JP6471704B2 - Electric compressor - Google Patents

Description

  The present invention relates to an electric compressor, and more particularly to an electric compressor suitable for a fuel cell system.

  A turbo blade disposed in the compression chamber for compressing a gas, a motor disposed in the motor chamber for rotationally driving the turbo blade, a rotating shaft connecting the turbo blade and the motor, and a bearing for rotatably holding the rotating shaft; , An electric compressor including the above is known. Patent Document 1 describes an electric compressor in which a seal mechanism is provided between a compression chamber and a motor chamber in order to prevent lubricating oil that lubricates bearings and the like in the motor chamber from flowing out to the compression chamber side. Yes.

JP 2006-177280 A

  An electric compressor for pumping air to a cathode of a fuel cell stack in a fuel cell system including a fuel cell stack that generates electricity by an electrochemical reaction between fuel gas supplied to an anode and oxygen in the air supplied to a cathode Is used. In the fuel cell system, when lubricating oil flows out from the motor chamber side to the compression chamber side in the electric compressor, the lubricating oil flows into the fuel cell stack and the output is greatly reduced. For this reason, in an electric compressor used in a fuel cell system, a seal mechanism that seals between the compression chamber and the motor chamber is indispensable.

  In an existing electric compressor used in a fuel cell system, as a sealing mechanism as described above, a disk-shaped oil discharge rotation that rotates around a rotation shaft connecting a turbo blade and a motor between a compression chamber and a motor chamber The body is provided. A plurality of curved grooves extending from the central portion to the outer periphery are formed on the motor-side surface of the oil discharge rotor. When the rotating shaft that connects the turbo blade and the motor rotates (forward rotation) during the operation of the electric compressor, the oil discharge rotator also rotates (forward rotation). During the operation of the electric compressor, the lubricating oil that has flowed from the motor chamber side through the rotating shaft to the center of the oil discharging rotating body is discharged toward the outer periphery by the centrifugal force through the groove of the oil discharging rotating body. The

  During the operation of the electric compressor, the rotating shaft connecting the turbo blade and the motor does not reversely rotate. However, when the electric compressor is stopped, there is a case where the rotating shaft rotates in a reverse direction although it is minute. When the rotating shaft rotates in the reverse direction, the oil discharge rotating body also rotates in the reverse direction. As described above, when the oil discharge rotator rotates in the forward direction, the lubricating oil that has flowed into the center of the oil discharge rotator is discharged in the outer circumferential direction through the groove by centrifugal force. In contrast, when the oil discharge rotator rotates in the reverse direction, the lubricating oil in the vicinity of the outer periphery of the oil discharge rotator flows through the groove toward the center, so that the lubricant flows out to the compression chamber side. There is a risk that.

  The present invention has been made in view of the above background, and suppresses the outflow of lubricating oil to the compression chamber caused by the reverse rotation of the rotating shaft that connects the turbo blade and the motor during operation stop. An object of the present invention is to provide an electric compressor that can be used.

  The present invention is an electric compressor, and is provided with a turbo blade disposed in a compression chamber for compressing gas, a motor disposed in a motor chamber for rotationally driving the turbo blade, and a rotating shaft connecting the turbo blade and the motor. And a centrifugal force generated by rotation so that the lubricating oil in the motor chamber is rotated between the compression chamber and the motor chamber and rotates around the rotation shaft, and the lubricating oil in the motor chamber does not flow to the compression chamber side through the rotation shaft. And a controller for controlling the rotation of the motor, wherein the motor includes a rotor provided with a magnet, and the rotor. And a stator having a tooth around which a coil is wound, and when the controller stops the rotating rotor, the magnet provided on the rotor comes to the position of the tooth. As such, the rotational speed and rotational acceleration of the rotor is used to apply a current to the coil at a timing equal to or less than a predetermined threshold value, respectively.

  According to the present invention, it is possible to suppress the outflow of lubricating oil to the compression chamber due to the reverse rotation of the rotary shaft that connects the turbo blade and the motor during operation stop.

