JP2009257214A - Scroll air compressor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a scroll compressor capable of sufficiently preventing creep phenomenon of a bearing and improving reliability. <P>SOLUTION: The scroll air compressor 4 includes a turning scroll member 14 provided with substantially scroll shape laps 14a, 14b, a fixed scroll member 15 provided with a substantially scroll shape lap 15a corresponding to the lap 14a of the turning scroll member 14, a fixed scroll member 16 provided with a substantially scroll shape lap 16a corresponding to the lap 14b of the turning scroll member 14, a main crankshaft 17 and an auxiliary crankshaft 18 swinging the turning scroll member 14, and ball bearings 22A, 22B, 23A, 23B provided in through-holes 15f, 15g of the fixed scroll member 15 and through-holes 16f, 16g of the fixed scroll 16 respectively, and rotatably supporting the main crankshaft 17 and the auxiliary crankshaft 18. Film 32 of solid lubrication material is formed on an outer circumference surface of an outer ring 28 of the ball bearings 23A, 23B. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an air compressor that compresses air, and more particularly, to a scroll air compressor that performs compression by swinging a orbiting scroll member with respect to a fixed scroll member.

  Originally, it has a fixed scroll member provided with a substantially spiral wrap standing upright on the end plate, and a orbiting scroll member provided with a wrap corresponding to the wrap of the fixed scroll member (substantially meshing shape), A scroll compressor that performs compression by swinging a scroll member with respect to a fixed scroll member has been used for refrigeration and air conditioning. In recent years, paying attention to the advantage of low noise, such scroll compressors are also used in air compressors. The scroll compressor for air compression is increasing in demand not only for small air volume applications such as painting but also for large air volume applications such as factory air sources because of its ease of use.

  In order to satisfy such a demand for a large air volume, a so-called double-tooth scroll air compressor having an orbiting scroll member provided with a substantially spiral wrap standing upright on both sides of the end plate has been proposed. In this double-tooth type scroll air compressor, because of the structure having wraps on both sides of the end plate, the crank portion of one crankshaft is connected to one side of the radially outer peripheral portion of the orbiting scroll member, and the radial outer peripheral portion Of these, the crank portion of the other crankshaft is connected to the opposite side across the lap shaft center from the one side, and the orbiting scroll member is swung (turned) by synchronously rotating these two crankshafts. It is like that.

  And the bearing which supports a crankshaft rotatably is provided in the bearing attachment part (through-hole) of the fixed scroll member of the one side and the other side, respectively, These bearings use a low-cost ball bearing etc., for example. In such a case, considering the convenience in assembly and the difference in thermal expansion during operation, the ball bearings attached to the fixed scroll member on one side are both inner and outer rings (in detail, on the inner peripheral side of the inner ring). The end of the crankshaft can be an interference fit (the outer ring outer peripheral side is on the bearing mounting portion), but the ball bearing provided on the fixed scroll member on the other side is, for example, the inner ring and the outer ring It is necessary to have a clearance fit (or the inner ring may be a clearance fit and the outer ring may be an interference fit). Then, an axial load is applied to the outer ring of the ball bearing fitted with a clearance through an elastic body (for example, an annular corrugated leaf spring or a ring-shaped polymer material) with a bearing holder, and the ball bearing is brought into a predetermined position. It comes to arrange.

  By the way, since the scroll air compressor has a structure that compresses the compressed fluid toward the center side, the outer ring turning load in which the load rotates as the compression reaction force is exerted on the clearance-fitted ball bearing as the inner ring (crankshaft) rotates. This may cause a creep phenomenon in which the outer ring of the ball bearing rolls in the bearing mounting portion. When such a creep phenomenon occurs, the outer ring or the bearing mounting portion of the ball bearing wears and becomes loose, resulting in problems such as fretting due to vibration. Therefore, for example, a structure in which an annular elastic body is provided between the outer ring of the ball bearing and the bearing mounting portion has been proposed in order to partially fill a gap between the outer ring of the ball bearing and the bearing mounting portion ( For example, see Patent Document 1).

