JP2007198212A - Fluid compressor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a root type fluid compressor capable of reducing motor torque for separating ice freezed between rotors 22, 23 and an axial direction inner surface 18a of a working chamber 18 at a time of start. <P>SOLUTION: The rotors 22, 23 are arranged in the working chamber 18 of the root type compressor 10. The rotors 22, 23 includes edge parts 22a, 23a projecting toward the axial direction inner surface 18a of the working chamber 18. The edge parts 22a and 23a are provided with tapered surfaces 22e and 23e. The rotors 22 and 23 oppose to the axial direction inner surface 18a at acute angles. Ice adhering on the axial direction inner surface 18a is separated by the acute angle part at a time of start of the compressor 10. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a fluid compressor.

One type of fluid compressor is known as a Roots type. This includes a pair of rotors that engage with each other in a working chamber in the housing, and the pair of rotors rotate in opposite directions in synchronism with each other so that gas is sucked from the suction port and discharged from the discharge port. Is.
An example of such a fluid compressor is shown in Patent Document 1.

JP 61-112792 A

  If the fluid handled by this type of compressor contains moisture, when the compressor stops, moisture tends to condense and remain in the housing including the working chamber. For example, in a compressor used as a hydrogen pump that supplies hydrogen to a fuel cell, water generated in the stack is often contained in the fluid. When such a compressor is placed in a low-temperature environment, moisture condensed between the rotor and the housing freezes and becomes ice while the compressor is stopped.

  The conventional fluid compressor as described above has a problem that a large motor torque is required to separate frozen ice between the rotor and the housing when the compressor is started.

  The present invention has been made to solve such a problem, and a fluid compressor capable of reducing a motor torque for separating ice frozen between a rotor and a housing at the time of startup. The purpose is to provide.

In order to solve the above-described problems, a fluid compressor according to the present invention is disposed inside a working chamber having a suction port and a discharge port communicating with the outside, and rotates in the opposite direction while being engaged with each other. A fluid compressor that includes a pair of rotors, conveys fluid flowing into the working chamber from the suction port by the rotation of the pair of rotors, and discharges the fluid from the discharge port. The both ends of the rotor have an inner surface in the axial direction opposite to both ends of the rotor, and each end of the rotor protrudes in a position facing the inner surface in the axial direction and toward the radially inner side of the rotor as it goes from the base toward the inner surface in the axial direction. And a step portion.
In this fluid compressor, the tapered surface of the stepped portion has an acute angle with respect to the inner surface in the axial direction of the working chamber. When ice is adhered between the rotor and the axially inner surface when the fluid compressor is started, the taper surface peels off the ice by a wedge effect due to an acute angle.

  The step portion may be composed of an edge portion and a tapered surface, and the edge portion may be connected to a flat surface portion as a base portion with the tapered surface.

The fluid compressor according to the present invention includes a working chamber having a suction port and a discharge port communicating with the outside, and a pair of rotors arranged inside the working chamber and rotating in opposite directions while being engaged with each other. A fluid compressor that conveys the fluid flowing from the suction port into the working chamber by rotation of the pair of rotors and discharges the fluid from the discharge port, and the working chamber has an inner surface in the axial direction with respect to both ends of each rotor in the rotational axis direction. And a plurality of indentations are formed on the inner surface in the axial direction.
In this fluid compressor, a part of ice pieces adhering between the inner surface in the axial direction of the working chamber and both ends of the rotor enters the inside of the recess. For this reason, the area of the end face where the ice piece comes into contact with each of the rotors is relatively small.

You may provide both the above-mentioned level difference part and the above-mentioned hollow.
The diameter of the dent may be smaller than the width of the step portion when viewed from the normal direction of the inner surface in the axial direction.

  According to the present invention, in the fluid compressor, when the frozen ice is peeled off between the rotor and the axial inner surface of the working chamber at the time of start-up, the taper surface peels off the ice with an acute angle. The motor torque can be reduced.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
Embodiment 1 FIG.
The fluid compressor of this embodiment is a hydrogen pump for supplying hydrogen gas to a stack of fuel cells, and the compressor is an electric roots compressor. The gas handled by this roots type compressor contains hydrogen. The gas also contains moisture generated by the reaction in the stack.

