JP2018204610A - Water pump - Google Patents

Abstract

To provide a water pump capable of augmenting water supply to a slide surface of a slide bearing provided in the pump, and improving low frication characteristic and antifriction characteristic of the slide bearing.SOLUTION: A water pump 1 comprises: an impeller 4; a shaft 5 for fixing the impeller 4; a slide bearing 8 for supporting the impeller 4 to the shaft 5 in a rotatable manner; thrust plates 9, 10 configured to slide with each end surface of the slide bearing 8; and a casing 6 and a cover 7 storing the impeller 4 and forming a pump chamber. The water pump is configured to suction/discharge circulation water through the pump chamber with rotation of the impeller 4. The slide bearing 8 comprises a resin composition having polyphenylene sulfide resin as base resin and containing at least carbon fiber.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a water pump used for circulating cooling water such as an automobile engine, an inverter, a battery, or a fuel cell, and circulating hot water such as a water heater or a floor heater.

  Water pumps are used to circulate cooling water for automobile engines, inverters, batteries or fuel cells, hot water circulation for hot water heaters and floor heating equipment. Conventionally, as a typical example of a water pump used for such an application, a magnet pump as disclosed in Patent Document 1 or a DC brushless pump as disclosed in Patent Document 2 is known. A conventional water pump will be described with reference to FIG. FIG. 5 is a cross-sectional view of the DC brushless pump. In the pump 21, the motor 32 has a winding 22 having a coil disposed therein, thereby generating a magnetic field, and the control unit controls the generation of the magnetic field. In order to follow the generated magnetic field, an impeller 24 to which a permanent magnet 23 is fixed is rotatably supported by a shaft 25. As the impeller 24 rotates following the rotating magnetic field, the circulating water is sucked and discharged. The shaft 25 is fixed to the casing 26 and supported by a shaft support 27 a of the cover 27. The impeller 24 is rotatably supported with respect to the shaft 25 via the slide bearing 28, and the shaft 25 and the slide bearing 28 rotate and slide. Further, both end surfaces of the sliding bearing 28 rotate and slide in the thrust direction with thrust plates 29 and 30 provided between the shaft support 27a of the cover 27 and the casing 26, respectively. A slight gap is provided between both end faces of the slide bearing 28 and the thrust plates 29 and 30.

  With the rotating magnetic field generated from the winding 22, the impeller 24 rotates following the attraction and repulsion of the fixed permanent magnet 23. As a result, a pumping action is generated, the circulating water is sucked in from the arrow X direction, and the circulating water is discharged in the arrow Y direction. The impeller 24 is pressed against the cover 27 by the differential pressure at this time, and the end surface of the sliding bearing 28 and the thrust plate 29 are rotated and slid. There is almost no sliding between the sliding bearing 28 and the thrust plate 30 on the casing 26 side, and this is limited to a moment when starting and stopping or an abnormal operation such as an idling operation in which the pump is operated without circulating water. Therefore, the thrust plate 30 may not be used on the casing 26 side, and the casing 26 may be directly slid with the sliding bearing 28.

  Circulating water is present on the sliding surfaces between the sliding bearing 28 and the shaft 25 and between the sliding bearing 28 and the thrust plate 29 on the cover 27 side. However, since the contact between two parts also occurs rather than fluid lubrication, the sliding bearing is required to have slidability. Therefore, as the sliding bearing, a carbon bearing or a resin bearing such as slidable polyether ketone ketone (PEEK) resin, polyphenylene sulfide (PPS) resin, polyacetal (POM) resin, phenol resin, etc. is used. Ceramics, stainless steel, etc. are used for a thrust board (refer patent document 3). In addition, in order to make it easier to form a water film on the sliding surface, an impeller or the like is provided with a hole that allows communication between the high pressure side and the low pressure side in the pump, and the differential pressure is used for the sliding surface of the sliding bearing. A method for supplying circulating water has been proposed (see Patent Document 4).

Japanese Patent No. 3099434 JP 2006-200197 A Japanese Patent No. 4936258 Japanese Patent No. 3780648

  In recent years, water pumps are increasingly required to have higher efficiency for energy saving and higher output for cooling effect. Therefore, low friction is required for the sliding bearing. Further, when the load applied to the slide bearing increases due to the increase in output, it becomes difficult to form a water film, and the friction coefficient increases. In addition, since the temperature of the sliding surface increases and wear resistance decreases, further improvement in friction and wear characteristics is required.

