the internal passage of the rotating shaft from the front end of the incoming pipe through the forward passage in the incoming pipe, and consists of a gap between the inner peripheral surface of the rotating shaft and the outer peripheral surface of the incoming pipe. It returns to the inside of the coolant box through the return passage and is discharged from the drain passage.

  Further, the one described in Patent Document 1 (hereinafter simply referred to as “conventional example”) has a sliding ring which is slidable in the axial direction of the rotary shaft attached to a mounting bracket provided on the inner surface of the rear end of the adapter. The fixing ring is attached to another mounting bracket that is extrapolated to the front end of the rotating shaft. Then, the sliding ring is urged forward by the urging means assembled to the adapter to bring the sliding ring and the fixing ring into surface contact, and the mechanical seal unit having these sliding ring and the fixing ring allows the inside of the housing. Intrusion of coolant into the water is prevented. In this case, in order to ensure the sealing performance, wear resistance, mechanical strength and deformation rigidity of the mechanical seal unit, the sliding ring has a base end portion urged by a urging means held by the mounting bracket, From the base end portion, it penetrated the inner surface of the adapter and extended forward, and provided at the front end of the connection portion, and a connection portion having a substantially Z-shape in cross-sectional view that closely contacts the inner peripheral surface of the sliding ring via the O-ring. It consisted of a seal part.

  In the conventional mechanical seal unit, the sliding ring is particularly long and heavy in the axial direction, and the length (overhang distance L) from the front bearing to the fixed portion of the mounting bracket with respect to the rotating shaft is also long. It has become. For this reason, there has been a problem that the whirling vibration caused by the forced external force induced by the unbalanced weight around the rotating shaft at the place where the mechanical seal unit is provided increases.

  Here, according to JIS B 0905-1992, the standard of the balance of the rigidity rotor of the rotating machine, the grade of balance is defined in 11 stages from G0.4 to G4000. If the allowable residual unbalance is Upper (g · mm) and the radius of the rigid rotor that balances the balance is R (mm), the allowable unbalance mass m (g) is m = Upper / R. Even if G0.4 having the best quality is selected and manufactured, the unbalanced mass m remains.

Assuming that the forced external force acting on the rotating shaft induced by the unbalanced mass m around the rotating shaft is P, and the rotational speed of the rigid rotor (rotating shaft and rotor) is n (min ⁻¹ ), P = mR · (2π × n / 60) ² In this case, δ is the amount of bending deformation around the rotation axis at the location where the mechanical seal unit is provided, M is the mass around the rotation axis at the location where the mechanical seal unit is provided, and C is the amount provided by the mechanical seal unit. The damping coefficient K around the rotation axis at a given location, where K is the flexural deformation spring constant around the rotation axis at the location where the mechanical seal unit is provided, is M · d ² δ / dt ² + C · dδ / dt + Kδ = The equation of motion (1) of forced vibration due to the swing of mR · (2π × n / 60) ² is established.

  From the above equation (1), the amplitude of the vibration of the run-out caused by the forced external force P is proportional to the first power of the unbalanced mass m, amplified in proportion to the square of the rotation speed n, and the vibration acceleration of the run-out Increases in proportion to the amplification degree of the amplitude of this vibration. At the same time, the amplitude of the vibration around the rotation axis caused by the amount of deformation δ around the rotation axis at the location where the mechanical seal unit is provided is also almost inversely proportional to the spring constant K of the deformation around the rotation axis. As a result, the amplitude of the vibration around the swing is amplified substantially in proportion to the three items of the overhang distance L, and the vibration acceleration around the swing is also increased in proportion to the amplification degree of the vibration amplitude. Will do.

By the way, in recent years, an electric motor having a higher output (for example, 200 kW) and a high-speed rotation speed (for example, 20000 min ^{−1 to} 35000 min ⁻¹ ) may be required, and as a liquid cooling device for the rotor of such an electric motor. When the above-mentioned conventional example is applied, scratching and spot wear occur on the contact surface as the sealing surface between the sliding ring and the fixing ring that prevents the coolant from entering the housing. This causes a problem that the mechanical seal unit is damaged.