As shown in FIG. 1, a compressor 10 that is a roots type fluid compressor includes a housing 11 that is an outer shell of the compressor 10.
In the housing 11, the electric motor 19, the drive shaft 20 that is driven and rotated by the electric motor 19, the driven shaft 21 that rotates in synchronization with the drive shaft 20, and the rotation of the drive shaft 20 are transmitted to the driven shaft 21. The driving side gear 26 and the driven side gear 27, the rotor 22 that is coaxially attached to the driving shaft 20 and rotates integrally, the rotor 23 that is coaxially attached to the driven shaft 21 and rotates integrally, and the driving shaft 20 A first radial bearing 28 and a second radial bearing 29 supporting the driven shaft 21, a third radial bearing 30 supporting the driven shaft 21, shaft seal members 31 and 32 attached to the outer periphery of the drive shaft 20, and the driven shaft 21. A shaft seal member 33 attached to the outer periphery of the housing is accommodated.
Here, the rotor 22 side with respect to the drive shaft 20 is the front side of the compressor 10, and the electric motor 19 side is the rear side of the compressor 10.

The housing 11 includes four housing bodies arranged in the axial direction. That is, the motor housing body 12, the gear housing body 13, the intermediate housing body 14, and the rotor housing body 15 in this order from the front side.
A space defined by the motor housing body 12 and the gear housing body 13 is a motor chamber 16 in which an electric motor 19 is accommodated. A space defined by the gear housing body 13 and the intermediate housing body 14 is a gear chamber 17 in which the driving side gear 26 and the driven side gear 27 are accommodated. A space defined by the intermediate housing body 14 and the rotor housing body 15 is a working chamber 18 in which the rotors 22 and 23 are accommodated.

As shown in FIG. 1, the rear shaft end of the drive shaft 20 is pivotally supported on the housing 11 by the first radial bearing 28 described above as a drive bearing.
The drive shaft 20 is further pivotally supported by the above-described second radial bearing 29 as another drive-side bearing provided in the intermediate housing body 14. A drive side gear 26 is disposed between the rotor 22 and the electric motor 19 in the drive shaft 20.

The shaft seal members 31 and 32 described above are provided in contact with the outer periphery of the drive shaft 20 in order to prevent gas leakage from the working chamber 18 or lubricating oil from the gear chamber 17. The shaft seal member 31 is provided between the motor chamber 16 and the gear chamber 17 in the gear housing body 13 and prevents leakage of the lubricating oil between them. The shaft seal member 32 is provided between the gear chamber 17 and the working chamber 18 in the intermediate housing body 14 to prevent gas leakage between them.
On the other hand, the driven shaft 21 is disposed in parallel to the drive shaft 20 so as to reach the working chamber 18 from the gear chamber 17.

  The driven gear 27 described above is attached to the gear side (rear surface side) shaft end of the driven shaft 21. The driven side gear 27 and the driving side gear 26 are engaged with each other, whereby the rotation of the driving shaft 20 is transmitted to the driven shaft 21. That is, the drive side gear 26 and the driven side gear 27 have a function of synchronously rotating the driven shaft 21 in a direction opposite to the rotation direction of the drive shaft 20.

  The driven shaft 21 is pivotally supported on the intermediate housing body 14 by the above-described third radial bearing 30 as a driven-side bearing provided between the rotor 23 and the driven-side gear 27. Since the driven shaft 21 is supported only by the third radial bearing 30, the rolling elements of the third radial bearing 30 are of a double row type, thereby preventing the rotor 23 on the driven side from swinging.

  A shaft seal member 33 is provided in contact with the outer periphery of the driven shaft 21 to prevent gas leakage from the working chamber 18 described above. The shaft seal member 33 is provided between the gear chamber 17 and the working chamber 18 and prevents gas leakage between them.