It is sectional drawing which shows schematic structure of the electric compressor concerning this Embodiment. It is a figure which shows an example of the relationship between the rotational speed of a rotor and time during deceleration control. It is the figure which expanded the area | region B enclosed with the broken line of FIG. It is the figure which looked at the rotary body for oil discharge in an oil discharge mechanism from the compression chamber side. It is a figure explaining the positional relationship of the rotor and stator teeth with which a rotating shaft may reversely rotate while the electric compressor is stopped. It is a figure which shows the positional relationship of the rotor and stator teeth when the magnet arrange | positioned at the rotor exists in the position of teeth. It is a figure explaining the method to stop a rotor so that the magnet arrange | positioned at the rotor may come to the position of teeth. It is a flowchart which shows the flow of a process at the time of stopping the rotor in rotational drive.

  Embodiments of the present invention will be described below with reference to the drawings.

First, a schematic configuration of the electric compressor according to the present embodiment will be described. The electric compressor according to the present embodiment is used, for example, in a fuel cell system to pump air to the cathode of a fuel cell stack.
FIG. 1 is a cross-sectional view illustrating a schematic configuration of an electric compressor 1 according to the present embodiment. As shown in FIG. 1, the electric compressor 1 includes a turbo blade (impeller) 2, a motor 3, a rotating shaft 4, a control unit 5, and an oil discharge mechanism 6.

  The turbo blade 2 is disposed in a compression chamber 8 formed in the compressor housing 7 and compresses gas. The motor 3 is disposed in a motor chamber 10 formed in the motor housing 9 and drives the turbo blade 2 to rotate at high speed. The rotating shaft 4 connects the turbo blade 2 and the motor 3. The rotating shaft 4 is rotatably supported by bearings 13 and 14.

  The motor 3 further includes a stator 11 fixed to the motor housing 9 and a rotor 12 fixed to the rotating shaft 4 corresponding to the stator 11. In the rotating shaft 4, a spacer 15 is attached between the bearing 13 and the rotor 12, and a spacer 16 is attached between the bearing 14 and the rotor 12.

  The oil discharge mechanism 6 is disposed between the compression chamber 8 and the motor chamber 10 and serves as a seal mechanism that prevents the lubricating oil in the motor chamber 10 from flowing out to the compression chamber 8 side. The structure of the oil discharge mechanism 6 and the mechanism by which the oil discharge mechanism 6 prevents the lubricating oil from flowing out into the compression chamber 8 will be described later.

  The control unit 5 performs deceleration control of the rotor 12 when receiving a stop signal of the electric compressor 1 from the external controller 50 or the like. FIG. 2 is a diagram showing an example of the relationship between the rotational speed of the rotor 12 and time (hereinafter referred to as “rotor deceleration curve”) during deceleration control. In FIG. 2, the horizontal axis represents time, and the vertical axis represents the rotational speed of the rotor 12. In addition, the inclination angle of the solid tangent is the rotational acceleration of the rotor 12. In the deceleration control of the rotor 12, as shown in FIG. 2, the rotor 12 is gradually decelerated and stopped.

Next, the structure of the oil discharge mechanism 6 and the mechanism by which the oil discharge mechanism 6 prevents the lubricating oil from flowing out into the compression chamber will be described. In the following description, FIG. 1 is also referred to as appropriate.
FIG. 3 is an enlarged view of a region B surrounded by a broken line in FIG. As shown in FIG. 3, the oil discharge mechanism 6 is opposed to a disk-shaped oil discharge rotating body 6 a that rotates about the rotation shaft 4 and a surface of the oil discharge rotating body 6 a on the compression chamber 8 side. And a disposed wall portion 6b. 4 is a view of the oil discharge rotator 6a as viewed from the compression chamber 8 side (viewed from the arrow A shown in FIG. 3). As shown in FIG. 4, a plurality of curved grooves 20 extending from the central portion to the outer periphery are formed on the surface of the oil discharge rotator 6a on the compression chamber 8 side. The curved groove 20 formed in the oil discharge rotator 6a and the wall 6b (see FIG. 3) constitute a lubricating oil discharge path.

  As shown in FIGS. 3 and 4, when the rotating shaft 4 rotates (forward rotation) during operation of the electric compressor 1, the oil discharge rotating body 6 a of the oil discharge mechanism 6 also rotates (forward rotation). To do. During operation of the electric compressor 1, the lubricating oil in the motor chamber 10 that has flowed into the center of the oil discharge rotator 6a is lubricated by the curved groove 20 and the wall 6b of the oil discharge rotator 6a by centrifugal force. The oil is discharged toward the outer periphery of the rotary shaft 4 through the oil discharge passage. The route of the lubricating oil when the rotating shaft 4 rotates forward is indicated by an arrow C in FIG.

