Patent Application
20250020379
The present disclosure relates to a drive system, a turbo compressor, and a refrigeration device.
PTL 1 discloses an electric motor system including an electric motor, a controller, and an electric-current sensor. The electric motor constitutes a bearingless motor that floats and contactlessly supports a rotor including a shaft.
A first aspect of the present disclosure relates to a drive system, the drive system including: a shaft (20) including a measurement target portion (25); a support portion (11) configured to support the shaft (20) contactlessly by an electromagnetic force; a drive portion (12) configured to rotationally drive the shaft (20) by an electromagnetic force; a touchdown bearing (50) configured to, when the shaft (20) is not supported by the support portion (11) contactlessly, come into contact with the shaft (20) and support the shaft (20) such that the shaft (20) is rotatable; a controller (80) configured to perform a starting process before the shaft (20) is supported contactlessly by the support portion (11), in which, in the starting process, the controller (80) detects a rotational angle of the shaft (20) in a state in which the shaft (20) is in contact with the touchdown bearing (50).
Hereinafter, an embodiment will be described in detail with reference to the drawings. In the drawings, the same or corresponding components are denoted by the same reference signs, and the description thereof is not repeated.
In
In the following description, a direction of an axis of a member is referred to as the “axial direction” of the member. A direction orthogonal to an axis of a member is referred to as the “radial direction” of the member. A direction around an axis of a member is referred to as the “circumferential direction” of the member. For example, the axial direction of the shaft (20) is a direction in which the rotational axis of the shaft (20) extends. The radial direction of the shaft (20) is a direction orthogonal to the rotational axis of the shaft (20). The circumferential direction of the shaft (20) is a direction around the rotational axis of the shaft (20).
The casing (2) is formed in a shape of a cylinder whose two ends are closed. A space in the casing (2) is partitioned into two spaces by a wall portion (2a). One of the spaces constitutes an impeller chamber (S1) and the other one of the spaces constitutes a motor chamber (S2). The impeller (3) is accommodated in the impeller chamber (S1). The bearingless motor (30), the magnetic bearing (40), and the touchdown bearing (50) are accommodated in the motor chamber (S2) and are fixed to an inner peripheral wall of the motor chamber (S2). In this example, the casing (2) is disposed such that the axis (the axis of the cylinder) of the casing (2) is horizontal.
The shaft (20) is accommodated in the casing (2). The shaft (20) extends from the impeller chamber (S1) to the motor chamber (S2) through the wall portion (2a). The impeller (3) is fixed to one end portion of the shaft (20). For example, the shaft (20) is made of a magnetic material, such as iron.
In this example, the shaft (20) includes a disk portion (21), a concave portion (22), and a measurement target portion (25). The disk portion (21) is provided at another end portion of the shaft (20). The concave portion (22) is provided in the vicinity of the other end portion of the shaft (20). The concave portion (22) is formed over the entire circumference of the shaft (20). The measurement target portion (25) is provided between the one end portion of the shaft (20) and the concave portion (22).
The measurement target portion (25) is configured such that a distance to a rotational-angle sensor (60), which is described later, changes in accordance with a change in the rotational angle of the shaft (20). In this example, the measurement target portion (25) is formed in a shaft shape. The measurement target portion (25) is provided with a plurality of first step portions (201) and a second step portion (202).
The plurality of first step portions (201) are arranged at predetermined intervals in the circumferential direction of the shaft (20). The plurality of first step portions (201) are provided to detect a change in the rotational angle of the shaft (20).
As illustrated in
The second step portion (202) is provided at a shaft portion adjacent to the first shaft portion (the shaft portion provided with the plurality of first step portions (201)) in the axial direction of the shaft (20). The second step portion (202) is provided to detect a rotation reference of the shaft (20).
As illustrated in
The impeller (3) includes a plurality of blades and is formed to have a substantially conical outer shape. The impeller (3) is accommodated, in a state of being fixed to one end portion of the shaft (20), in the impeller chamber (S1). A suction pipe (P1) and a discharge pipe (P2) are connected to the impeller chamber (S1). The suction pipe (P1) is provided to guide a fluid from the outside into the impeller chamber (S1). The discharge pipe (P2) is provided to guide a fluid compressed in the impeller chamber (S1) and having a high pressure to the outside. In this example, the impeller (3) and the impeller chamber (S1) constitute a compression mechanism.
The bearingless motor (30) includes a rotor (31) and a stator (32), and the bearingless motor (30) supports the shaft (20) contactlessly by an electromagnetic force and rotationally drives the shaft (20). The rotor (31) is fixed to the shaft (20), and the stator (32) is fixed to an inner peripheral wall of the casing (2). In this example, the bearingless motor (30) is disposed between one end portion (the end portion to which the impeller (3) is fixed) of the shaft (20) and the measurement target portion (25).
Specifically, the bearingless motor (30) includes a support winding (35) and a drive winding (36). The support winding (35) and the drive winding (36) are provided at the stator (32).
The support winding (35) is a winding that generates, by being energized, an electromagnetic force for supporting the shaft (20) contactlessly. The support winding (35) functions as a support portion (11) that supports the shaft (20) contactlessly by an electromagnetic force. The support winding (35) is an example of the support portion (11).
The drive winding (36) is a winding that generates, by being energized, an electromagnetic force for rotationally driving the shaft (20). The drive winding (36) functions as a drive portion (12) that rotationally drives the shaft (20) by an electromagnetic force. The drive winding (36) is an example of the drive portion (12).
As illustrated in
The rotor (31) includes a rotor core (310) and a plurality of permanent magnets (311). The rotor core (310) is made of a magnetic material and formed in a columnar shape. For example, the rotor core (310) is constituted by a laminated core in which disc-shaped electromagnetic steel sheets are laminated. A shaft hole into which the shaft (20) is inserted is provided at a central portion of the rotor core (310). The plurality of permanent magnets (311) are disposed at a predetermined angular pitch in the circumferential direction of the rotor (31).
In this example, the rotor (31) is provided with four permanent magnets (311). The four permanent magnets (311) are disposed at an angular pitch of 90° in the circumferential direction of the rotor (31) and embedded in an outer peripheral portion (in the vicinity of the outer peripheral surface) of the rotor core (310). In addition, the four permanent magnets (311) are formed in an arc shape along the outer peripheral surface of the rotor core (310), and the outer peripheral surface side becomes an N pole.
