JP2018119517A - Refrigerant pump - Google Patents

Abstract

A refrigerant pump capable of improving reliability and reducing manufacturing costs is provided. A refrigerant pump (10) includes a shaft (12), a bearing (13), a casing (11) and vanes (14). Shaft 12 is rotatably supported by bearing 13 . The casing 11 has a pump chamber 15 through which refrigerant flows. The vane portion 14 is rotatably provided inside the pump chamber 15 and rotates together with the shaft 12 to suck the refrigerant into the pump chamber 15 and pump the refrigerant from the pump chamber 15 to the outside. At least one of the blade portion sliding contact surface 141 and the pump chamber sliding contact surface 151 is provided with a hard thin film coating 24 containing DLC, nitride, carbide or carbonitride. [Selection drawing] Fig. 6

Description

  The present invention relates to a refrigerant pump that pumps liquid refrigerant, and is particularly suitable for pumping low-viscosity liquid refrigerant used in a refrigeration cycle.

  Conventionally, a refrigerant pump that pumps liquid refrigerant used in a refrigeration cycle is known. In general, a liquid refrigerant having a low viscosity and poor lubricity is used in the refrigeration cycle. For this reason, the coolant pump used in the refrigeration cycle has a problem of wear of sliding portions.

  The refrigerant pump described in Patent Document 1 includes an inner rotor that is locked to a motor shaft, an outer rotor that meshes with an outer wall on the radially outer side of the inner rotor, and the like. The motor shaft is rotatably supported by a bearing or the like and rotates together with the inner rotor. In this refrigerant pump, a diamond coating is provided on a portion of the outer wall of the shaft that is in sliding contact with a bearing or the like, and a portion in which the inner rotor and the outer rotor are in sliding contact. Thereby, this refrigerant | coolant pump reduces the abrasion of those sliding locations.

  On the other hand, Patent Document 2 describes a Wesco pump that pumps fuel. This pump includes a blade portion (also referred to as an impeller) locked to a motor shaft, a casing having a pump chamber for housing the blade portion, and the like. This pump is provided with a plurality of grooves on the surface of the blade portion in the direction of the rotation axis. Thereby, this refrigerant pump avoids the linking phenomenon in which the surface of the blade portion in the rotation axis direction and the inner wall of the pump chamber are in close contact.

JP-A-2-264188 JP-A-6-280776

  However, Patent Document 1 described above does not mention the linking phenomenon in which the surface in the rotation axis direction of the inner rotor or the outer rotor is in close contact with the inner wall of the pump chamber. Moreover, in patent document 1, when providing a diamond membrane | film | coat in a shaft, an inner rotor, or an outer rotor, the hardness improvement process with respect to the base material is not mentioned.

  On the other hand, in the Wesco pump of Patent Document 2, a plurality of grooves are provided on the surface of the blade portion in the rotation axis direction in order to avoid the linking phenomenon, so that the configuration of the blade portion is complicated.

  Here, the mechanism by which the linking phenomenon occurs in the Wesco pump will be described.

  First, the configuration of the Wesco pump will be described with reference to FIGS. 1 and 2. The Wesco pump includes a casing 11 having a pump chamber 15, a shaft 12 that is rotatably supported by a bearing 13 in the casing 11, and a blade portion 14 that rotates together with the shaft 12 in the pump chamber 15.

  The casing 11 includes a first casing member 111 and a second casing member 112. A pump chamber 15 through which refrigerant flows is formed between the first casing member 111 and the second casing member 112. The casing 11 has a shaft hole 16 into which the shaft 12 is inserted. The shaft 12 is formed in a column shape and is rotatably supported by two bearings 13 provided on the inner wall of the shaft hole 16.

  The shaft 12 is inserted through a central hole 17 provided at the center of the blade portion 14. Torque transmitting means such as a key member 19 is fitted into the groove 18 provided in the inner wall of the central hole 17 of the blade portion 14 and the groove 181 provided in the outer wall of the shaft 12. Thereby, the shaft 12 and the blade | wing part 14 are mutually latched. The blade portion 14 is formed in a substantially disk shape, and a plurality of groove portions 20 for increasing the pressure of the liquid refrigerant are provided on the outer periphery thereof. As a result, when the blade portion 14 of the shaft 12 rotates, the liquid refrigerant as a medium is sucked into the pump chamber 15 from the suction port 21, and the liquid refrigerant is pumped from the pump chamber 15 to the outside through the discharge port 22.

  In FIGS. 1 and 2, the rotation direction of the shaft 12 and the blade portion 14 is indicated by a solid line arrow IR. Further, in FIG. 1, the flow of the liquid refrigerant is indicated by broken arrows L1, L2, and L3.

  FIGS. 3A to 3D show a state in which a linking phenomenon occurs in the Wesco pump having the above-described configuration.

  FIG. 3A shows a state where the blade 14 is rotating in a state where a certain gap is formed between the surface of the blade 14 in the rotation axis direction and the inner wall of the pump chamber 15.

  FIG. 3B shows a state in which the blade portion 14 is inclined with respect to the inner wall of the pump chamber 15 and a part of the radially outer side of the blade portion 14 approaches the inner wall of the pump chamber 15. In addition, since there is a minute gap between the inner wall of the central hole 17 of the blade portion 14 and the outer wall of the shaft 12, even if the shaft 12 is rotating vertically with respect to the inner wall of the pump chamber 15, The blade portion 14 may be inclined with respect to the inner wall of the pump chamber 15. When the blade portion 14 continues to rotate in this state, the side where the gap between the inner wall of the pump chamber 15 and the blade portion 14 is small is depressurized and a pressure drop occurs. On the other hand, the side where the gap between the inner wall of the pump chamber 15 and the blade portion 14 is large is absolute pressure. For this reason, the blade portion 14 is placed on the inner wall of the pump chamber 15 due to a pressure difference between the side where the gap between the inner wall of the pump chamber 15 and the blade portion 14 is small and the side where the gap between the inner wall of the pump chamber 15 and the blade portion 14 is large. Thrust load to be pressed is generated. In FIGS. 3B and 3C, the thrust load is indicated by an arrow TL.

