Patent ID: 12231019

DESCRIPTION OF EMBODIMENTS

Next, an embodiment of the present invention will be described. A direction perpendicular to the plane of paper inFIG.1(a vertical direction of the plane of paper inFIGS.2(a) and2(b)) is defined as an axial direction. A radial direction of a rotor11(to be described later), which is a direction orthogonal to the axial direction, will be hereinafter simply referred to as a radial direction. A direction orthogonal to both the axial direction and the radial direction is referred to as a circumferential direction.

(Rotary Electrical Machine)

First, the configuration of a rotary electrical machine1according to this embodiment will be described with reference toFIG.1andFIGS.2(a) and2(b).FIG.1is a plan view of the rotary electrical machine1.FIG.2(a)is a cross-sectional view taken along line II(a)-II(a) ofFIG.1.FIG.2(b)is a diagram viewed in the direction of an arrow II(b) ofFIG.1.

As shown inFIG.1, the rotary electrical machine1includes a motor2and a housing3. The motor2is, for example, a publicly known AC motor. The motor2includes a rotor11that is rotatable using the above-mentioned axial direction as the direction of the axis of rotation and a stator12that is disposed outside the rotor11in the radial direction. The motor2is adapted so that the rotor11is rotated by a rotating magnetic field that is generated in a case where alternating current flows through coils (not shown) wound around the stator12.

The rotor11is, for example, a substantially cylindrical member that includes a permanent magnet (not shown). The rotor11is disposed inside the stator12in the radial direction. A rotating shaft13is fitted to the rotor11. The configuration of the rotor11is not limited thereto. For example, the rotor11may include a plurality of salient poles that protrude in a direction orthogonal to the direction of the axis of rotation (that is, the motor2may be, for example, a switched reluctance motor). The stator12is a substantially tubular member that is formed of a magnetic member made of, for example, carbon steel or the like. The stator12is disposed outside the rotor11in the radial direction. The stator12is fitted to the housing3. The stator12includes a substantially cylindrical yoke portion21that is formed over the entire circumference in the circumferential direction and a plurality of teeth22which each extend inward in the radial direction from a part of the yoke portion21in the circumferential direction. In other words, the yoke portion21and the teeth22are integrally provided, and a part of the yoke portion21in the circumferential direction is connected to each of the teeth22. In this embodiment, six teeth22are arranged at substantially regular intervals in the circumferential direction. The yoke portion21includes portions (first portions21a) that are connected to the respective teeth22and portions (second portions21b) which are each disposed between the first portions21aadjacent to each other in the circumferential direction. The second portion21bis a portion that is thinner than a portion of the stator12, at which the first portion21aand the tooth22are connected to each other, in the radial direction. In this embodiment, six second portions21bare formed. In this embodiment, the sizes of all the second portions21bin the circumferential direction are substantially equal to each other, and the sizes of all the second portions21bin the radial direction are substantially equal to each other.

The coil (not shown) is wound around each of the teeth22. The coils are electrically connected to a power supply (not shown). The power supply supplies power, which causes alternating current to flow through the coils, to the motor2. More specifically, the power supply supplies power so that alternating current having the same phase flows through a pair of coils wound around a pair of teeth22positioned on sides opposite to each other with the rotor11interposed therebetween among the six teeth22. In this embodiment, the power supply supplies power so that three types of alternating current having phases different from each other by 120° flow through three pairs of coils, respectively (general three-phase alternating current).

In a case where the above-mentioned power is supplied to the coils in such a motor2, a rotating magnetic field rotating in the circumferential direction in a predetermined cycle is generated and a magnetic force is generated between magnetic poles of the rotating magnetic field and the rotor11. Accordingly, the rotor11is rotated together with the rotating shaft13so as to follow the rotating magnetic field.

