Patent Application
20210340990
This application claims priority to Japanese Patent Application No. 2020-081289 filed on May 1, 2020, the entire disclosure of which is incorporated herein by reference.
The present disclosure relates to a fluid machine.
Japanese Patent Application Publication No. 2010-144537, for example, mentions a fluid machine having a bladed wheel that is rotated together with a rotary shaft. This rotary shaft is required to be rotated at a high speed by an electric motor. Japanese Patent Application Publication No. 2017-158395, for example, mentions a resolver that is configured to sense a rotation angle of a motor rotor of the electric motor. The resolver includes a resolver rotor that is fixed to the rotary shaft and has a cylindrical shape. The bladed wheel is fixed to the rotary shaft.
However, the resolver rotor and the bladed wheel fixed to the rotary shaft may be unstable if creep occurs in the resolver rotor, for example. This may cause runout of the rotary shaft when the rotary shaft is rotated, and may prevent high-speed rotation of the rotary shaft by the electric motor.
The present disclosure, which has been made in light of the above-mentioned problem, is directed to providing a fluid machine that allows a rotary shaft to be rotated at a high speed by an electric motor.
In accordance with an aspect of the present invention, there is provided a fluid machine that includes a bladed wheel, an electric motor, a resolver, a first fastener, and a second fastener. The bladed wheel is rotated together with a rotary shaft. The electric motor includes a motor rotor fixed to the rotary shaft, and is configured to rotate the rotary shaft. The resolver includes a resolver rotor that has a cylindrical shape, and is configured to sense a rotation angle of the motor rotor. The first fastener fixes the resolver rotor to the rotary shaft. The second fastener fixes the bladed wheel to the rotary shaft. The rotary shaft has a large-diameter portion and a small-diameter portion that has a diameter smaller than a diameter of the large-diameter portion. The resolver rotor is held between the first fastener and the rotary shaft and fixed to the large-diameter portion. The bladed wheel is held between the second fastener and the rotary shaft and fixed to the small-diameter portion. While the resolver rotor is fixed by the first fastener in a same direction as the bladed wheel is fixed by the second fastener along an axial direction of the rotary shaft, the resolver rotor is fixed by the first fastener at a position away in a radial direction of the rotary shaft from a position where the bladed wheel is fixed by the second fastener so that the resolver rotor does not receive an axial force from the second fastener.
Other aspects and advantages of the disclosure will become apparent from the following description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the disclosure.
The disclosure together with objects and advantages thereof, may best be understood by reference to the following description of the embodiment together with the accompanying drawings in which:
The following will describe a first embodiment of a fluid machine with reference to accompanying
As illustrated in
The housing 11 includes a first partition wall 11a and a second partition wall 11b that partition the housing 11 into the motor chamber 23, the turbine chamber 24, and the impeller chamber 25. The first partition wall 11a is disposed between the motor chamber 23 and the turbine chamber 24, and the second partition wall 11b is disposed between the motor chamber 23 and the impeller chamber 25. The motor chamber 23 accommodates an electric motor 16 and a resolver 20. The motor chamber 23 serves as a first accommodation chamber for accommodating the electric motor 16 and the resolver 20. The turbine chamber 24 accommodates a turbine wheel 13 that serves as a bladed wheel. The turbine chamber 24 serves as a second accommodation chamber for accommodating the turbine wheel 13 as the bladed wheel. The impeller chamber 25 accommodates a compressor impeller 14.
The one end of the rotary shaft 12 penetrates into the turbine chamber 24 through the first partition wall 11a. The turbine wheel 13 is fixed to the one end of the rotary shaft 12. The turbine wheel 13 is rotated together with the rotary shaft 12. The other end of the rotary shaft 12 penetrates into the impeller chamber 25 through the second partition wall 11b. The compressor impeller 14 is fixed to the other end of the rotary shaft 12. The compressor impeller 14 is rotated together with the rotary shaft 12.