JP 2001-123968 A

  In the said patent document 1, in order to partially fill the clearance gap between the outer ring | wheel of a ball bearing, and a bearing attaching part, providing the annular elastic body between the outer ring | wheel of a ball bearing and a bearing attaching part is proposed. . However, an actual machine test by the inventors of the present application revealed that the effect of alleviating fretting was hardly obtained. On the contrary, by arranging the annular elastic body, the contact area between the outer ring of the ball bearing and the bearing mounting portion is reduced, so that the contact surface pressure increases and fretting may occur easily.

  An object of the present invention is to provide a scroll air compressor that can sufficiently prevent a creep phenomenon of a bearing and can improve reliability.

  In order to achieve the above object, the present invention provides a orbiting scroll member having a substantially spiral wrap, a plurality of fixed scroll members having a substantially spiral wrap corresponding to the wrap of the orbiting scroll member, Two crankshafts each provided with a crank portion connected to a radially outer peripheral portion of the orbiting scroll member, swinging the orbiting scroll member, and a plurality of bearing mounting portions respectively provided in the plurality of fixed scroll members; A scroll air compressor provided at each of the plurality of bearing mounting portions and rotatably supporting the crankshaft, wherein at least one of the plurality of bearings is a ball bearing; A solid lubricant film is formed on at least one of the outer peripheral surface of the outer ring and the inner peripheral surface of the bearing mounting portion opposed thereto.

  According to the present invention, the creep phenomenon of the bearing can be sufficiently prevented, and the reliability can be improved.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  FIG. 2 is a schematic diagram showing the structure of an air compressor unit to which an embodiment of the scroll air compressor of the present invention is applied.

  In FIG. 2, an air compressor unit 1 includes a housing 2 that forms an outline and a skeleton thereof, a motor 3 that is fixed on a base 2 a in the housing 2, and is known as this type, and an interior of the housing 2. An outer peripheral drive type scroll air compressor 4 that is fixed to the supporting member 2b and generates compressed air; a cooling fan 5 that attracts outside air into the housing 2 to cool the motor 3 and the scroll air compressor 4 and the like; A heat exchanger 6 for precooling the compressed air from the scroll air compressor 4 and a dryer 7 for cooling the compressed air from the heat exchanger 6 to an appropriate temperature are provided.

  The outer peripheral drive type scroll air compressor 4 includes a pulley 8, and the pulley 9 provided on one side (the right side in FIG. 2) of the rotating shaft 3 a of the motor 3 and the pulleys 8, 9 together with the rotation driving of the motor 3. Rotational power is transmitted through the mounted V-belt 10.

  The cooling fan 5 has a rotating shaft connected to the other side (left side in FIG. 2) of the motor rotating shaft 3 a and is driven together with the driving of the motor 3. Then, by driving the cooling fan 5, as indicated by an arrow A in FIG. 2, outside air flows into the housing 2 from the intake port 11 </ b> A and is discharged from the exhaust port 13 </ b> A through the cooling fan 5 and the duct 12. Yes. Thereby, the motor 3 and the scroll air compressor 4 etc. in the housing | casing 2 are outside air cooled. At the same time, as indicated by an arrow B in FIG. 2, the outside air from the intake port 11B is caused to flow out to the heat exchanger 6 provided in the duct 11 through the cooling fan 5, and then discharged from the exhaust port 13A. is doing. Thereby, the heat exchanger 6 precools the compressed air from the scroll air compressor 4 to a limit temperature (for example, 55 ° C. or less) at which the compressed air flows into the dryer 7.

  The dryer 7 is a heat pump type refrigeration cycle provided with a compressor 7a, a condenser 7b, a capillary 7c, and an evaporator 7d, so that the compressed air from the heat exchanger 6 is cooled to an appropriate temperature. It has become. Further, the dryer 7 is provided with a fan 7e for air-cooling the condenser 7b and the evaporator 7d, and exhausts from the exhaust port 13B as indicated by an arrow C in FIG.

  FIG. 3 is a cross-sectional view showing the detailed structure of the scroll air compressor 4.