With such a configuration, a portion of the outer peripheral portion of the rotor core (310), the portion being located among the four permanent magnets (311) in the circumferential direction of the rotor (31), becomes a pseudo S pole. The outer peripheral surface side of the four permanent magnets (311) may be the S pole. In this case, a portion of the outer peripheral portion of the rotor core (310), the portion being located among the four permanent magnets (311) in the circumferential direction of the rotor (31), becomes a pseudo N pole.
The stator (32) faces the rotor (31) with a predetermined air gap therebetween. The stator (32) includes a stator core (320), the support winding (35), and the drive winding (36). The stator core (320) is made of a magnetic material. For example, the stator core (320) is constituted by a laminated core in which annular electromagnetic steel sheets are laminated. The stator core (320) includes a back yoke formed in a cylindrical shape and a plurality of teeth (not illustrated) provided on an inner peripheral surface of the back yoke.
The support winding (35) is wound around a radially outside portion of the teeth of the stator core (320). In this example, the bearingless motor (30) is provided with three types of the support windings (35). Specifically, the support windings (35) surrounded by a thick solid line in
The drive winding (36) is wound around a radially inside portion of the teeth of the stator core (320). In this example, the bearingless motor (30) is provided with three types of the drive windings (36). Specifically, the drive windings (36) surrounded by a thick solid line in
The magnetic bearing (40) includes a plurality of electromagnets and supports the shaft (20) contactlessly by the electromagnetic forces of the plurality of electromagnets. The magnetic bearing (40) controls the position of the shaft (20) by an electromagnetic force. The magnetic bearing (40) functions as the support portion (11) that supports the shaft (20) contactlessly by an electromagnetic force. The magnetic bearing (40) is an example of the support portion (11). In this example, a radial magnetic bearing (41) and a thrust magnetic bearing (42) are provided as the magnetic bearing (40).
The radial magnetic bearing (41) controls a radial position of the shaft (20) contactlessly by an electromagnetic force. In this example, the radial magnetic bearing (41) is disposed between the bearingless motor (30) and the measurement target portion (25) of the shaft (20).
As illustrated in
Specifically, the radial magnetic bearing (41) includes a core (410) and a plurality of windings (415). The core (410) is made of a magnetic material and is formed in a cylindrical shape. The core (410) includes a back yoke (411) formed in a cylindrical shape and a plurality of teeth (412) provided on an inner peripheral surface of the back yoke (411). The plurality of windings (415) are wound around the plurality of teeth (412). The windings (415) wound around the teeth (412) constitute a radial electromagnet.
An electromagnetic force for supporting the shaft (20) contactlessly in the radial direction of the radial magnetic bearing (41) is generated by energization of the windings (415) of the first to fourth radial electromagnets (41a to 41d). The position of the shaft (20) in the direction in which the first radial electromagnet (41a) and the second radial electromagnet (41b) face each other is controlled by controlling electric current that flows through the windings (415) of the first radial electromagnet (41a) and the second radial electromagnet (41b). The position of the shaft (20) in the direction in which the third radial electromagnet (41c) and the fourth radial electromagnet (41d) face each other is controlled by controlling electric current that flows through the windings (415) of the third radial electromagnet (41c) and the fourth radial electromagnet (41d).
In this example, the radial magnetic bearing (41) is disposed such that the axis of the radial magnetic bearing (41) coincides with the axis of the stator (32) of the bearingless motor (30).
The thrust magnetic bearing (42) controls the axial position of the shaft (20) contactlessly by an electromagnetic force. As illustrated in
Specifically, the first thrust electromagnet (42a) includes a core formed in an annular shape and a winding wound in an annular shape. For example, an annular groove is formed on the core of the first thrust electromagnet (42a), and a coil of the first thrust electromagnet (42a) is accommodated in the groove of the core of the first thrust electromagnet (42a). The configuration of the second thrust electromagnet (42b) is the same as the configuration of the first thrust electromagnet (42a).
An electromagnetic force for supporting the shaft (20) contactlessly in the axial direction of the thrust magnetic bearing (42) is generated by energization of the windings of the first thrust electromagnet (42a) and the second thrust electromagnet (42b). The position of the shaft (20) in the direction in which the first thrust electromagnet (42a) and the second thrust electromagnet (42b) face each other is controlled by controlling electric current that flows through the windings of the first thrust electromagnet (42a) and the second thrust electromagnet (42b).
For example, during the operation of the turbo compressor (1), the support portion (11) is controlled such that the position of the shaft (20) is at a predetermined reference position. In this example, the reference position is the position of the shaft (20) when the rotational axis of the shaft (20) coincides with a predetermined reference axis and the axial position of the shaft (20) is at a predetermined reference axial position. The reference axis is the axis of the stator (32) of the bearingless motor (30). The reference axial position is the central position between the first thrust electromagnet (42a) and the second thrust electromagnet (42b) of the thrust magnetic bearing (42).
When the shaft (20) is not supported contactlessly by the support portion (11), the touchdown bearing (50) is in contact with the shaft (20) and supports the shaft (20) such that the shaft (20) is rotatable. In this example, a radial touchdown bearing (51) and a radial thrust touchdown bearing (52) are provided as the touchdown bearing (50).
The radial touchdown bearing (51) is formed in an annular shape. The shaft (20) is inserted into the radial touchdown bearing (51). In this example, the radial touchdown bearing (51) is disposed between one end portion (the end portion to which the impeller (3) is fixed) of the shaft (20) and the bearingless motor (30). Specifically, the radial touchdown bearing (51) is disposed at the wall portion (2a) of the casing (2).
The radial touchdown bearing (51) is disposed such that the axis of the radial touchdown bearing (51) coincides with the reference axis (specifically, the axis of the stator (32) of the bearingless motor (30) and the axis of the radial magnetic bearing (41)). The inner diameter of the radial touchdown bearing (51) is smaller than the inner diameter (the diameter of an imaginary cylindrical surface in contact with the tips of the teeth (412)) of the radial magnetic bearing (41).
When the position of the shaft (20) is at the reference position, a gap between the radial thrust touchdown bearing (52) and the shaft (20) is narrower than each of “the gap between the radial magnetic bearing (41) and the shaft (20)” and “the gap between the rotor (31) and the stator (32) of the bearingless motor (30)”.