The electric motor 16 is configured to rotate the rotary shaft 12. The electric motor 16 includes a motor rotor 15 fixed to the rotary shaft 12 and having a cylindrical shape and a motor stator 17 fixed to the housing 11 and having a cylindrical shape. The motor rotor 15 is disposed inside the motor stator 17 and rotated together with the rotary shaft 12. The motor rotor 15 includes a motor rotor core 15a and a plurality of permanent magnets (not illustrated). The motor rotor core 15a is fixed to the rotary shaft 12 and has a cylindrical shape. The permanent magnets are disposed in the motor rotor core 15a. The motor stator 17 surrounds the motor rotor 15. The motor stator 17 includes a motor stator core 17a and a coil 17b. The motor stator core 17a is fixed to the housing 11 and has a cylindrical shape. The coil 17b is wound around the motor stator core 17a. The coil 17b receives current from a battery (not illustrated) so that the motor rotor 15 is rotated together with the rotary shaft 12. This causes the turbine wheel 13 and the compressor impeller 14 to be rotated together with the rotary shaft 12. The rotary shaft 12 of the fluid machine 10 is rotated, for example, at a speed of 80,000 rpm or more.
The resolver 20 senses a rotation angle of the motor rotor 15. The resolver 20 includes a resolver rotor 21 fixed to the rotary shaft 12 and having a cylindrical shape and a resolver stator 22 fixed to the housing 11 and having a cylindrical shape. The resolver rotor 21 is disposed inside the resolver stator 22 and rotated together with the rotary shaft 12. The resolver stator 22 surrounds the resolver rotor 21. The resolver stator 22 includes a resolver stator core 22a and a coil 22b. The resolver stator core 22a is fixed to the housing 11 and has a cylindrical shape. The coil 22b is wound around the resolver stator core 22a. A resolver lead wire (not illustrated) extends from the coil 22b of the resolver stator 22. The resolver lead wire is electrically connected to a controller (not illustrated). The resolver 20 measures degrees of the rotation of the resolver rotor 21, and outputs the measured degrees of the rotation of the resolver rotor 21 as a resolver signal, which is a two-phase signal, from the coil 22b to the controller via the resolver lead wire.
The fluid machine 10 includes a first radial bearing 31 and a second radial bearing 32 that are disposed in the housing 11. The first radial bearing 31 and the second radial bearing 32 each have a cylindrical shape and support the rotary shaft 12 in a radial direction of the rotary shaft 12 such that the rotary shaft 12 is rotatable. The electric motor 16 is disposed between the first radial bearing 31 and the second radial bearing 32 along the axial direction of the rotary shaft 12. The first radial bearing 31 is located between the electric motor 16 and the turbine wheel 13. The second radial bearing 32 is located between the electric motor 16 and the compressor impeller 14.
The fluid machine 10 includes two thrust bearings 33 disposed in the housing 11. The thrust bearings 33 each have a flat ring shape and support the rotary shaft 12 in the axial direction of the rotary shaft 12 such that the rotary shaft 12 is rotatable. The thrust bearings 33 are disposed between the electric motor 16 and the compressor impeller 14, specifically, between the second radial bearing 32 and the compressor impeller 14 along the axial direction of the rotary shaft 12. The two thrust bearings 33 are supported by the housing 11.
As illustrated in
The rotary shaft 12 has a first shaft portion 12a, a second shaft portion 12b, and a third shaft portion 12c. The first shaft portion 12a, the second shaft portion 12b, and the third shaft portion 12c each have a cylindrical shape. The first shaft portion 12a, the second shaft portion 12b, and the third shaft portion 12c are arranged in this order along the rotary shaft 12 from the one end toward the other end. The first shaft portion 12a has the largest outer diameter among outer diameters of the shaft portions 12a, 12b, 12c, and the second shaft portion 12b has the outer diameter larger than the outer diameter of the third shaft portion 12c. The outer diameters of the shaft portions 12a, 12b, 12c are smaller than an inner diameter of the insertion hole 11h. The first shaft portion 12a, the second shaft portion 12b, and the third shaft portion 12c are coaxial with each other. The first shaft portion 12a, the second shaft portion 12b, and the third shaft portion 12c cooperate to form the one end of the rotary shaft 12.