Japanese Patent Laid-Open No. 2738814

  In view of the above points, the present invention suppresses an increase in vibration acceleration at a mechanical seal unit mounting location caused by a forced external force induced by an unbalanced mass and a rotational speed, and at the same time, reduces the amount of bending deformation around the rotation axis. It is an object of the present invention to provide a durable rotor liquid cooling device capable of suppressing an increase in vibration acceleration at a mechanical seal unit mounting location and preventing damage to the mechanical seal unit due to wear. To do.

  In order to solve the above-described problems, the rotor liquid cooling apparatus of the present invention includes a rotor that is extrapolated to a rotating shaft and a stator that surrounds the rotor, and supports the rotating shaft. In the axial direction of the shaft, the front end portion of the rotary shaft that protrudes outward from the outer cover is attached to the outer cover that covers the front bearing in close contact with the housing provided with a pair of front and rear bearings. A cooling liquid box is provided, and the cooling liquid box is provided with a liquid inlet pipe inserted into the internal passage of the rotating shaft whose front end is open and a drainage passage communicating with the cooling liquid box. It flows into the internal passage of the rotating shaft from the front end of the liquid pipe, returns to the cooling liquid box through the gap between the inner peripheral surface of the rotating shaft and the outer peripheral surface of the liquid inlet pipe, and is discharged from the drain passage. The adapter has a sliding ring that is slidable in the axial direction of the rotating shaft. At the same time, the fixing ring is attached to the mounting bracket that is extrapolated to the front end of the rotary shaft, and the sliding ring is urged forward to contact the sliding ring and the fixing ring. And a mechanical seal unit with a fixing ring to prevent the intrusion of coolant into the housing. The adapter is characterized in that the sliding ring is fitted and biasing means for biasing the sliding ring forward is built in the adapter.

  According to the present invention, since the biasing means is built in the adapter, the mounting bracket for holding the biasing means, which has been used in the above-described conventional example, is omitted, and the concave portion provided in the front surface of the adapter is provided. By directly fitting the sliding ring, the length (overhang distance) from the front bearing to the fixed portion of the mounting bracket with respect to the rotating shaft can be significantly shortened as compared with the conventional example. In addition, the weight of the mechanical seal unit itself can be significantly reduced as compared with the conventional example, and as a result, the mechanical seal unit is installed at the place where the mechanical seal unit is attached due to the forced external force induced by the unbalanced mass and the rotational speed. The vibration acceleration can be greatly suppressed compared to the above conventional example, and the vibration acceleration at the mechanical seal unit mounting location due to the bending deformation amount around the rotation axis is greatly compared to the above conventional example. Can be suppressed.

  Therefore, even if the liquid cooling device for a rotor of the present invention is applied to an electric motor having a high output and a high speed, the contact between the sliding ring and the rotating ring as a sealing surface that prevents the liquid from entering the housing. Scratch wear and spot wear can be made difficult to occur on the surface, and damage to the mechanical seal unit accompanying wear can be suppressed and durability can be improved.

  In the present invention, both the front and rear bearings are angular ball bearings, and the direction of both angular ball bearings is such that the intersection of the contact angle extension of the angular ball bearing and the axis of the rotary shaft is the axis of the rotary shaft. It is preferable to dispose each so as to go to the center. According to this, the intersection of the extension of the contact angle of the angular ball bearing and the axis of the rotating shaft, that is, the position of the so-called point of action of the rotor mass is arranged so as to be directed toward the center of the rotating shaft. Induced by unbalanced mass and rotational speed, the distance between the acting points of the angular ball bearing rotor mass is shortened and can adversely affect the mechanical seal unit damage in terms of vibration acceleration. Indirect secondary vibration acceleration at the location where the mechanical seal unit is mounted due to forced external force can be suppressed, and indirect secondary vibration at the location where the mechanical seal unit is mounted due to the amount of bending deformation around the rotation axis. Vibration acceleration can be suppressed, the mechanical seal unit can be made more difficult to break, and durability can be further improved. The angular ball bearings may be provided in a plurality of rows in the axial direction of the rotating shaft.