  In a resin-made sliding bearing, in order to improve slidability, high heat resistance such as PEEK resin or PPS resin is adopted as a base resin, and a solid lubricant is blended. However, the effect of reducing the friction coefficient is insufficient, and the contact between the sliding bearing and the shaft and the sliding bearing and the thrust plate cannot be reduced, so that the wear reducing effect is also insufficient.

  Moreover, even when it is going to supply circulating water to the sliding surface of a sliding bearing using differential pressure, it is difficult for water to enter into the closed sliding surface, and other gaps with less resistance are used as flow paths. For this reason, the supply of water to the sliding surface is insufficient particularly under high surface pressure conditions, and the effect of reducing the friction coefficient is poor. Further, the sliding surface is not sufficiently cooled.

  The present invention has been made in order to cope with such a problem, and improves the water supply capability to the sliding bearing sliding surface provided in the pump, thereby reducing the low friction characteristics and wear resistance characteristics of the sliding bearing. An object is to provide an improved water pump.

  The water pump of the present invention includes an impeller, a shaft for fixing the impeller, a sliding bearing fixed to the impeller for rotatably supporting the impeller with respect to the shaft, and the sliding A thrust receiving member that slides on each end face of the bearing, and a casing and a cover that house the impeller and form a pump chamber, and absorbs circulating water through the pump chamber by the rotation of the impeller. A water pump for discharging, wherein the sliding bearing is made of a resin composition containing PPS resin as a base resin and containing at least carbon fiber.

  The carbon fiber is a carbonized product fired at 1000 to 1500 ° C. The carbon fiber has an average fiber diameter of 5 to 15 μm and an average fiber length of 20 to 200 μm.

  The resin composition is a resin composition further containing at least one of a polytetrafluoroethylene resin or graphite. The resin composition is characterized in that the blending ratio of the polytetrafluoroethylene resin and / or graphite is 3 to 30% by volume, the carbon fiber is 5 to 30% by volume, and the balance is the PPS resin.

  A suction means for sucking the circulating water from one end face side of the sliding bearing to a bearing inner diameter face side by relative rotation of the thrust receiving member and the sliding bearing during rotation of the impeller; and It has both the discharge means which discharges | circulates a circulating water from the bearing inner peripheral surface side of the said slide bearing to the other end surface side, It is characterized by the above-mentioned. The “thrust receiving member” includes not only a dedicated thrust plate provided for receiving the thrust load of the sliding bearing but also other members when the thrust load is received by another member such as a casing.

  The suction means is a liquid suction groove formed on at least one thrust sliding surface selected from the end surface of the sliding bearing on the circulating water suction side and the thrust receiving member sliding with the end surface. And The groove is a dynamic pressure groove.

  The discharge means is a liquid discharge groove formed on at least one thrust sliding surface selected from the end surface on the circulating water discharge side of the sliding bearing and the thrust receiving member sliding with the end surface. And The groove is a dynamic pressure groove.

  The inner diameter corner of the end surface on the circulating water suction side of the sliding bearing has an inclined surface whose diameter increases toward the end surface.

  A dynamic pressure groove is formed on at least one radial sliding surface selected from an inner diameter surface of the sliding bearing and an outer diameter surface of the shaft.

  The slide bearing and the impeller are integrally molded products that are integrally injection-molded using the resin composition.

  The water pump of the present invention sucks circulating water from one end face side of the sliding bearing to the bearing inner diameter face side by relative rotation of the sliding bearing and the thrust receiving member that slides with the sliding bearing during rotation of the impeller. Means and a discharge means for discharging the circulating water from the bearing inner surface side of the sliding bearing to the other end surface side, so that a large amount of water can be circulated and supplied to the sliding surface, The water pump has a sliding bearing with improved lubrication characteristics and low friction and wear.

  Since the suction means is a liquid suction groove formed on at least one thrust sliding surface selected from an end surface of the sliding bearing on the circulating water suction side and a thrust receiving member sliding with the end surface, an existing pump Water supply performance (suction capacity) can be improved only by forming a groove on the end face of the slide bearing or the like without greatly changing the device configuration.