  Further, when the blade portion 14 continues to rotate, the negative pressure region expands due to an increase in pressure drop on the side where the gap between the inner wall of the pump chamber 15 and the blade portion 14 is small, and the above-described thrust load increases. Then, as shown in FIG. 3C, a linking phenomenon occurs in which the surface in the rotation axis direction of the blade portion 14 and the inner wall of the pump chamber 15 are in close contact with each other. When the linking phenomenon occurs, no liquid refrigerant is interposed between the surface of the blade portion 14 in the rotation axis direction and the inner wall of the pump chamber 15, and the blade portion 14 and the inner wall of the pump chamber 15 are in a sliding state where the surface pressure is high. It becomes.

  As shown in FIG. 3D, when the blade portion 14 continues to rotate in a state where the linking phenomenon has occurred, foreign matter M generated by wear is generated between the blade portion 14 and the inner wall of the pump chamber 15. If the foreign matter M is sandwiched between the blade portion 14 and the inner wall of the pump chamber 15 and there is no gap between the blade portion 14 and the inner wall of the pump chamber 15, there is a risk of reaching a so-called pump lock in which the rotation of the blade portion 14 stops. There is.

  Alternatively, if the blade portion 14 continues to rotate while the linking phenomenon occurs, the material forming the blade portion 14 and the inner wall of the pump chamber 15 is melted by frictional heat between the blade portion 14 and the inner wall of the pump chamber 15, Even when seizure occurs due to the adhesion of, the pump may be locked.

  As described above, when the linking phenomenon occurs, the side where the gap between the inner wall of the pump chamber 15 and the blade portion 14 is small becomes negative pressure. Therefore, the higher the absolute pressure of the refrigerant, the greater the thrust load that presses the blade portion 14 against the inner wall of the pump chamber 15 due to the linking phenomenon. Therefore, the inventor predicted that the operation of the refrigerant pump used in the refrigeration cycle in which the refrigerant was sealed in a state where the absolute pressure was high during the closed loop cycle would be severe in principle.

  Therefore, the inventor actually conducted an experiment on the operation state of the refrigerant pump with respect to the absolute pressure of the refrigerant, using the refrigerant pump. FIG. 4 shows the experimental results.

  The refrigerant pump used in this experiment has the same shape as that shown in FIG. 2, and both the blade portion 14 and the casing 11 are made of SUS304 stainless steel. In addition, the refrigerant pump has a clearance (hereinafter referred to as a side clearance SC) between a surface of the inner wall of the pump chamber 15 that faces the surface in the rotational axis direction of the blade portion 14 and a surface in the rotational axis direction of the blade portion 14, and the blade Two types of refrigerant pumps having different relationships with the outer diameter Di of the portion 14 were used. The side clearance SC includes a clearance SC1 between one surface in the rotation axis direction of the blade portion 14 and one inner wall of the pump chamber, and the other surface in the rotation axis direction of the blade portion 14 and the other inner wall of the pump chamber. And the clearance SC2 (ie, SC = SC1 + SC2). Here, the side clearance SC with respect to the outer diameter Di of the blade portion 14 is referred to as a clearance ratio (SC / Di). The first refrigerant pump has a clearance ratio of 0.0008. The second refrigerant pump has a clearance ratio of 0.0015.

  The experimental conditions were that the rotation speed of the refrigerant pump was 4000 rpm, and the suction pressure of the refrigerant pump was 0.6 MPa, 1.1 MPa, and 2.1 MPa, respectively. For those with suction pressures of 0.6 MPa and 1.1 MPa, R134a was used as the refrigerant. For those with a suction pressure of 2.1 MPa, R410A was used as the refrigerant. The refrigerant pressure difference (discharge pressure-suction pressure) when the pump pumps the refrigerant was 0.1 MPa.

  As a result of the experiment, the first refrigerant pump having a clearance ratio of 0.0008 was operable when R134a was used as the refrigerant and the suction pressures were 0.6 MPa and 1.1 MPa. However, this first refrigerant pump used R410A as the refrigerant, and adhesion occurred when the suction pressure was 2.1 MPa, leading to a pump lock.

  The second refrigerant pump having a clearance ratio of 0.015 was operable when R134a was used as the refrigerant and the suction pressure was 1.1 MPa. Further, the second refrigerant pump was operable even when R410A was used as the refrigerant and the suction pressure was 2.1 MPa.

  From the above-mentioned experiment, the inventor has found that a refrigerant pump that pumps refrigerant in a state where the absolute pressure is high increases the thrust load due to the linking phenomenon and may lead to a pump lock, so that the operation becomes severe. It was.

  In view of the above points, an object of the present invention is to provide a refrigerant pump capable of achieving both improvement in reliability and reduction in manufacturing cost.

In order to achieve the above object, the invention according to claim 1 is a refrigerant pump used in a refrigeration cycle in which a refrigerant is enclosed during a closed loop cycle,
A shaft (12) formed in a columnar shape;
A bearing (13) for rotatably supporting the shaft;
A casing (11) having a pump chamber (15) through which refrigerant flows;
A vane portion (14) is provided inside the pump chamber so as to be rotatable, sucks refrigerant into the pump chamber by rotating together with the shaft, and pumps the refrigerant from the pump chamber to the outside.