  On the other hand, when the rotating shaft 4 rotates in the reverse direction, the oil discharge rotating body 6a also rotates in the reverse direction. When the oil discharge rotator 6a rotates in the reverse direction, the lubricating oil in the vicinity of the outer periphery of the oil discharge rotator 6a passes through the lubricating oil discharge path formed by the curved groove 20 and the wall 6b of the oil discharge rotator 6a. And flows into the center of the oil discharge rotor 6a. For this reason, there exists a possibility that lubricating oil may flow out to the compression chamber 8 side. The route of the lubricating oil when the rotating shaft 4 rotates in the reverse direction is indicated by an arrow D in FIG. In order to prevent the lubricating oil from flowing out to the compression chamber 8 side, it is necessary to prevent the rotating shaft 4 from rotating backward. During the operation of the electric compressor 1, the rotating shaft 4 is not reversely rotated.

Next, the positional relationship between the rotor 12 and the teeth 17 of the stator 11 that may cause the rotating shaft 4 to reversely rotate while the electric compressor 1 is stopped will be described.
FIG. 5 is a diagram for explaining the positional relationship between the rotor 12 and the teeth 17 of the stator 11 that may cause the rotating shaft 4 to reversely rotate while the electric compressor 1 is stopped. FIG. 5 shows a positional relationship between the rotor 12 and the stator 11 when the motor 3 is viewed in the axial direction from the compression chamber 8 side. As shown in FIG. 5, the stator 11 has a plurality of teeth 17 protruding toward the rotor 12 and wound with a coil. The rotor 12 is provided with two magnets 19 having different magnetic poles on the outer peripheral portion (a rotor having one magnetic pole pair). The two magnets 19 are permanent magnets, one of which has an S magnetic pole and the other has an N magnetic pole, and are disposed at an angle of 180 degrees.

  In the stator 11, an angle formed between adjacent teeth 17 is θ. When the electric compressor 1 is stopped, it is assumed that the angle α formed between the teeth 19a and 17b located closest to the magnet 19 disposed on the rotor 12 and the magnet 19 is θ / 2 or less. While the electric compressor 1 is stopped, the coil wound around the teeth 17 is not energized. For this reason, the magnet 19 of the rotor 12 is attracted to the teeth 17a and 17b formed of a ferromagnetic metal such as iron by the magnetic force, and the rotor 12 rotates in the reverse direction.

  As described above, when the rotor 12 rotates in the reverse direction, the lubricating oil flows out to the compression chamber 8 side (see FIG. 3). In order to prevent such reverse rotation of the rotor 12, as shown in FIG. 6, the rotor 12 may be stopped so that the magnet 19 disposed on the rotor 12 is positioned at the teeth 17a and 17b. .

  FIG. 7 is a diagram for explaining a method of stopping the rotor 12 so that the magnet 19 disposed in the rotor 12 comes to the positions of the teeth 17a and 17b. As shown in FIG. 7, when a direct current is applied to the coils 18 a and 18 b wound around the teeth 17 a and 17 b when the rotational speed of the rotor 12 is sufficiently decelerated, the magnets disposed on the rotor 12. The rotor 12 can be stopped so that the magnet 19 disposed on the rotor 12 comes to the position of the teeth 17a and 17b by being attracted to the teeth 17a and 17b by the magnetic force exerted by the coils 18a and 18b. The state in which the rotor 12 can be stopped so that the rotation speed of the rotor 12 is sufficiently reduced and the magnet 19 disposed in the rotor 12 comes to the position of the teeth 17a and 17b. It is said that it is in a state that can be stopped.

  Whether or not the rotor 12 can be stopped quasi-statically can be determined by the rotational speed and rotational acceleration of the rotor 12. As shown in FIG. 2, the second rotational speed of the rotor 12 is equal to or lower than a first threshold value P (rotational speed ≦ P) which is a predetermined threshold value, and the absolute value of the rotational acceleration of the rotor 12 is a predetermined threshold value When the value is equal to or less than the threshold value Q (| rotational acceleration | ≦ Q), it is determined that the rotor 12 can be stopped quasi-statically.