  Since the discharge means is a groove for discharging liquid formed on at least one thrust sliding surface selected from the end surface of the sliding bearing on the circulating water discharge side and the thrust receiving member sliding with the end surface, the existing pump The water supply ability (discharge capacity) can be improved only by forming a groove on the end face of the slide bearing or the like without greatly changing the device configuration.

  Since the liquid suction groove or the liquid discharge groove is a dynamic pressure groove, the suction or discharge effect is enhanced, and the effect of pushing water into the sliding surface closed by the generated dynamic pressure is also added, thereby cooling the sliding surface. And lubrication characteristics are further improved. In addition, if necessary, a dynamic pressure groove is formed on at least one radial sliding surface selected from the inner diameter surface of the sliding bearing and the outer diameter surface of the shaft. There is an effect to push. Moreover, since the pressure by these dynamic pressure grooves is in the opposite direction to the load that the sliding bearing receives, the load force is reduced and the coefficient of friction is reduced.

  The inner diameter corner of the end surface on the circulating water suction side of the sliding bearing has an inclined surface that expands the inner diameter toward the end surface, so that the water suction effect is improved and a large amount of water is supplied to the sliding surface. it can.

  Since the slide bearing is made of a resin composition containing PPS resin as a base resin, it has high heat resistance and high rigidity even when the temperature of the cooling water rises. In addition, even if the sliding surface temperature is increased due to frictional heat generation, there is an advantage that low wear and seizure hardly occur even in an abnormal state of running out of water. Furthermore, since the water absorption is low, the dimensional change of the bearing including grooves and blades during use is very small. In particular, since carbon fiber is included in the resin composition, rigidity, wear resistance, and dimensional accuracy are improved.

  Since the slide bearing and the impeller are integrally molded products that are integrally injection-molded using a resin composition that can be injection-molded, a slide bearing that has been injection-molded in advance is inserted into a mold, and the impeller is injection-molded. Compared with such a case, it is possible to form a liquid suction groove, a liquid discharge groove, or a liquid suction blade and a liquid discharge blade with high dimensional accuracy, and a water pump can be manufactured at low cost.

It is a cross-sectional view which shows an example of the water pump of this invention. It is a figure which shows the groove | channel formed in the sliding bearing end surface. It is a figure which shows the cross-sectional shape of a groove | channel. An inclined surface is provided on the inner diameter corner of the suction-side end surface of the slide bearing. It is a cross-sectional view showing a conventional water pump.

  An embodiment of the water pump of the present invention will be described with reference to FIG. In the water pump 1, the casing 6 and the cover 7 are fixed to form a pump chamber that houses the impeller 4. The casing 6 and the cover 7 are sealed through the packing 11 to prevent the circulating water in the pump chamber from leaking. The motor 12 has a winding 2 provided with a coil to generate a magnetic field, and the control unit controls the generation of the magnetic field. In order to follow this generated magnetic field, the impeller 4 to which the permanent magnet 3 is fixed is rotatably supported by the shaft 5 in the pump chamber. As the impeller 4 follows the rotating magnetic field and rotates in the pump chamber, the circulating water is sucked and discharged. Specifically, with the rotating magnetic field generated from the winding 2, the impeller 4 rotates following the attraction and repulsion of the fixed permanent magnet 3, thereby generating a pumping action and circulating water from the direction of the arrow X. And the circulating water is discharged in the direction of arrow Y.

  The shaft 5 is fixed to the approximate center of the casing 6 and is supported by a shaft support 7 a of the cover 7. The impeller 4 is rotatably supported with respect to the shaft 5 via a sliding bearing 8 fixed at the center thereof. The shaft 5 is a fixed shaft (not rotating), and the outer diameter surface of the shaft 5 and the inner diameter surface of the slide bearing 8 are slid and slid. Both end surfaces of the sliding bearing 8 rotate and slide in the thrust direction with thrust plates 9 and 10 which are thrust receiving members provided between the shaft support 7a of the cover 7 and the casing 6, respectively. A “sliding bearing” is a part that receives and slides on its inner diameter and end face, and is not necessarily limited to one part, but may be divided into two or more parts and even different in material. Good.

