JPS61175300A - Centrifugal pump - Google Patents

Abstract

PURPOSE:To improve the sealing performance considerably by constructing such that a sealing member having planar section contacting tightly against the planar section of an impeller to seal the liquid is pressed through a resilient member against the impeller. CONSTITUTION:The planar section of seal member 14 is pressed through the force of bellows 16 having the opposite ends secured to the housing 4 and the seal member 14 against the planar section of an impeller 10 and contacted tightly. Since the seal member 14 is held by the bellows 16, when contacting tightly against the planar section of the impeller 10 to construct a sealed section, clearance for absorbing the error of parallelism between the planar sections of the impeller 10 and the seal member 14 caused through accumulated dimensional error of respected component of pump and the error of tightness due to thermal expansion of them 10, 14 caused through frictional heat produced in the tight contact face under operation can be provided to improve the sealing performance considerably. While employment of bellows 16 as a resilient member will enable simplification of structure and reduction of size.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Industrial Application Field The present invention relates to a centrifugal pump used in fields such as medical and chemical processes.

(2) Prior Art Conventionally, so-called pumps for transporting liquids in fields such as medical and chemical processes include pulsating pumps and straining pumps that supply pulsating flow, and pumps that supply continuous flow. There are centrifugal pumps, etc.

Pulsating pumps and squeezing pumps have disadvantages such as a large and heavy pump body and poor discharge response.

On the other hand, conventional centrifugal pumps have advantages such as being lightweight and having good discharge response, but have a drawback in sealing performance.

Conventionally used centrifugal pumps rotate an impeller within a casing having an inlet port for the liquid to be pumped and an outlet port, and as a result, the liquid sucked in from the inlet port is pumped by centrifugal force. The liquid is discharged from the outlet port, but the sealing method between the part that comes into contact with the liquid to be delivered (hereinafter referred to as the wetted part) and the part that does not come in contact with the liquid (hereinafter referred to as the non-wetted part) is fixed. A method in which the shaft of an impeller is inserted through a hole provided in a sealing member and sealing is performed at the contact surface between the shaft of the impeller and the sealing member (hereinafter referred to as the "shaft sealing method"), or a sealing member having a flat part is used. A method of sealing by fixing the impeller, providing a flat surface on the opposite side of the surface with the impeller blades, and bringing the flat surface of the impeller into close contact with the flat surface of the sealing member with a constant force (hereinafter referred to as the flat sealing method). ) etc. In either case, the sealing member is virtually fixed to the casing or another member integrated with the casing, and in terms of sealing effect, there is little structural escape and the liquid to be delivered is likely to leak.

An example of using the former shaft sealing method is U.S. Patent 4,1.
35.253 etc.

On the other hand, mechanical seals are widely used as a sealing method for rotating shafts (see Figure 4), but mechanical seals are primarily used for industrial purposes and are used in fields such as medical and chemical processes. However, it is practically impossible to use it in a centrifugal pump due to structural limitations, compatibility with the liquid to be transported, and miniaturization.

From the above points of view, there has been a long-awaited demand for a small, lightweight, low-cost centrifugal pump that has good sealing properties of 1JL and is used in fields such as medicine and chemical processes.

(3) Problems to be solved by the invention As mentioned above, in centrifugal pumps conventionally used in the medical and chemical process fields, there are two methods for sealing the wetted parts and non-wetted parts: shaft sealing method and flat sealing method. However, in both methods, the seal part +J is virtually fixed to the casing or other parts integrated with the casing, and in terms of sealing effect, there is little structural escape and the liquid to be delivered tends to leak. .

For example, in the former shaft sealing method, if the shaft center of the impeller and the center of the hole in the sealing member do not completely align, a gap may occur between the impeller shaft and the sealing member, resulting in direct contact between the impeller shaft and the sealing member. This caused the liquid to leak.

Furthermore, even if leakage of the liquid does not occur immediately after pump operation, while the pump is operating, the contact pressure between the sealing member and the impeller shaft may locally increase due to the same reason as above. As the height increases, wear and deformation of the sealing member in that area gradually increases, and the liquid to be delivered may leak.