The rotary shaft 12 has a first receiving surface 121 that has an annular shape and connects an outer peripheral surface of the second shaft portion 12b to an outer peripheral surface of the third shaft portion 12c. The first receiving surface 121 has a flat-surface shape that extends in the radial direction of the rotary shaft 12. The rotary shaft 12 has a second receiving surface 122 that has an annular shape and connects an outer peripheral surface of the first shaft portion 12a to the outer peripheral surface of the second shaft portion 12b. The second receiving surface 122 has a flat-surface shape and extends in the radial direction of the rotary shaft 12. The second receiving surface 122, the second shaft portion 12b, the first receiving surface 121, and the third shaft portion 12c are located inside the motor chamber 23. The first shaft portion 12a protrudes into the turbine chamber 24 through the insertion hole 11h.
The second shaft portion 12b is passed through the resolver rotor 21. The resolver rotor 21 is disposed on the second shaft portion 12b and surrounds the outer peripheral surface of the second shaft portion 12b. The second shaft portion 12b has a length that is longer than the length of the resolver rotor 21 in the axial direction. The resolver rotor 21 is disposed on the second shaft portion 12b and is in contact with the first receiving surface 121. The resolver rotor 21 has an outer diameter that is smaller than the inner diameter of the insertion hole 11h.
The second shaft portion 12b has an external threads 120b on a part of the outer peripheral surface of the second shaft portion 12b that is more adjacent to the second receiving surface 122 than a part of the outer peripheral surface of the second shaft portion 12b on which the resolver rotor 21 is disposed. The external threads 120b is continued to the second receiving surface 122. A first nut 41 serving as a first fastener is mounted on the external threads 120b to fix the resolver rotor 21 to the rotary shaft 12. The first nut 41 has an outer diameter that is approximately equal to the outer diameter of the resolver rotor 21. Accordingly, the outer diameter of the first nut 41 is smaller than the inner diameter of the insertion hole 11h.
The first nut 41 has an internal threaded hole 41a. The internal threaded hole 41a is engaged with the external threads 120b of the second shaft portion 12b to press the resolver rotor 21 against the first receiving surface 121, so that the first nut 41 cooperates with the first receiving surface 121 to fix the resolver rotor 21 between the first nut 41 and the first receiving surface 121 in the axial direction of the rotary shaft 12. Accordingly, the resolver rotor 21 is held between the first nut 41 and the rotary shaft 12 and fixed to the second shaft portion 12b. The first nut 41 generates axial force to fix the resolver rotor 21 to the rotary shaft 12. The first receiving surface 121 receives the axial force from the first nut 41 in the motor chamber 23.
An end face of the first nut 41 distant from the resolver rotor 21 is located between the second receiving surface 122 and the first receiving surface 121 in the axial direction of the rotary shaft 12 with the resolver rotor 21 fixed to the rotary shaft 12 by the first nut 41. Accordingly, the second receiving surface 122 is located between the end face of the first nut 41 distant from the resolver rotor 21 and the turbine chamber 24 in the axial direction of the rotary shaft 12 with the resolver rotor 21 fixed to the rotary shaft 12 by the first nut 41.
The turbine wheel 13 includes a vane portion 13a. The vane portion 13a has a vane insertion hole 13b that extends in an axial direction of the turbine wheel 13 and through which the first shaft portion 12a is inserted. The vane portion 13a has a back surface 130a and a cylindrical portion 13c that has a cylindrical shape and protrudes from the back surface 130a. The cylindrical portion 13c is formed on the circumference of the vane insertion hole 13b and in communication with the vane insertion hole 13b.