  In the present invention, in this water pump, the relative rotation of the thrust receiving members (thrust plates 9 and 10) and the sliding bearing 8 during the rotation of the impeller 4 causes (1) circulating water to be on one end face side of the sliding bearing 8. At least one selected from suction means for sucking from the bearing inner surface to the bearing inner surface, and (2) a discharging means for discharging the circulating water from the bearing inner surface to the other end surface of the slide bearing 8 by the relative rotation. Have. (1) By having either one of (2), the ability to supply water to the sliding surface can be improved, but because the water on the sliding surface is circulated by stably sucking and discharging a large amount of water. , (1) and (2). By the circulation of this water, a large amount of water is supplied not only to the bearing inner surface (radial sliding surface) but also to the bearing end surface (thrust sliding surface).

  As the suction means, for example, the liquid suction formed on at least one thrust sliding surface selected from the end surface of the sliding bearing 8 on the circulating water suction side and the thrust receiving members (thrust plates 9, 10) that slide with the end surface. For example, a groove or a blade. Further, as the discharging means, for example, it is formed on at least one thrust sliding surface selected from the end surface on the circulating water discharge side of the sliding bearing 8 and the thrust receiving member (thrust plate 9, 10) sliding with the end surface. Examples include grooves or blades for discharging liquid.

  In the slide bearing 8, it can be determined as appropriate which end face is the circulating water suction side or the circulating water discharge side. However, since a large amount of water is easily supplied to the sliding face, the sliding bearing is arranged in the pump chamber. It is preferable to match the flow of water at the location. That is, it is preferable that the end face located on the upstream side of the water flow is the circulating water suction side and the end face located on the downstream side is the circulating water discharge side.

  Here, in the form of FIG. 1, during rotation, the impeller 4 is pressed against the cover 7 side by the differential pressure, and one end face of the slide bearing 8 rotates and slides with the thrust plate 9. There is almost no sliding between the other end face of the sliding bearing 8 and the thrust plate 10 on the casing 6 side. The direction of water flow due to the differential pressure is from the thrust plate 10 side to the thrust plate 9 side. Therefore, in FIG. 1, a liquid suction groove is formed as a suction means on the end face of the slide bearing 8 on the thrust plate 10 side, and a liquid discharge groove is provided as a discharge means on the end face on the thrust plate 9 side. Forming. The shape of the groove is a spiral described later.

  The liquid suction groove and the liquid discharge groove are not particularly limited as long as they generate a suction and discharge action when the sliding bearing rotates. A groove shape (dynamic pressure groove) in which dynamic pressure is generated is preferable because water is pushed into the closed sliding surface and the cooling effect of the sliding surface is enhanced. A herringbone, spiral, or dynamic pressure groove with a complicated flow path that generates dynamic pressure on each bearing end face during suction and discharge, and these can be used alone or in combination to lubricate the cooling effect of the sliding surface. It is preferable because the state can be improved. More preferred is a herringbone or spiral having a high dynamic pressure effect. FIG. 2 shows the planar shape of the groove. FIGS. 2A to 2F are herringbones, FIGS. 2G and 2H are spirals, and FIGS. 2I and 2J are radial shapes with complicated flow paths. Black portions in the figure are liquid discharge grooves. The groove shown in each drawing of FIG. 2 has a function of sending water from the inner diameter side to the outer diameter side (discharge direction) by rotating in the bearing rotation direction shown in the figure. The groove may be either a groove (communication groove) communicating the inner and outer diameters of the sliding bearing end face or a groove (non-communication groove) not communicating. In the non-communication groove, the flow of water is hindered on the way, so that dynamic pressure is likely to occur. On the other hand, since the communication groove has a role of discharging foreign matter such as wear powder and cooling the sliding surface of the shaft, it is preferable to use a communication groove and a non-communication groove in combination.