It is extremely difficult in terms of structure to perfectly align the axis of the impeller and the center of the hole in the sealing member, and in order to achieve this goal, the processing accuracy and assembly process required for each part that makes up the pump are very difficult. The amount of attention paid to "quality control" was extremely high, contributing to a significant increase in costs.

On the other hand, in the plane seal method, the seal member is fixed to the casing or another member integrated with the casing, as in the case of the shaft seal method described above, and the plane part of the seal member and the impeller are fixed to each other. It is structurally very difficult to make complete contact with the flat part.

In order to maintain the adhesion of the seal surface, the processing precision required for each part that makes up the pump is extremely strict, and as with shaft seals, the assembly process and quality control are extremely laborious, resulting in a significant increase in costs. was.

In addition, due to the frictional heat generated between the impeller and the seal member during pump operation, both the impeller and the seal member are thermally deformed, and the seal member, which is fixed in particular, cannot escape when it is thermally deformed, so the seal surface Because of this structure, it is difficult to maintain proper flatness, which often causes the liquid to be delivered to leak.

When centrifugal pumps are used in the medical field, a slight leak can lead to serious consequences, especially when the liquid being delivered is blood, and traditional centrifugal pumps are prone to leakage of the delivered liquid. This was considered to be the biggest drawback.

On the other hand, as mentioned above, mechanical seals are widely used for industrial purposes as a sealing method for rotating shafts.

FIG. 4 shows an example of the structure of a commonly used mechanical seal.

The fixed ring 152 is fixed to the ground cover 170 by a fixed ring gas furnace y I·l 58 such as an O-ring or a square ring which also serves as a seal. Collar 164 is secured to shirt I-172 by set screws 166 and also holds spring 162 and one live bin 168.

The rotating ring 154 is connected to a compression ring 160, which is fixed to the shirt 172 by a shaft basogin 156 and is pressed against the fixed ring 152 by a spring 162 with a predetermined force.

The compression ring 160 has a hole for guiding a drive bin 168.

Therefore, although the rotating ring 154 has a degree of freedom in the axial direction, it does not have a degree of freedom in the rotational direction because it is indirectly connected to the collar 164 fixed to the shirt I-172 by the drive pin 168. Rotates with shirt I-1'72.

The shaft sealing action is performed at the contact portion between the cylindrical end surfaces of the fixed ring 152 and the rotating ring 154.

Since a mechanical seal is constructed more than usual, a space is basically required to accommodate each component constituting the mechanical seal, which becomes a bottleneck in achieving R1 in downsizing. Normally, both ends of the shirt l-172 shown in FIG. The car must be fixed, and since the hair ring can be used by fitting it onto a non-wetted part, it is supported in a cantilevered manner, which is extremely disadvantageous in terms of rotational runout of the shaft.

Furthermore, the rotating ring must be fixed to the shaft by the shaft packing, and since the shirt 1 rotates at a fairly high speed, it is necessary to restrict the degrees of freedom of the rotating ring other than in the axial direction as much as possible to secure the seal contact area. It is difficult to maintain proper surface contact between the ring and the rotating ring.

Therefore, if a mechanical seal is adopted for the shirt 1~ that rotates at high speed with cantilever support, the rotating ring virtually fixed to the shaft will also vibrate as the shirt 1 rotates, so the seal contact surface will be parallel to the It is difficult to maintain the temperature and appropriate surface pressure.

In addition, when using blood or medicinal liquid as the liquid to be delivered,
It is necessary to consider the compatibility of all the parts of the id with the liquid to be sent, and when disposable parts are considered, this can lead to a considerable increase in complaints.

As mentioned above, there are many problems in adopting mechanical seals used for general industrial purposes in the centrifugal pump based on the present invention in terms of miniaturization, structural restrictions, compatibility with the liquid to be transported, etc. .

As is clear from the above, centrifugal pumps conventionally used in fields such as medical treatment and chemical processing have had many problems in terms of sealing performance, cost, etc.

The present invention aims to solve the above problems.