By the way, the coolant is caused to flow from the front end of the liquid inlet pipe into the internal passage of the rotary shaft, and the coolant is passed through a gap (annular passage) between the inner peripheral surface of the rotary shaft and the outer peripheral surface of the liquid inlet pipe. When it is returned to the box and discharged from the drainage passage, the cooling liquid evaporates and bubbles are generated, causing cavitation, resulting in incidental vibration (and noise) for the mechanical seal unit. There is a case to let you. That is, the cooling liquid is caused to flow from the front end of the liquid inlet pipe into the inner space of the rotary shaft, and is returned to the cooling liquid box through the gap between the inner surface of the rotary shaft and the outer peripheral surface of the liquid inlet pipe. in the flow path to be discharged, the pressure p, the density of the cooling liquid [rho, if the flow velocity of the cooling liquid and V, formula (2) is satisfied that p + pV ^2/2 = constant from Bernoulli's theorem. Then, assuming that the cross-sectional area at each location of the flow path is S and the flow rate of the coolant necessary for cooling the rotor is Q, the equation (3) SV = Q is established.

  From the above equation (3), when the cross-sectional area S at each location of the flow path changes, a location where the flow velocity V of the coolant increases and a location where it slows down are generated. Where the pressure becomes narrower, the pressure p is low, and when the pressure p becomes equal to or lower than the vapor pressure of the coolant, the coolant evaporates and bubbles are generated. And at the downstream side of the flow path where the cross-sectional area S of the flow path is wide and the flow velocity V of the cooling liquid is slow, the pressure p rises and bubbles are crushed and a sudden pressure fluctuation occurs. In addition, an incidental vibration (and noise) is generated.

  Therefore, in the present invention, the mounting bracket is formed with a bulging portion that protrudes in the radial direction, and the extension portion having a drainage port that surrounds the bulging portion and that leads to the drainage passage is formed in the adapter. Preferably, the swelled portion and the extending portion define a narrowed passage having a cross-sectional area equivalent to the cross-sectional area of the passage between the inner surface of the rotating shaft and the outer peripheral surface of the liquid inlet pipe. According to this, the coolant passes through the gap (annular passage) between the inner peripheral surface of the rotating shaft and the outer peripheral surface of the liquid inlet pipe, to the front end of the rotating shaft having a relatively large flow path area. When reaching the flow path between the inner surfaces of the opposing cooling liquid boxes, the flow rate becomes slow and the pressure rises, but since the narrow passage is provided on the downstream side, the coolant that has reached the flow path enters the narrow passage. And the pressure increase is suppressed, and bubbles can be prevented from being crushed and generating a sudden pressure fluctuation. In the present invention, the equivalent cross-sectional area includes not only the case where the cross-sectional areas are exactly the same, but also the case where the pressure does not increase as the generated bubbles are crushed.

  Further, in the present invention, the outer ring of the front bearing is biased rearward through an outer ring spacer in which the outer cover is provided with an oil supply hole for supplying lubricating oil to the front bearing. It is preferable to adopt a configuration in which other urging means is incorporated and a predetermined set load acts on the outer ring of the front bearing. According to this, during assembly of the liquid cooling device into the housing and during maintenance including cleaning of the oil supply holes, replacement of the urging means, and inspection, for example, the parts such as the urging means and the outer ring spacer are outside the housing from the front bearing. Therefore, the bearing and the rotary shaft itself may be assembled in the housing, and the assembling and disassembling workability can be improved.

Sectional drawing of the electric motor provided with the liquid cooling device of the rotor of this invention. Sectional drawing which expands and shows the liquid cooling device shown in FIG. (A)-(c) is a figure which models and shows the support by the angular ball bearing of a rotating shaft. (A) is a deformation | transformation figure when the bending deformation amount (delta) around the rotating shaft in the attachment location of a mechanical seal unit is finite element analysis in this invention. (B) is a deformation | transformation figure when the bending deformation amount (delta) around the rotating shaft in the attachment location of a mechanical seal unit in a prior art example is analyzed by finite element.

  Hereinafter, an embodiment in which a rotor liquid cooling device of the present invention is applied to an electric motor will be described with reference to the drawings. In the following, terms indicating directions such as “up” and “down” are based on FIG. 1, and in FIG. 1, the left side which is the non-transmission side of the motor is the front, and the right side which is the transmission side of the motor is the rear. To do.