  In FIG. 3, a scroll air compressor 4 is a double-tooth scroll air compressor that operates, for example, in an oil-free state (without lubricating oil) in a compression working chamber, and the substantially spiral wraps 14a and 14b are connected to a mirror plate. An orbiting scroll member 14 provided on both sides (left and right in FIG. 3) of the portion 14c, and a substantially spiral wrap 15a corresponding to (substantially meshing) the wrap 14a of the orbiting scroll 14 A fixed scroll member 15 provided on the inner side (right side in FIG. 3) of 15b, and a substantially spiral wrap 16a corresponding to (substantially meshing) the wrap 14b of the orbiting scroll 14 is provided inside the end plate portion 16b. The crank portion 1 connected to one side (the lower side in FIG. 3) of the fixed scroll member 16 provided on the side (left side in FIG. 3) and the radially outer peripheral portion of the orbiting scroll member 14 a main crankshaft 17 having a in the center, an auxiliary crankshaft 18 having in the center a crank portion 18a connected to the opposite side (upper side in FIG. 3) of the radially outer peripheral portion of the orbiting scroll member 14, and the main crank Toothed pulleys 19A and 19B provided on one end side of the shaft 17 and the auxiliary crankshaft 18 (the right side in FIG. 2 and the left side in FIG. 3), and the main crankshaft 17 and auxiliary A timing belt 20 for synchronously rotating the crankshaft 18 and the pulley 8 provided on one end side of the main crankshaft 17 are provided.

  As the orbiting scroll member 14 swings (orbits), the wrap 14a of the orbiting scroll member 14, the wrap 15a of the fixed scroll member 15, and the wrap 14b of the orbiting scroll member 14 and the wrap 16a of the fixed scroll member 16 are moved. The compression working chambers 21A and 21B are formed by meshing with each other, and these compression working chambers 21A and 21B are continuously moved from the radially outer peripheral portion to the inner peripheral portion to reduce the volume thereof. Further, the orbiting scroll member 14 includes the wraps 14a and 14b, the end plate portion 14c, a communication hole 14d provided at the center in the radial direction of the end plate portion 14c and communicating with the compression working chambers 21A and 21B on both sides, and the end plate portion 14c. A plurality of cooling air passages 14e are provided which communicate with the interior in the vertical direction (perpendicular to the paper surface in FIG. 3) and cool the end plate portion 14c with air.

  The fixed scroll member 15 includes the wrap 15a, the end plate portion 15b, a substantially circular dust wrap 15c provided on the outer peripheral side in the radial direction of the wrap 15a of the end plate portion 15b and preventing dust from entering from the outside. A suction port (not shown) provided on the inner side in the radial direction of the strap 15c, a discharge port 15d provided in the center in the radial direction of the end plate portion 15b and for discharging compressed air in the compression working chamber 21A, and an end of the end plate portion 15b The heat dissipating fin 15e is provided on the external side (left side in FIG. 3) side surface. Similarly to the fixed scroll member 15, the fixed scroll member 16 is provided on the radially outer peripheral side of the wrap 16 a, the end plate portion 16 b, and the wrap 15 a of the end plate portion 15 b to prevent dust from entering from the outside. A dust trap 16c having a shape, a suction port (not shown) provided in communication with the dust strap 16c in the radial direction, and a compressed air in the compression working chamber 21B provided at the center in the radial direction of the end plate portion 16b are discharged. The discharge port 16d and the radiation fin 16e provided in the external side (right side in FIG. 3) side surface of the end plate part 16b are provided.

  The fixed scroll members 15 and 16 are combined in parallel and fastened with bolts (not shown) or the like to constitute a housing that encloses the orbiting scroll member 14. Cooling air vents (not shown) are respectively provided on the upper and lower surfaces of the fixed scroll members 15 and 16, and the cooling air described above passes through the vents in the housing (specifically, the fixed scroll members 15. The outer side of the inner lap strap 15c, the outer peripheral side of the lap strap 16c in the fixed scroll member 16, the cooling air passage 14e of the orbiting scroll member 14 and the like, and cools the inside of the housing. ing.