  The return position of the groove in the herring bone as shown in FIG. 2A can be set as appropriate. In the shape and the bearing rotation direction shown in FIGS. 2A to 2F, the force from the inner diameter side toward the outer diameter side increases as the turn-back position goes to the outer circumferential side. 2 (i) and 2 (j) are such that the groove channel from the inner diameter to the outer diameter is longer than the case where the inner diameter and the outer diameter are connected by a radial straight line or curve from the center. Forming. Specifically, a circumferential groove concentric with the center of the end face is provided at a substantially central position in the radial direction of the end face of the slide bearing, an inner diameter side groove from the inner diameter to the circumferential groove, and an outer diameter from the circumferential groove to the outer diameter. The side groove has a shape connected to the circumferential groove at a circumferential position that does not overlap the circumferential groove. Furthermore, the connection position of the inner diameter side groove and the circumferential groove and the connection position of the outer diameter side groove and the circumferential groove are arranged alternately at substantially equal intervals in the circumferential direction.

  The cross-sectional shape of the groove is not particularly limited as long as the above-described suction and discharge functions are generated, and may be any of a square groove, an R groove, and a V groove. The cross-sectional shape of the groove is shown in FIG. 3A and 3D are square grooves, FIG. 3B is an R groove, and FIG. 3C is a V groove. In the water pump, the load capacity of the liquid film due to the dynamic pressure effect is smaller than the thrust load due to the restriction of the bearing size, and it is difficult to completely make no contact between the bearing end surface and the thrust receiving member. Therefore, the sliding bearing and the thrust receiving member come into contact with each other and slide to be in a mixed lubrication state. In this way, when the liquid film cannot be completely contactlessly supported, the V-groove and the R-groove having a wedge shape (a narrowed shape) in the groove cross-sectional shape are more likely to generate dynamic pressure due to the wedge effect than the square groove. Therefore, the V-groove and R-groove are preferable to the square groove. Furthermore, since the pressure of the water filled in the wedge-shaped space increases as the gap becomes smaller, a V-groove having a large area with a small clearance as a cross-sectional shape is preferable to the R-groove. Therefore, the R groove is preferable to the square groove, and the V groove is preferable to the R groove. The angle of the V-groove is not particularly limited, but it is not necessary to be a symmetric groove. As shown in FIG. 3 (f), the angle between the groove on the side where the liquid flows into the sliding surface by rotation and the groove has an acute angle. Is preferred. The same applies to the R groove, and as shown in FIG. 3 (e), it is preferable that the inclination on the side where the liquid flows into the sliding surface by rotation is gentle. The groove width and depth make it easy to generate dynamic pressure by widening the inlet from the direction of water flow and narrowing the outlet. Also, the greater the number of grooves, the easier it is to generate dynamic pressure, but the surface pressure on the sliding surface increases, so it may be set in consideration of usage conditions.

  From the flow of water at the inner diameter of the bearing, the end face on the upstream side of the water flow tends to flow from the outer diameter to the inner diameter, and the end face on the downstream side tends to flow from the inner diameter to the outer diameter. Therefore, when providing a dynamic pressure groove, the flow of water is also used, and the upstream end surface is a groove that draws water from the inner diameter to the inner diameter and the downstream end surface is a groove that draws water from the inner diameter to the outer diameter to generate dynamic pressure. It is preferable to make it.

  Further, in FIG. 1, a liquid suction blade is formed as a suction means on the end face of the slide bearing 8 on the thrust plate 10 side, and a liquid discharge blade is provided as a discharge means on the end face on the thrust plate 9 side. It may be formed. A blade | wing here means the blade | wing shaped part mainly formed in a sliding bearing end surface. The supply amount of water can be increased by providing a blade having a shape capable of sending water more directly instead of the groove. The liquid suction blade and the liquid discharge blade are not particularly limited as long as they generate suction and discharge when the sliding bearing rotates. When the surface pressure on the sliding surface is increased, the wear characteristics are deteriorated. Therefore, grooves such as the end face of the sliding bearing 8 and the thrust plate 9 in FIG.

  Moreover, as shown in FIG. 4, it is preferable to have the inclined surface 8a which expands an internal diameter toward this end surface side in the internal diameter corner | angular part of the end surface by the side of circulating water suction of the sliding bearing 8. As shown in FIG. Providing such an inclined surface 8a on the circulating water suction side makes it easier for water to enter the gap (sliding surface) between the outer diameter surface 5a of the shaft 5 and the inner diameter surface 8b of the slide bearing 8, and more Water can be supplied to the sliding surface. Furthermore, the suction effect is further enhanced by providing a suction groove or suction blade such as a spiral on the inclined surface 8a.

