JPH0932738A - Solution pump for absorption heat pump - Google Patents

Abstract

(57) [Abstract] [Object] The present invention relates to a solution pump used for transporting a working solution of an absorption heat pump, which improves sliding characteristics of a shaft and a bearing of the pump and has excellent durability. Provide a solution pump. [Structure] The solution pump of the present invention uses martensitic stainless steel for the shaft 7 or austenite steel with a nitride film layer formed on the surface thereof, and carbonizes the bearings 8a, 28 exhibiting excellent lubricating performance in a water atmosphere. A silicon-based ceramic material is used, chemical and mechanical wear is suppressed, and durability is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to improvement of lubricity of a solution pump used for conveying a working solution of an absorption heat pump.

[0002]

2. Description of the Related Art As a conventional absorption pump, especially a solution pump used in a refrigerator using an ammonia solution as a working medium, a diaphragm pump driven by a hydraulic pump has been generally used. The structure of this type of pump is a piston type hydraulic pump that can ensure high pump efficiency by using high-viscosity hydraulic oil, and a diaphragm type low viscosity fluid pump that is entirely driven by the hydraulic pressure generated by this hydraulic pump. Consists of. This is a method in which the medium such as ammonia and the pump mechanism are separated from each other by the diaphragm because the refrigerant such as ammonia has low viscosity and is highly corrosive, and the pump efficiency and the pump reliability are secured.

[0003]

However, in the above-mentioned conventional configuration, when a hydraulic pump drive type diaphragm pump is used, two types of pumps are required, which is a problem in terms of downsizing of equipment and cost. It was Further, the absorption type system in which this type of pump is used is a pump having a diaphragm and hydraulic oil, which is predominantly for commercial use and is required to be regularly maintained.

Further, instead of this diaphragm pump,
Even when a rotary type positive displacement pump is used as a direct drive type pump, there are the following problems. In other words, absorption heat pumps, especially solution pumps using an aqueous ammonia solution as the medium, have a very high pump differential pressure of 20 kg / cm ² and are very high for solution pumps that use a low-viscosity fluid as the working fluid. It was extremely difficult to ensure the lubricity of sliding parts such as bearings, which is important in terms of performance.

Further, as a means for improving the lubricity of the shaft and the bearing portion, a shaft and a bearing made of silicon carbide ceramics having excellent sliding resistance and chemical resistance are put to practical use for special applications such as for plants. However, especially for the shaft, since a joint is required for power transmission and the shape becomes large, there are many problems remaining in applying it to household equipment in terms of processing and cost. . This silicon-based ceramic containing silicon carbide is slightly excellent in that the sliding surface is smoothed and mirror-finished due to a slight decomposition called tribochemical reaction due to the heat generated on the sliding surface in water. Exhibits lubricity. However, there are many problems in constructing the sliding surfaces of the ceramic parts from each other in terms of processing accuracy and cost, and how to make this excellent slidability practical for household appliances has been a problem.

The present invention is intended to solve the above-mentioned problems, and a particularly important shaft and bearing in the sliding part of a pump is applied with a material of silicon nitride ceramics to ensure excellent lubricity in water. The first object is to provide a highly reliable solution pump for an absorption heat pump.
The second purpose is to further improve the initial familiarity, which is important for ensuring lubricity and enhancing mass productivity.

[0007]

In order to achieve the above first object, the sliding surface is smoothed by a tribochemical reaction in the material of the shaft or the bearing portion in a water atmosphere, and exhibits a lubricating property which is not available in the past. Basically, a silicon-based ceramic material was used, and since this silicon-based ceramic material was used in a practical form, it was combined with a metal-based material having good corrosion resistance. For the main shaft that drives the rotary positive displacement pump, select martensitic stainless steel, which has the highest hardness among the stainless steel materials, which has excellent corrosion resistance and is mass-produced as the shaft material. did. For the bearing, silicon nitride or silicon carbide, which has excellent lubricity especially in a water atmosphere, is selected from the silicon-based ceramic materials.

In order to achieve the above-mentioned second object, austenitic stainless steel which is excellent in initial familiarity due to the nitriding treatment to increase the surface hardness and the porous characteristics of the nitrided layer is selected, and the silicon ceramics for the bearing are selected. Among the materials, silicon nitride or silicon carbide having excellent lubricity especially in a water atmosphere is selected.