  2 shows an enlarged view around the rotors 22 and 23 in FIG. 1, and FIG. 3 shows a cross-sectional view taken along line III-III in FIG. The working chamber 18 is a substantially glasses-like space as viewed from the front. A suction port 24 is provided on the upper side of the working chamber 18, that is, in the center on the front side in FIG. 1, and a discharge port 25 is provided on the lower side of the working chamber 18, that is, on the back side in FIG.

  The rotor 22 is formed in a bowl shape when viewed from the axial direction. Two bulging portions 22b that bulge in the radial direction are formed in opposite directions, and two depressed portions 22c that are depressed in the radial direction are formed in opposite directions. The bulging portion 22b and the depressed portion 22c are arranged at equal intervals in the circumferential direction.

The working chamber 18 has an axial inner surface 18a that is an inner surface with respect to both ends of the rotors 22 and 23 in the rotational axis direction.
The rotor 22 has a flat surface portion 22d as a base portion and edge portions 22a which are step portions protruding from the flat surface portion 22d in the axial direction of the rotor 22 toward the axial inner surface 18a on both end sides in the axial direction. . The edge portion 22a and the plane portion 22d are each parallel to the axial inner surface 18a.
The edge 22a is formed with a certain width in the radial direction of the rotor 22 along the edge of the end face. The radially outer surface of the edge 22a is configured such that the cross section of the rotor 22 by a surface parallel to the axis of the rotor 22 is always a straight line.

The edge portion 22a includes a tapered surface 22e on the radially inner side, and is connected to the flat surface portion 22d with the tapered surface 22e. The inclination of the taper surface 22e is directed toward the inner side in the radial direction of the rotor 22 toward the axial inner surface 18a. That is, the edge portion 22 a is at an acute angle with respect to the axial inner surface 18 a on the radially inner side of the rotor 22. As described above, the rotor 22 has the edge portion 22a that protrudes inward in the axial direction as it approaches the axial inner surface 18a at a position facing the axial inner surface 18a.
A clearance 22f is provided between the edge 22a and the axial inner surface 18a. That is, the edge 22a and the axial inner surface 18a are arranged slightly apart.

  The rotor 23 is also formed in the same shape as the rotor 22, and is similarly provided with an edge portion 23a, a bulging portion 23b, a depressed portion 23c, a flat surface portion 23d, and a tapered surface 23e. A clearance 23f is provided in the same manner.

  As each of the rotor 22 and the rotor 23 rotates, one of the bulging portions is disposed so as to engage with the other depressed portion. In FIG. 2 and FIG. 3, the bulging portion 22 b of the rotor 22 is engaged with the depressed portion 23 c of the rotor 23.

Next, the operation of the compressor 10 according to Embodiment 1 will be described.
When the drive shaft 20 is rotated by the electric motor 19, the drive side gear 26 transmits the rotation to the driven shaft 21 via the driven side gear 27. As a result, the driven shaft 21 rotates in the direction opposite to the drive shaft 20 in synchronization with the drive shaft 20. When the drive shaft 20 and the driven shaft 21 rotate in different directions, the rotors 22 and 23 in the working chamber 18 rotate in opposite directions. In FIG. 3, the rotor 22 rotates in the direction of arrow B and the rotor 23 rotates in the direction of arrow C. Thus, the rotation of the rotors 22 and 23 causes the gas from the suction port 24 to be sucked into the working chamber 18 in the direction of arrow D, and the gas in the working chamber 18 is discharged from the discharge port 25 in the direction of arrow E.

