KR100636050B1 - Turbo blower capable of actively adjusting tip clearance of impeller - Google Patents

Abstract

A turbo blower capable of actively adjusting the tip clearance of an impeller is provided to improve the aerodynamic stability by the active response as to the serge and stole phenomena. A turbo blower capable of actively adjusting the tip clearance of an impeller includes a casing(102) having air inlet and outlet ports(104,106); a rotary shaft(107) rotatably supported in the casing, movably installed to the axial direction of the casing, and projected with a thrust collar(108) at the end adjacent to the outlet port; an impeller(110) placed around the air inlet port and combined with the rotary shaft; a motor rotating the rotary shaft; a first pressure unit formed with a pair of electrodes facing each other and a piezoelectric ceramic pad(140) installed between the electrodes to contain the piezoelectric actuator connected to the power supply, and fixed at the casing to face the thrust collar so as to press the rotary shaft to the inlet port side; and a second pressure unit pressing the rotary shaft to the opposite direction to the applied pressure of the first pressure unit.

Description

Turbo blower with active control of impeller tip clearance {TURBO BLOWER CAPABLE OF ACTIVELY ADJUSTING TIP CLEARANCE OF IMPELLER}

1 is a cross-sectional view showing the internal structure of a conventional turbo blower,

Figure 2 is a cross-sectional view showing the internal structure of the turbo blower capable of actively adjusting the impeller tip clearance according to the present invention,

3 is a cross-sectional view showing a coupling structure of a rotary shaft and an air foil journal bearing of a turbo blower according to the present invention;

4A is an enlarged view of a portion “A” of FIG. 2;

4B is an enlarged view of a portion “B” of FIG. 2;

5 is a front view showing a piezoelectric ceramic pad of the turbo blower according to the present invention;

6 is a cross-sectional view showing a turbo blower with a piezoelectric ceramic pad in operation;

7A is an enlarged view of a “C” part of FIG. 6, FIG.

FIG. 7B is an enlarged view of a portion “D” of FIG. 6.

<Explanation of symbols for the main parts of the drawings>

102: casing 104: air inlet

106: air outlet 107: axis of rotation

108: thrust collar 110: impeller

112: armature 116: permanent magnet

120: air foil journal bearing 130: first air foil thrust bearing

140: piezoelectric ceramic pads 142a and 142b: electrodes

144: PZT film 146: PVDF film

150: second air foil thrust bearing 160: variable position plate

164: spring d ₂ : tip clearance

The present invention relates to a turbo blower, and more particularly, to a turbo blower capable of controlling the air flow rate with low power consumption and actively adjusting the impeller tip clearance, which can improve aerodynamic stability.

In general, in a fuel cell system using hydrogen as a fuel, oxygen must be supplied to the cathode as part of a mechanism for generating electricity by reacting with the hydrogen fuel. Turbo blowers and compressors are used.

An example of a conventional turbo blower is disclosed in US Pat. No. 6,682,324, which will be described with reference to FIG.

The conventional turbo blower shown in FIG. 1 is a radial turbo blower, which includes a pump housing 10 and an armature housing 30. The pump housing 10 has a pump chamber 11 for introducing air and an outlet 12 for discharging the introduced air.

In the pump chamber 11, a rotor 13 including a hub 14 and vanes 15 protruding therefrom is disposed. The hub 14 of the rotor 13 comprises a support member 16 consisting of a tube section 16a and a flange section 16b. The flange section 16b forms the rear wall of the rotor 13 and a permanent magnet 17 is disposed.

An inner center of the pump housing 10 is provided with a bearing pin 20 in the axial direction, and an inner center of the armature housing 30 is provided with a base pin 21 integrally formed with the bearing pin 20 in the axial direction. . The base pin 21 is fixed to the rear wall 33 of the armature housing 30. The front ball bearing 22 and the rear ball bearing 23 are installed around the bearing pin 20. These ball bearings 22, 23 support the tube section 16a of the support member 16 of the rotor 13.