In this example, the inner peripheral surface of the radial touchdown bearing (51) comes into contact with the shaft (20) that moves in the radial direction of the radial touchdown bearing (51), and the radial touchdown bearing (51) supports the shaft (20) such that the shaft (20) is rotatable. Further, the contact between the shaft (20) and the inner peripheral surface of the radial touchdown bearing (51) can avoid “contact between the rotor (31) and the stator (32) of the bearingless motor (30)” and “contact between the shaft (20) and the radial magnetic bearing (41)”.
The radial thrust touchdown bearing (52) is formed in an annular shape. The shaft (20) is inserted into the radial thrust touchdown bearing (52). In this example, the radial thrust touchdown bearing (52) is disposed between the measurement target portion (25) of the shaft (20) and the thrust magnetic bearing (42). Specifically, the radial thrust touchdown bearing (52) is disposed to face the concave portion (22) of the shaft (20).
The radial thrust touchdown bearing (52) is disposed such that the axis of the radial thrust touchdown bearing (52) coincides with the reference axis (specifically, the axis of the stator (32) of the bearingless motor (30) and the axis of the radial magnetic bearing (41)).
In this example, the radial thrust touchdown bearing (52) faces the concave portion (22) of the shaft (20). Specifically, the inner peripheral surface of the radial thrust touchdown bearing (52) faces a bottom surface of the concave portion (22) of the shaft (20), and two end surfaces of the radial thrust touchdown bearing (52) in the axial direction face two side surfaces of the concave portion (22) of the shaft (20).
When the position of the shaft (20) is at the reference position, a gap between the radial thrust touchdown bearing (52) and the bottom surface of the concave portion (22) of the shaft (20) is narrower than each of “the gap between the radial magnetic bearing (41) and the shaft (20)” and “the gap between the rotor (31) and the stator (32) of the bearingless motor (30)”.
When the position of the shaft (20) is at the reference position, a gap between the radial thrust touchdown bearing (52) and one side surface of the concave portion (22) of the shaft (20) is narrower than a gap between the first thrust electromagnet (42a) of the thrust magnetic bearing (42) and the disk portion (21) of the shaft (20). A gap between the radial thrust touchdown bearing (52) and another side surface of the concave portion (22) of the shaft (20) is narrower than a gap between the second thrust electromagnet (42b) of the thrust magnetic bearing (42) and the disk portion (21) of the shaft (20).
In this example, the inner peripheral surface of the radial thrust touchdown bearing (52) comes into contact with the bottom surface of the concave portion (22) of the shaft (20) that moves in the radial direction of the radial thrust touchdown bearing (52), and the radial thrust touchdown bearing (52) supports the shaft (20) such that the shaft (20) is rotatable. Further, the contact between the bottom surface of the concave portion (22) of the shaft (20) and the inner peripheral surface of the radial thrust touchdown bearing (52) can avoid “the contact between the rotor (31) and the stator (32) of the bearingless motor (30)” and “the contact between the shaft (20) and the radial magnetic bearing (41)”.
Further, in this example, an end surface of the radial thrust touchdown bearing (52) in the axial direction comes into contact with a side surface of the concave portion (22) of the shaft (20) that moves in the axial direction of the radial thrust touchdown bearing (52), and the radial thrust touchdown bearing (52) supports the shaft (20) such that the shaft (20) is rotatable. Further, the contact between the side surface of the concave portion (22) of the shaft (20) and the radial thrust touchdown bearing (52) can avoid contact between the disk portion (21) of the shaft (20) and the thrust magnetic bearing (42).
In the following description, a state in which the shaft (20) is in contact with the touchdown bearing (50) is referred to as “touchdown state”. As illustrated in
The drive system (10) also includes various sensors such as the rotational-angle sensor (60), a position sensor (70), and an electric-current sensor (not shown).
The rotational-angle sensor (60) outputs a signal corresponding to a rotational angle of the measurement target portion (25) of the shaft (20). In this example, the rotational-angle sensor (60) is a gap sensor that outputs a signal corresponding to a distance to the measurement target portion (25). For example, this gap sensor is an eddy-current gap sensor.
Specifically, in this example, the first rotational-angle sensor (61) and the second rotational-angle sensor (62) are provided as the rotational-angle sensor (60). Each of the first rotational-angle sensor (61) and the second rotational-angle sensor (62) is a gap sensor that outputs a signal corresponding to a distance to a measurement target. As the distance between the gap sensor and the measurement target increases, the level (amplitude value) of a signal output from the gap sensor increases.
The first rotational-angle sensor (61) is disposed to face the first shaft portion (the shaft portion provided with the first step portions (201)) of the measurement target portion (25) of the shaft (20), and outputs a signal corresponding to a distance to the first shaft portion of the measurement target portion (25) of the shaft (20). As illustrated in
The second rotational-angle sensor (62) is disposed to face the second shaft portion (the shaft portion provided with the second step portion (202)) of the measurement target portion (25) of the shaft (20), and outputs a signal corresponding to a distance to the second shaft portion of the measurement target portion (25) of the shaft (20). As illustrated in
In this example, the first rotational-angle sensor (61) and the second rotational-angle sensor (62) are disposed vertically below the shaft (20). Further, the first rotational-angle sensor (61) and the second rotational-angle sensor (62) are disposed so as to face the reference axis.
The position sensor (70) outputs a signal corresponding to the position of the shaft (20). In this example, the position sensor (70) is a gap sensor that outputs a signal corresponding to a distance to the shaft (20).
Specifically, in this example, a radial position sensor (71) and a thrust position sensor (72) are provided as the position sensor (70). Each of the radial position sensor (71) and the thrust position sensor (72) is a gap sensor that outputs a signal corresponding to a distance to a measurement target. As the distance between the gap sensor and a measurement target increases, the level (amplitude value) of a signal output from the gap sensor increases.
The radial position sensor (71) outputs a signal corresponding to a radial position of the shaft (20). In this example, the radial position sensor (71) is disposed to face “a shaft portion (hereinafter referred to as “the cylindrical surface portion”) where neither the first step portions (201) nor the second step portion (202) is provided” of the measurement target portion (25) of the shaft (20), and outputs a signal corresponding to a distance to the cylindrical surface portion of the measurement target portion (25) of the shaft (20).