The fluid machine 10 includes a seal ring 40 that is disposed inside the insertion hole 11h and creates a seal between the motor chamber 23 and the turbine chamber 24. A seal holding member 44 has a cylindrical shape, and is disposed inside the insertion hole 11h. The seal holding member 44 has an annular seal accommodation groove 43 in which the seal ring 40 is accommodated. The seal accommodation groove 43 and the seal ring 40 extend in a circumferential direction of the insertion hole 11h. Accordingly, in this embodiment, the seal holding member 44, which has the seal accommodation groove 43 in which the seal ring 40 is accommodated, is formed separately from the turbine wheel 13. The seal holding member 44 is, for example, made of iron.
The seal holding member 44 has a diameter L2 that is larger than an outer diameter L1 of the second shaft portion 12b, the outer diameter of the first nut 41, and the outer diameter of the resolver rotor 21. Accordingly, a part of the seal holding member 44 is disposed between the first nut 41 and the turbine wheel 13 in the axial direction of the rotary shaft 12. The seal accommodation groove 43 is formed in an outer peripheral surface of the seal holding member 44. The seal accommodation groove 43 has a bottom surface 43a that has a flat-surface shape extending in the axial direction of the rotary shaft 12. Accordingly, the bottom surface 43a of the seal accommodation groove 43 forms a cylindrical shape that surrounds the axis of the rotary shaft 12 and extends in the axial direction of the rotary shaft 12. The seal holding member 44 has the diameter L2 that is defined by the bottom surface 43a of the seal accommodation groove 43. The diameter L2 is larger than the outer diameter L1 of the second shaft portion 12b. The diameter L2 of the seal holding member 44, which is defined by the bottom surface 43a of the seal accommodation groove 43, is the minimum diameter of the seal accommodation groove 43 defined by the bottom surface 43a that forms an inner circumference of the seal accommodation groove 43. Further, in this embodiment, the outer diameter L1 of the second shaft portion 12b is an outer diameter of the most flexible portion of the rotary shaft 12. The seal ring 40 supported by the seal accommodation groove 43 creates a seal between an inner peripheral surface of the insertion hole 11h and the outer peripheral surface of the seal holding member 44.
The cylindrical portion 13c of the turbine wheel 13 is fitted into the seal holding member 44. The seal holding member 44 has a length that is equal to the length of the cylindrical portion 13c in the axial direction. The seal holding member 44 has an end face that is adjacent to the vane portion 13a and in contact with the back surface 130a of the vane portion 13a and the other end face that is distant from the vane portion 13a and located in plane with a distal end face of the cylindrical portion 13c with the cylindrical portion 13c fitted into the seal holding member 44.
The first shaft portion 12a has a protruding end portion 120 that is passed through the cylindrical portion 13c and the vane insertion hole 13b and protrudes from a distal end face 131a of the vane portion 13a. Accordingly, the rotary shaft 12 penetrates the resolver rotor 21, the insertion hole 11h, and the turbine wheel 13. The seal holding member 44 has an inner diameter that is smaller than the outer diameter of the second shaft portion 12b. Accordingly, an inner peripheral region of the other end face of the seal holding member 44 distant from the vane portion 13a and the distal end face of the cylindrical portion 13c face the second receiving surface 122 in the axial direction of the rotary shaft 12.
The protruding end portion 120 of the first shaft portion 12a has an external threads 120a on an outer peripheral surface of the protruding end portion 120. A second nut 42 serving as a second fastener is mounted on the external threads 120a to fix the turbine wheel 13 to the rotary shaft 12. The second nut 42 has an internal threaded hole 42a. The internal threaded hole 42a is engaged with the external threads 120a of the first shaft portion 12a to press the turbine wheel 13 and the seal holding member 44 against the second receiving surface 122, so that the second nut 42 cooperates with the second receiving surface 122 to fix the turbine wheel 13 and the seal holding member 44 between the second nut 42 and the second receiving surface 122 in the axial direction of the rotary shaft 12. The turbine wheel 13 is held between the second nut 42 and the rotary shaft 12 and fixed to the first shaft portion 12a. Accordingly, the rotary shaft 12 has the second shaft portion 12b that serves as a large-diameter portion to which the resolver rotor 21 is fixed and the first shaft portion 12a that serves as a small-diameter portion to which the turbine wheel 13 is fixed. The first shaft portion 12a has a diameter smaller than the diameter of the second shaft portion 12b.
