JP2021011830A - Method for assembling pump - Google Patents

Abstract

To provide a method for assembling a pump, which can suppress a side clearance between a cover and a rotor during pump operation to a predetermined design value to prevent deterioration in the discharge performance of the pump.SOLUTION: A pump 1 is composed by fastening a body 3 to a cover 5 that has a coefficient of thermal expansion larger than that of the body 3, and by housing a rotor 10 rotationally driven by a pump shaft 8 in a pump chamber S that is defined by the body 3 and the cover 5. As a method for assembling the pump, the cover 5 and the body 3 are fastened in a state that the internal stresses of them are corrected so that the thermal expansion amounts of the body 3 and the cover 5 become equal to each other in the operating state of the pump 1. Specifically, for example, the cover 5 is heated to a temperature that is higher than a room temperature and is lower than the pump operating temperature, and the heated cover 5 and the body 3 at the room temperature are fastened to each other.SELECTED DRAWING: Figure 1

Description

The present invention relates to a method for assembling a pump that is assembled by fastening a cover to a body having different coefficients of thermal expansion.

For example, a positive displacement pump such as a trochoid pump is used as an oil pump for supplying lubricating oil to a vehicle engine or the like. This type of pump is configured by bolting the body and cover and housing a rotor driven by a rotating shaft in a pump chamber defined by these bodies and cover (eg, patented). Reference 1).

By the way, in the pump configured as described above, the body and the cover are generally made of metals having different coefficients of thermal expansion. For example, the body is made of cast iron and the cover is made of an aluminum alloy, which has a higher coefficient of thermal expansion than cast iron.

JP-A-2016-065493

However, in a pump that adopts a structure in which a body and a cover having different coefficients of thermal expansion are fastened to each other, the temperature rises to, for example, about 80 ° C. to 100 ° C. during operation when the pump is driven at a specified normal rotation speed. , The difference in the amount of thermal expansion between the body and the cover becomes large. For example, if the outer peripheral portion of the cover is fastened to the body with bolts or the like, and the cover is made of aluminum alloy and the body is made of cast iron, the difference in the amount of thermal expansion between the body and the cover is different. growing. Then, since the central portion of the cover having a large amount of thermal expansion that is not fastened to the body swells, the axial clearance with the rotor in the pump chamber (hereinafter referred to as "side clearance") becomes large, and the discharge performance of the pump deteriorates. The problem arises. That is, when the pump is assembled at room temperature, the side clearance between the cover and the rotor is the value as designed, but during operation, the side clearance becomes larger than the design value, and the above-mentioned problem occurs. ..

The present invention has been made in view of the above problems, and an object of the present invention is to suppress the side clearance between the cover and the rotor during pump operation to a predetermined design value to prevent deterioration of the discharge performance of the pump. Is to provide a method of assembling.

In order to achieve the above object, in the present invention, the body (3) and the cover (5) having a coefficient of thermal expansion larger than that of the body (3) are fastened, and the body (3) and the cover (5) are used to draw a picture. A method of assembling a pump (1) in which a rotor (10) rotationally driven by a pump shaft (8) is housed in the formed pump chamber (S), and the operating state of the pump (1). In order to make the thermal expansion amounts of the body (3) and the cover (5) equal to each other, both are fastened in a state where the internal stresses of the body (3) and the cover (5) are corrected. It is characterized by that.

According to the present invention, by fastening the body and the cover with the internal stress corrected so that the thermal expansion amount of the body and the cover becomes equal in the operating state of the pump which becomes high temperature, the cover and the rotor The side clearance of the pump is suppressed to a predetermined design value, and deterioration of the discharge performance of the pump is prevented. Further, as a specific method, the present invention heats the cover (5) to a temperature higher than room temperature and lower than the pump operating temperature, and the heated cover (5) and the body (3) at room temperature are combined. May be concluded.

In the above method, the temperature at which the cover is heated is set to a value at which the thermal expansion amount of the cover is equal to the difference in the thermal expansion amount between the body and the cover in the operating state when the body temperature is normal temperature and only the cover is heated. If set, the amount of thermal expansion of the cover and the body becomes equal at the operating temperature of the pump, and the difference in the amount of thermal expansion between the cover and the body becomes zero. Therefore, the side clearance between the cover and the rotor in the operating state of the pump is suppressed to be small, and the deterioration of the discharge performance of the pump due to the increase in the side clearance can be prevented.

Alternatively, as another method, the body (3) may be cooled to a temperature lower than room temperature, and the cooled body (3) may be fastened to the cover (5) at room temperature.

In the above method, the temperature at which the body is cooled is such that when the cover temperature is normal temperature and only the body is cooled, the amount of thermal contraction of the body becomes equal to the difference in the amount of thermal expansion between the body and the cover in the operating state. When set to, the amount of thermal expansion of the cover and the body becomes equal at the operating temperature of the pump, and the difference in the amount of thermal expansion between the cover and the body becomes zero. Therefore, the side clearance between the cover and the rotor in the operating state of the pump is suppressed to be small, and the deterioration of the discharge performance of the pump due to the increase in the side clearance can be prevented.