  This refrigerant pump has diamond-like carbon, nitrided on at least one of the surface (141) of the blade portion in the rotation axis direction and the surface (151) of the inner wall of the pump chamber facing the surface of the blade portion in the rotation axis direction. A hard thin film (24) containing a material, carbide or carbonitride is provided.

  According to this, the surface of the blade portion in the rotation axis direction (hereinafter referred to as the blade portion sliding contact surface) or the surface of the inner wall of the pump chamber facing the surface of the blade portion in the rotation axis direction (hereinafter referred to as pump chamber sliding). The durability against sliding of the contact surface is improved. For this reason, when this refrigerant pump is used for pumping refrigerant with a high absolute pressure, the thrust load increases due to the linking phenomenon, and the refrigerant is interposed between the sliding surface of the blade portion and the sliding surface of the pump chamber. Even if it becomes difficult to do so, it is possible to suppress the generation of foreign matter due to wear during that time. Moreover, it is suppressed that the material which forms the blade | wing part and the inner wall of a pump chamber fuse | melts and adheres. Therefore, even when this refrigerant pump is used for pumping the refrigerant having a high absolute pressure, it is possible to prevent the pump from being locked, so that the reliability can be improved.

  Further, this refrigerant pump does not have a complicated configuration of the blade sliding surface as in the above-described pump of Patent Document 2, and can simplify the configuration of the blade. Therefore, this refrigerant pump can reduce the manufacturing cost.

  In addition, the code | symbol in the bracket | parenthesis of each said structure shows an example of a corresponding relationship with the specific means as described in embodiment mentioned later.

It is a schematic diagram which shows the structure of a Wesco pump. It is sectional drawing of the II-II line | wire of FIG. It is explanatory drawing explaining the state which a pump lock generate | occur | produces in a Wesco pump. It is the table | surface which showed the experimental result regarding the driving | running state of the refrigerant | coolant pump according to the absolute pressure of a refrigerant | coolant. It is a block diagram of the boiling refrigeration cycle in which the refrigerant pump of one embodiment is used. It is sectional drawing of the refrigerant | coolant pump of one Embodiment. It is the table | surface which showed the experimental result regarding the state after the refrigerant | coolant pump driving | running | working according to the surface treatment method of a blade | wing part. It is explanatory drawing explaining the driving | running state of the refrigerant pump of one Embodiment. It is sectional drawing of the IX part of FIG. In a refrigerant pump of a comparative example, it is an explanatory view explaining the state where crack fracture occurred in the hard thin film coat of the shaft. It is the table | surface which showed the experimental result regarding the state after the refrigerant | coolant pump driving | operation according to the surface treatment method of a shaft. It is the table | surface which showed the experimental result regarding the state after a refrigerant | coolant pump driving | running | working according to the material of the hard thin film membrane | film | coat provided in a blade | wing part.

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

(One embodiment)
An embodiment will be described with reference to the drawings. The refrigerant pump of this embodiment is used for a refrigeration cycle in which a refrigerant is enclosed during a closed loop cycle.

  FIG. 5 shows a thermosiphon cycle 1 as an example of a refrigeration cycle including the refrigerant pump 10 of the present embodiment. This type of thermosiphon type cycle 1 is used for cooling the room of a base station in which a large computer is installed, for example.

  The thermosiphon type cycle 1 includes a refrigerant pump 10, an evaporator 2, a condenser 3, a liquid storage unit 4, and the like that are connected in a ring shape by a pipe 5 to form a closed loop cycle. In this closed loop cycle, the refrigerant is sealed in a state where the absolute pressure is high.

  The refrigerant pump 10 is provided at a position that is the lowest part in the gravity direction in the closed-loop cycle. The refrigerant pump 10 is used to pressure-feed the liquid refrigerant condensed in the condenser 3 and flowing down the pipe 5 by its own weight toward the evaporator 2.

  The evaporator 2 is provided in a room 6 that is a space to be cooled. The evaporator 2 is an indoor heat exchanger for exchanging heat between air and the refrigerant that have been heated by computer equipment or the like provided in the room 6. In the evaporator 2, the liquid refrigerant supplied from the refrigerant pump 10 absorbs heat from the air in the room 6 and evaporates. The air in the room 6 is cooled by the latent heat of vaporization of the refrigerant.

  The evaporator 2 and the condenser 3 are connected through a pipe 5. The condenser 3 is provided outside the room. The condenser 3 is an outdoor heat exchanger that exchanges heat between the outdoor low-temperature air and the refrigerant. In the condenser 3, the gas-phase refrigerant supplied from the evaporator 2 dissipates heat to the outdoor low-temperature air and condenses. The liquid refrigerant condensed in the condenser 3 flows down the pipe 5 by its own weight and flows into the liquid storage unit 4. Note that, in the condenser 3, the condensed liquid refrigerant flows down toward the liquid storage unit 4 through the pipe 5, so that the space on the gas phase refrigerant side inside the condenser 3 becomes negative pressure. Therefore, the vapor phase refrigerant is supplied from the evaporator 2 to the space on the vapor phase refrigerant side inside the condenser 3.

  The liquid reservoir 4 is provided below the condenser 3 in the direction of gravity. In the liquid reservoir 4, the gas-phase refrigerant and the liquid refrigerant are separated. The refrigerant pump 10 is provided below the liquid reservoir 4 in the direction of gravity. The refrigerant pump 10 pumps the liquid refrigerant supplied from the liquid reservoir 4 toward the evaporator 2. Thus, the thermosiphon type cycle 1 can cool the air in the room 6 that is the space to be cooled basically by natural circulation of the refrigerant without using a compressor. The refrigerant pump 10 can circulate the refrigerant in a closed-loop cycle when the pipe 5 of the thermosiphon type cycle 1 is bent in the gravity direction up and down due to the equipment structure. As described above, the closed loop cycle formed by the thermosiphon type cycle 1 is filled with refrigerant in a state where the absolute pressure is high. Therefore, in the thermosiphon type cycle 1, it is desirable to use the highly reliable refrigerant pump 10 in order to pump the refrigerant.