Since the gas flowing through the compressor 10 contains moisture, when the temperature of the compressor 10 is low when the compressor 10 is started, the moisture freezes between the rotor 22 or the rotor 23 and the axial inner surface 18a. There may be.
4 is a cross-sectional view taken along the line IV-IV in FIG. 3 and shows a state where the ice piece 40 is fixed in contact with the edge 22a and the axial inner surface 18a when the compressor 10 is started. is there. Here, the compressor 10 is activated and a force to rotate the rotor 22 is applied, whereby the edge 22a has a force toward the inner side in the radial direction of the rotor 22, that is, the arrow A side in FIG. Let the ingredients work.
The tapered surface 22e of the edge portion 22a has an acute angle with respect to the axial inner surface 18a. For this reason, the taper surface 22e separates the ice piece 40 from the axial inner surface 18a with a relatively small force, and starts the rotor 22. The tip of the taper surface 22e makes it easy to start the rotors 22 and 23 by scraping the ice piece 40 from the axial inner surface 18a, that is, scraping the ice piece 40 from the axial inner surface 18a.
Here, the ice piece 40 can be peeled off with a relatively small force when the edge 22a moves in the direction of arrow A, and the tapered surface 22e pushes the ice piece 40 in the direction of arrow A and This is because it also pushes in the direction of peeling from the axial inner surface 18a.

  As described above, according to the compressor 10 according to the first embodiment, the edge 22a of the rotor 22 has an acute angle with respect to the axial inner surface 18a of the working chamber 18. The same applies to the rotor 23. For this reason, even when ice adheres between the rotor 22 and the rotor 23 and the axial inner surface 18a of the working chamber 18 at the time of starting the compressor 10, the ice can be peeled off by the wedge effect. Therefore, it is possible to start with a relatively small torque. Therefore, according to the compressor 10, it is possible to reduce the motor torque required for the electric motor 19 in order to separate the frozen ice between the rotors 22 and 23 and the axial inner surface 18a at the time of startup. it can. Moreover, by this, the electric motor 19 can be reduced in size and the compressor 10 can be reduced in size in connection with this.

Embodiment 2. FIG.
In the second embodiment, the periphery of the rotors 22 and 23 shown in FIGS. 2 and 3 in the first embodiment is configured as shown in FIGS. 5 and 6, respectively. 6 is a cross-sectional view taken along line VI-VI in FIG. Hereinafter, the compressor 110 according to Embodiment 2 will be described with reference to FIGS. 5 and 6.
Rotors 122 and 123 are respectively attached to the drive shaft 120 and the driven shaft 121, and the rotors 122 and 123 are disposed in the working chamber 118. The shapes of the rotors 122 and 123 are the same as in the first embodiment except for the respective axial end faces.

  The working chamber 118 has a planar axial inner surface 118a perpendicular to the axis at both ends of the rotors 122 and 123 in the axial direction. The rotors 122 and 123 have planar end surfaces 122a and 123a that are parallel to the inner surface in the axial direction at both ends in the axial direction. Clearances 122 f and 123 f are provided between the end surfaces 122 a and 123 a and the axial inner surface 118 a of the working chamber 118. That is, the end surfaces 122a and 123a and the axial inner surface 118a are disposed slightly apart.

  A plurality of dimples 118b that are semi-ellipsoidal depressions are formed on the inner surface 118a in the axial direction of the working chamber 118. The dimple 118b is circular when viewed from the axial direction. Further, the dimple 118b has a semi-elliptical shape in a cross section parallel to the axis, and its center portion is deepest.

FIG. 7 is a view showing a state where moisture freezes between the end face 122a and the axially inner face 118a and becomes an ice piece 140 when the compressor 110 is started. Part of the ice piece enters the dimple 118b and another part exists in the clearance 122f. The ice piece 140 is in contact with the end face 122a and the end face 140a. The area of the end face 140a is Sa.
Here, since a part of the ice piece 140 enters the dimple 118b, the volume in the clearance 122f is reduced by that amount, and the area Sa is accordingly reduced.

FIG. 8 is a comparative example for explaining the reduction of the area Sa due to the dimples 118b. In this comparative example, the inner surface 118a in the axial direction is planar, and the dimple 118b is not formed.
The ice piece 140 ′ in FIG. 8 has the same volume as the ice piece 140 in FIG. Here, since the whole ice piece 140 'exists in the clearance 122'f, the area Sb of the end face 140'a becomes relatively large. That is, the area Sb in FIG. 8 is larger than the area Sa in FIG.
7 and 8 is the same for the end surface 123a of the rotor 123.