The housing3is a case member that is opened on one side thereof in the axial direction and houses the motor2. The housing3is formed of, for example, a die casting that is formed by a general die casting method and is made of an aluminum alloy. The material of the housing3does not necessarily need to be an aluminum alloy. For example, the housing3may be made of metal, such as iron, or may be formed of a member other than metal. Further, the housing3does not necessarily need to be formed by a die casting method and may be formed by another publicly known casting method or the like. The housing3includes a flow passage portion30in which a refrigerant flow passage31through which a refrigerant for cooling the motor2flows is formed. As shown inFIG.1andFIGS.2(a) and2(b), the flow passage portion30includes an inner peripheral wall32, an outer peripheral wall33, a bottom portion34, an inlet portion35, an outlet portion36, and a partition wall portion37.

The inner peripheral wall32extends in the axial direction and is formed over the entire circumference in the circumferential direction. An inner peripheral surface32aof the inner peripheral wall32is in contact with an outer peripheral surface12aof the stator12. In this way, the stator12is fitted to the inner peripheral wall32of the housing3. Like the inner peripheral wall32, the outer peripheral wall33extends in the axial direction and is formed over the entire circumference in the circumferential direction. The outer peripheral wall33is disposed outside the inner peripheral wall32in the radial direction, and is disposed side by side with the inner peripheral wall32in the radial direction. The outer peripheral wall33is provided so that a gap having a predetermined size is formed between the inner peripheral wall32and the outer peripheral wall33in the radial direction. For example, the size of the gap is substantially constant in the circumferential direction. The bottom portion34is provided on the other end portion of the housing3in the axial direction, and connects the inner peripheral wall32to the outer peripheral wall33in the radial direction. The refrigerant flow passage31having a substantially U-shaped cross-section (seeFIG.2(a)) is formed by the inner peripheral wall32, the outer peripheral wall33, and the bottom portion34to extend in the circumferential direction. In other words, the refrigerant flow passage31is formed between the inner peripheral wall32and the outer peripheral wall33.

The inlet portion35is a portion at which an inlet41used to supply a refrigerant to the refrigerant flow passage31is formed. As shown inFIG.1, the inlet41is opened to an inner peripheral surface33aof the outer peripheral wall33at a predetermined position in the circumferential direction. Further, the outer peripheral wall33is provided with a supply pipe portion42that protrudes outward in the radial direction. A through-hole (supply flow passage43) including the inlet41is formed from the tip of the supply pipe portion42to the inner peripheral surface33aof the outer peripheral wall33. The supply flow passage43is connected to the refrigerant flow passage31through the inlet41. The supply flow passage43extends in a direction substantially orthogonal to the axial direction in this embodiment, but is not limited thereto.

The outlet portion36is a portion at which an outlet44used to discharge a refrigerant from the refrigerant flow passage31is formed. Like the inlet41, the outlet44is opened to the inner peripheral surface33aof the outer peripheral wall33. The position of the outlet44in the circumferential direction is different from the position of the inlet41in the circumferential direction (the above-mentioned predetermined position). Further, the outer peripheral wall33is provided with a discharge pipe portion45that protrudes outward in the radial direction. A through-hole (exhaust flow passage46) including the outlet44is formed from the inner peripheral surface33aof the outer peripheral wall33to the tip of the discharge pipe portion45. The exhaust flow passage46is connected to the refrigerant flow passage31through the outlet44. In this embodiment, as viewed in the axial direction, the inlet portion35and the outlet portion36are disposed with the partition wall portion37interposed therebetween to be substantially symmetric with respect to a line (seeFIG.1). Further, the supply flow passage43and the exhaust flow passage46are disposed substantially in parallel to each other, but are not limited thereto.

As shown inFIG.1, the refrigerant flow passage31is broadly divided into two portions by, for example, an imaginary straight line L1that extends in the radial direction and that passes through the center of the inlet41and an imaginary straight line L2that extends in the radial direction and that passes through the center of the outlet44. That is, the refrigerant flow passage31is divided into a first flow passage51of which the length from the inlet41to the outlet44in the circumferential direction is a predetermined length and a second flow passage52of which the length from the inlet41to the outlet44in the circumferential direction is shorter than the predetermined length. The first flow passage51occupies substantially the entire circumference of the refrigerant flow passage31. In this embodiment, the width of the first flow passage51in the radial direction is substantially constant in the circumferential direction. The second flow passage52is a remaining portion of the refrigerant flow passage31that excludes the first flow passage51.