  Further, the fixed scroll member 15 has a through hole 15f communicating with the end plate portion 15b in the axial direction (left and right direction in FIG. 3) corresponding to the main crankshaft 17, and the end plate portion 15b corresponding to the auxiliary crankshaft 18. A through hole 15g communicating in the direction is provided. The fixed scroll member 16 is provided with a through hole 16 f that communicates the end plate portion 16 b in the axial direction corresponding to the main crankshaft 17, and a through hole 16 g that communicates the end plate portion 16 b in the axial direction corresponding to the auxiliary crankshaft 18. It has been. One end side and the other end side (right side in FIG. 3) of the main crankshaft 17 are rotatably supported by ball bearings 22A and 23A provided in the through holes 15f and 16f, respectively. The other end is rotatably supported by ball bearings 22B and 23B provided in the through holes 15g and 16g, respectively.

  The crank portion 17a of the main crankshaft 17 and the crank portion 18a of the auxiliary crankshaft 18 are eccentric with the same eccentric amount from the axis, and the orbiting scroll member 14 is interposed via ball bearings 24A and 24B provided on the crank portions 17a and 18a, respectively. It is pivotally supported so that it can swivel. Further, in order to cancel out the unbalance due to the orbiting movement of the orbiting scroll member 14, balance weights 25A and 25B are fixedly arranged on the main crankshaft 17, and balance weights 26A and 26B are fixedly arranged on the auxiliary crankshaft 18. ing.

  In the scroll air compressor 4 configured as described above, it is necessary to assemble the main crankshaft 17 and the auxiliary crankshaft 18 in an appropriate positional relationship at the time of manufacture and assembly, and the main crankshaft 17 and the auxiliary crankshaft 18 at the time of operation. Excessive axial load is generated from the difference in thermal expansion caused by the temperature difference between the fixed scroll members 15 and 16. In the present embodiment, the ball bearings 22A and 22B provided in the through holes 15f and 15g of the fixed scroll member 15 on the load side (specifically, on the pulleys 8, 19A and 19B side) have an interference fit for both the inner ring and the outer ring. The inner ring 27 (see FIG. 1 to be described later) of the ball bearings 23A and 23B provided in the through holes 16f and 16g of the fixed scroll member 16 on the non-load side is tightly fitted, and the outer ring 28 (see FIG. 1 to be described later) is clearance-fitted. And In this way, the outer ring 28 of the ball bearings 23A and 23B is fitted with a clearance to absorb an excessive axial load due to a difference in thermal expansion during operation.

  FIG. 1A is an axial sectional view showing the detailed structure of the ball bearings 23A and 23B, and FIG. 1B is a radial sectional view taken along the line DD in FIG. 1A.

  In these FIG. 1A and FIG. 1B, the ball bearing 23A (or 23B, the same corresponding to the parenthesis in the parentheses hereinafter) includes, for example, the inner ring 27, the outer ring 28, and the inner ring 27 and the outer ring 28. A plurality of balls (rolling elements) 29 that can rotate in the direction, a cage (not shown) that holds the plurality of balls 29 in a circumferential direction between the inner ring 27 and the outer ring 28, and the like It consists of

  On the inner peripheral side of the inner ring 27 of the ball bearing 23A (or 23B), the other end side (the right side in FIG. 1A) of the main crankshaft 17 (or the auxiliary crankshaft 18) is fitted and the outer peripheral side of the outer ring 28 is fitted. Is fitted into the through hole 16f (or 16g) of the fixed scroll member 16. The outer ring 28 of the ball bearing 23A (or 23B) is, for example, an annular shape by a bearing retainer 30 attached to the outside (the right side in FIG. 1A) of the through-hole 16f (or 16g) of the fixed scroll member 16. Positioning is performed by applying a load on the inner side in the axial direction (left side in FIG. 1A) via a corrugated leaf spring (pressurizing spring) 31 and the like.

  As a major feature of this embodiment, a solid lubricant is applied over the entire outer peripheral surface of the outer ring 28 of the ball bearings 23A and 23B to form a film 32.