In the armature housing 30, an armature 31 having a winding 32 facing the permanent magnet 17 is provided.

When power is applied to the conventional turbo blower, the rotor 13 rotates by the interaction between the armature 31 and the permanent magnet 17. By the rotation of the rotor 13, air is introduced into the pump chamber 11 of the pump housing 10 and discharged through the outlet 12.

However, in the conventional turbo blower configured as described above, the ball bearing supports the rotor of the turbo blower that rotates at a high speed of 30,000 rpm or more at large, so that friction, heat generation, noise and vibration are large, which is not suitable. There is a problem of deterioration of the operating stability. Moreover, there is a disadvantage in that power consumption by friction is large.

In addition, in order to control the air flow rate of the conventional turbo blower, the rotation speed of the rotor must be adjusted according to the motor output. When the conventional turbo blower is used as the air supply device of the fuel cell vehicle, Approximately 15% to 20% of the power appears to be consumed by the turbo blower. Therefore, efforts to improve the efficiency of fuel cells are difficult to achieve without solving the problem of power consumption of the turbo blower.

The present invention is to solve the problems of the prior art, it is an object of the present invention to provide a turbo blower capable of actively adjusting the impeller tip clearance that can ensure the operation stability at high speed.

Another object of the present invention is to provide a turbo blower capable of actively adjusting the impeller tip clearance, which can easily adjust the air flow rate with low power consumption by controlling the axial displacement of the impeller.

Turbo blower capable of actively adjusting the impeller tip clearance according to the present invention for achieving the above object is a casing having an air inlet and outlet; A rotating shaft rotatably supported in the casing, the rotating shaft being provided movably in the axial direction of the casing, and having a thrust collar protruding from an end adjacent to the outlet; An impeller coupled to the rotating shaft adjacent the air inlet; A motor for rotating the rotating shaft; Composed of a pair of electrodes facing each other and a piezoelectric ceramic pad including a piezoelectric actuator provided between the pair of electrodes and connected to a power source, and fixed to the casing to face the thrust collar to press the rotary shaft toward the inlet side. First pressing means; And second pressurizing means for pressurizing the rotating shaft in a direction against the pressing force of the first pressurizing means. Preferably, the piezoelectric actuator is a lead zirconate titanate film.

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 The piezoelectric ceramic pad further includes a piezoelectric pressure sensor provided overlapping the piezoelectric actuator between the pair of electrodes. Preferably, the piezoelectric pressure sensor is a polyvinylidene fluoride film.

 The second pressing means includes a position variable plate corresponding to the first pressure means with the thrust collar therebetween and provided to move in the axial direction of the casing, and a spring for biasing the position variable plate toward the thrust collar side.

An air foil thrust bearing is installed between the thrust collar and the first and second pressurizing means, respectively, and at least one air foil journal bearing is installed around the rotation shaft.

Hereinafter, with reference to the accompanying drawings will be described in detail a preferred embodiment of the present invention.

Figure 2 is a cross-sectional view showing the internal structure of the turbo blower capable of actively adjusting the impeller tip clearance according to the present invention. As shown, the turbo blower according to the present invention is a hybrid turbo blower having both the high compression ratio of the centrifugal blower and the large flow rate of the axial blower. One end of the casing 102 is provided with an air inlet 104 and the other end is provided with an air outlet 106. The inside of the casing 102, the rotating shaft 107 is rotatably disposed along the central axis (X-X) of the casing 102, it is provided to be movable in the axis (X-X) direction of the casing 102. Preferably, the rotating shaft 107 is formed of a lightweight hollow shaft.

An impeller 110 for sucking air through the inlet 104 is coupled to one end of the rotating shaft 107 located at the inlet 104 side of the casing 102. The thrust collar 108 protrudes in the radial direction of the rotating shaft 107 at the other end of the rotating shaft 107 located on the outlet 106 side of the casing 102. The thrust collar 108 opposes the rear wall 109 secured to the casing 102.