[0009]

According to the present invention, the sliding surface is smoothed by the tribochemical reaction in the water atmosphere of the silicon-based ceramics used for the bearing which is the main part of the sliding portion of the rotary positive displacement pump. Since it exhibits unprecedented lubrication characteristics, the sliding reliability of the main shaft and the bearing is secured. For the main shaft, martensitic stainless steel, which has the highest hardness in terms of material, is selected from the stainless steel materials with excellent corrosion resistance, so chemical and mechanical wear can be suppressed.

Further, by selecting an austenitic stainless steel whose surface is nitrided as the material of the main shaft, the surface hardness is high, chemical and mechanical wear is suppressed, and the action of a slightly porous nitrided layer is obtained. Can improve the initial familiarity characteristics.

Also, in terms of manufacturing, martensite and austenitic stainless steels, which are the base material of the main shaft, are mass-produced as the shaft material, and there is no problem in terms of processing. The bearing uses silicon-based ceramics, but the shape is simple and the amount of material used is small, so that the bearing can be put to practical use.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the accompanying drawings. 1 to 10, reference numeral 1 denotes a canned motor using a DC brushless motor, which is hermetically separated from the rotor 4 by a liner 3 inserted inside the stator 2. The positive displacement pump unit 5 is integrally formed in front of the body 6. The positive displacement pump unit 5 is a trochoid type pump driven by a main shaft 7 press-fitted into the rotor 4,
It has a structure for boosting pressure in stages. The main shaft 7 is made of martensitic stainless steel (for example, SUS440C or S
US 420J) is used, and surface finishing is performed by polishing after predetermined heat treatment.

The main member of the positive displacement pump section 5 is a body 6.
It is press-fitted into the cavity 6a provided in front of, and the positive displacement pump unit 5 is constructed with a laminated structure. The side plate A8 is located at the bottom of the main components of the stacked pumps.
Having a bearing A8a in the center, it also functions as a bearing for the main shaft 7 of the canned motor 1. The bearing A8 is made of silicon nitride ceramics, processed into a thin sleeve shape, and press-fitted into the side plate A8a.

Among general ceramic materials, silicon nitride ceramics have high toughness, and mechanical processing such as press fitting can be performed relatively easily. Also, when silicon nitride ceramics slide in a water atmosphere, the tribochemical reaction causes the surface of the sliding surface to slightly dissolve, and the surface becomes a mirror surface. Dynamic conditions are achieved. This tribochemical reaction is a phenomenon confirmed by both silicon-based ceramics, but a similar phenomenon occurs between the hardened metal material and the silicon-based ceramics within a certain range of conditions, and a good endurance test is performed. Results were obtained.

However, in order to realize a good sliding state as described above by sliding the extremely hard silicon-based ceramics (Vickers hardness of about 3000) and the metal material.
It is necessary to make the surface roughness on the hard side sufficiently small.
The inner surface of the bearing A8a made of silicon-based ceramics has a Vickers hardness of 7 even though the mating material is martensite.
Since it is about 00, it is desirable to perform mirror polishing in order to improve wear resistance. What is stacked on the side plate A8 is
The eccentric ring A9. The eccentric ring A9 rotatably holds the trochoidal outer gear A10 while maintaining an appropriate eccentricity with the inner gear A11. Further, the eccentric ring A9 includes the outer gear A10 and the inner gear A.
It has a function of keeping the clearance 11 in the thickness direction at an appropriate value. The main shaft 7 and the inner gear A11 are fixed by a D cut 7a. Side plate A of the intermediate spacer 12
There is a notch 14 that communicates with the suction port 13 of the pump on the 8 side, and also communicates with the suction groove 15 provided in the intermediate spacer 12, and the discharge groove 16 has a discharge hole 16a. The pump unit A17 that constitutes the first-stage pump is configured in this manner.

The eccentric ring B18 is further stacked on the intermediate spacer 12, and the eccentric direction of the eccentric ring B18 is set to be 180 degrees opposite to that of the eccentric ring A9. A suction groove 19 and a discharge groove 20 similar to those on the eccentric ring A9 side of the intermediate spacer 12 are provided on the surface of the intermediate spacer 12 on the eccentric ring B18 side, but the angles are set at positions shifted by 180 degrees. The discharge hole 16a of the discharge groove 16 provided on the eccentric ring A9 side of the intermediate spacer 12 communicates with the suction groove 19 provided on the surface of the eccentric ring B18 side. The eccentric ring B18 is a trochoidal outer gear B22.
Is rotatably held while maintaining an appropriate eccentric amount with the inner gear B23, and the eccentric ring B18 has a function of holding the clearance in the thickness direction of the outer gear B22 and the inner gear B23 at an appropriate value. The main shaft 7 and the inner gear B23 are fixed by a D cut 7a. Further, side plates B24 are stacked on the eccentric ring B18. The side plate B24 has a discharge groove 20 of the intermediate spacer 12.
The discharge port 24a is provided at a position corresponding to.
The pump portion B25 that constitutes the second-stage pump is configured in this manner, and the main members of the first-stage and second-stage pumps are laminated in this manner to form the pump main portion.