As the radial position sensor (71), two types of radial position sensors (a first radial position sensor (71) and a second radial position sensor (71)) are provided. The first radial position sensor (71) outputs a signal corresponding to the position of the shaft (20) in a direction in which the first radial electromagnet (41a) and the second radial electromagnet (41b) of the radial magnetic bearing (41) face each other. The second radial position sensor (71) outputs a signal corresponding to the position of the shaft (20) in a direction in which the third radial electromagnet (41c) and the fourth radial electromagnet (41d) of the radial magnetic bearing (41) face each other. The radial position sensor (71) is disposed to face the reference axis.
The thrust position sensor (72) outputs a signal corresponding to the axial position of the shaft (20). In this example, the thrust position sensor (72) is disposed to face another end surface of the shaft (20), and outputs a signal corresponding to a distance to the other end surface of the shaft (20).
The drive system (10) includes a controller (80). The controller (80) is connected by signal lines to various sensors provided in the drive system (10), and receives signals output from the various sensors. The controller (80) is connected to a component of the drive system (10) by a signal line and controls the component of the drive system (10). In this example, the controller (80) is connected by signal lines to the bearingless motor (30), the radial magnetic bearing (41), the thrust magnetic bearing (42), the first rotational-angle sensor (61), the second rotational-angle sensor (62), the radial position sensor (71), and the thrust position sensor (72).
Further, the controller (80) receives various instructions, such as a start instruction for starting an operation. Then, the controller (80) performs various processes on the basis of various instructions and signals output from various sensors.
For example, the controller (80) includes a processor, a memory that is electrically connected to the processor and stores a program for actuating the processor, a power supply unit that supplies electric power in accordance with an instruction from the processor, and the like.
The controller (80) performs float position control when the shaft (20) is supported by the support portion (11) contactlessly. In the float position control, the controller (80) detects the position of the shaft (20) on the basis of a signal output from the position sensor (70) and controls the support portion (11) such that the position of the shaft (20) is at a predetermined reference position.
Specifically, the controller (80) detects the radial position (the position of the rotational axis) of the shaft (20) on the basis of a signal output from the radial position sensor (71) and controls electric current that flows through the support windings (35) of the bearingless motor (30) and electric current that flows through the windings (415) of the radial magnetic bearing (41) such that the radial position of the shaft (20) is at a predetermined reference radial position (the position of the reference axis). Further, the controller (80) detects the axial position of the shaft (20) on the basis of a signal output from the thrust position sensor (72) and controls electric current that flows through the winding of the thrust magnetic bearing (42) such that the axial position of the shaft (20) is at the predetermined reference axial position.
Further, when the shaft (20) is rotationally driven by the drive portion (12), the controller (80) detects the rotational angle of the shaft (20) on the basis of a signal output from the rotational-angle sensor (60). In this example, the controller (80) detects the rotational angle of the shaft (20) as follows.
The controller (80) detects a change in the rotational angle of the shaft (20) on the basis of a signal output from the first rotational-angle sensor (61). Hereinafter, a signal output from the first rotational-angle sensor (61) is referred to as “first sensor signal (SS1)”.
Specifically, as illustrated in
For example, the first threshold (Th1) is set to a level that is lower than the level of the first sensor signal (SS1) when the first rotational-angle sensor (61) faces the first step portions (201) of the first shaft portion of the measurement target portion (25) of the shaft (20) and that is higher than the level of the first sensor signal (SS1) when the first rotational-angle sensor (61) faces the remaining portion, excluding the first step portions (201), of the first shaft portion of the measurement target portion (25) of the shaft (20).
Further, the controller (80) detects the rotation reference (reference of the rotational angle) of the shaft (20) on the basis of a signal output from the second rotational-angle sensor (62). Hereinafter, a signal output from the second rotational-angle sensor (62) is referred to as “second sensor signal (SS2)”.
Specifically, as illustrated in
For example, the second threshold (Th2) is set to a level that is lower than the level of the second sensor signal (SS2) when the second rotational-angle sensor (62) faces the second step portion (202) of the second shaft portion of the measurement target portion (25) of the shaft (20) and that is higher than the level of the second sensor signal (SS2) when the second rotational-angle sensor (62) faces the remaining portion, excluding the second step portion (202), of the second shaft portion of the measurement target portion (25) of the shaft (20).
Then, the controller (80) detects the rotational angle of the shaft (20) on the basis of the “change in the rotational angle of the shaft (20)”, which is detected on the basis of the first sensor signal (SS1), and the “rotation reference of the shaft (20)”, which is detected on the basis of the second sensor signal (SS2).
Specifically, as illustrated in
In addition, the controller (80) performs a starting process before the shaft (20) is supported contactlessly by the support portion (11). In the starting process, the controller (80) controls the drive portion (12) to rotate the shaft (20) in a state in which the shaft (20) is in contact with the touchdown bearing (50), and the controller (80) detects the rotational angle of the shaft (20) on the basis of a signal output from the rotational-angle sensor (60).
Next, the starting process will be described with reference to
First, the controller (80) controls the drive portion (12) to rotate the shaft (20) in a state in which the shaft (20) is in contact with the touchdown bearing (50). The controller (80) also controls the drive portion (12) such that the rotational speed of the shaft (20) rotating in the state of being in contact with the touchdown bearing (50) becomes constant.
In this example, the controller (80) supplies electric current to the drive winding (36) of the bearingless motor (30). Consequently, the shaft (20) rotates in the touchdown state. Then, the controller (80) controls electric current that is supplied to the drive winding (36) of the bearingless motor (30) such that the rotational speed of the shaft (20) becomes constant.
Next, the controller (80) detects the rotational angle of the shaft (20) on the basis of a signal output from the rotational-angle sensor (60). In this example, the controller (80) detects the rotational angle of the shaft (20) on the basis of the first sensor signal (SS1) output from the first rotational-angle sensor (61) and the second sensor signal (SS2) output from the second rotational-angle sensor (62).
When the detection of the rotational angle of the shaft (20) is completed, the controller (80) ends the starting process. When the starting process is ended, the controller (80) controls the support portion (11) such that the support portion (11) supports the shaft (20) contactlessly.