An armature housing 114 is installed around the rotating shaft 107 to accommodate the armature 112 wound around the coil. On the outer circumferential surface of the rotating shaft 107, a permanent magnet 116 facing the armature 112 is mounted. That is, it has a structure of a brushless DC motor.

Between the outer surface of the armature housing 114 and the inner wall surface of the casing 102 to suppress the swirl of air flowing into the casing 102 through the air inlet 104 and flowing toward the outlet 106 A plurality of vortex suppression unit 118 is provided for.

In order to smoothly support the high speed rotation of the rotating shaft 107 and the impeller 110, at least one air foil journal bearing 120 is installed around the rotating shaft 107. As shown in FIG. 3, the air foil journal bearing 120 includes a frame 122 having a circular cross section, a bump foil 124 provided on an inner circumferential surface of the frame 122, and a bump foil. A top foil 126 provided over the top of 124 and subjected to a load acting perpendicular to the axial direction of the rotation axis 107.

As shown in FIG. 4B, a first air foil thrust bearing 130 is provided between the thrust collar 108 and the rear wall 109 to support the axial thrust of the rotation shaft 107. . The first air foil thrust bearing 130 is in contact with the thrust collar 108 to support the rotating shaft 107 by an oil film force, the first thrust top foil 132, and the first thrust top foil 132 with elastic force And a first thrust bump foil 134 for imparting vibration absorption force.

Piezoelectric ceramic pads 140 are installed between the first air foil thrust bearing 130 and the rear wall 109. The piezoelectric ceramic pad 140 is a first pressing means for moving the rotating shaft 107 toward the inlet 104 side in the axis XX direction of the casing 102, and has a pair of electrodes 142a and 142b facing each other. , the first and second piezoelectric materials 144 and 146, which are different from each other, overlap each other. As shown in FIG. 5, a plurality of first piezoelectric materials 144 is superimposed on a single second piezoelectric material 146, wherein the plurality of first piezoelectric materials 144 are formed in a substantially fan shape and disposed at an isometric angle. do. The first piezoelectric material 144 is for performing the function of the piezoelectric actuator, and the second piezoelectric material 146 is for performing the function of the piezoelectric pressure sensor. In this embodiment, a zirconium titanate (Pb (Zr, Ti) O ₃ ) film (hereinafter referred to as PZT film) was used as the first piezoelectric material 144 to perform the function of the actuator. When the voltage is applied to the 144, the PZT film 144 expands. In addition, a polyvinylidene fluoride (Polyvinylidene Fluoride) film (hereinafter referred to as PVDF film) was used as the second piezoelectric material 146 to perform the function of the pressure sensor, which was applied to the PVDF film 146. When the voltage is generated in proportion to the pressure is used. Since PZT and PVDF materials are already widely known as representative piezoelectric materials, detailed descriptions of these materials are omitted. As described above, in this embodiment, the PZT film 144 is used as the actuator and the PVDF film 146 is used as the pressure sensor. However, the present invention is not limited thereto, and other piezoelectric materials may be applied. The operation and effect of the piezoelectric ceramic pad 140 will be described later.

A second air foil thrust bearing 150 is provided between the thrust collar 108 of the rotary shaft 107 and the armature housing 114 to support the axial thrust of the rotary shaft 107. The second air foil thrust bearing 150 is in contact with the thrust collar 108 to support the rotation shaft 107 by oil film force, and the second thrust top foil 152 has elastic force and And a second thrust bump foil 154 to impart vibration absorbing power.

Between the second air foil thrust bearing 150 and the armature housing 114, the rotary shaft 107 is moved in the axial (XX) direction of the casing 102 against the pressing force of the piezoelectric ceramic pad 140 against the thrust collar 108. The position variable plate 160 is installed as a second pressurizing means for pressurizing toward the outlet 106. The positioning plate 160 is guided by a guiding rod 162 protruding from one side thereof and inserted into the armature housing 114. The guiding rod 162 is provided with a spring 164 wound to bias the positioning plate 160 toward the second air foil thrust bearing 150.