The turbine wheel 13 and the seal holding member 44 are rotated together with the rotary shaft 12. The turbine wheel 13 and the seal holding member 44 cooperate to form a rotating body 45 that is fixed to the rotary shaft 12 and rotated together with the rotary shaft 12.
The second nut 42 generates axial force to fix the turbine wheel 13 and the seal holding member 44 to the rotary shaft 12. Accordingly, the resolver rotor 21 is fixed by the first nut 41 in the same direction as the turbine wheel 13 is fixed by the second nut 42 along the axial direction of the rotary shaft 12. The first nut 41 is fixed to the second shaft portion 12b, and the second nut 42 is fixed to the first shaft portion 12a. The resolver rotor 21 is fixed by the first nut 41 at a position away from a position where the turbine wheel 13 is fixed by the second nut 42 in the radial direction of the rotary shaft 12.
The second receiving surface 122 is located between the end face of the first nut 41 distant from the resolver rotor 21 and the turbine chamber 24 in the axial direction of the rotary shaft 12 with the resolver rotor 21 fixed to the rotary shaft 12 by the first nut 41. The seal holding member 44 is distant from the first nut 41 in the axial direction of the rotary shaft 12. Accordingly, a clearance is formed between the seal holding member 44 and the first nut 41 in the axial direction of the rotary shaft 12.
The following will describe a method for fixing the resolver rotor 21 and the turbine wheel 13 to the rotary shaft 12.
First, the first shaft portion 12a of the rotary shaft 12 is inserted from the motor chamber 23 into the turbine chamber 24 through the insertion hole 11h so that the first shaft portion 12a protrudes into the turbine chamber 24. The first shaft portion 12a is inserted through the resolver rotor 21. Then, the resolver rotor 21 is passed from the turbine chamber 24 to the motor chamber 23 through the insertion hole 11h to be placed in the motor chamber 23 with the second shaft portion 12b inside the resolver rotor 21. The resolver rotor 21 is disposed on the rotary shaft 12 such that the resolver rotor 21 surrounds the outer peripheral surface of the second shaft portion 12b and is in contact with the first receiving surface 121.
Next, the first shaft portion 12a is passed through the first nut 41. The first nut 41 is then passed through the insertion hole 11h from the turbine chamber 24 so that the internal threaded hole 41a of the first nut 41 is engaged with the external threads 120b of the second shaft portion 12b. The first nut 41 is tightened to the external threads 120b of the second shaft portion 12b so that the first nut 41 comes into contact with the resolver rotor 21 and cooperates with the first receiving surface 121 to hold the resolver rotor 21 between the first nut 41 and the first receiving surface 121. The axial force of the first nut 41 is transmitted to the first receiving surface 121 via the resolver rotor 21. That is, the first receiving surface 121 receives the axial force of the first nut 41, so that the resolver rotor 21 is fixed to the first shaft portion 12a.
Then, the cylindrical portion 13c of the turbine wheel 13 is fitted into the seal holding member 44 with the seal ring 40 preliminarily disposed in the seal accommodation groove 43 so that the first shaft portion 12a is inserted through the cylindrical portion 13c and the vane insertion hole 13b of the rotating body 45, which is integrally formed by the seal holding member 44 and the turbine wheel 13. While the seal holding member 44 and the cylindrical portion 13c are placed inside the insertion hole 11h, the seal holding member 44 and the turbine wheel 13 are disposed on the first shaft portion 12a such that the inner peripheral region of the other end face of the seal holding member 44 distant from the vane portion 13a and the distal end face of the cylindrical portion 13c are in contact with the second receiving surface 122. The seal ring 40 supported by the seal accommodation groove 43 is disposed inside the insertion hole 11h and creates a seal between the inner peripheral surface of the insertion hole 11h and the outer peripheral surface of the seal holding member 44.