As described above, in the embodiment, the controller (80) performs the starting process before the shaft (20) is supported contactlessly by the support portion (11). In the starting process, the controller (80) detects the rotational angle of the shaft (20) in the state in which the shaft (20) is in contact with the touchdown bearing (50). Specifically, in the starting process, the controller (80) controls the drive portion (12) to rotate the shaft (20) in the state in which the shaft (20) is in contact with the touchdown bearing (50), and the controller (80) detects the rotational angle of the shaft (20) on the basis of a signal output from the rotational-angle sensor (60).
With the aforementioned configuration, the rotational angle of the shaft (20) can be detected before the shaft (20) is supported contactlessly.
In addition, by detecting the rotational angle of the shaft (20) before the shaft (20) is supported contactlessly, it is possible to perform, at the time of starting support of the shaft (20) by the support portion (11) contactlessly, control in accordance with the rotational angle of the shaft (20).
For example, when the bearingless motor (30) is used to start support of the shaft (20) contactlessly, the position of the magnetic pole of the rotor (31) fixed to the shaft (20) can be detected on the basis of the rotational angle of the shaft (20). Consequently, it is possible to appropriately control the electric current that flows through the support windings (35) of the bearingless motor (30) to generate an electromagnetic force (an electromagnetic force that can move the shaft (20) toward the reference position) for supporting the shaft (20) contactlessly.
In addition, by detecting the rotational angle of the shaft (20), it is possible to appropriately control the electric current that flows through the drive windings (36) of the bearingless motor (30) to generate an electromagnetic force for rotationally driving the shaft (20).
Thus, control (float control) for supporting the shaft (20) contactlessly and control (rotation control) for rotationally driving the shaft (20) can be stably performed.
In the embodiment, the rotational-angle sensor (60) is a gap sensor that outputs a signal corresponding to a distance to the measurement target portion (25) of the shaft (20). The measurement target portion (25) of the shaft (20) is configured such that the distance to the rotational-angle sensor (60) changes in accordance with a change in the rotational angle of the shaft (20).
With the aforementioned configuration, when the rotational angle of the shaft (20) changes, the distance between the measurement target portion (25) of the shaft (20) and the rotational-angle sensor (60) changes, and, as a result, the signal output from the rotational-angle sensor (60) changes. Therefore, the rotational angle of the shaft (20) can be detected on the basis of the signal output from the rotational-angle sensor (60).
The turbo compressor (1) in Modification 1 of the embodiment is different from the turbo compressor (1) in the embodiment in terms of the arrangement and the performance of the rotational-angle sensor (60). Other configurations and processes of the turbo compressor (1) in Modification 1 of the embodiment are the same as the configurations and the processes of the turbo compressor (1) in the embodiment.
As illustrated in
The first rotational-angle sensor (61) is disposed such that “the distance (G1) between the first rotational-angle sensor (61) and the first shaft portion (the shaft portion provided with the first step portions (201)) of the measurement target portion (25) of the shaft (20) when the shaft (20) is not supported contactlessly by the support portion (11)” is smaller than or equal to “the distance (G0) between the first rotational-angle sensor (61) and the first shaft portion of the measurement target portion (25) of the shaft (20) when the positon of the shaft (20) supported contactlessly by the support portion (11) is at the reference position”.
The second rotational-angle sensor (62) is disposed such that “a distance between the second rotational-angle sensor (62) and the second shaft portion (the shaft portion provided with the second step portion (202)) of the measurement target portion (25) of the shaft (20) when the shaft (20) is not supported contactlessly by the support portion (11)” is smaller than or equal to “a distance between the second rotational-angle sensor (62) and the second shaft portion of the measurement target portion (25) of the shaft (20) when the position of the shaft (20) supported contactlessly by the support portion (11) is at the reference position”.
In Modification 1 of the embodiment, the dynamic range of the rotational-angle sensor (60) is the same as the dynamic range of the position sensor (70). Specifically, the dynamic range of each of the gap sensors that are the first rotational-angle sensor (61) and the second rotational-angle sensor (62) is the same as the dynamic range of the gap sensor that is the radial position sensor (71).
In
As illustrated in
As described above, as the distance between the gap sensor and the measurement target decreases, the signal change corresponding to the distance change of the gap sensor increases. Therefore, as the distance between the rotational-angle sensor (60), which is a gap sensor, and the measurement target portion (25) of the shaft (20) decreases, the signal change corresponding to the distance change of the rotational-angle sensor (60) increases and, as a result, improves accuracy of detection of the rotational angle of the shaft (20) on the basis of the signal output from the rotational-angle sensor (60).
As described above, in Modification 1 of the embodiment, the rotational-angle sensor (60) is disposed such that “the distance (G1) between the rotational-angle sensor (60) and the measurement target portion (25) of the shaft (20) when the shaft (20) is not supported contactlessly by the support portion (11)” is less than or equal to “the distance (G0) between the rotational-angle sensor (60) and the measurement target portion (25) of the shaft (20) when the position of the shaft (20) supported contactlessly by the support portion (11) is at the reference position”.
With the aforementioned configuration, in the starting process in which the shaft (20) is in the touchdown state (state of being in contact with the touchdown bearing (50)), the distance between the rotational-angle sensor (60) and the measurement target portion (25) of the shaft (20) can be made less than or equal to the distance (G0) between the rotational-angle sensor (60) and the measurement target portion (25) of the shaft (20) when the position of the shaft (20) supported by the support portion (11) contactlessly is at the reference position. Consequently, in the starting process, the signal change corresponding to the distance change of the rotational-angle sensor (60) can be avoided to be excessively small. It is thus possible to suppress a decrease in the accuracy of the process of detecting the rotational angle of the shaft (20) on the basis of an output signal of the rotational-angle sensor (60).
In Modification 1 of the embodiment, the dynamic range of the rotational-angle sensor (60) is the same as the dynamic range of the position sensor (70).
With the aforementioned configuration, the type of the gap sensor serving as the rotational-angle sensor (60) and the type of the gap sensor serving as the position sensor (70) can be unified. In other words, the rotational-angle sensor (60) and the position sensor (70) can be configured using the same type of gap sensors. Consequently, procurement costs of the sensors can be reduced.
In
In Modification 2 of the embodiment, the distance between the rotational-angle sensor (60) and the measurement target portion (25) of the shaft (20) when the shaft (20) is in the touchdown state is longer than the distance between the rotational-angle sensor (60) and the measurement target portion (25) of the shaft (20) when the position of the shaft (20) is at the reference position. In this example, the first rotational-angle sensor (61) and the second rotational-angle sensor (62) are disposed vertically above the shaft (20).