The partition wall portion37is made to suppress the outflow of a refrigerant, which flows into the refrigerant flow passage31through the inlet41, from the outlet44through the short second flow passage52. As shown inFIG.1, the partition wall portion37is provided in a part (in the middle of the second flow passage52) in the circumferential direction, and is disposed between the inner peripheral wall32and the outer peripheral wall33in the radial direction. The partition wall portion37is formed integrally with the inner peripheral wall32and the outer peripheral wall33and extends in the axial direction (seeFIG.2(a)). The partition wall portion37connects the inner peripheral wall32to the outer peripheral wall33. That is, the second flow passage52is divided into two portions by the partition wall portion37. Accordingly, in a case where a refrigerant, which flows into the refrigerant flow passage31through the inlet41, flows toward the second flow passage52, the partition wall portion37can prevent the refrigerant as it is from reaching the outlet44. The partition wall portion37may be provided as a member separate from the inner peripheral wall32and the outer peripheral wall33.

Further, for example, a substantially disc-like lid member38is fixed to one end portion of the housing3in the axial direction by a fixture (not shown). Accordingly, the refrigerant flow passage31is sealed except for the inlet41and the outlet44.

In the above-mentioned refrigerant flow passage31, most of a refrigerant, which flows in through the inlet41, flows into the first flow passage51, flows through the first flow passage51over substantially the entire circumference in the circumferential direction, and flows out through the outlet44. Since the refrigerant flows in this way, the housing3is cooled by the refrigerant and the motor2in contact with the housing3is further cooled by thermal conduction.

Here, in a case where the rotor11is rotating, a magnetic force intermittently acts between the teeth22of the stator12and the rotor11. Accordingly, the teeth22vibrate, and the vibration is transmitted to the entire stator12. In a case where such vibration is transmitted to the inner peripheral wall32from the stator12and is further transmitted to the outer peripheral wall33from the inner peripheral wall32through, for example, the partition wall portion37, the outer peripheral wall33is vibrated and noise may be generated. A method of suppressing the transmission of vibration from the inner peripheral wall32to the outer peripheral wall33without providing the partition wall portion37is conceivable as one of the measures against noise. However, in this case, there is a concern that the second flow passage52will be discontinued between the inlet41and the outlet44and a large amount of refrigerant will likely flow into the second flow passage52. For this reason, there may be a problem in that the amount of refrigerant flowing through the first flow passage51is significantly reduced and that a cooling function significantly deteriorates.

Accordingly, the present inventor focused on a positional relationship between the stator12and the partition wall portion37in order to suppress the transmission of the vibration of the stator12to the outer peripheral wall33of the housing3even in a case where the inner peripheral wall32and the outer peripheral wall33are connected to each other by the partition wall portion37. Specifically, the present inventor focused on a relationship between the position of each second portion21bof the yoke portion21of the stator12in the circumferential direction and the position of the partition wall portion37in the circumferential direction. As described above, the second portion21bis a portion of the yoke portion21disposed between two first portions21athat are adjacent to each other in the circumferential direction (see first portions63and64connected to teeth61and62ofFIG.1, respectively). In more detail, for example, a portion of an outer edge of the tooth61, which extends substantially in the radial direction and is closer to the tooth62in the circumferential direction, as viewed in the axial direction is defined as an outer edge61a. Further, a portion of an outer edge of the tooth62, which extends substantially in the radial direction and is closer to the tooth61in the circumferential direction, as viewed in the axial direction is defined as an outer edge62a. The second portion21bis, for example, a portion of the yoke portion21interposed between an extension line L3of the outer edge61aand an extension line L4of an outer edge62aof the tooth62. A positional relationship between the second portion21band the partition wall portion37in Examples 1 and 2 and a comparative example to be described later will be described below.