Hereinafter, the operation and operation of the turbo blower according to the present invention configured as described above will be described.

When power is applied to the turbocharger in the steady state as shown in FIGS. 2, 4A and 4B, the rotary shaft 107 and the impeller 110 coupled thereto by the interaction of the armature 112 and the permanent magnet 116. ) Will rotate. By the rotation of the impeller 110, outside air flows in through the air inlet 104 of the casing 102, flows along the inner wall surface of the casing 102, and is discharged through the outlet 106. At this time, the tip clearance between the casing 102 and the impeller 110 maintains the size of d ₁ .

As the rotating shaft 107 rotates, air is introduced into the space between the rotating shaft 107 and the top foil 126 of the air foil journal bearing 120, and the top foil 126 having the elastic force is rotated by the rotating shaft ( 107) in a direction away from it. That is, while the top foil 126 keeps in contact with the rotating shaft 107 until the rotation speed of the rotating shaft 107 reaches a predetermined speed, the bump foil 124 is rotated due to the air flowing therein. By elastically deforming in a direction away from the rotation shaft 107 is rotated in a state spaced apart from the top foil 126.

In addition, since the thrust collar 108 rotates together with the rotation shaft 107, air is introduced into the space between the thrust collar 108 and the first and second air foil thrust bearings 130 and 150, and the air flows into the introduced air. Due to this, the first and second top foils 132 and 152 having elastic force deform in a direction away from the thrust collar 108. That is, the first and second top foils 132 and 152 keep in contact with the thrust collar 108 until the rotational speed of the thrust collar 108 reaches a predetermined speed. As the first and second bump foils 134 and 154 are elastically deformed in a direction away from the thrust collar 108, the thrust collar 108 is rotated in a state spaced apart from the first and second top foils 132 and 152. Done.

When the turbo blower of the present invention is applied to an air supply device of a fuel cell vehicle, an operation mode of varying air flow rate is required. When a voltage having a predetermined magnitude is applied to the first piezoelectric material of the piezoelectric ceramic pad 140, that is, the PZT film 144, the PZT film 144 is expanded, that is, becomes thick, due to the characteristics of the piezoelectric material. As a result, as shown in FIG. 7B, the expansion force of the PZT film 144 is transmitted to the thrust collar 108 of the rotation shaft 107 against the elastic force of the spring 164 acting on the position plate 160. The rotating shaft 107 and the impeller 110 coupled thereto are advanced toward the air inlet 104 in the direction of the axis XX of the casing 102 (left direction in FIG. 6). Thus, as shown in FIG. 7A, the tip clearance d ₂ between the casing 102 and the impeller 110 is the gap size d ₁ before applying voltage to the PZT film 144. Smaller than 4a).

On the contrary, when the magnitude of the voltage applied to the PZT film 144 is reduced, the PZT film 144 is reduced to reduce its thickness, and the position change plate is caused by the elastic restoring force of the spring 164 acting on the position change plate 160. 160 and thrust collar 108 retract toward the original position (rightward in FIG. 6). Accordingly, the tip gap d ₂ is increased while the rotary shaft 107 and the impeller 110 are gradually spaced apart from the air inlet 104. That is, by adjusting the magnitude of the voltage applied to the PZT film 144, the tip gap d ₂ between the casing 102 and the impeller 110 can be easily adjusted.

As described above, in the present embodiment, the variable position plate 160 and the spring 164 are applied as the second pressing means for pressing the thrust collar 108 of the rotary shaft 107 against the pressing force of the first pressing means. In addition, even if the piezoelectric actuator having a piezoelectric actuator (for example, a PZT film provided between the two electrodes) instead of the variable position plate 160 and the spring 164 is applied to the rotary shaft ( Of course, it is possible to adjust the forward and backward movements of 107).