Then, the internal threaded hole 42a of the second nut 42 is engaged with the external threads 120a of the protruding end portion 120 of the first shaft portion 12a. The second nut 42 is tightened to the external threads 120a of the protruding end portion 120 so that the second nut 42 comes into contact with the distal end face 131a of the vane portion 13a and cooperates with the second receiving surface 122 to hold the turbine wheel 13 and the seal holding member 44 between the second nut 42 and the second receiving surface 122. The axial force of the second nut 42 is transmitted to the second receiving surface 122 via the turbine wheel 13 and the seal holding member 44. That is, the second receiving surface 122 receives the axial force of the second nut 42, so that the rotating body 45, which is formed by the turbine wheel 13 and the seal holding member 44, is fixed to the rotary shaft 12. Accordingly, the resolver rotor 21 and the turbine wheel 13 are fixed to the rotary shaft 12.
Next, the following will describe the operation of the fluid machine 10 according to the first embodiment.
While the resolver rotor 21 is fixed by the first nut 41 in the same direction as the turbine wheel 13 is fixed by the second nut 42 along the axial direction of the rotary shaft 12, the resolver rotor 21 is fixed by the first nut 41 at a position away in the radial direction of the rotary shaft 12 from a position where the turbine wheel 13 is fixed by the second nut 42. This configuration prevents the resolver rotor 21 from receiving the axial force from the second nut 42. Accordingly, even if creep occurs in the resolver rotor 21, for example, the axial force of the second nut 42 does not decrease. Further, the diameter L2 of the seal holding member 44 defined by the bottom surface 43a of the seal accommodation groove 43 is larger than the outer diameter L1 of the second shaft portion 12b. That is, the minimum diameter of the seal accommodation groove 43 defined by the inner circumference of the seal accommodation groove 43 is larger than the outer diameter of the most flexible portion of the rotary shaft 12. This configuration allows the eigenvalue of the rotary shaft 12 to be easily secured, thereby reducing the runout of the rotary shaft 12.
The first embodiment provides the following advantageous effects.
(1-1) While the resolver rotor 21 is fixed by the first nut 41 in the same direction as the turbine wheel 13 is fixed by the second nut 42 along the axial direction of the rotary shaft 12, the resolver rotor 21 is fixed by the first nut 41 at a position away in the radial direction of the rotary shaft 12 from a position where the turbine wheel 13 is fixed by the second nut 42. This configuration prevents the resolver rotor 21 from receiving the axial force from the second nut 42. Accordingly, even if creep occurs in the resolver rotor 21, for example, the axial force of the second nut 42 does not decrease. This allows the resolver rotor 21 and the turbine wheel 13 to be stably fixed to the rotary shaft 12 respectively by the first nut 41 and the second nut 42. This therefore facilitates the high-speed rotation of the rotary shaft 12 by the electric motor 16.
(1-2) The cylindrical seal holding member 44 having the seal accommodation groove 43 is disposed inside the insertion hole 11h, and the clearance is formed between the seal holding member 44 and the first nut 41 in the axial direction of the rotary shaft 12. This configuration allows, for example, the seal holding member 44 to be made of material different from the material of the turbine wheel 13. For example, the seal holding member 44 may be made of material with higher strength than that of the turbine wheel 13. This enhances the durability of the fluid machine 10.
(1-3) The minimum diameter of the seal accommodation groove 43 defined by the inner circumference of the seal accommodation groove 43 is larger than the outer diameter of the most flexible portion of the rotary shaft 12. This configuration allows the eigenvalue of the rotary shaft 12 to be easily secured, thereby reducing the runout of the rotary shaft 12. Therefore, this facilitates the high-speed rotation of the rotary shaft 12 by the electric motor 16.