  Next, the refrigerant pump 10 of this embodiment will be described.

  As shown in FIG. 6, the refrigerant pump 10 of the present embodiment is a Wesco pump, and includes a motor unit 7, a magnet coupling unit 8, and a pump unit 9. The motor unit 7 includes a stator 71, a rotor 72, and the like. A motor shaft 73 is fixed to the central portion of the rotor 72. A coil (not shown) is wound around one of the stator 71 and the rotor 72. When the coil is energized, a rotating magnetic field is generated, and the rotor 72 and the motor shaft 73 rotate around the axis.

  The magnet coupling portion 8 includes an outer magnet 81, an inner magnet 82, a bottomed cylindrical can 83, and the like. The outer magnet 81 is fixed to the end of the motor shaft 73 provided in the motor unit 7. The inner magnet 82 is fixed to the end of the shaft 12 provided in the pump unit 9. The can 83 is provided between the outer magnet 81 and the inner magnet 82, and prevents high-pressure refrigerant filling the pump unit 9 from leaking to the motor unit 7. The can 83 is made of a nonmagnetic material. For this reason, when the outer magnet 81 rotates together with the motor shaft 73, the inner magnet 82 rotates due to the rotation of the magnetic force. As a result, torque is transmitted from the motor unit 7 to the pump unit 9.

  The pump unit 9 includes a casing 11, a shaft 12, a bearing 13, a blade unit 14, and the like. The schematic configuration of the pump unit 9 is substantially the same as the Wesco pump shown in FIGS. 1 and 2. In FIG. 6, the same reference numerals as those described with reference to FIGS. 1 and 2 are attached to the configuration of the pump unit 9. The pump unit 9 of the present embodiment also faces the surface in the rotation axis direction of the blade portion 14 (hereinafter referred to as the blade portion sliding contact surface 141) and the surface in the rotation axis direction of the blade portion 14 on the inner wall of the pump chamber 15. A surface (hereinafter referred to as a pump chamber sliding contact surface 151) is in surface contact.

  Here, the side clearance between the blade portion sliding contact surface 141 and the pump chamber sliding contact surface 151 is SC (SC = SC1 + SC2), and the outer diameter of the blade portion 14 is Di. The side clearance SC with respect to the outer diameter Di of the blade portion 14 is referred to as a clearance ratio (SC / Di). In this embodiment, the clearance ratio is set to 0.0015 or less. By setting the clearance ratio to be small in this way, the pressure increase performance of the refrigerant by the pump unit 9 is improved. Therefore, the pump performance can be improved, for example, the flow rate of the refrigerant pumped by the pump unit 9 is increased, and the pressure of the pumped refrigerant is increased.

  However, if the clearance ratio is set small, a linking phenomenon is likely to occur as described with reference to FIGS. When the linking phenomenon occurs, liquid refrigerant does not exist between the blade portion sliding contact surface 141 and the pump chamber sliding contact surface 151, and the blade portion sliding contact surface 141 and the pump chamber sliding contact surface 151 slide with high surface pressure. It becomes a moving state. At this time, the higher the absolute pressure of the refrigerant, the greater the thrust load that presses the blade portion sliding contact surface 141 against the pump chamber sliding contact surface 151. In this state, the blade portion 14 continues to rotate, and foreign matter generated due to wear is generated between the blade portion sliding contact surface 141 and the pump chamber sliding contact surface 151, and the foreign matter is generated between the blade portion sliding contact surface 141 and the pump chamber sliding contact surface. If it is sandwiched between the contact surface 151, the pump may be locked. In addition, even when the material forming the blade portion sliding contact surface 141 and the pump chamber sliding contact surface 151 is melted by frictional heat and sticks due to the adhesion thereof, the pump may be locked.

  Therefore, in the present embodiment, the hard thin film 24 is applied to the blade portion sliding contact surface 141. The hard thin film 24 provided on the blade sliding surface 141 corresponds to an example of the first hard thin film described in the claims. In FIG. 6, a broken line 241 is schematically attached to the boundary between the base material constituting the blade portion 14 and the hard thin film 24 for the purpose of explanation. The hard thin film 24 includes diamond-like carbon (hereinafter referred to as DLC), nitride, carbide or carbonitride. Examples of the nitride, carbide, or carbonitride include chromium nitride (hereinafter referred to as CrN), titanium nitride (hereinafter referred to as TiN), and titanium nitride aluminum (hereinafter referred to as TiAlN). The hard thin film 24 containing DLC, CrN, TiN, TiAlN, or the like has a characteristic of high resistance to sliding. In the refrigerant pump 10 of the present embodiment, the hard thin film 24 is provided on the blade portion sliding contact surface 141, thereby suppressing the generation of foreign matter between the blade portion sliding contact surface 141 and the pump chamber sliding contact surface 151. In addition, seizure between the pump chamber sliding contact surface 151 and the blade sliding contact surface 141 is suppressed. Therefore, the refrigerant pump 10 of this embodiment can avoid pump lock.

  The thickness of the hard thin film 24 is set to be greater than 0 and 5 μm or less, for example. In general, the size of the blade portion 14 is several millimeters, and the side clearance SC between the blade portion sliding contact surface 141 and the pump chamber sliding contact surface 151 is several tens of micrometers. The thickness of the thin film 24 can be made sufficiently thin. Thereby, when the hard thin film 24 is formed on the base material, even if unevenness due to tolerance occurs in the hard thin film 24, it is not necessary to perform an adjustment process such as a polishing process thereafter. Therefore, the manufacturing cost can be reduced.