Example 1

A positional relationship between the second portion21bof the stator12and the partition wall portion37in the circumferential direction in a rotary electrical machine1of Example 1 will be described with reference toFIG.1. In Example 1, the partition wall portion37is inside the second portion21bin the circumferential direction. In other words, the partition wall portion37faces the second portion21bin the radial direction. In other words, the second portion21bis interposed between the partition wall portion37and the teeth22that are vibrated by an intermittent magnetic force during the operation of the motor2.

In more detail, the partition wall portion37and the center of the second portion21bin the circumferential direction (see a straight line L5ofFIG.1) face each other in the radial direction. In other words, the center of the second portion21bin the circumferential direction is inside the partition wall portion37in the circumferential direction. More strictly speaking, the position of the center of the second portion21bin the circumferential direction and the position of the center of the partition wall portion37in the circumferential direction (see a straight line L6ofFIG.1) coincide with each other.

The present inventor thought that the transmission of the vibration of the stator12to the outer peripheral wall33of the housing3could be suppressed by the following principle in a case where such a configuration was applied. That is, in a case where the stator12is vibrated, the second portion21bthin in the radial direction is deformed and functions as a weak spring element, so that the transmission of the vibration of the stator12to the inner peripheral wall32of the housing3is suppressed. Accordingly, the transmission of vibration to the outer peripheral wall33of the housing3through the partition wall portion37is suppressed. In this way, an anti-vibration function is exhibited by the second portion21b. In addition, since the central portion of the second portion21bin the circumferential direction is farthest from the positions at which the teeth22are provided, the central portion of the second portion21bin the circumferential direction has the lowest stiffness and is most likely to be deformed. For this reason, in a case where the partition wall portion37faces the central portion in the radial direction, an anti-vibration function obtained from the second portion21bis most effectively exhibited.

Example 2

A positional relationship between the second portion21bof the stator12and the partition wall portion37in the circumferential direction in a rotary electrical machine1aof Example 2 will be described with reference toFIG.3. A common point between Example 1 and Example 2 is that the partition wall portion37faces the second portion21bin the radial direction. On the other hand, a difference between Example 1 and Example 2 is that the partition wall portion37does not face the center of the second portion21bin the circumferential direction (see a straight line L5ofFIG.3). Specifically, in Example 2, the center of the second portion21bin the circumferential direction and the center of the partition wall portion37in the circumferential direction are shifted from each other by 15°. The present inventor thought that the transmission of vibration to the inner peripheral wall32of the housing3was suppressed to some extent since the second portion21bwas deformed during the vibration of the stator12even in such a configuration.

Comparative Example

A positional relationship between the second portion21bof the stator12and the partition wall portion37in the circumferential direction in a rotary electrical machine1b of a comparative example will be described with reference toFIG.4. In the comparative example, the partition wall portion37does not face the second portion21bin the radial direction. The partition wall portion37faces the first portion21aof the yoke portion21in the radial direction. In such a configuration, the vibration of the tooth22is transmitted to the inner peripheral wall32without passing through the second portion21band is further transmitted to the outer peripheral wall33through the partition wall portion37. For this reason, the present inventor thought that the outer peripheral wall33would vibrate significantly.

(Analysis of Vibration Amplitude of Outer Peripheral Wall)

The present inventor analyzed the magnitude of the vibration of the outer peripheral wall33in Examples 1 and 2 and the comparative example described above via simulation. Analysis conditions (for example, the size of the tooth22, the size of the partition wall portion37, and the amplitude and frequency of current flowing through the coils) other than a positional relationship between the second portion21band the partition wall portion37in the circumferential direction are common to Examples 1 and 2 and the comparative example. Moreover, the present inventor simulated the strain of the stator12and the strain of the housing3with regard to Examples 1 and 2 and the comparative example. In addition, the present inventor calculated the frequency components of the vibration amplitude of the outer peripheral wall33on the basis of results of the simulation.