  In addition to the end surface of the sliding bearing 8 described above, it is preferable to form a groove on at least one radial sliding surface selected from the inner diameter surface 8 b of the sliding bearing 8 and the outer diameter surface 5 a of the shaft 5. For example, a linear groove or a spiral groove parallel to the axial direction can be formed. Moreover, it is preferable to make this groove into a dynamic pressure groove. By providing the dynamic pressure groove, it becomes possible to push water into the closed sliding surface and supply a large amount of water, generate a load in the anti-load direction, form a water film, and have a low coefficient of friction. In addition, an air cooling effect can be expected even in an abnormal state of running out of water. In the spiral groove, it is easy to generate dynamic pressure by making the spiral rotation direction the same as the rotation direction of the shaft. About the cross-sectional shape of this groove | channel, it is the same as the case where it forms in the above-mentioned slide bearing end surface. In addition, herringbone and spiral grooves can be formed by rolling or the like. Further, for the same reason as in the case where the groove is formed on the end face of the sliding bearing, it is preferable to use a communication groove (a groove communicating from one end face of the bearing to the other end face) and a non-communication groove in combination. .

  When grooves are provided on one or both of the end surfaces of the plain bearing and the inner diameter surface, the positional relationship of the grooves is not particularly limited. Easy to do. Further, since the lubricating water supplied to another surface through the groove hits the sliding surface and the flow is hindered, water easily enters the sliding surface and the lubrication state is improved. On the other hand, since the effect of the foreign matter discharge groove is further enhanced by the communication, the combined use of the communication groove and the non-communication groove is preferable. The same applies to the case where a groove is provided on one or both of the thrust plate surfaces and the outer periphery of the shaft.

  As the material of the sliding bearing, it is sufficient if it has sliding properties. For example, carbon, PEEK resin, PPS resin, POM resin, polytetrafluoroethylene (PTFE) resin, etc., phenol resin, epoxy Examples thereof include thermosetting resins such as resins and polyimide resins. A resin composition that can be injection-molded is preferable because a complex-shaped liquid suction groove, liquid discharge groove, liquid suction blade, and liquid discharge blade can be formed accurately and inexpensively. Specifically, those based on PEEK resin, PPS resin, or phenol resin are preferable.

  It is preferable that the slide bearing and the impeller are made of a thermoplastic resin composition that can be injection-molded, and the slide bearing and the impeller are simultaneously formed at the time of injection molding. The method for fixing the permanent magnet to the impeller is not particularly limited. Insert molding when molding the slide bearing and the impeller is less expensive than press-fitting or physical fixing after molding. When a slide bearing that has been injection molded in advance is inserted into a mold and an impeller is injection molded, the inner diameter of the slide bearing, the groove (dynamic pressure groove), and the size of the blade can change depending on the injection molding pressure. On the other hand, by simultaneously forming the sliding bearing and the impeller, it is possible to form an inner diameter and a groove (dynamic pressure groove) with high dimensional accuracy and to manufacture at low cost.

  Among the above-mentioned resin compositions that can be injection-molded, a composition comprising a PEEK resin or a PPS resin as a base resin is preferable. Since these resins have high heat resistance, the rigidity is high even when the temperature of the cooling water rises. In addition, even if the sliding surface temperature is increased due to frictional heat generation, there is an advantage that low wear and seizure hardly occur even in an abnormal state of running out of water. Furthermore, since the water absorption is low, the dimensional change of the bearing including grooves and blades during use is very small. Therefore, it is preferable as the material of the sliding bearing and the material of the impeller. In order to obtain an inexpensive water pump, PPS resin is particularly preferable.

  The PPS resin is a crystalline thermoplastic resin having a polymer structure in which a benzene ring is in a para position and connected by a sulfur bond. PPS resin has a melting point of about 280 ° C. and a glass transition point of 93 ° C., and has extremely high rigidity, excellent heat resistance, dimensional stability, wear resistance, and the like. Depending on the molecular structure of the PPS resin, there are types such as a cross-linked type, a semi-cross-linked type, a linear type, and a branched type. In order to obtain a sliding bearing that takes into account the abrasive wear state such as a water out condition where a water film is not formed or a state where foreign matter is bitten, a linear type with toughness is preferred.