  By the way, although the hard thin film 24 containing DLC, CrN, TiN, TiAlN or the like has a high resistance to sliding, the film itself is very thin, so the film strength is weak and the film cracks when it hits the edge. Or peeling of the film may occur. However, although the sliding contact surface 141 of the blade part and the sliding contact surface 151 of the pump chamber are poorly lubricated due to close contact, since they are per surface, there is almost no possibility that the film will crack or peel off. Therefore, in the present embodiment, the hard thin film 24 is provided on a so-called raw material (as it is) without performing a hardness improvement process such as a heat treatment on the metal base material constituting the blade part 14. If the base material constituting the blade portion 14 is subjected to a hardness improvement process such as a heat treatment, the cost of the heat treatment increases, and further, the cost due to a subsequent process such as grinding increases in order to remove distortion generated by the heat treatment. . On the other hand, in this embodiment, it is possible to achieve both reduction in manufacturing cost and improvement in reliability by not performing hardness improvement processing such as heat treatment on the base material constituting the blade portion 14.

  As described above, FIG. 7 shows the result of an experiment for confirming the effectiveness of providing the hard thin film 24 on the base material constituting the blade part 14 without performing a hardness improvement process such as a heat treatment.

  As shown in FIG. 7, the first sample specification of the refrigerant pump 10 uses SUS304 stainless steel as a base material constituting the blade portion 14 and applies a hard thin film 24 containing DLC without heat treatment. It is what.

  The second sample specification of the refrigerant pump 10 uses SUS304 stainless steel as a base material constituting the blade portion 14 and a hard thin film 24 containing CrN without heat treatment.

  The third sample specification of the refrigerant pump 10 uses SUJ2 high-carbon chromium bearing steel as the base material constituting the blade portion 14 and performs a heat treatment by QT treatment, and then applies a hard thin film 24 containing DLC. It is what.

  The experimental conditions were the same as the conditions in which the pump lock occurred in the experimental results shown in FIG. That is, the conditions are as follows: R410A is used as the refrigerant, the refrigerant pump 10 has a clearance ratio of 0.0008, a rotational speed of 4000 rpm, a suction pressure of 2.1 MPa, and a discharge pressure of 2.2 MPa. The casing 11 constituting the inner wall of the pump chamber 15 was made of SUS304 stainless steel.

  As for the experimental results, in any of the first to third sample specifications, the experimental results shown in FIG. 4 show a significant improvement over the refrigerant pump in which the pump lock is generated, and it is good without reaching the pump lock. Driving was possible. Therefore, as described above, it is not necessary to subject the base material constituting the blade part 14 to a hardness improvement process such as heat treatment, and the manufacturing cost can be reduced by providing the hard thin film 24 while using the base material as a raw material. In addition, it was proved that the reliability can be improved.

  By the way, as shown in FIGS. 8 and 9, the refrigerant pump 10 has two bearings when torque is transmitted from the motor unit 7 to the pump unit 9 and the shaft 12 and the blade unit 14 of the pump unit 9 rotate. The shaft 12 may be inclined with respect to the 13 center lines 131. Therefore, in the present embodiment, the hard thin film 25 containing DLC, CrN, TiN, TiAlN, or the like is provided on the outer wall of the shaft 12. The hard thin film 25 should just be provided in the site | part which contacts the bearing 13 among the outer walls of the shaft 12. FIG.

  The hard thin film 25 provided on the outer wall of the shaft 12 corresponds to an example of a second hard thin film described in the claims.

  FIG. 9 shows a state where the hard thin film 25 provided on the outer wall of the shaft 12 and the bearing 13 are in contact with the edge. When the shaft 12 and the blade portion 14 of the pump portion 9 are rotated, if the shaft 12 is tilted with respect to the center line 131 of the two bearings 13, the sliding between the hard thin film 25 provided on the shaft 12 and the bearing 13 will occur. The moving point is per edge.

  On the other hand, what was shown in FIG. 10 is the fragmentary sectional view of the shaft 12 and the bearing 13 with which the refrigerant | coolant pump of the comparative example for comparing with 1st Embodiment is provided. In the refrigerant pump of this comparative example, the base material constituting the shaft 12 is not subjected to a hardness improving process such as heat treatment, and the base material remains a raw material, and the hard thin film 25 is applied. As described above, the hard thin film 25 containing DLC, CrN, TiN, TiAlN or the like has a high resistance to sliding, but the film itself is very thin, so that the film strength is weak, and when it hits the edge, the film is applied to the film. There is a risk of cracking or peeling of the film. Therefore, when the stress applied to the shaft 12 from the bearing 13 reaches the base material constituting the shaft 12, the base material is depressed, and thereby the hard thin film 25 is broken (location indicated by reference numeral C in FIG. 10). See).

  Therefore, in the present embodiment, as shown in FIG. 9, the metal base material (for example, SUJ2 high-carbon chromium bearing steel) constituting the shaft 12 is subjected to hardness improvement processing such as heat treatment, and then the hard thin film is formed. A film 25 is provided. Thereby, while ensuring the abrasion resistance of the site | part which contacts the bearing 13 among the outer walls of the shaft 12, the crack destruction and peeling of the hard thin film 25 by the edge of the bearing 13 can be avoided.

  In addition, in order to prevent the depression due to the edge of the shaft 12, the bearing 13 may be made of a soft material such as a resin material. However, although the hard thin film containing DLC or the like has a small self-wear, it has a strong attacking property against the mating member. Therefore, if the bearing 13 is made of a soft material such as a resin material, the wear of the bearing 13 increases. Therefore, in the present embodiment, at least a metal, desirably a hardened metal, is employed as the material of the bearing 13 without employing a soft material such as a resin material.