The results of the analysis will be described with reference to a graph shown inFIG.5. The graph is a graph showing the frequency components of the above-mentioned vibration amplitude. A horizontal axis represents a frequency. A vertical axis represents a vibration amplitude. In the comparative example (see a solid line ofFIG.5), there was a tendency that a vibration amplitude was significantly increased in a frequency range of 8000 Hz to 11000 Hz as compared to other frequency ranges. On the other hand, an analysis result that a vibration amplitude in a frequency range of 8000 Hz to 11000 Hz was significantly reduced (was substantially reduced by half or more) as compared to the comparative example was obtained in Example 1 (see a broken line ofFIG.5). That is, it was found in Example 1 that an effect of suppressing the vibration of the outer peripheral wall33was significant. Further, an analysis result that a vibration amplitude in the frequency range was generally smaller than a vibration amplitude of the comparative example (was reduced by substantially 20% or more from the vibration amplitude in the comparative example) was also obtained in Example 2 (see a one-dot chain line ofFIG.5). That is, it was also found in Example 2 that an effect of suppressing vibration more significantly than that in the comparative example was obtained.

As described above, in a case where the stator12is vibrated, the second portion21bis deformed and functions as a weak spring element, so that the transmission of vibration to the inner peripheral wall32of the housing3can be suppressed. Accordingly, the transmission of vibration to the outer peripheral wall33of the housing3through the partition wall portion37can be suppressed. Therefore, even in a case where the inner peripheral wall32and the outer peripheral wall33of the housing3are connected to each other by the partition wall portion37, the transmission of the vibration of the stator12to the outer peripheral wall33can be suppressed.

Further, since the central portion of the second portion21bin the circumferential direction is farthest from the positions at which the teeth22are provided, the central portion of the second portion21bin the circumferential direction has the lowest stiffness and is most likely to be deformed. For this reason, particularly, in a case where the partition wall portion37faces the central portion in the radial direction, an anti-vibration function obtained from the second portion21bcan be most effectively exhibited. Accordingly, the transmission of vibration to the outer peripheral wall33through the partition wall portion37can be effectively suppressed.

Next, a modification example in which the embodiment is modified will be described. Here, components having the same configuration as those of the above-mentioned embodiment will be denoted by the same reference numerals as those of the above-mentioned embodiment, and the description thereof will be appropriately omitted.

(1) The number of the teeth22of the stator12has been six and three-phase alternating current has flowed through the coils in the above-mentioned embodiment, but the present invention is not limited thereto. The number of the teeth22may not be six. Further, current (for example, single-phase alternating current) other than three-phase alternating current may flow through the coils. Furthermore, the teeth22do not necessarily need to be arranged at regular intervals in the circumferential direction. That is, the sizes of the plurality of second portions21bin the circumferential direction may be different from each other. In this case, the partition wall portion37may be disposed to be inside the second portion21b, which has the lowest stiffness (for example, longest in the circumferential direction) among the plurality of second portions21b, in the circumferential direction. Further, all the teeth22do not necessarily need to have the same size.

(2) The motor2has been an AC motor in the above-mentioned embodiment, but is not limited thereto. The present invention may be applied to a DC motor.

(3) The rotary electrical machine1and the like include the motor2for rotating the rotating shaft13in the above-mentioned embodiment, but are not limited thereto. For example, a generator that generates an electromotive force on coils by electromagnetic induction in a case where the rotating shaft13is rotated via an external force may be provided instead of the motor2. Alternatively, the motor2may be used as a generator. A magnetic force is intermittently generated between the rotor11and the teeth22even in such a case, so that the stator12is vibrated. Accordingly, it is effective that the partition wall portion37is disposed to face the second portion21bin the radial direction.

REFERENCE SIGNS LIST

1: rotary electrical machine3: housing11: rotor12: stator12a: outer peripheral surface21: yoke portion21a: first portion21b: second portion22: tooth30: flow passage portion31: refrigerant flow passage32: inner peripheral wall33: outer peripheral wall37: partition wall portion