  With reference to FIG. 1, EM is an electric motor provided with the liquid cooling device CM of the rotor of this embodiment. The electric motor EM includes a housing 1, and a rotating shaft 12 is pivotally supported on the housing 1 via a pair of bearings 11 a and 11 b arranged on front and rear wall surfaces 10 a and 10 b facing each other. A rotor 13 is extrapolated to the rotary shaft 12, and a stator 14 is disposed in the housing so as to surround the rotor 13. In addition, since the thing of a well-known structure can be utilized as the electric motor EM, the detailed description beyond this is abbreviate | omitted. And the liquid cooling device CM of this embodiment is attached to the outer side of the wall surface 10a of the housing 1 located in the left side in FIG.

  Referring also to FIG. 2, the liquid cooling device CM is attached to the outer cover 2 that is in close contact with the wall surface 10 a of the housing 1 and covers the front bearing 11 a via the adapter 3 and protrudes outward from the outer cover 2. It has a coolant box 4 that receives the front end portion of the rotating shaft 12. The outer cover 2 is extrapolated to the rotary shaft 12 so that its rear surface is in close contact with the housing 1 via an O-ring 2a. In this case, an oil drain groove 21 is formed at a position where the outer cover 2 contacts the rotating shaft 12. A first recess 22 for receiving the nut member 5 for retaining the front bearing 11a is provided in the center of the front surface of the outer cover 2, and is positioned around the first recess 22 so as to be positioned on the front surface of the outer cover 2. Are provided with four second recesses 23 at intervals of 90 degrees in the radial direction. The second recess 23 incorporates coil springs 24 and 24 as other urging means. The coil springs 24, 24 are directed to the outer ring of the front bearing 11 a rearward through an outer ring spacer 25 provided with an oil supply hole 25 a that communicates with an oil supply passage 15 formed in the housing 1 and supplies lubricating oil. The predetermined set load acts on the outer ring of the front bearing 11a. Further, the center of the front surface of the outer cover 2 is formed in a convex shape, and the adapter 3 is fitted through the convex portion. In addition, about the number of the 2nd recessed parts 23 and the coil springs 24, it can provide in the range of 4-16 pieces at equal distribution angular intervals.

  In a state where the adapter 3 is closely attached to the outer cover 2 via the O-ring 2b, the coolant leaked from the sealing surface of the mechanical seal unit described later between the front surface of the outer cover 2 and the rear surface of the adapter 3. The liquid reservoir 31 for storing the water is defined. A drain hole 26 is formed in the outer cover 2 so as to communicate with the leakage reservoir 31 and reach the outer peripheral surface of the outer cover 2 so that the leakage is discharged to the outside. As a result, it is reliably prevented that the liquid leaks into the oil drain groove 21 of the outer cover 2, the bearing 11 a, and eventually into the housing 1.

  The cooling liquid box 4 is assembled in close contact with the adapter 3 via the O-ring 2c. The cooling liquid box 4 is inserted into the cooling pipe 4 and the liquid inlet pipe 41 concentrically inserted in the internal passage 12a of the rotary shaft 12 whose front end is open. A drainage passage 42 communicating therewith is provided. The coolant made of incompressible fluid flows from the front end of the inlet pipe 41 through the forward passage 41a in the inlet pipe 41 into the internal passage 12a of the rotary shaft 12, and the coolant that has bounced back at the rear end of the internal passage 12a. Then, it returns to the cooling liquid box 4 through a return passage 41b formed by a gap between the inner peripheral surface of the rotating shaft 12 and the outer peripheral surface of the liquid inlet pipe 41, and is discharged from the drainage passage 42 (see FIG. 1). . A mechanical seal unit 6 is provided to prevent the coolant from entering the housing 1 when the coolant is flowed in this way.