The PVDF film 146, which is a piezoelectric pressure sensor, has an axial thrust of the rotary shaft 107 determined by the pressing force of the PZT film 144 against the thrust collar 108, the elastic force of the spring 164, and the rotation of the impeller 110. By applying a and generating a voltage proportional thereto, it is possible to measure the thrust of the rotation shaft 107 actually generated. By feedback control of the thrust information of the rotary shaft 107 output from the PVDF film 146 to properly adjust the voltage applied to the PZT film 144 to maximize the operational stability of the turbo blower including the operation of the rotary shaft 107. It will be possible.

The present invention is not limited to the above embodiments, and various modifications may be made by those skilled in the art without departing from the gist of the present invention as claimed in the claims.

As described above in detail, the turbo blower according to the present invention has an effect of controlling tip clearance between the casing and the impeller and thus aerodynamic performance control by only adjusting the voltage applied to the piezoelectric actuator. In addition, by providing a piezoelectric pressure sensor and feedback control of the thrust information of the rotating shaft outputted therefrom, the voltage applied to the piezoelectric actuator is appropriately adjusted to actively avoid rubbing, as well as air discharge pressure and discharge amount. It is also possible to actively cope with such repeated fluctuations and stalls, thereby improving the aerodynamic safety of the turbo blower.

In addition, by adopting an air foil bearing to support the rotating shaft, there is an effect of reducing the vibration of the rotating shaft rotating at high speed, and can stably support the load.

In particular, when the turbo blower of the present invention is applied to an air supply device of a fuel cell vehicle, not only can actively cope with rubbing, stall, and surge, but also friction and heat generation due to the above-mentioned phenomenon. And by preventing the noise phenomenon there is an advantage that can prevent unnecessary power consumption, increase the operational stability and ultimately maximize the efficiency of the fuel cell.

Claims (11)

A casing having an air inlet and an outlet; A rotating shaft rotatably supported in the casing, the shaft being rotatably provided in the axial direction of the casing, and having a thrust collar protruding from an end portion adjacent to the outlet; An impeller coupled to the rotating shaft adjacent the air inlet; A motor for rotating the rotating shaft; A pair of electrodes opposed to each other, and a piezoelectric ceramic pad including a piezoelectric actuator provided between the pair of electrodes and connected to a power source, and fixed to the casing to face the thrust collar so that the rotating shaft is moved toward the inlet side. First pressing means for pressurizing; And And a second pressurizing means for pressurizing the rotating shaft in a direction against the pressing force of the first pressurizing means. delete The turbo blower of claim 1, wherein a plurality of piezoelectric actuators are provided, form a fan shape, and are disposed at equal angles to each other. The turbo blower of claim 1, wherein the piezoelectric actuator is a zirconium titanate film. The turbo blower of claim 1, wherein the piezoelectric ceramic pad further includes a piezoelectric pressure sensor provided overlapping the piezoelectric actuator between the pair of electrodes. 6. The turbo blower of claim 5, wherein the piezoelectric pressure sensor is a polyvinylidene fluoride film. The thrust collar according to claim 1, wherein the second pressurizing means corresponds to the first pressurizing means with the thrust collar interposed therebetween and is provided to move in the axial direction of the casing. Turbo blower capable of actively adjusting the impeller tip clearance, characterized in that it comprises a spring for biasing to the side. The method of claim 1, wherein the second pressing means is a piezoelectric ceramic pad provided corresponding to the first pressing means with the thrust collar therebetween, The piezoelectric ceramic pad may include a pair of electrodes facing each other, and a piezoelectric actuator provided between the pair of electrodes and connected to a power source. 9. The turbo blower of claim 8, wherein the piezoelectric actuator is a zirconium titanate film. The turbo blower of claim 1, wherein an air foil thrust bearing is installed between the thrust collar and the first and second pressurizing means, respectively. 11. The turbo blower of claim 10, wherein at least one air foil journal bearing is installed around the rotation shaft.

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