Next, the flow of processing when stopping the rotor 12 being rotationally driven will be described. In the following description, reference is also made to FIGS. 1 and 7 as appropriate. In addition, the rotor 12 being rotationally driven means a state in which the rotor 12 is rotating by receiving a driving force from the motor 3.
FIG. 8 is a flowchart showing the flow of processing when stopping the rotor 12 being rotationally driven. As shown in FIG. 8, first, it is determined whether or not the control unit 5 has received a stop signal for the electric compressor 1 (step S1). When the control unit 5 receives the stop signal of the electric compressor 1 in step S1 (in the case of YES), the rotor deceleration curve (see FIG. 2) is calculated from the current rotation speed of the rotor 12 and the rotor 12 is stopped. The position is predicted (step S2). In the prediction of the stop position of the rotor 12, when the rotor 12 is stopped according to the calculated rotor deceleration curve, the teeth 17a and 17b located closest to the magnet 19 disposed in the rotor 12 when the rotor 12 is stopped. Predict. Subsequently, the control unit 5 performs deceleration control of the rotor 12 so that the rotor 12 is gradually decelerated at the rotational acceleration calculated in step S2 (step S3).

  Following step S3, it is determined whether or not the rotor 12 can be quasi-statically stopped (step S4). When it is determined in step S3 that the rotor 12 can be stopped quasi-statically (in the case of YES), the control unit 5 controls the magnet 19 disposed on the rotor 12 in step S2. The coils 19a and 18b wound around the teeth 17a and 17b that are predicted to be positioned closest to each other are controlled so that a direct current is applied, and the magnet 19 disposed on the rotor 12 is controlled by the teeth 17a and 17b. It is drawn to 17b (step S5). If it is determined in step S3 that the rotor 12 cannot be stopped quasi-statically (NO), the process returns to step S2.

  As described above, immediately before the rotor 12 stops (when it is determined that the rotor 12 can be stopped quasi-statically), the rotor 12 is disposed in the rotor 12 in predicting the stop position of the rotor 12. A direct current is passed through the coils 18a and 18b wound around the teeth 17a and 17b that are predicted to be closest to the magnet 19 of the rotor 12. By doing in this way, the magnet 19 arrange | positioned at the rotor 12 can be drawn near to the teeth 17a and 17b, and the rotor 12 can be stopped so that the magnet 19 of the rotor 12 may come to the position of the teeth 17a and 17b. Thereby, it can prevent that the rotor 12 reversely rotates at the time of a stop and lubricating oil flows out into the compression chamber 8 side.

  Note that the present invention is not limited to the above-described embodiment, and can be changed as appropriate without departing from the spirit of the present invention. In the above-described embodiment, the case where the rotor has one magnetic pole pair has been described. However, the present invention describes a rotor having two or more magnetic pole pairs (two or more magnetic pole pairs each having N and S poles as one pair). It can also be applied to a provided rotor). Further, the rotor is not limited to a magnet provided on the outer peripheral portion, but may be a rotor in which a magnet is embedded, such as an interior permanent magnet (IPM) motor.

DESCRIPTION OF SYMBOLS 1 Electric compressor 2 Turbo blade 3 Motor 4 Rotating shaft 5 Control part 6 Oil discharge mechanism 6a Oil discharge rotary body 7 Compressor housing 8 Compression chamber 9 Motor housing 10 Motor chamber 11 Stator 12 Rotor 17 (17a, 17b) Teeth 18a, 18b Coil 19 Magnet

Claims (1)

A turbo blade arranged in the compression chamber to compress gas;
A motor disposed in a motor chamber for rotationally driving the turbo blade;
A rotating shaft connecting the turbo blade and the motor;
It is disposed between the compression chamber and the motor chamber, rotates around the rotation shaft, and the centrifugal force by rotation prevents the lubricating oil in the motor chamber from flowing to the compression chamber side through the rotation shaft. An oil discharge rotating body for discharging lubricating oil toward the outer periphery of the rotating shaft;
A control unit for controlling the rotation of the motor,
The motor includes a rotor provided with a magnet, and a stator having teeth that protrude toward the rotor and are wound with a coil.
When the controller stops the rotor that is being rotationally driven, the rotational speed and rotational acceleration of the rotor are less than or equal to predetermined threshold values so that the magnet provided on the rotor comes to the position of the teeth. An electric compressor that applies current to the coil at timing.

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