(1-4) The cylindrical seal holding member 44 is disposed inside the insertion hole 11h. The seal holding member 44 is rotated together with the rotary shaft 12, and has the annular seal accommodation groove 43 in which the seal ring 40 is accommodated. This configuration eliminates the need to form the seal accommodation groove 43, which supports the seal ring 40, in the outer peripheral surface of the rotary shaft 12, thereby preventing the reduction in the outer diameter of the rotary shaft 12 due to the formation of the seal accommodation groove 43. This therefore reduces the runout of the rotary shaft 12.
The following will describe a second embodiment of a fluid machine with reference to accompanying
As illustrated in
The first nut 41 is mounted on the external threads 120b of the second shaft portion 12b, so that the first nut 41 is disposed inside the insertion hole 11h. The first nut 41 has the annular seal accommodation groove 43 in which the seal ring 40 is accommodated. The seal accommodation groove 43 is formed in an outer peripheral surface of the first nut 41 and extends in the circumferential direction of the insertion hole 11h. The seal ring 40 is disposed inside the insertion hole 11h and extends in the circumferential direction of the insertion hole 11h. In the second embodiment, the first nut 41 serves as the first fastener that fixes the resolver rotor 21 to the rotary shaft 12, and also serves as the seal holding member that has a cylindrical shape and has the seal accommodation groove 43 in which the seal ring 40 is accommodated. The first nut 41 has a diameter L3 that is defined by the bottom surface 43a of the seal accommodation groove 43. The diameter L3 is larger than the outer diameter L1 of the second shaft portion 12b. The diameter L3 of the first nut 41, which is defined by the bottom surface 43a of the seal accommodation groove 43, is the minimum diameter of the seal accommodation groove 43 defined by the bottom surface 43a that forms the inner circumference of the seal accommodation groove 43. Further, the outer diameter L1 of the second shaft portion 12b is the outer diameter of the most flexible portion of the rotary shaft 12. The diameter L3 of the first nut 41, which is the minimum diameter of the seal accommodation groove 43 defined by the inner circumference of the seal accommodation groove 43, is larger than the outer diameter L1 of the second shaft portion 12b.
The back surface 130a of the vane portion 13a is in contact with the second receiving surface 122 of the rotary shaft 12 in the turbine chamber 24. The second nut 42 cooperates with the second receiving surface 122 to hold the turbine wheel 13 between the second nut 42 and the second receiving surface 122 in the axial direction of the rotary shaft 12 to fix the turbine wheel 13 to the rotary shaft 12. In this embodiment, the turbine wheel 13 serves as the rotating body to which the rotary shaft 12 is fixed. The vane portion 13a is distant from the first nut 41 in the axial direction of the rotary shaft 12. That is, the turbine wheel 13 is distant from the first nut 41 in the axial direction of the rotary shaft 12. Accordingly, a clearance is formed between the first nut 41 and the turbine wheel 13 in the axial direction of the rotary shaft 12.
The following will describe a method for fixing the resolver rotor 21 and the turbine wheel 13 to the rotary shaft 12.
First, the first shaft portion 12a and the second shaft portion 12b of the rotary shaft 12 are inserted from the motor chamber 23 into the turbine chamber 24 through the insertion hole 11h, so that the first shaft portion 12a and a part of the external threads 120b of the second shaft portion 12b protrude into the turbine chamber 24. The first shaft portion 12a is inserted through the resolver rotor 21. Then, the resolver rotor 21 is passed from the turbine chamber 24 to the motor chamber 23 through the insertion hole 11h to be placed in the motor chamber 23 with the second shaft portion 12b inside the resolver rotor 21. The resolver rotor 21 is disposed on the rotary shaft 12 such that the resolver rotor 21 surrounds the outer peripheral surface of the second shaft portion 12b and is in contact with the first receiving surface 121.