(4) Means for solving the problem = 9 In the present invention, the inlet port and the outlet port of the liquid to be transported are
an impeller that rotates within the liquid contact part and has blades for feeding liquid by centrifugal force during rotation, and has a flat part on the opposite side of the surface having the blades;
A shaft having a function of fixing the impeller and transmitting rotational force, a sealing member having a flat part for sealing the liquid to be sent by coming into close contact with the flat part of the impeller, and the sealing member are connected directly or (1) By configuring a centrifugal pump with an elastic part necessary for indirectly applying pressure and sealing the liquid to be sent by bringing the flat part of the sealing member into close contact with the flat part of the impeller, The aim is to provide a small, lightweight centrifugal pump at low cost that has improved sealing performance, which was a major problem in the past.

(5) Function As mentioned above, in the present invention, the sealing member having a flat surface that comes into close contact with the flat surface of the impeller to seal the sent liquid is pressed against the impeller by the shearing force generated by the elastic member. Therefore, when constructing the seal part, it is necessary to avoid parallelism between the flat part of the impeller and the flat part of the sealing member that occurs during assembly due to cumulative dimensional errors of each component that makes up the pump, or if the impeller It has a relief that can absorb deviations in adhesion due to thermal expansion distortion of the impeller and seal member caused by frictional heat generated on the close contact surface of the impeller and seal member,
Very suitable for sealing performance.

(6) Examples An embodiment of the present invention will be specifically described based on the drawings.

As shown in FIG. 1, the shaft 2 is installed through a hair ring (A) 6 and a bearing (B) 8 installed inside the housing 4, and this shaft 2 is a coupling that directly receives the rotational motion of the drive motor 102. Doesn't play a role. In other words, a pin 104 is inserted and fixed to the shaft of the drive motor 102,
If a slit is provided in the shaft 2, the rotational force of the drive motor 102 can be directly transmitted to the shaft by passing the pin 104 through the slit.

Impeller 1 is placed on the opposite side of the shaft 2 from the end where the slit is provided.
Fix 0. There are several ways to fix the impeller, but in the embodiment shown in FIG.
2 is fixed to the stud 12, and then the stud 2 is screwed onto the shaft 2. By doing this, even if the stud 12 is strongly screwed into the shaft 2, the impeller 1
2, no force is applied at all, and the flatness of the flat part of the impeller can be maintained suitably.

A force generated by a bellows 16 whose both ends are fixed to the flat part of the impeller 10 by the housing 4 and the seal member 14 presses the flat part of the seal member 14 into close contact. The force generated by the bellows 16 is unnecessary and sufficient for the flat surface of the impeller 10 and the flat surface of the sealing member 14 to come into close contact and exhibit a sealing effect. When the bellows 16 is used as the elastic member as in this embodiment, it has the function of generating a force that brings the sealing member into close contact with the impeller, and the function of preventing the components inside the bellows from coming into contact with the liquid to be transported. Since it has both, the structure can be simplified.

The cap 18 is fixed to the housing 4 via an O-ring 20. It is preferable to use a highly rigid metal such as stainless steel as the material for the bellows 16 because it can absorb the torsion caused by the frictional force that occurs between the flat surface of the impeller 10 and the flat surface of the seal member 12 when the pump starts operating. be.

With the above configuration, since the seal member 14 is held by the bellows 16, the seal member 14 is in close contact with the flat surface of the impeller 10 to form a seal portion. It has a clearance that can absorb deviations in the parallelism between the plane part of the impeller 10 and the plane part of the seal member 14 that occur during assembly, or deviations in the degree of adhesion due to thermal expansion strain between the wheel 10 and the seal member 14, and improves sealing performance. Very suitable.

Other embodiments based on the present invention will be specifically described based on the drawings.