  As described above, FIG. 11 shows the result of an experiment for confirming the effectiveness of providing the hard thin film 25 on the base material constituting the shaft 12 after the hardness improvement treatment such as heat treatment is performed.

  As shown in FIG. 11, the fourth sample specification of the refrigerant pump 10 uses SUJ2 high carbon chrome bearing steel as a base material constituting the shaft 12, and does not perform heat treatment, and the hard thin film 24 containing DLC is used. Is given.

  The fifth sample specification of the refrigerant pump 10 uses SUJ2 high-carbon chromium bearing steel as a base material constituting the shaft 12, heat-treated by QT treatment, and then applied a hard thin film 24 containing DLC. Is.

  The experimental conditions were the same as the experimental conditions shown in FIG. That is, the conditions are as follows: R410A is used as the refrigerant, the refrigerant pump 10 has a clearance ratio of 0.0008, a rotational speed of 4000 rpm, a suction pressure of 2.1 MPa, and a discharge pressure of 2.2 MPa. In addition, the bearing 13 used what heat-processed by QT process to the high carbon chromium bearing steel of SUJ2. Moreover, in this experiment, since the shaft 12 and the bearing 13 do not come into close contact as in the blade portion 14, the test time was increased to 100 hours.

  As a result of the experiment, in the fourth sample specification, the hard thin film 25 of the shaft 12 was worn with concave peeling. On the other hand, in the fifth sample specification, no abnormality was found in the hard thin film 25 of the shaft 12. Accordingly, as described above, the base material constituting the shaft 12 is subjected to a hardness improvement process such as heat treatment and then provided with the hard thin film 25, thereby ensuring the wear resistance of the shaft 12 and the hard thin film 25. It was demonstrated that cracking and delamination can be avoided.

  Next, FIG. 12 shows a result of an experiment conducted by replacing the hard thin film 24 provided on the blade portion 14 in this embodiment with a general material for a surface treatment film.

  As shown in FIG. 12, the sixth sample specification of the refrigerant pump 10 uses SUS304 stainless steel for the base material constituting the blade portion 14 and performs nickel phosphor plating as a surface treatment film without performing heat treatment. It is a thing.

  The seventh sample specification of the refrigerant pump 10 uses a stainless steel of SUS304 as a base material constituting the blade portion 14, and is subjected to polytetrafluoroethylene coating (hereinafter referred to as PTFE coating) as a surface treatment film without performing heat treatment. Is given.

  The experimental conditions were the same as the experimental conditions shown in FIG. That is, the conditions are as follows: R410A is used as the refrigerant, the refrigerant pump 10 has a clearance ratio of 0.0008, a rotational speed of 4000 rpm, a suction pressure of 2.1 MPa, and a discharge pressure of 2.2 MPa. The casing 11 constituting the inner wall of the pump chamber 15 was made of SUS304 stainless steel.

  As a result of the experiment, in the sixth sample specification, adhesion occurred and the pump was locked. This is presumably because the nickel phosphor plating is a metal base similar to the material of the blade portion 14 and has the same melting point as that of the metal.

  On the other hand, in the seventh sample specification, although the pump lock was not reached, peeling occurred in the PTFE coating, which was not good. This is because PTFE coating has a low coefficient of friction, so it generates little heat and does not reach melt adhesion, but because the film itself has low hardness and strength, it leads to wear and delamination under high surface pressure. Conceivable.

  With respect to the sixth and seventh sample specifications, in the refrigerant pump 10 of this embodiment, the hard thin film 24 provided on the blade portion 14 includes DLC or CrN.

  Since DLC is a carbon-based hard thin film 24, it has a low coefficient of friction, and the film itself has a higher strength than PTFE coating, so it is considered difficult to cause adhesion, peeling, and wear. On the other hand, CrN, TiN and TiAlN are ceramic-based hard thin film 24 and have a high melting point.

  The refrigerant pump 10 of this embodiment described above has the following effects.

  (1) In the present embodiment, a hard thin film 24 containing DLC, CrN, TiN, TiAlN, or the like is provided on the blade sliding surface 141.

  According to this, durability with respect to sliding of the blade | wing part sliding contact surface 141 improves. Therefore, even when this refrigerant pump 10 is used for pumping the refrigerant in a state where the absolute pressure is high, the refrigerant pump 10 is prevented from reaching the pump lock, so that the reliability can be improved.

  Further, the refrigerant pump 10 does not have a complicated configuration of the blade sliding surface as in the above-described pump of Patent Document 2, and the configuration can be simplified. Therefore, this refrigerant pump 10 can reduce the manufacturing cost.

  (2) In this embodiment, the hard thin film 24 is provided on the blade sliding surface 141 without the base material being subjected to the hardness improvement process.

  According to this, although the blade portion sliding contact surface 141 and the pump chamber sliding contact surface 151 are poorly lubricated due to close contact, since they are in contact with each other, the film is often cracked or peeled off. Absent. Therefore, it is possible to achieve both reduction in manufacturing cost and improvement in reliability by not performing hardness improvement processing such as heat treatment on the base material.

  (3) In the present embodiment, the refrigerant pump 10 is a Wesco pump having a configuration in which the blade portion sliding contact surface 141 and the pump chamber sliding contact surface 151 are in surface contact.

  According to this, when the configuration of the present embodiment is applied to a Wesco pump, the side clearance SC can be made a minute gap, and the pump performance such as the increase in the flow rate of the pressure-feeding refrigerant and the increase in the pressure of the pressure-feeding refrigerant can be improved. it can. Further, in this embodiment, even when the side clearance SC in the Wesco pump is a minute gap, the occurrence of foreign matter due to wear in the minute gap is suppressed, so that the pump lock is prevented and the reliability is improved. be able to.

  (4) In this embodiment, the clearance ratio (SC / Di) is 0.0015 or less.