Next, the operation of the compressor 110 according to Embodiment 2 will be described.
Since the operation after the compressor 110 is started is the same as that in the first embodiment, description thereof is omitted.

  When a force to rotate the rotor 122 is applied at the time of starting the compressor 110, a resistance force to stop the rotation is applied to the rotor 122 from the ice piece 140 as a reaction. Here, the force to rotate overcomes the resistance force, the end surface 122a of the rotor 122 and the end surface 140a of the ice piece 140 are separated, and the rotor 122 begins to rotate. Thus, the compressor 110 is started. Here, since the area Sa of the end surface 140a of the ice piece 140 is smaller than Sb as described above, it is sufficient if the force that the rotor 122 tries to rotate is relatively small. The same applies to the rotor 123.

Thus, in the compressor 110 according to the second embodiment, a part of the ice piece 140 adhering between the axial inner surface 118a of the working chamber 118 and the end surfaces 122a and 123a of the rotors 122 and 123 is partly. It enters the inside of the dimple 118b. For this reason, the end surface 140a of the ice piece 140 which contacts the end surfaces 122a and 123a of the rotors 122 and 123 has a relatively small area Sa.
Therefore, according to the compressor 110, the motor torque for causing the ice frozen between the rotors 122 and 123 and the axial inner surface 118a to peel off at the end surface 140a at the time of startup can be made relatively small. Moreover, by this, an electric motor can be reduced in size and the compressor 110 can be reduced in size in connection with this.

Embodiment 3 FIG.
The third embodiment is a combination of a rotor having a stepped portion as in the first embodiment and an axial inner surface of a working chamber having dimples as in the second embodiment. That is, the periphery of the rotors 22 and 23 shown in FIGS. 2 and 3 in the first embodiment is configured as shown in FIGS. 9 and 10. That is, FIG. 10 is a sectional view taken along line XX of FIG. Hereinafter, the compressor 210 according to Embodiment 3 will be described with reference to FIGS. 9 and 10.
Rotors 222 and 223 are respectively attached to the drive shaft 220 and the driven shaft 221, and the rotors 222 and 223 are disposed in the working chamber 218.

The shapes of the rotors 222 and 223 are the same as those in the first embodiment shown in FIGS. That is, the rotors 222 and 223 are similarly provided with edge portions 222a and 223a, flat surface portions 222d and 223d, and tapered surfaces 222e and 223e, respectively. Further, clearances 222f and 223f are similarly provided.
Further, the shape of the inner surface 218a in the axial direction of the working chamber 218 is the same as that of the second embodiment shown in FIGS. That is, a plurality of dimples 218b, which are indentations in the axial direction, are formed on the axial inner surface 218a.

  The diameter La of the dimple 218b is smaller than the width Lb of the edges 222a and 223a when viewed from the rotation axis direction of the rotors 222 and 223, that is, the normal direction of the axial inner surface 218a. Therefore, for example, when the dimple 218b and the edge 222a overlap when viewed from the axial direction, the dimple 218b is entirely included in the edge 222a, or part of the dimple 218b protrudes radially inward of the rotor 222, or , Or a part of which protrudes radially outward of the rotor 222. That is, the same dimple 218b does not have a positional relationship that protrudes simultaneously inside and outside the edge 222a.

As described above, in the compressor 210 according to the third embodiment, the taper surface 222e of the edge portion 222a can peel the ice pieces (not shown) from the axial inner surface 218a in the same manner as the first embodiment. . Similarly to the second embodiment, the area of the end surface where the ice piece contacts the edge 222a can be made relatively small.
For this reason, the compressor 210 can be started with a relatively small torque. Therefore, the motor torque required for the electric motor can be reduced. In addition, this makes it possible to reduce the size of the electric motor, and accordingly, to reduce the size of the compressor 210.