The basic dimensions of the pump portion A17 and the pump portion B25 are the inner gear A11 and the inner gear B23.
And the outer diameter, and the pump portion A17 and the pump portion B25 have the same dimensional values. A cavity 6 a provided in front of the body 6 is closed by a pump lid 26. The body 6 is provided with a flow path A27, and the solution discharged from the discharge port 24a of the side plate B24 passes through the flow path A27 and a gap between the liner 3 and the rotor 4 inserted inside the stator 2. And a bearing sleeve 2 for fixing a bearing B28 that rotatably supports the rotor 4
After passing through the flow path B30 provided in 9, it reaches the discharge port 31 and flows out to the system system. Similar to the bearing A8a, the bearing B28 is made of silicon nitride ceramics having excellent lubricity in a water atmosphere. The drive of the canned motor 1 is performed by directly rectifying a single-phase AC 100V, which is a commercial power source, by the rectifier 32 and performing a switching operation by the transistors 33 to 38.

The operation of the above configuration will be described. When the rotor 4 of the canned motor 1 rotates, the main shaft 7 press-fitted into the rotor 4 rotates. When the main shaft 7 rotates, the inner gear A11 and the inner gear B23 fixed to the main shaft 7 rotate, and the outer gear A1 that meshes with these gears, respectively.
0, the outer gear B22 rotates as a driven gear and performs a pump operation as a trochoid pump. The pump operation is performed in two stages in series and the inner gear A11 and the outer gear A10 perform the pump action, and the inner gear B23 and the outer gear B22 perform the pump action.
The step-up action is divided by the stage.

In the case of a pump used with a low viscosity fluid and a high differential pressure, the load on the bearing becomes very large, and in a product such as an absorption heat pump whose durability time is on the order of tens of thousands of hours, the lubrication condition of the bearing is also substantial. It is desirable to ensure a fluid lubrication state where almost no upper wear occurs. In this embodiment, the main shaft 7 is made of martensite stainless steel which becomes a martensite structure by heat treatment and the surface hardness of the shaft is hardened to a sufficient depth from the surface of the shaft. It is possible to obtain a metal structure that is sufficiently hard as a metal-based material in which shape accuracy such as roundness is ensured. In addition, bearing A8a and bearing B28
Is made of silicon nitride ceramics that has good lubricity in a water atmosphere, its inner surface is mirror-finished, this mirror surface is transferred to the side of the main shaft 7 having a lower surface hardness, and a bearing A8a is formed by a tribochemical reaction. Since the surface of is further smoothed during the operation of the pump, it is possible to secure a fluid lubrication state in which virtually no wear occurs, and it is very effective in improving the slidability. Furthermore, silicon nitride ceramics undergoes a tribochemical reaction when rubbed in water,
The surface of silicon nitride is slightly stronger than that of silicon carbide-based ceramics in which the surface is slightly melted. Due to this characteristic, the initial familiarizing effect absorbs misalignment of the shaft system, and the driving torque of the pump is stabilized early.

Next, another embodiment of the present invention will be described. This embodiment is different from the above embodiments in that the bearing A8a and the bearing B28 are made of silicon carbide ceramics. The silicon carbide-based ceramics used for the bearing A8a has a higher surface hardness than the silicon nitride-based ceramics, and the single body has better wear resistance than the silicon nitride-based ceramics. It also has the feature of high chemical stability. Further, like silicon nitride-based ceramics, it has a feature that it has good lubricity in a water atmosphere, it is possible to secure a fluid lubrication state, and it is very effective in improving slidability. However, since the hardness difference with the main shaft 7 is large, it is preferable to use porous ceramics and slightly lower the surface hardness in terms of initial familiarity.

Next, examples for improving the initial familiarity of lubrication of the present invention will be described. Compared with the previous embodiment, this embodiment uses a silicon carbide based material for the bearing A8a and the bearing B28, and has a nitride film 7a provided on the surface of the main spindle 7 as the material for the main spindle 7, which is excellent in corrosion resistance. The difference is that austenitic stainless steel is used. Nitride film 7a
Has a slightly porous structure, has a good initial familiarity, and requires a short time for familiarizing operation after the pump is incorporated, and a pump with stable performance can be obtained.