Next, the operation and effect of this embodiment will be described.
When the air compressor unit 1 is used as a factory air source or the like, the motor 3 is driven to transmit the rotational power via the pulleys 8 and 9 and the V-belt 10, and the main crankshaft of the scroll air compressor 4. 17 is driven to rotate. Simultaneously with the start of rotation of the main crankshaft 17, rotational power is transmitted through the toothed pulleys 19A and 19B and the timing belt 20, and the auxiliary crankshaft 18 rotates. Then, by rotating the main crankshaft 17 and the auxiliary crankshaft 18 synchronously, the orbiting scroll member 14 is prevented from rotating, and the eccentric amount of the crank portion 17a of the main crankshaft 17 (= auxiliary crankshaft). (18) The eccentric movement of the 18 crank portions 18a is performed. As the orbiting scroll member 14 revolves, air flows in from the suction port, and the inflowed air is compressed to a predetermined pressure while reducing its volume toward the center in the compression working chambers 21A and 21B. It discharges from exit 15d, 16d. The compressed air from the scroll air compressor 4 is precooled by the heat exchanger 6, cooled to an appropriate temperature by the dryer 7, and pumped from the air compressor unit 1.

  In the operation of the scroll air compressor 4 as described above, a creep phenomenon that occurs in a normal gap-fitted ball bearing will be described. 4 (a) and 4 (b) are radial cross-sectional views for explaining the creep phenomenon of a ball bearing fitted with a clearance.

  4 (a) and 4 (b), the ball bearing 33 is attached to the through hole 34 with a clearance fit (the inner diameter D of the through hole 34> the outer diameter d of the outer ring 35 of the ball bearing 33) ( Note that the gap (Dd) is shown large for convenience in FIG. 4). As described above, since the scroll air compressor 4 compresses the sucked air toward the center side, the ball bearing 33 is subjected to an outer ring turning load in which the load rotates as the inner ring 36 rotates as a compression reaction force. The outer ring 35 is pressed against the through hole 34 and rolls (for example, from the state shown in FIG. 4A to the state shown in FIG. 4B). At this time, for example, when the inner ring 36 rotates once and the load rotates one time, the outer ring 35 is restored to the original amount by a difference π (D−d) between the inner peripheral dimension πD of the through hole 34 and the outer peripheral dimension πd of the outer ring 35. It will be in the state which cannot return to a position (namely, the state which does not make 1 rotation). Therefore, the outer ring 35 of the ball bearing 33 is gradually delayed with respect to the rotation of the inner ring 36, and a creep phenomenon occurs as if the outer ring 35 is rotating on the opposite side to the rotation direction of the inner ring 36 (screw compressor) In this case, the creep reaction of the bearing does not occur because the compression reaction force does not rotate.

Thus, it is known that the creep force acting on the ball bearing 33 is generally determined by the equation (1).
(Creep force) = (Friction coefficient between outer ring and through-hole) × (Rotational load) (1)

  Therefore, in the present embodiment, the solid lubricant film 32 is formed on the outer peripheral surface of the outer ring 28 of the ball bearings 23A and 23B, respectively, to reduce the friction coefficient between the outer ring 28 and the through holes 16f and 16g of the fixed scroll member 16. . Thereby, a creep force can be reduced. The solid lubricant film 32 fills an extra gap between the ball bearing 23A and the inner peripheral surface of the through hole 16f and an extra gap between the ball bearing 23B and the inner peripheral surface of the through hole 16g. Therefore, the creep phenomenon can be reduced, and the vibration caused by rattling of the ball bearings 23A and 23B can be reduced, so that fretting can be reduced. Further, since the solid lubricant film 32 serves as a cushioning material, fretting can be reduced. Such an effect of reducing fretting has been made clear by the inventors' actual machine test. By reducing fretting, it is possible to prevent an increase in the coefficient of friction over time due to surface roughness and rust on the outer peripheral surface of the outer ring 28 of the ball bearings 23A and 23B and the inner peripheral surfaces of the through holes 16f and 16g. Can be prevented from increasing.