  The mechanical seal unit 6 includes a sliding ring 61 that is slidably attached to the adapter 3 in the axial direction of the rotation shaft, and a fixing ring 62 that is attached to the mounting bracket 7. In this case, an annular recess 32 is recessed in the center of the front surface of the adapter 3, and a receiving hole 33 is further recessed in the bottom surface of the recess 32. The sliding ring 61 is composed of a base portion 61a inserted into the indented portion 32 via the O-ring 34 and an annular flat portion 61b extending continuously from the front end of the base portion 61a toward the inside in the radial direction. The sliding ring 61 is directly fitted into the indented portion 32 with the coil spring 35 as a biasing means for biasing the sliding ring 61 forward. On the other hand, the mounting bracket 7 is extrapolated to the front end of the rotating shaft 12 and fixed by a screw 71, and a fixing ring 62 is extrapolated to the rear peripheral edge portion of the mounting bracket 7 via an O-ring 73. In this case, the fixing ring 62 is formed so as to cover the outer peripheral edge portion of the rear surface from the peripheral surface of the mounting bracket 7. Then, the sliding ring 61 is urged forward, and the annular convex portion provided on the front surface of the sliding ring 61 is brought into surface contact with the rear surface of the fixing ring 62 so that the coolant enters the housing 1. Try to prevent.

  According to the above, by installing the coil spring 35 in the adapter 3, the mounting bracket for holding the urging means used in the conventional example can be omitted, and the recessed portion provided in the front of the adapter 3 is recessed. By directly fitting the sliding ring 61 to 32, the length from the front bearing 11a to the fixed portion of the mounting bracket 7 with respect to the rotating shaft 12, that is, the overhang distance L can be significantly shortened (the above conventional example) 40% less). In addition, the weight of the mechanical seal unit 6 itself can be significantly reduced (40% less than the above conventional example). As a result, the mechanical seal unit 6 is installed at a place where the mechanical seal unit is attached due to the forced external force induced by the unbalanced mass and the rotational speed. Compared with the conventional example, the vibration acceleration at the mounting position of the mechanical seal unit due to the amount of bending deformation around the rotation axis can be suppressed by 40% or more. 45% or more.

  By the way, as in the above embodiment, when the liquid cooling device CM is configured and the rotating shaft 12 is rotated, it is desirable to suppress indirect secondary vibration acceleration at the mounting position of the mechanical seal unit 6. Therefore, in the present embodiment, the bearings respectively provided in the housing 1 are angular ball bearings in which the front bearing 11a located on the counter-transmission side on the left side in FIG. 1 is positioned on the transmission side on the right side in FIG. The rear bearing 11b was also an angular ball bearing. The orientations of the angular ball bearings 11a and 11b are arranged such that the intersection of the extension line of the contact angle of the angular ball bearings 11a and 11b and the axis of the rotating shaft is directed to the center of the rotating shaft. The intersections of the extension lines of the contact angles of the angular ball bearings 11a and 11b and the axis of the rotary shaft, that is, the position of the so-called rotor mass acting point are arranged so as to be directed to the center of the rotary shaft, respectively. The unbalanced mass and the number of rotations, which can adversely affect the damage of the mechanical seal unit 6 in terms of vibration acceleration in a superimposed manner, because the distance between the acting points of the rotor masses of the angular ball bearings 11a and 11b is shortened. Indirect secondary vibration acceleration at the mounting position of the mechanical seal unit 6 due to the forced external force induced by the rotation can be suppressed, and the mechanical seal unit 6 mounted due to the amount of bending deformation around the rotating shaft 12 Indirect secondary vibration acceleration at a location can be suppressed. In other words, the amplitude of vibration caused by the amount of bending deformation around the rotor 13 increases or decreases in proportion to the cube of the distance between the operating points. Therefore, by reducing the distance l, the mechanical seal unit can be reduced. It is possible to reduce the vibration acceleration that indirectly influences.

Here, in FIG. 3A, as described above, the direction of the angular ball bearing is the intersection of the contact angle extension line of the angular ball bearing and the axis of the rotary shaft 12 (so-called point of action of the rotor mass). This is a model in which the rotor 13 is arranged so as to be directed toward the center. The action point of the mass of the rotating shaft 12, that is, the fulcrum of the rotating shaft 12, can be modeled as a simply supported beam. Here, the amount of deflection deformation of the rotating shaft is δ ′, the forced external force P ′ acting on the rotating shaft at the location where the rotor is extrapolated, the distance between the fulcrums of the angular ball bearings, l, Assuming that the bending rigidity is EI, the bending deformation amount δ ′ can be calculated by the equation (4) of δ ′ = P ′ · l ³ / 48EI. As a result, the amount of bending deformation of the modeled rotating shaft increases in proportion to the cube of the distance l between the fulcrums. Therefore, if the distance between the fulcrums 1 is shortened, the amplitude of vibration caused by the amount of bending deformation δ ′ is reduced. It can be reduced by the cube of the distance l between the fulcrums. As a result, in the above-described embodiment, vibration acceleration that is indirect secondary to the mechanical seal unit 6 but has an adverse effect in a superimposed manner can be reduced.