Next, the first shaft portion 12a is passed through the first nut 41 in which the seal ring 40 is preliminarily accommodated in the seal accommodation groove 43. Then, the first nut 41 is then inserted into the insertion hole 11h so that the internal threaded hole 41a of the first nut 41 is engaged with the external threads 120b of the second shaft portion 12b. The first nut 41 is tightened to the external threads 120b of the second shaft portion 12b so that the first nut 41 comes into contact with the resolver rotor 21 and cooperates with the first receiving surface 121 to hold the resolver rotor 21 between the first nut 41 and the first receiving surface 121. The axial force of the first nut 41 is transmitted to the first receiving surface 121 via the resolver rotor 21. That is, the first receiving surface 121 receives the axial force of the first nut 41, so that the resolver rotor 21 is fixed to the rotary shaft 12. The seal ring 40 supported by the seal accommodation groove 43 is disposed inside the insertion hole 11h and creates a seal between the inner peripheral surface of the insertion hole 11h and the outer peripheral surface of the seal holding member 44.
Then, the first shaft portion 12a is inserted through the vane insertion hole 13b of the vane portion 13a. The turbine wheel 13 is disposed on the first shaft portion 12a such that the back surface 130a of the vane portion 13a is in contact with the second receiving surface 122. Then, the internal threaded hole 42a of the second nut 42 is engaged with the external threads 120a of the protruding end portion 120 of the first shaft portion 12a. The second nut 42 is tightened to the external threads 120a of the protruding end portion 120 so that the second nut 42 comes into contact with the distal end face 131a of the vane portion 13a and cooperates with the second receiving surface 122 to hold the turbine wheel 13 between the second nut 42 and the second receiving surface 122. The axial force of the second nut 42 is transmitted to the second receiving surface 122 via the turbine wheel 13. That is, the second receiving surface 122 receives the axial force of the second nut 42, so that the turbine wheel 13 is fixed to the rotary shaft 12. Accordingly, the resolver rotor 21 and the turbine wheel 13 are fixed to the rotary shaft 12.
Next, the following will describe the operation of the fluid machine 10 according to the second embodiment.
While the resolver rotor 21 is fixed by the first nut 41 in the same direction as the turbine wheel 13 is fixed by the second nut 42 along the axial direction of the rotary shaft 12, the resolver rotor 21 is fixed by the first nut 41 at a position away in the radial direction of the rotary shaft 12 from a position where the turbine wheel 13 is fixed by the second nut 42. This configuration prevents the resolver rotor 21 from receiving the axial force from the second nut 42. Accordingly, even if creep occurs in the resolver rotor 21, for example, the axial force of the second nut 42 does not decrease. The diameter L3 of the first nut 41, which is defined by the bottom surface 43a of the seal accommodation groove 43, is larger than the outer diameter L1 of the second shaft portion 12b. That is, the minimum diameter of the seal accommodation groove 43 defined by the inner circumference of the seal accommodation groove 43 is larger than the outer diameter of the most flexible portion of the rotary shaft 12. This configuration allows the eigenvalue of the rotary shaft 12 to be easily secured, thereby reducing the runout of the rotary shaft 12.
The second embodiment provides the following advantageous effects in addition to the effects mentioned in (1-1), (1-3), and (1-4) of the first embodiment.
(2-1) The first nut 41 having the seal accommodation groove 43 is disposed inside the insertion hole 11h, and the clearance is formed between the first nut 41 and the turbine wheel 13 in the axial direction of the rotary shaft 12. This configuration enables the first nut 41 for fixing the resolver rotor 21 to the rotary shaft 12 to also serve as the seal holding member, thereby allowing the size reduction of the fluid machine 10 in the axial direction of the rotary shaft 12, compared with a fluid machine provided with a seal holding member in addition to the first nut 41.
The aforementioned embodiments may be modified as below. The embodiments may be combined with the following modifications within technically consistent range.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2020-081289 | May 2020 | JP | national |