Further, as another method, the cover (5) and the body (3) are fastened at room temperature in a state where the cover (5) is subjected to a radial outward load (F) at room temperature. May be good.

In the above method, the magnitude of the load applied to the cover radially outward at room temperature is equal to the difference in the amount of thermal expansion between the body and the cover at the operating temperature of the pump by the amount of axial contraction of the cover at room temperature. When set to a value, the amount of thermal expansion of the cover and the body becomes equal at the operating temperature of the pump, and the difference in the amount of thermal expansion between the cover and the body becomes zero. Therefore, the side clearance between the cover and the rotor in the operating state of the pump is suppressed to be small, and the deterioration of the discharge performance of the pump due to the increase in the side clearance can be prevented.

Further, in the above method, the body (3) and the cover (5) are fastened with a bolt (7), and the body (3) and the cover (5) are fitted to each other at the pump operating temperature. The side knock hole (3a) and the cover side knock hole (3b) are formed at positions displaced from each other at the time of assembly, and knocks are performed on the body side knock hole (3a) and the cover side knock hole (3b) that are displaced from each other. At the time of assembly through the member (12), the body (3) or the cover (5) is deformed to match the body-side knock hole (3a) and the cover-side knock hole (3b) formed in both. The body (3) and the cover (5) may be fastened with the bolts (7) inserted into the body-side knock holes (3a) and the cover-side knock holes (3b).

According to the above method, the body-side knock holes and the cover-side knock holes formed on the body and the cover, respectively, coincide with each other during the operation of the pump. Therefore, the bolts inserted into the body-side knock holes and the cover-side knock holes are used. The acting shear force is suppressed to a small value and the durability of the bolt is enhanced.

Further, the body (3) and the cover (5) are fastened with bolts (7), and knock holes (3a) and bolts that match each other at the pump operating temperature are attached to the body (3) and the cover (5). A dish in which holes (5a) are formed at positions displaced from each other at the time of assembly, and the body (3) and the cover (5) are inserted into the knock holes (3a) and the bolt holes (5a) formed therein. It may be fastened with a bolt (11).

According to the above method, the displacement between the knock hole and the bolt hole formed in the body and the cover during pump operation is corrected by the countersunk bolt, so that the shearing force acting on the knock hole and the bolt inserted into the bolt hole is applied. It is kept small and the durability of the bolt is enhanced.

According to the present invention, the side clearance between the cover and the rotor during pump operation can be suppressed to a predetermined design value to prevent deterioration of the discharge performance of the pump.

It is a partial sectional view of the pump to which the assembly method which concerns on Embodiment 1 of this invention is applied. It is a figure which shows the temperature change of the thermal expansion amount of the body and cover of the pump assembled by the assembly method which concerns on Embodiment 1 of this invention. It is a partial cross-sectional view of the pump which shows the fastening structure of a body and a cover in the assembly method which concerns on Embodiment 1 of this invention. It is a figure which shows the temperature change of the thermal expansion amount of the body and cover of the pump assembled by the assembly method which concerns on Embodiment 2 of this invention. It is a partial sectional view of the pump to which the assembly method which concerns on Embodiment 3 of this invention is applied. It is a figure which shows the temperature change of the thermal expansion amount of the body and cover of the pump assembled by the assembly method which concerns on Embodiment 3 of this invention.

Embodiments of the present invention will be described below with reference to the accompanying drawings.

<Embodiment 1>
FIG. 1 is a partial cross-sectional view of a pump to which the assembly method according to the first embodiment of the present invention is applied. The pump 1 shown is a positive displacement oil pump, and the pump housing 2 thereof is in the axial direction ( It is composed of a cylindrical body 3 and a ring plate-shaped spacer 4 arranged along the left-right direction in FIG. 1, and covers 5 and 6 arranged on both sides of the body 3 and the spacer 4 in the axial direction. There is. Here, in the pump housing 2, the body 3, the spacer 4, and the two covers 5 and 6 are fastened to each other by a plurality of bolts 7 (only two are shown in FIG. 1) that are inserted into them in the axial direction. The body 3 and the spacer 4 are sandwiched and fixed in the axial direction by the two covers 5 and 6.

In the pump 1, the pump shaft 8 is inserted into the central portion of the pump housing 2 along the axial direction, and the two points (the intermediate portion and one end portion in the axial direction) of the pump shaft 8 are covered by the bush 9. It is rotatably supported by 5 and 6, respectively.

Further, a pump chamber S is formed inside the pump housing 2, and the pump chamber S includes an inner rotor 10A that is spline-fitted on the outer circumference of the pump shaft 8 and rotates integrally with the pump shaft 8. The outer rotor 10B arranged on the outer peripheral side of the inner rotor 10A is housed. Here, the inner rotor 10A and the outer rotor 10B mesh with each other, and in the following description, the two are collectively referred to as a "rotor 10".