In Modification 2 of the embodiment, the controller (80) controls the support portion (11) in the starting process such that the shaft (20) is moved by an electromagnetic force and the measurement target portion (25) of the shaft (20) approaches the rotational-angle sensor (60).
In Modification 2 of the embodiment, the controller (80) controls, while controlling the support portion (11) such that a state in which the measurement target portion (25) of the shaft (20) is close to the rotational-angle sensor (60) is maintained, the drive portion (12) in the starting process to rotate the shaft (20).
In the following description, a state in which the measurement target portion (25) of the shaft (20) is close to the rotational-angle sensor (60) is referred to as “approached state”. In the approached state, the shaft (20) is in contact with the touchdown bearing (50).
As illustrated in
In this example, the distance between the rotational-angle sensor (60) and the measurement target portion (25) of the shaft (20) when the shaft (20) is in the approached state is less than or equal to the distance (G0) (see
Specifically, the distance between the first rotational-angle sensor (61) and the first shaft portion (the shaft portion provided with the first step portions (201)) of the measurement target portion (25) of the shaft (20) when the shaft (20) is in the approached state is less than or equal to the distance (G0) between the first rotational-angle sensor (61) and the first shaft portion of the measurement target portion (25) of the shaft (20) when the position of the shaft (20) supported by the support portion (11) contactlessly is at the reference position.
The distance between the second rotational-angle sensor (62) and the second shaft portion (the shaft portion provided with the second step portion (202)) of the measurement target portion (25) of the shaft (20) when the shaft (20) is in the approached state is less than or equal to the distance between the second rotational-angle sensor (62) and the second shaft portion of the measurement target portion (25) of the shaft (20) when the position of the shaft (20) supported by the support portion (11) contactlessly is at the reference position.
Next, with reference to
First, the controller (80) controls the support portion (11) such that the shaft (20) is moved by an electromagnetic force and the measurement target portion (25) of the shaft (20) approaches the rotational-angle sensor (60).
In this example, the controller (80) supplies electric current to the windings (415) of the radial magnetic bearing (41) to generate an electromagnetic force for moving the shaft (20) vertically upward, and controls the electric current that is supplied to the windings (415) of the radial magnetic bearing (41). Consequently, the shaft (20) moves vertically upward into the approached state (see
Next, in the starting process, the controller (80) controls, while controlling the support portion (11) such that the state in which the measurement target portion (25) of the shaft (20) is close to the rotational-angle sensor (60) is maintained, the drive portion (12) to rotate the shaft (20). The controller (80) also controls the drive portion (12) such that the rotational speed of the shaft (20) rotating in a state of being in contact with the touchdown bearing (50) becomes constant.
In this example, the controller (80) supplies electric current to the drive windings (36) of the bearingless motor (30) while continuing supplying of electric current to the windings (415) of the radial magnetic bearing (41). Consequently, the shaft (20) rotates in the approached state. Then, the controller (80) controls the electric current that is supplied to the drive windings (36) of the bearingless motor (30) such that the rotational speed of the shaft (20) becomes constant.
Next, as in the step (S12), the controller (80) detects the rotational angle of the shaft (20) on the basis of a signal output from the rotational-angle sensor (60). When the detection of the rotational angle of the shaft (20) is completed, the controller (80) ends the starting process. When the starting process is ended, the controller (80) controls the support portion (11) such that the support portion (11) supports the shaft (20) contactlessly.
As described above, in the starting process in Modification 2 of the embodiment, the controller (80) controls the support portion (11) such that the shaft (20) is moved by an electromagnetic force and the measurement target portion (25) of the shaft (20) approaches the rotational-angle sensor (60).
With the aforementioned configuration, in the starting process, the distance between the rotational-angle sensor (60) and the measurement target portion (25) of the shaft (20) can be made shorter than the distance between the rotational-angle sensor (60) and the measurement target portion (25) of the shaft (20) at the start of the starting process. Consequently, in the starting process, the signal change corresponding to the distance change of the rotational-angle sensor (60) can be increased, and accuracy of the process of detecting the rotational angle of the shaft (20) on the basis of an output signal of the rotational-angle sensor (60) can be improved.
In Modification 2 of the embodiment, in the starting process, the controller (80) controls, while controlling the support portion (11) such that a state in which the measurement target portion (25) of the shaft (20) is close to the rotational-angle sensor (60) is maintained, the drive portion (12) to rotate the shaft (20).
With the aforementioned configuration, a state in which the distance between the rotational-angle sensor (60) and the measurement target portion (25) of the shaft (20) is shorter than the “distance between the rotational-angle sensor (60) and the measurement target portion (25) of the shaft (20) at the start of the starting process” can be maintained in the starting process. Consequently, a state in which the signal change corresponding to the distance change of the rotational-angle sensor (60) is large can be maintained in the starting process. It is thus possible to continuously improve accuracy of the process of detecting the rotational angle of the shaft (20) on the basis of an output signal of the rotational-angle sensor (60).
In Modification 2 of the embodiment, the dynamic range of the rotational-angle sensor (60) may be the same as the dynamic range of the position sensor (70). Specifically, the dynamic range of each of the gap sensors that are the first rotational-angle sensor (61) and the second rotational-angle sensor (62) may be the same as the dynamic range of the gap sensor that is the radial position sensor (71).
In
In Modification 3 of the embodiment, the casing (2) is disposed such that the axis (the axis of the cylinder) of the casing (2) is vertical. In this example, the casing (2) is disposed such that one end portion (the end portion to which the impeller (3) is fixed) of the shaft (20) is on the upper side.
In Modification 3 of the embodiment, the measurement target portion (25) of the shaft (20) includes a first measurement target portion (26) and a second measurement target portion (27). The first measurement target portion (26) is provided between one end portion of the shaft (20) and the concave portion (22). The second measurement target portion (27) is provided between one end portion of the shaft (20) and the first measurement target portion (26). In this example, the first measurement target portion (26) is provided between the radial magnetic bearing (41) and the concave portion (22) of the shaft (20). The second measurement target portion (27) is provided between the bearingless motor (30) and the radial magnetic bearing (41).