In the present embodiment, the rotating shaft is supported by one angular ball bearing provided on the wall surfaces 10a and 10b of the housing 1 facing each other. However, the present invention is not limited to this. Two angular ball bearings may be arranged in a row on the wall surface 10a of the front housing 1 on the counter-transmission side. In FIG. 3B, the angular ball bearings 10 a, 10 a are oriented so that the intersection of the contact angle extension line of the angular ball bearing and the axis of the rotary shaft 12 (so-called mass operating point of the rotor) is the rotor 13. Of the rotating shaft 12, the front supporting point among the supporting points of the rotating shaft 12 is fixed support, and the rear supporting point is simply supported. Can be modeled as a beam. In this case, the bending deformation amount of the rotating shaft can be calculated by the equation (5) where δ ′ = 1 / √5 × P ′ · l ³ / 48EI. As a result, the amount of bending deformation of the modeled rotating shaft calculated from the above equation (4) can be reduced to 1 / √5, and accordingly, indirect secondary to the mechanical seal unit 6 is superimposed. The vibration acceleration that adversely affects the image can be further reduced.

On the other hand, two angular ball bearings 11a, 11a, 11b, and 11b may be provided on the wall surfaces 10a and 10b of the housing 1, respectively. FIG. 3 (c) shows the direction of the angular ball bearings 11a, 11a, 11b, and 11b at the intersection of the contact angle extension of the angular ball bearings 11a, 11a, 11b, and 11b and the axis of the rotary shaft 12 (so-called rotation). The mass action point of the child is arranged so as to be directed toward the center of the rotor 13, and the mass action point of the rotating shaft 12, that is, both fulcrums are modeled as fixed support beams. Can be In this case, the bending deformation amount of the rotating shaft 12 can be calculated by the following equation (6): δ ′ = 1/4 × P ′ · l ³ / 48EI. As a result, it is possible to reduce the deformation amount of the rotating shaft of the modeling calculated from the above formula (4) to ¼, and accordingly, indirect secondary to the mechanical seal unit 6 is superimposed. It is possible to further reduce the vibration acceleration that adversely affects the vibration.

  Here, in order to confirm the effect of the liquid cooling device CM of the present invention, in the liquid cooling device CM of the above embodiment, the bending deformation amount δ around the rotary shaft 12 at the mounting position of the mechanical seal unit 6 is analyzed by finite element analysis. FIG. 4A shows this modification. FIG. 4B corresponds to the conventional example. According to this, the amount of deformation δ around the rotating shaft 12 is 32.compared with that of the above-mentioned conventional example in combination with the reduction in size and weight of the mechanical seal unit 6 and the shortening of the overhang distance L. It was confirmed that it was reduced to 4%. Therefore, the amplitude of the vibration around the rotation due to the amount of bending deformation around the rotation axis at the mounting position of the mechanical seal unit 6 can be reduced by 67.6%.

  By the way, the cooling liquid made of an incompressible fluid flows into the internal passage 12a of the rotating shaft 12 through the forward passage 41a in the incoming pipe 41 from the front end of the incoming pipe 41 and bounces off at the rear end of the internal passage 12a. When the liquid returns into the cooling liquid box 4 through the return passage 41b and is discharged from the drainage passage 42, the cooling liquid evaporates to generate bubbles, thereby causing a cavitation phenomenon. 6 may generate incidental vibration (and noise). For this reason, it is desirable to suppress such incidental vibrations.