  Further, since the diameter La of the dimple 218b is smaller than the width Lb of the edge portions 222a and 223a when viewed from the axial direction, the width between the edge portions 222a and 223a and the axial inner surface 218a is always narrow at any position. There are clearances 222f and 223f. That is, the spaces on both sides of the edge portion 222a and on both sides of the edge portion 223a do not directly communicate with each other via the dimple 218b. For this reason, gas does not leak through the dimple 218b, and as a result, leakage from the discharge port 225 side to the suction port 224 side in the working chamber 218 can be reduced.

In Embodiments 2 and 3, the shape of dimples 118b and 218b viewed from the axial direction is a circle, but this need not be a circle. For example, it may be oval or polygonal. In that case, the diameter in the direction in which the diameter is maximum may be smaller than the width Lb of the edges 222a and 223a.
Further, in the cross section parallel to the axis, the surfaces of the dimples 118b and 218b are semi-elliptical, but this may be arcuate or may be a shape including a straight line such as a rectangle.

It is a figure which shows the structure of the compressor 10 which concerns on Embodiment 1 of this invention. FIG. 2 is an enlarged view around the rotors 22 and 23 in FIG. 1. It is sectional drawing in the III-III line of FIG. It is a figure which shows the state of the ice piece 40 at the time of starting of the compressor 10 of FIG. It is an enlarged view of rotor 122 and 123 periphery of the compressor 110 which concerns on Embodiment 2 of this invention. It is sectional drawing in the VI-VI line of FIG. It is a figure which shows the state of the ice piece 140 at the time of starting of the compressor 110 of FIG. 5 and FIG. It is a figure which shows the comparative example for demonstrating the effect | action of the dimple 118b of FIG. 5 and FIG. It is an enlarged view of the rotor 222 and 223 periphery of the compressor 210 which concerns on Embodiment 3 of this invention. It is sectional drawing in the XX line of FIG.

Explanation of symbols

  10, 110, 120 Compressor (fluid compressor), 18, 118, 218 Working chamber, 18a, 118a, 218a Axial inner surface, 118b, 218b Dimple (recess), 20, 120, 220 Drive shaft (rotary shaft), 21, 121, 221 Driven shaft (rotating shaft), 22, 23, 122, 123, 222, 223 Rotor, 22d, 23d, 222d, 223d Base portion (plane portion), 22a, 23a, 222a, 223a Edge portion (stepped portion) ), 24, 224 Suction port, 25, 225 Discharge port, La Dimple diameter (recess diameter), Lb Edge width (step width).

Claims (5)

A working chamber having a suction port and a discharge port communicating with the outside;
A pair of rotors disposed inside the working chamber and rotating in opposite directions while engaging with each other;
In the fluid compressor for conveying the fluid flowing into the working chamber from the suction port by the rotation of the pair of rotors and discharging the fluid from the discharge port,
The working chamber has an inner surface in the axial direction opposite to both ends of each rotor in the rotation axis direction,
Each end of the rotor has a base at a position facing the inner surface in the axial direction, and a stepped portion projecting from the base toward the inner side in the radial direction of the rotor as it goes from the base toward the inner surface in the axial direction. Compressor.   2. The fluid compressor according to claim 1, wherein the stepped portion includes an edge portion and a tapered surface, and the edge portion is connected to the flat portion serving as the base portion with the tapered surface. A working chamber having a suction port and a discharge port communicating with the outside;
A pair of rotors disposed inside the working chamber and rotating in opposite directions while engaging with each other;
In the fluid compressor for conveying the fluid flowing into the working chamber from the suction port by the rotation of the pair of rotors and discharging the fluid from the discharge port,
The working chamber has an inner surface in the axial direction with respect to both ends of the rotation axis direction of the rotor,
A fluid compressor in which a plurality of depressions are formed on the inner surface in the axial direction.   The fluid compressor according to claim 1, comprising a plurality of indentations according to claim 3.   5. The fluid compressor according to claim 3, wherein a diameter of the recess is smaller than a width of the step portion when viewed from a normal direction of the inner surface in the axial direction.

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