The first measurement target portion (26) is configured such that a distance to the first rotational-angle sensor (61) changes in accordance with a change in the rotational angle of the shaft (20). Specifically, the first measurement target portion (26) is formed in a shaft shape. The first measurement target portion (26) is provided with a plurality of first step portions (201). The shaft portion of the first measurement target portion (26) of the shaft (20) where the first step portions (201) are provided is a measurement target of the first rotational-angle sensor (61).
The second measurement target portion (27) is configured such that a distance to the second rotational-angle sensor (62) changes in accordance with a change in the rotational angle of the shaft (20). Specifically, the second measurement target portion (27) is formed in a disk shape. A second step portion (202) is provided on one end surface (the side surface on the upper side) of the second measurement target portion (27) in the axial direction. The second measurement target portion (27) is a measurement target of the second rotational-angle sensor (62).
In Modification 3 of the embodiment, the second rotational-angle sensor (62) is disposed to face one end surface (the side surface on the upper side) of the second measurement target portion (27) in the axial direction and outputs a signal corresponding to the distance to the one end surface of the second measurement target portion (27) in the axial direction. When the position of the shaft (20) is at the reference position, the distance between the second step portion (202) of the one end surface of the second measurement target portion (27) in the axial direction and the second rotational-angle sensor (62) is longer than the distance (D20) between the remaining portion, excluding the second step portion (202), of the one end surface of the second measurement target portion (27) in the axial direction and the second rotational-angle sensor (62). Therefore, the level (amplitude value) of a signal output from the second rotational-angle sensor (62) increases when the second rotational-angle sensor (62) faces the second step portion (202).
As illustrated in
As illustrated in
In Modification 3 of the embodiment, the thrust magnetic bearing (42) functions as the support portion (11) that supports the shaft (20) contactlessly by an electromagnetic force. The thrust magnetic bearing (42) is an example of the support portion (11).
The starting process in Modification 3 of the embodiment is the same as the starting process (see
Specifically, first, in the step (S20), the controller (80) supplies electric current to the winding of the thrust magnetic bearing (42) so as to generate an electromagnetic force for moving the shaft (20) vertically upward and controls the electric current that is supplied to the winding of the thrust magnetic bearing (42). Consequently, the shaft (20) moves vertically upward into the approached state (see
Next, in a step (S21), the controller (80) supplies electric current to the drive winding (36) of the bearingless motor (30) while continuing supplying of the electric current to the winding of the thrust magnetic bearing (42). Consequently, the shaft (20) rotates in the approached state. Then, the controller (80) controls the electric current that is supplied to the drive winding (36) of the bearingless motor (30) such that the rotational speed of the shaft (20) becomes constant.
Next, in a step (S22), the controller (80) detects the rotational angle of the shaft (20) on the basis of a signal output from the rotational-angle sensor (60). When the detection of the rotational angle of the shaft (20) is completed, the controller (80) ends the starting process. When the starting process is ended, the controller (80) controls the support portion (11) such that the support portion (11) supports the shaft (20) contactlessly.
In Modification 3 of the embodiment, the same effects as those in Modification 2 of the embodiment can be obtained.
In Modification 3 of the embodiment, the dynamic range of the rotational-angle sensor (60) may be the same as the dynamic range of the position sensor (70). Specifically, the dynamic range of the gap sensor that is the first rotational-angle sensor (61) may be the same as the dynamic range of the gap sensor that is the radial position sensor (71). The dynamic range of the gap sensor that is the second rotational-angle sensor (62) may be the same as the dynamic range of the gap sensor that is the thrust position sensor (72).
In the step (S20) in Modification 3 of the embodiment, the controller (80) may control, while controlling the thrust magnetic bearing (42) to generate an electromagnetic force for moving the shaft (20) vertically upward, the radial magnetic bearing (41) to generate an electromagnetic force for moving the shaft (20) toward (leftward in the example in
In Modification 3 of the embodiment, the casing (2) may be disposed such that the axis (the axis of the cylinder) of the casing (2) is horizontal. In this case, in the starting process, the controller (80) may control the support portion (11) such that the first shaft portion (the shaft portion provided with the first step portions (201)) of the first measurement target portion (26) of the shaft (20) approaches the first rotational-angle sensor (61) and the second measurement target portion (27) of the shaft (20) approaches the second rotational-angle sensor (62). Specifically, in the starting process, the controller (80) may control the radial magnetic bearing (41) such that the first shaft portion of the first measurement target portion (26) of the shaft (20) approaches the first rotational-angle sensor (61) and control the thrust magnetic bearing (42) such that the second measurement target portion (27) of the shaft (20) approaches the second rotational-angle sensor (62).
The turbo compressor (1) in Modification 4 of the embodiment is different from the turbo compressor (1) in the embodiment in terms of “the measurement target portion (25) of the shaft (20)”, “the rotational-angle sensor (60)”, and “the process for detecting the rotational angle of the shaft (20)”. Other configurations and processes of the turbo compressor (1) in Modification 4 of the embodiment are the same as the configurations and the processes of the turbo compressor (1) in the embodiment.
In Modification 4 of the embodiment, one of the plurality of first step portions (201) provided at the measurement target portion (25) of the shaft (20) also serves as the second step portion (202). As illustrated in
In Modification 4 of the embodiment, the rotational-angle sensor (60) is constituted by one rotational-angle sensor. In this example, the rotational-angle sensor (60) is a gap sensor that outputs a signal corresponding to a distance to a measurement target.
The rotational-angle sensor (60) outputs a signal corresponding to the distance to the first shaft portion (the shaft portion provided with the first step portions (201)) of the measurement target portion (25) of the shaft (20).
As illustrated in
Therefore, the level (amplitude value) of a signal output from the rotational-angle sensor (60) increases when the rotational-angle sensor (60) faces the first step portions (201). The level of a signal output from the rotational-angle sensor (60) when the rotational-angle sensor (60) faces the first step portion (201) that is used also as the second step portion (202) is higher than the level of a signal output from the rotational-angle sensor (60) when the rotational-angle sensor (60) faces the first step portions (201) that are not used also as the second step portion (202).