  According to this, by reducing the clearance ratio, it is possible to improve pump performance such as an increase in the flow rate of the pressure-feeding refrigerant and an increase in the pressure of the pressure-feeding refrigerant. Further, in the present embodiment, even when the clearance ratio is reduced, the occurrence of foreign matter due to wear in the minute gap is suppressed, so that the pump lock can be prevented and the reliability can be improved.

  (5) In the present embodiment, a hard thin film 25 containing DLC, CrN, TiN, TiAlN or the like is provided on the portion of the outer wall of the shaft 12 that comes into contact with the bearing 13 after being subjected to hardness improvement processing. .

  According to this, it is possible to ensure the wear resistance of the portion of the outer wall of the shaft 12 that comes into contact with the bearing 13, and to avoid cracking and peeling of the film due to the edge of the bearing 13.

  (6) In the present embodiment, the thickness of the hard thin film 24 provided on the blade sliding surface 141 is greater than 0 and 5 μm or less.

  According to this, generally the dimension of the blade | wing part 14 is a several millimeter unit, whereas the side clearance SC between the blade | wing part sliding contact surface 141 and the pump chamber sliding contact surface 151 is a several dozen micrometer unit, It is possible to make the thickness of the hard thin film 24 sufficiently thin. Therefore, when the hard thin film 24 is formed on the base material, even if unevenness due to tolerance occurs in the hard thin film 24, it is not necessary to perform an adjustment process such as a polishing process after that. Therefore, the manufacturing cost can be reduced.

(Other embodiments)
The present invention is not limited to the embodiment described above, and can be appropriately changed within the scope described in the claims. Further, the above embodiments are not irrelevant to each other, and can be combined as appropriate unless the combination is clearly impossible. In each of the above-described embodiments, it is needless to say that elements constituting the embodiment are not necessarily essential unless explicitly stated as essential and clearly considered essential in principle. Yes. Further, in each of the above embodiments, when numerical values such as the number, numerical value, quantity, range, etc. of the constituent elements of the embodiment are mentioned, it is clearly limited to a specific number when clearly indicated as essential and in principle. The number is not limited to the specific number except for the case. Further, in each of the above embodiments, when referring to the shape, positional relationship, etc. of the component, etc., the shape, unless otherwise specified and in principle limited to a specific shape, positional relationship, etc. It is not limited to the positional relationship or the like.

  (1) For example, in the said embodiment, it was set as the structure which provides the hard thin film 24 on the blade | wing part sliding contact surface 141. FIG. On the other hand, in another embodiment, the hard thin film 24 may be provided on the pump chamber sliding contact surface 151. Moreover, it is good also as a structure which provides the hard thin film 24 on both the blade | wing part sliding contact surface 141 and the pump chamber sliding contact surface 151. FIG.

  (2) In other embodiments, the hard thin film 24, 25 may include a plurality of types of DLC, CrN, TiN, TiAlN, or the like, or may include other materials.

  (3) In the above-described embodiment, the four types of hard thin film have been described. However, the hard thin film of the present invention is not limited to these four types, and PVD (physical vapor) having high hardness similarly. Naturally, a thin film (TiCN, WC / C, AlCrN) or the like produced by a so-called physical vapor deposition method in which a substance is vapor-deposited in a vacuum such as a deposition) is also included.

(Summary)
According to the 1st viewpoint shown by one part or all part of said each embodiment, a refrigerant | coolant pump is provided with a shaft, a bearing, a casing, and a blade | wing part. The shaft is formed in a column shape. The bearing rotatably supports the shaft. The casing has a pump chamber through which the refrigerant flows. The blade portion is rotatably provided inside the pump chamber, and rotates together with the shaft to suck the refrigerant into the pump chamber and pump the refrigerant from the pump chamber to the outside. A hard surface containing diamond-like carbon, nitride, carbide, or carbonitride is provided on at least one of the surface in the rotation axis direction of the blade portion and the surface of the inner wall of the pump chamber that faces the surface in the rotation axis direction of the blade portion. A thin film is provided.

  According to the second aspect, the hard thin film includes at least one of diamond like carbon, chromium nitride, titanium nitride, titanium nitride aluminum, titanium carbonitride, tungsten carbide, or AlCrN.

  According to the third aspect, at least one of the surface of the blade portion in the rotation axis direction and the surface of the inner wall of the pump chamber that faces the surface of the blade portion in the rotation axis direction is subjected to hardness improvement treatment on the base material. Without being provided, a hard thin film is provided.

  According to this, the hard thin film containing diamond-like carbon, nitride, carbide or carbonitride has high resistance to sliding. Therefore, although the sliding contact surface of the blade portion and the sliding contact surface of the pump chamber are poorly lubricated due to the close contact, since they are per surface, the film hardly cracks or peels off. Therefore, by not performing hardness improvement processing such as heat treatment on the base material, it is possible to prevent an increase in the cost of heat treatment and to eliminate post-processing such as grinding for removing distortion generated by the heat treatment. . Therefore, it is possible to achieve both reduction in manufacturing cost and improvement in reliability.

  According to the fourth aspect, the refrigerant pump includes a configuration in which the surface of the blade portion in the rotation axis direction and the surface of the inner wall of the pump chamber facing the surface of the blade portion in the rotation axis direction are in surface contact. It is a pump.

  According to this, the Wesco pump can make the side clearance between the blade portion sliding contact surface and the pump chamber sliding contact surface a minute gap, and the pump for increasing the flow rate of the pressure-feeding refrigerant and increasing the pressure of the pressure-feeding refrigerant. The performance can be improved. In addition, in the Wesco pump, even when the side clearance between the blade sliding surface and the pump chamber sliding surface is a minute gap, the generation of foreign matter due to wear in the minute gap is suppressed. Can be prevented and reliability can be improved.