  In the above-described embodiment, the bulging portion 72 that protrudes in the radial direction is formed around the mounting bracket 7, and the drainage port 36 a that communicates with the drainage passage 42 is provided in the adapter 3 so as to surround the bulging portion 72. The provided cylindrical extending portion 36 was formed, and the bulging portion 72 and the extending portion 36 defined a narrowed passage 41c. The cross-sectional area of the narrowed passage 41c is made equal to the cross-sectional area of the return passage 41b. Thus, when the coolant reaches the flow path between the front end of the rotating shaft 12 and the inner surface 4a of the coolant box 4 facing the front end of the rotating shaft 12 through the return passage 41b, the flow path area is relatively wide. Although the flow rate becomes slow and the pressure rises, the stenosis passage 41c is provided on the downstream side thereof, so that the coolant that reaches the flow passage flows into the stenosis passage 41c, thereby suppressing the pressure rise and causing the bubbles to collapse rapidly. Generation of pressure fluctuation can be suppressed. Note that the equivalent cross-sectional area includes not only the case where the cross-sectional areas are exactly the same, but also the case where the pressure does not rise so much that the generated bubbles are crushed.

  As mentioned above, although embodiment of this invention was described, this invention is not limited above. In the above embodiment, the liquid cooling device is applied to an electric motor as an example. However, the liquid cooling device may be applied to cooling a rotating shaft of a generator.

EM ... electric motor, CM ... liquid cooling device, 1 ... housing, 11a, 11b ... angular ball bearing (bearing), 12 ... rotary shaft, 12a ... internal passage, 13 ... rotor, 14 ... stator, 2 ... outer cover, 24 ... Coil spring (other biasing means), 25 ... Outer ring spacer, 25a ... Oil supply hole, 3 ... Adapter, 32 ... Recessed part, 35 ... Coil spring (biasing means), 36 ... Extension part, 36a ... Drain port, 4 ... Coolant box, 41 ... Inlet pipe, 41b ... Return passage (gap between the inner peripheral surface of the rotating shaft and the outer peripheral surface of the input pipe), 41c ... Constricted passage, 42 ... Drain A passage, 6 ... a mechanical seal unit, 61 ... a sliding ring, 62 ... a fixing ring, 7 ... a mounting bracket, 72 ... a bulging portion.

Claims (4)

A rotor extrapolated to the rotating shaft and a stator surrounding the rotor are accommodated, and the front of the rotating shaft is supported in close contact with a housing provided with a pair of front and rear bearings in the axial direction of the rotating shaft. A cooling liquid box that receives the front end portion of the rotating shaft that is mounted via an adapter and protrudes outward from the outer cover to the outer cover that covers the bearing of
The cooling liquid box is provided with a liquid inlet pipe inserted into an internal passage of the rotating shaft whose front end is open and a drainage passage communicating with the inside of the cooling liquid box. And is returned to the cooling liquid box through the gap between the inner peripheral surface of the rotating shaft and the outer peripheral surface of the liquid-intake pipe, and is discharged from the drainage passage.
A sliding ring that is slidable in the axial direction of the rotating shaft is attached to the adapter, and a fixing ring is attached to a mounting bracket that is externally attached to the front end of the rotating shaft, and the sliding ring is urged forward. In the liquid cooling device for the rotor, the sliding ring and the fixing ring are brought into contact with each other, and the infiltration of the cooling liquid into the housing is prevented by the mechanical seal unit having the sliding ring and the fixing ring.
A biasing means is provided for extrapolating the fixing ring to the peripheral edge of the rear end of the mounting bracket, and for fitting the sliding ring into a recessed portion recessed in the front surface of the adapter and biasing the sliding ring forward. A liquid cooling device for a rotor, which is built into an adapter.   Both the front and rear bearings are angular ball bearings, and the angular ball bearings are oriented so that the intersection of the contact angle extension of the angular ball bearing and the axis of the rotary shaft is directed to the center of the rotary shaft. The rotor liquid cooling device according to claim 1, wherein the liquid cooling device is arranged in each of the above.   The mounting bracket is formed with a bulging portion projecting in the radial direction, and the adapter is formed with an extending portion surrounding the bulging portion and having a drainage port leading to a drainage passage. The narrowed passage having the cross-sectional area equivalent to the cross-sectional area of the passage between the inner surface of the rotating shaft and the outer peripheral surface of the liquid inlet pipe is defined by the extension portion and the extension portion. The rotor liquid cooling apparatus according to 2.   Another urging means for urging the outer ring of the front bearing toward the rear is incorporated in the outer cover via an outer ring spacer provided with an oil supply hole for supplying lubricating oil to the front bearing. The rotor liquid cooling device according to any one of claims 1 to 3, wherein a predetermined set load is applied to an outer ring of a front bearing.

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