As shown in FIG.
It is also possible to use the spring 54 as an elastic body for forming a seal portion by pressing against the flat surface of the spring 54 . In this case, a means is required to isolate the components such as the spring 54 and the shaft 2 from the liquid to be fed, and in this embodiment, the bellofram 56 plays this role. In addition, in order to prevent twisting occurring in the bellofram 56 and the spring 54 due to the frictional force between the flat surface of the impeller 10 and the flat surface of the sealing member 52 when the impeller 10 starts rotating, the housing 62 is attached as shown in FIG. Fixed 3
Adapter 5 with book pin 60 fixed to sealing member 52
The DJ is installed in 3 places of 8.It passes through the slit. With this configuration, the housing 62 and the seal member 52
During this time, it is possible to prevent relative rotational deviation from occurring around the rotational axis of the shaft 2 as the central axis. In addition, in the embodiment shown in FIG. 2, the wetted part and non-wetted part are separated by the bellofram 56, so the amount of liquid to be filled in the pump head can be smaller than in the embodiment shown in FIG. . Of course, in the embodiment shown in FIG. 1 as well, it is possible to reduce the amount of liquid to be filled in the liquid-contacting part of the pump by using a bellofram or the like as in the embodiment shown in FIG. Particularly when blood is used as the liquid to be delivered, if there is a retaining part within the liquid-contacting part, it is likely to become a sign of thrombus formation, and in this sense as well, it is desirable that the volume of the non-liquid-contacting part is small.

By configuring as described above, good sealing performance can be obtained in the embodiment shown in FIG. 2 as well as in the embodiment shown in FIG. 1.

In any of the examples, carbon is used as the material of the sealing member that forms the seal part, stainless steel, ceramic, or stainless steel with ceramic coating on the sealing surface is used as the material of the impeller, and the entire material is treated with Toughflamm (aluminum and aluminum alloy). A hard anodic oxide film is applied to the surface, the porous film is impregnated and coated with Teflon, and the Teflon is fused)
Good results have been obtained using aluminum, etc.

It goes without saying that various combinations of materials are possible.

(7) Effects of the Invention Due to the above-mentioned effects, good sealing performance can be obtained due to the relief provided by the structure of the seal part of the liquid to be transported, and there is no need to require particularly strict processing precision for each component, and assembly is possible. It has advantages over conventional centrifugal pumps in terms of process and quality control, and can reduce costs as well as being smaller and lighter.

At the same time, the improved sealing performance makes it possible to apply it to the medical field, which was previously difficult (111), which is of great significance.

[Brief explanation of drawings]

Fig. 1 is an embodiment of a centrifugal pump based on the present invention. Fig. 2 is an embodiment of a centrifugal pump based on the present invention. Fig. 3 is a sectional view taken along line A-A in Fig. 2. Fig. 4 is a mechanical seal. Example of use. 2..Shaft, 4..Housing, 6..Hair ring (A), 8..Bearing (B), 10.. Impeller.
12... Stud, 14... Seal member, 16... Bellows, 18... Can '7', 20... ○ ring, 52
Seal member, 54 Spring, 56 Verofram, 58 Adapter, 60 Pin, 62 Housing, 102 Drive motor, 104 Pin, 15
2... Fixed ring, 154... Rotating ring, 156... (Ql+
Packing, 158...Fixed ring gasket, 160...
Compression ring, 162...Spring, 16
4...Collar, 166...Set screw, 168...Drive pin, 170...Ground cover, 172...Shaft.

Claims (4)

[Claims] (1) A liquid-contacted part that has an inlet port and an outlet port for the liquid to be transported, and a surface that rotates within the liquid-contacted part and has blades for transporting the liquid to be transported by centrifugal force during rotation. an impeller having a flat part on the opposite side thereof; a shaft having a function of fixing the impeller and transmitting rotational force; and a shaft that comes into close contact with the flat part of the impeller to form a sealing part for the liquid to be transported. a sealing member having a flat surface, and an elastic member for pressurizing the sealing member directly or indirectly, and for the flat surface of the sealing member to come into close contact with the flat surface of the impeller to seal the liquid to be transported. A centrifugal pump consisting of. (2) The centrifugal pump according to claim 1, characterized in that a bellows is used as the elastic member. (3) The centrifugal pump according to claim 1, characterized in that a spring is used as the elastic member. (4) The centrifugal pump according to claim 1, characterized in that velofram is used as a sealing member for the liquid-contacted part and the non-liquid-contacted part.