  According to the fifth aspect, the clearance between the surface of the inner wall of the pump chamber that faces the surface of the blade portion in the rotational axis direction and the surface of the blade portion in the rotational axis direction is SC, and the outer diameter of the blade portion is Di. Then, the relationship SC / Di ≦ 0.0015 is established.

  According to this, by reducing the clearance ratio (SC / Di), it is possible to improve pump performance such as an increase in the flow rate of the pressure-feeding refrigerant and an increase in the pressure of the pressure-feeding refrigerant. Further, even when the clearance ratio is reduced, the generation of foreign matter due to wear in the minute gap is suppressed, so that the pump lock can be prevented and the reliability can be improved.

  According to the sixth aspect, the thickness of the hard thin film provided on at least one of the surface in the rotation axis direction of the blade portion and the surface of the inner wall of the pump chamber that faces the surface in the rotation axis direction of the blade portion. Is greater than 0 and less than or equal to 5 μm.

  According to this, the size of the blade portion is generally several millimeters, and the side clearance between the blade portion sliding contact surface and the pump chamber sliding contact surface is several tens of micrometers, whereas the hard thin film coating It is possible to make the thickness sufficiently thin. Therefore, when a hard thin film is formed on the base material, even if irregularities due to tolerance occur in the hard thin film, it is not necessary to perform an adjustment process such as a polishing process after that. Therefore, the manufacturing cost can be reduced.

  According to the seventh aspect, the portion of the outer wall of the shaft that comes into contact with the bearing is a second hard thin film containing diamond-like carbon, nitride, carbide, or carbonitride after the base material is subjected to a hardness improvement treatment. A film is provided.

  According to this, although the hard thin film containing diamond-like carbon, nitride, carbide or carbonitride has high resistance to sliding, the film itself is very thin, for example, several micrometers, so the film strength is weak, In the case of per edge, there is a risk that the film may crack or the film may peel off. In view of this, a portion of the outer wall of the shaft that comes into contact with the bearing is provided with a hard thin film after the base material is increased in strength by a hardness improvement process such as heat treatment. Thereby, the abrasion resistance of the site | part which contacts a bearing among the outer walls of a shaft is ensured, and the crack destruction and peeling of the film | membrane by the edge contact of a bearing can be avoided.

  According to the eighth aspect, the second hard thin film includes at least one of diamond-like carbon, chromium nitride, titanium nitride, titanium nitride aluminum, titanium carbonitride, tungsten carbide, or AlCrN.

  According to the 9th viewpoint, the thickness of the 2nd hard thin film membrane | film | coat provided in the site | part which contacts a bearing among the outer walls of a shaft is larger than 0 and is 5 micrometers or less.

10 Refrigerant pump 11 Casing 12 Shaft 13 Bearing 14 Blade portion 15 Pump chamber 24 Hard thin film

Claims (9)

A refrigerant pump used in a refrigeration cycle in which a refrigerant is enclosed during a closed loop cycle,
A shaft (12) formed in a columnar shape;
A bearing (13) for rotatably supporting the shaft;
A casing (11) having a pump chamber (15) through which refrigerant flows;
A vane portion (14) provided rotatably inside the pump chamber, sucking refrigerant into the pump chamber by rotating together with the shaft, and pumping the refrigerant from the pump chamber to the outside; and
At least one of the surface (141) in the rotation axis direction of the blade portion and the surface (151) of the inner wall of the pump chamber facing the surface in the rotation axis direction of the blade portion is diamond-like carbon, nitride. A refrigerant pump provided with a hard thin film (24) containing carbide or carbonitride.   2. The refrigerant pump according to claim 1, wherein the hard thin film includes at least one of diamond-like carbon, chromium nitride, titanium nitride, titanium aluminum nitride, titanium carbonitride, tungsten carbide, or AlCrN.   At least one of the surface in the rotation axis direction of the blade portion and the surface of the inner wall of the pump chamber that faces the surface in the rotation axis direction of the blade portion without being subjected to hardness improvement processing on the base material, The refrigerant pump according to claim 1 or 2, wherein the hard thin film is provided.   The refrigerant pump is a Wesco pump having a configuration in which a surface in the rotation axis direction of the blade portion and a surface of the inner wall of the pump chamber facing the surface in the rotation axis direction of the blade portion are in surface contact. The refrigerant pump according to any one of claims 1 to 3. The clearance between the surface of the inner wall of the pump chamber that faces the surface of the blade portion in the rotation axis direction and the surface of the blade portion in the rotation axis direction is SC, and the outer diameter of the blade portion is Di,
The refrigerant pump according to claim 4, having a relationship of SC / Di ≦ 0.0015.   The thickness of the hard thin film provided on at least one of the surface in the rotation axis direction of the blade portion and the surface of the inner wall of the pump chamber that faces the surface in the rotation axis direction of the blade portion is greater than zero. The refrigerant pump according to claim 1, wherein the refrigerant pump is 5 μm or less. When the hard thin film is the first hard thin film,
A portion of the outer wall of the shaft that comes into contact with the bearing is provided with a second hard thin film (25) containing diamond-like carbon, nitride, carbide, or carbonitride after the base material is subjected to hardness improvement treatment. The refrigerant pump according to any one of claims 1 to 6, wherein:   The refrigerant pump according to claim 7, wherein the second hard thin film includes at least one of diamond like carbon, chromium nitride, titanium nitride, titanium nitride aluminum, titanium carbonitride, tungsten carbide, or AlCrN.   9. The refrigerant pump according to claim 7, wherein a thickness of the second hard thin film provided on a portion of the outer wall of the shaft that is in contact with the bearing is greater than 0 and equal to or less than 5 μm.

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