Still another embodiment will be described. Compared with the previous embodiment, this embodiment has a bearing A8a and a bearing B2.
The difference is that the material of No. 8 is a silicon nitride-based material. In addition to the fact that the structure of the nitride film 7a on the surface of the main shaft 7 is slightly porous and the initial familiarity is good, the silicon nitride-based ceramics used for the bearing A8a and the bearing B28 are also used in an aqueous solution. It has a high initial familiarity,
Due to the combined effects of both, the familiar operation time required after the pump has been installed is further shortened, and a pump with stable performance can be obtained.

[0023]

As described above, according to the solution pump for absorption heat pump of the present invention, the following effects can be obtained.

(1) Unprecedented lubrication in which the sliding surface is smoothed by the tribochemical reaction of the silicon-based ceramics used for the bearings forming the main part of the sliding portion of the rotary positive displacement pump in a water atmosphere. Since the characteristics are exhibited, the sliding reliability between the main shaft and the bearing is secured. For the main shaft, martensitic stainless steel, which has the highest hardness in terms of material, is selected from the stainless steel materials with excellent corrosion resistance, so chemical and mechanical wear can be suppressed.

(2) As for the spindle, since austenitic stainless steel having excellent corrosion resistance is used and a nitride film layer having good initial familiarity is formed on the surface of the spindle, chemical and mechanical wear is caused. Can be suppressed.

(3) In terms of manufacturing, martensitic stainless steel, which is the base material of the main shaft, is mass-produced as the shaft material, and there is no problem in terms of processing. The bearing uses silicon-based ceramics, but the shape is simple and the amount of material used is small, so that the bearing can be put to practical use.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of a solution pump for an absorption heat pump according to a first embodiment of the present invention.

FIG. 2 is a sectional view of the spindle.

FIG. 3 is a sectional view of a main part of a first stage of a solution pump.

FIG. 4 is a sectional view of an intermediate spacer.

FIG. 5 is a plan view of a side plate A side end surface of the intermediate spacer.

FIG. 6 is a plan view of an end surface of the intermediate spacer on the side plate B side.

FIG. 7 is a sectional view of a main part of a second stage of the solution pump.

FIG. 8 is a plan view of a partial main part of the solution pump with the pump lid removed.

FIG. 9 is a plan view of a bearing and a sleeve.

FIG. 10 is a drive circuit diagram of a canned motor.

[Explanation of symbols]

 1 canned motor 4 rotor 5 positive displacement pump unit 7 main shaft 8a bearing A 28 bearing B

Claims (4)

[Claims] 1. A main shaft fixed to a rotor of the canned motor, which has a rotary positive displacement pump unit integrally formed with a canned motor using an aqueous ammonia solution as a working fluid.
The bearing A provided in the rotary positive displacement pump section and the bearing B provided in the canned motor are rotatably supported, and the main shaft is made of martensitic stainless steel. Solution pump for absorption heat pump made of silicon nitride ceramics. 2. A main shaft fixed to the rotor of the canned motor, which has a rotary positive displacement pump unit integrally formed with the canned motor, using an aqueous ammonia solution as a working fluid.
The bearing A provided in the rotary positive displacement pump section and the bearing B provided in the candle motor are rotatably supported, and the main shaft is made of martensitic stainless steel. Solution pump for absorption heat pump made of silicon carbide ceramics. 3. A main shaft fixed to the rotor of the canned motor, which has a rotary positive displacement pump unit integrally formed with the canned motor, using an aqueous ammonia solution as a working fluid.
A bearing A provided in the rotary positive displacement pump section and a bearing B provided in the canned motor are rotatably supported, and the main shaft is made of austenitic stainless steel whose surface is nitrided. And a solution pump for an absorption heat pump in which the bearing B is made of silicon nitride ceramics. 4. A rotary positive displacement pump unit integrally formed with a canned motor, using an aqueous ammonia solution as a working fluid, and a main shaft fixed to a rotor of the canned motor,
A bearing A provided in the rotary positive displacement pump section and a bearing B provided in the canned motor are rotatably supported, and the main shaft is made of austenitic stainless steel whose surface is nitrided. And a solution pump for an absorption heat pump in which the bearing B is made of silicon carbide ceramics.