  The PEEK resin is a crystalline thermoplastic resin having a polymer structure in which a benzene ring is in a para position and is connected to a carbonyl group by an ether bond. PEEK resin has a melting point of about 340 ° C and a glass transition point of 143 ° C. In addition to excellent heat resistance, creep resistance, load resistance, wear resistance, sliding characteristics, fatigue characteristics, etc., excellent moldability Have

  In the above resin composition, it is preferable to blend PTFE resin in order to give a frictional property in a water draining state where a water film is not formed. Moreover, in order to provide the friction characteristic in cooling water, it is preferable to mix | blend graphite. Furthermore, graphite has the effect of improving the wear characteristics and elastic modulus, and improving the dimensional accuracy of the sliding bearing during injection molding.

  In the resin composition, it is preferable to blend carbon fiber in order to improve rigidity, wear resistance, and dimensional accuracy as a sliding bearing or an impeller. The carbon fibers may be either pitch-based or PAN-based classified from raw materials. The firing temperature is not particularly limited, but the carbonized product fired at about 1000 to 1500 ° C. has higher water absorption than the one fired at a high temperature of 2000 ° C. or higher and converted into graphite. It is preferable because it contributes to lower friction and is less susceptible to wear damage to the mating material. The average fiber diameter of the carbon fibers is 20 μm or less, preferably 5 to 15 μm. A thick carbon fiber exceeding the above range is not preferable because extreme pressure is generated, so that the effect of improving load resistance is poor, and when the shaft or the like which is the counterpart material is stainless steel, the wear damage of the counterpart material becomes large.

  The carbon fiber may be a chopped fiber or a milled fiber, but a milled fiber having a fiber length of less than 1 mm is preferable, and an average fiber length is more preferably 20 to 200 μm. If it is less than 20 μm, sufficient rigidity and reinforcing effect cannot be obtained, and the wear resistance may be inferior. When exceeding 200 μm, an extreme pressure is generated, and therefore, when the shaft or the like which is the counterpart material is stainless steel, the wear damage of the counterpart material becomes large, which is not preferable.

  In the above resin composition, improving the elastic modulus lowers the real contact area of the sliding surface and lowers friction, and therefore blends flake fillers such as mica and talc that can improve this. Is also effective.

  The blending ratio in the resin composition is such that the blending ratio of at least PTFE resin and / or graphite is 3 to 30% by volume, more preferably 5 to 20% by volume, and carbon fiber is 5 to 30% by volume, more preferably 10 to 20%. It is preferable that the volume% and the balance be synthetic resin (base resin). Furthermore, it is preferable to use PTFE resin and graphite together.

  In addition, you may mix | blend a well-known resin additive with respect to a resin composition to such an extent that the effect of this invention is not inhibited. Examples of the additives include friction property improvers such as boron nitride, molybdenum disulfide, and tungsten disulfide, colorants such as carbon powder, iron oxide, and titanium oxide, and thermal conductivity improvers such as metal oxide powder. Can be mentioned.

  In the water pump of the present invention, examples of the material of the shaft and the thrust plate that slide with the sliding bearing include ceramics such as alumina excellent in rust prevention, stainless steel, and the like. Ceramics are preferred because of their high hardness and excellent wear resistance. When a thrust plate is provided with a liquid suction groove, a liquid discharge groove, or a liquid suction blade or a liquid discharge blade, it is not easy to form into ceramics, so stainless steel that can be formed by machining, rolling, etc. is preferable. . If the groove or blade is provided on a ceramic or stainless steel thrust plate, the slide bearing may be worn at the groove edge portion. In this case, the groove is preferably formed on the slide bearing side. Further, when the sliding bearing is formed of a thermoplastic resin that can be injection-molded, it is preferable to form the groove on the sliding bearing side because a groove or the like can be formed by mold transfer and the cost becomes low.

  A surface treatment for forming a lubricating coating such as diamond-like carbon (DLC) may be applied to the mating surface that slides with the shaft and the sliding bearing end surface. Since DLC has excellent friction characteristics in water, it is possible to reduce the coefficient of friction at a minute portion that comes into contact with the sliding bearing while water is supplied to the dynamic pressure grooves. Moreover, since it is a hard film, abrasion of stainless steel can be prevented. Further, surface irregularities such as dimples may be formed on the mating surface that slides with the shaft and the sliding bearing end surface. Since there is a dynamic pressure effect and the contact area is reduced, the friction is reduced. The dimples can be formed by shot blasting or the like, and fine irregularities are more effective.