In Modification 4 of the embodiment, as described below, the controller (80) detects the rotational angle of the shaft (20) on the basis of a result of comparison of the level (amplitude value) of a signal output from the rotational-angle sensor (60) with two predetermined thresholds (the first threshold (Th1) and the second threshold (Th2)). The second threshold (Th2) is higher than the first threshold (Th1). Hereinafter, a signal output from the rotational-angle sensor (60) is referred to as a “sensor signal (SS)”.
Specifically, as illustrated in
For example, the first threshold (Th1) is set to a level that is lower than the level of the sensor signal (SS) when the rotational-angle sensor (60) faces the “first step portions (201) that are not used also as the second step portion (202)” of the first shaft portion of the measurement target portion (25) of the shaft (20) and that is higher than the level of the sensor signal (SS) when the rotational-angle sensor (60) faces the remaining portion, excluding the first step portions (201), of the first shaft portion of the measurement target portion (25) of the shaft (20).
Further, the controller (80) compares the level of the sensor signal (SS) with the second threshold (Th2) and generates the second result signal (PP2) in accordance with a result of the comparison. The controller (80) changes the level of the second result signal (PP2) from a low level to a high level when the level of the sensor signal (SS) is higher than the second threshold (Th2) and changes the level of the second result signal (PP2) from a high level to a low level when the level of the sensor signal (SS) is lower than the second threshold (Th2).
For example, the second threshold (Th2) is set to a level that is lower than the level of the sensor signal (SS) when the rotational-angle sensor (60) faces “the first step portion (201) that is used also as the second step portion (202)” of the first shaft portion of the measurement target portion (25) of the shaft (20) and that is higher than the first threshold (Th1).
Then, as illustrated in
As described above, in Modification 4 of the embodiment, one of the plurality of first step portions (201) provided at the measurement target portion (25) of the shaft (20) also serves as the second step portion (202).
With the aforementioned configuration, the number of the rotational-angle sensors (60) can be reduced compared with a case where the first step portions (201) and the second step portion (202) are separately provided at the measurement target portion (25) of the shaft (20). Consequently, costs required for sensors can be reduced.
In
In a refrigeration cycle, the refrigerant discharged from the turbo compressor (1) dissipates heat in the radiator (RR5). The refrigerant that has flowed out from the radiator (RR5) is decompressed in the decompression mechanism (RR6) and evaporates in the evaporator (RR7). The refrigerant that has flowed out from the evaporator (RR7) is sucked into the turbo compressor (1).
In this example, the refrigeration device (RR) is an air conditioner. The air conditioner may be a machine dedicated to cooling or a machine dedicated to heating. The air conditioner also may be an air conditioner in which cooling and heating are switched. In this case, the air conditioner includes a switching mechanism (for example, a four-way switching valve) that switches the circulation direction of a refrigerant. The refrigeration device (RR) also may be a water heater, a chiller unit, a cooling device for cooling air in a device, or the like. The cooling device cools air inside a refrigerator, a freezer, a container, or the like.
In the above description, an example in which the drive system (10) includes the bearingless motor (30) and the magnetic bearing (40) (specifically, the radial magnetic bearing (41) and the thrust magnetic bearing (42)) is presented. The drive system (10) is, however, not limited thereto.
For example, the drive system (10) may include another bearingless motor (30) instead of the radial magnetic bearing (41). The support windings (35) of the bearingless motor (30) function as the support portion (11). The drive windings (36) of the bearingless motor (30) function as the drive portion (12).
Alternatively, the drive system (10) may include, instead of the bearingless motor (30), another radial magnetic bearing (41) and a motor that only rotationally drives the shaft (20). The radial magnetic bearing (41) functions as the support portion (11). This motor functions as the drive portion (12).
In the above description, an example in which the first step portions (201) are concave portions is presented. The first step portions (201) are, however, not limited thereto. For example, the first step portions (201) may be projecting portions. The same applies to the second step portion (202).
Further, in the above description, an example in which the gap sensor is the eddy current gap sensor is presented. The gap sensor is, however, not limited thereto. For example, the gap sensor may be a gap sensor of another type, such as an ultrasonic type or an optical type. When the measurement target portion (25) of the shaft (20) includes a magnetic body, a Hall element may be used as the gap sensor.
Further, in the description of the embodiment, an example in which “the first shaft portion provided with the plurality of first step portions (201)” and “the second shaft portion provided with the second step portion (202)” are adjacent to each other in the axial direction of the shaft (20) is presented. The first shaft portion and the second shaft portion are, however, not limited thereto. For example, the second shaft portion may be disposed at a position away from the first shaft portion.
In the description of Modification 2 of the embodiment, an example in which the drive portion (12) is controlled to rotate the shaft (20) after the support portion (11) is controlled such that the shaft (20) is moved by an electromagnetic force and the measurement target portion (25) of the shaft (20) approaches the rotational-angle sensor (60). Control is, however, not limited thereto. For example, the controller (80) may control, while controlling the drive portion (12) to rotate the shaft (20), the support portion (11) such that the shaft (20) is moved by an electromagnetic force and the measurement target portion (25) of the shaft (20) approaches the rotational-angle sensor (60). The same applies to Modification 3 of the embodiment.
Further, in the description of Modification 4 of the embodiment, an example in which “the first step portion (201) used also as the second step portion (202)” is a concave portion that is deeper than “the other first step portions (201) not used also as the second step portion (202)” is presented. The first step portions (201) are, however, not limited thereto. The first step portion (201) that is used also as the second step portion (202) may be a concave portion that is shallower than the other first step portions (201) that are not used also as the second step portion (202).
In the above description, an example in which the measurement target portion (25) of the shaft (20) is provided with the first step portions (201) and the second step portion (202) is presented. The measurement target portion (25) is, however, not limited thereto. For example, as illustrated in
While embodiments and modifications have been described, it will be understood that forms and details can be variously changed without departing from the spirit and the scope of the claims. In addition, components according to the embodiments, the modifications, and the other embodiments described above may be combined or replaced, as appropriate.
As described above, the present disclosure is useful as a drive system, a turbo compressor, and a refrigeration device.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2022-058244 | Mar 2022 | JP | national |
The present application is a continuation of PCT Application No. PCT/JP2023/011162, filed on Mar. 22, 2023, which claims priority from Japanese Patent Application No. 2022-058244 filed on Mar. 31, 2022, with the Japan Patent Office, and the entire disclosures of these applications are incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/JP2023/011162 | Mar 2023 | WO |
| Child | 18900980 | US |