  Although not described in the above embodiment, for example, in order to further prevent the occurrence of a creep phenomenon, for example, a substantially cylindrical shape that engages with the outer ring 28 of the ball bearing 23A and the through hole 16f of the fixed scroll member 16, respectively. A pin and a substantially cylindrical pin that respectively engages with the outer ring 28 of the ball bearing 23 </ b> B and the through hole 16 g of the fixed scroll member 16 may be provided. Specifically, as shown in FIG. 5, an end of a pin 37 is attached to a pin hole 28 a formed in the outer ring 28 of the ball bearing 23 </ b> A (or 23 </ b> B), and a through hole 16 f (or 16 g) corresponding to the pin 37. A recess (groove) 16fA (or 16gA) may be formed on the inner peripheral surface of In addition, for example, a substantially rectangular parallelepiped key may be provided instead of the substantially cylindrical pin.

  In the above embodiment, the ball bearings 22A and 22B provided on the fixed scroll member 15 on the load side are interference fits on both the inner and outer rings, and the ball bearings 23A and 23B provided on the fixed scroll member 16 on the anti-load side. In the configuration in which the inner ring 27 is tightened and the outer ring 28 is a clearance fit, the case where the solid lubricant film 32 is formed on the outer peripheral surface of the outer ring 28 of the ball bearings 23A and 23B has been described as an example. Not exclusively. That is, for example, the ball bearing provided on the fixed scroll member 16 on the anti-load side is an interference fit on both the inner and outer rings, and the ball bearing provided on the fixed scroll member 15 side on the load side is an interference fit on the inner ring and the outer ring is a clearance fit. In the first configuration, a solid lubricant film may be formed on the outer peripheral surface of the outer ring of the ball bearing provided on the fixed scroll member 15 side. In the above-described embodiment, the case where the coating 32 is formed by applying a solid lubricant to the outer peripheral surface of the outer ring 28 of the ball bearings 23A and 23B has been described as an example. That is, for example, a solid lubricant may be applied to the inner peripheral surfaces of the through holes 16f and 16g of the fixed scroll member 16 to form a film. In these cases, the same effect as described above can be obtained.

It is the axial direction sectional view showing the detailed structure of the ball bearing and bearing mounting part in one embodiment of the scroll air compressor of the present invention, and the radial direction sectional view by section DD. It is the schematic showing the structure of the air compressor unit to which one Embodiment of the scroll air compressor of this invention was applied. It is a horizontal sectional view showing the detailed structure of one embodiment of the scroll air compressor of the present invention. It is radial direction sectional drawing for demonstrating the creep phenomenon of the ball bearing which carried out clearance fitting. It is an axial sectional view showing a detailed structure of a ball bearing and a bearing mounting portion in a modified example of the scroll air compressor of the present invention, and a sectional radial sectional view.

Explanation of symbols

4 Scroll air compressor 14 Orbiting scroll member 14a Wrap 14b Wrap 15 Fixed scroll member 15a Wrap 15f Through hole (bearing mounting portion)
15g Through hole (bearing mounting part)
16 Fixed scroll member 16a Wrap 16f Through hole (bearing mounting part)
16g Through hole (bearing mounting part)
17 Main crankshaft 17a Crank portion 18 Auxiliary crankshaft 18a Crank portion 22A Ball bearing 22B Ball bearing 23A Ball bearing 23B Ball bearing 28 Outer ring 32 Solid lubricant film 37 Pin

Claims (2)

A orbiting scroll member provided with a substantially spiral wrap, a plurality of fixed scroll members provided with a substantially spiral wrap corresponding to the wrap of the orbiting scroll member, and a radially outer peripheral portion of the orbiting scroll member. Two crankshafts each provided with a crank portion and swinging the orbiting scroll member, a plurality of bearing mounting portions respectively provided in the plurality of fixed scroll members, and a plurality of bearing mounting portions, respectively. In a scroll air compressor having a plurality of bearings that rotatably support a crankshaft,
At least one of the plurality of bearings is a ball bearing, and a solid lubricant film is formed on at least one of the outer ring outer peripheral surface of the ball bearing and the inner peripheral surface of the bearing mounting portion facing the outer ring. Features a scroll air compressor.   2. The scroll air compressor according to claim 1, further comprising a substantially cylindrical pin or a substantially rectangular parallelepiped key that engages with both the outer ring of the ball bearing and the bearing mounting portion. .

Images