  In the water pump of the present invention, the material of the casing and the cover is not particularly limited, and an injection moldable resin composition or the like can be used. For example, a composition having a base resin such as polyethylene terephthalate (PET) resin, polybutylene terephthalate (PBT) resin, PPS resin, POM resin, polyamide (PA) resin (PA66 resin, modified PA resin, etc.) can be used. Moreover, in order to improve the intensity | strength and elastic modulus of these compositions, it is preferable to mix | blend fibrous fillers, such as glass fiber and carbon fiber.

  The water pump of the present invention is excellent in the ability to supply water to the sliding bearing sliding surface provided inside the pump, and is excellent in the low friction characteristics and wear resistance characteristics of the sliding bearing. Or it can utilize suitably as a pump for circulating the cooling water, such as a fuel cell, and the circulating hot water, such as a water heater and a floor heating apparatus. The water pump of the present invention is not limited to water circulation, but is useful as a pump for moving and supplying water. The same effect can be expected even if the medium is a pump that circulates and moves liquids such as chemicals other than water, solvents, oils, and beverages.

DESCRIPTION OF SYMBOLS 1 Water pump 2 Winding 3 Permanent magnet 4 Impeller 5 Shaft 6 Casing 7 Cover 8 Slide bearing 9 Thrust plate 10 Thrust plate 11 Packing 12 Motor

Claims (12)

An impeller, a shaft for fixing the impeller, a sliding bearing fixed to the impeller for rotatably supporting the impeller with respect to the shaft, and a sliding surface of each end surface of the sliding bearing A water pump that includes a moving thrust receiving member, a casing that houses the impeller and forms a pump chamber, and a cover that sucks and discharges circulating water through the pump chamber by rotation of the impeller. ,
The water pump according to claim 1, wherein the sliding bearing is made of a resin composition containing polyphenylene sulfide resin as a base resin and containing at least carbon fiber.   The water pump according to claim 1, wherein the carbon fiber is a carbonized product fired at 1000 to 1500 ° C.   The water pump according to claim 1 or 2, wherein the carbon fiber has an average fiber diameter of 5 to 15 µm and an average fiber length of 20 to 200 µm.   The water pump according to any one of claims 1 to 3, wherein the resin composition is a resin composition further containing at least one of polytetrafluoroethylene resin or graphite.   5. The resin composition according to claim 4, wherein the blending ratio of polytetrafluoroethylene resin and / or graphite is 3 to 30% by volume, carbon fiber is 5 to 30% by volume, and the balance is polyphenylene sulfide resin. Water pump.   A suction means for sucking the circulating water from one end face side of the sliding bearing to a bearing inner diameter face side by relative rotation of the thrust receiving member and the sliding bearing during rotation of the impeller; and the circulating water; The water pump according to any one of claims 1 to 5, further comprising: a discharging unit that discharges the sliding bearing from the bearing inner diameter surface side to the other end surface side.   The suction means is a liquid suction groove formed on at least one thrust sliding surface selected from an end surface of the sliding bearing on the circulating water suction side and the thrust receiving member sliding with the end surface. The water pump according to claim 6.   The discharge means is a liquid discharge groove formed on at least one thrust sliding surface selected from an end surface of the sliding bearing on the circulating water discharge side and the thrust receiving member sliding with the end surface. The water pump according to claim 6 or 7.   The water pump according to claim 7 or 8, wherein the groove is a dynamic pressure groove.   10. The inclined surface according to claim 6, further comprising an inclined surface whose diameter increases toward the end surface at an inner diameter corner portion of the end surface of the sliding bearing on the circulating water suction side. Water pump.   The dynamic pressure groove is formed in at least one radial sliding surface selected from the inner diameter surface of the sliding bearing and the outer diameter surface of the shaft. Water pump.   The water pump according to any one of claims 1 to 11, wherein the sliding bearing and the impeller are an integrally molded product integrally injection-molded using the resin composition.

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