By the way, in the pump 1 according to the present embodiment, the body 3 constituting the pump housing 2 is made of cast iron, and the spacer 4 and the rotor 10 (inner rotor 10A and outer rotor 10B) are iron-based sintered parts. It is configured as. On the other hand, the covers 5 and 6 constituting the pump housing 2 are made of an aluminum alloy having a coefficient of thermal expansion larger than that of a metal such as cast iron or iron. That is, the body 3 and the covers 5 and 6 constituting the pump housing 2 are made of materials having different coefficients of thermal expansion from each other.

Here, the temperature change of each thermal expansion amount of the body 3 and the cover 5 is shown in FIG. 2. In the assembly of the pump 1 having the above configuration, the body 3 and the cover 5 having different coefficients of thermal expansion are at room temperature ( When fastened with a plurality of bolts 7 at 20 ° C. in the present embodiment), the respective thermal expansion amounts of the body 3 and the cover 5 are linear as the temperature increases along the straight lines A and B shown in FIG. Increase to. Then, during operation in which the pump 1 is driven at a specified normal rotation speed, when the temperature of the pump 1 rises to the operating temperature (100 ° C. in the present embodiment), the body 3 and the cover 5 The difference in the amount of thermal expansion Δδ ₁₀₀ becomes large as shown in FIG. When the difference Δδ ₁₀₀ between the thermal expansion amounts of the body 3 and the cover 5 becomes large in this way, the side clearance (axial clearance) between the cover 5 having a large thermal expansion amount and the rotor 10 in the pump chamber S becomes large, and the pump 1 As described above, there is a problem that the discharge performance of the pump is lowered.

Therefore, in the assembly method according to the present invention, both are used in a state where the internal stresses of the body 3 and the cover 5 are corrected so that the thermal expansion amounts of the body 3 and the cover 5 are equal in the operating state of the pump 1. I try to conclude. As one method for realizing such an assembly method, the following method is adopted in the present embodiment. In the following description, for convenience, the method of assembling the body 3 and the cover 5 will be limited.

In the assembly method according to the present embodiment, the cover 5 is heated to a temperature higher than room temperature (20 ° C.) and lower than the pump operating temperature (100 ° C.) (50 ° C. in the present embodiment), and this heating is performed. The cover 5 and the body 3 at room temperature are fastened with bolts 7. Here, the temperature of heating the cover 5 is 50 ° C., when the temperature of the body 3 is normal temperature (20 ° C.) and only the cover 5 is heated, the thermal expansion amount δ _{50 of the} cover 5 is the same as that of the body 3 in the operating state. The temperature is equal to the difference in thermal expansion amount Δδ _{100 from the} cover 5 (δ ₅₀ = Δδ ₁₀₀ ).

As described above, when the cover 5 is heated to 50 ° C. and the heated cover 5 and the body 3 at room temperature are fastened with the bolt 7, the cover 5 starts at a temperature of 50 ° C. a (as shown in FIG. 2). As the thermal expansion amount = 0), the thermal expansion is performed along the broken line B', and the thermal expansion amount of the cover 5 and the body 3 becomes equal at the operating temperature (100 ° C.) of the pump 1 (the broken line B'and the straight line A are points. (Intersect at b), the difference in the amount of thermal expansion between the cover 5 and the body 3 Δδ ₁₀₀ becomes 0 (Δδ ₁₀₀ = 0). The difference Δδ in the amount of thermal expansion between the body 3 and the cover 5 at each temperature is shown by diagonal lines in FIG.

As described above, when the difference in thermal expansion amount Δδ ₁₀₀ between the cover 5 and the body 3 at the operating temperature (100 ° C.) of the pump 1 becomes 0 (Δδ ₁₀₀ = 0), the cover 5 and the rotor in the operating state of the pump 1 The side clearance with 10 is kept as small as the design value. As a result, it is possible to prevent a decrease in the discharge performance (discharge pressure and flow rate) of the pump 1 due to an increase in the side clearance.

By the way, the actual assembly of the pump 1 may be performed as follows. That is, the body 3 and the cover 5 have a knock hole (body side knock hole) 3a of the body 3 and a knock hole (cover side knock hole) 3b of the cover 5 that match each other at the operating temperature (100 ° C.) of the pump 1 (FIG. 1) and are formed at positions that are offset from each other during processing. Then, the sleeve-shaped knock member 12 is driven into the knock hole 3a of the body 3 and the knock hole 3b of the cover 5 which are displaced from each other to deform the cover 5 at the time of assembly, and the knock hole 3a and the cover 5 formed in the body 3 are formed. The knock holes 3b formed in the above are matched with each other. Then, the body 3 and the cover 5 are fastened by the bolts 7 inserted into the knock hole 3a, the knock hole 3b, the bolt hole 5a, and the knock member 12.

When the body 3 and the cover 5 are fastened in the same manner as described above, the knock holes 3a formed in the body 3 and the knock holes 3b (bolt holes 5a) formed in the cover 5 coincide with each other during the operation of the pump 1. The shearing force acting on the bolt 7 inserted into the knock hole 3a and the knock hole 3b (bolt hole 5a) is suppressed to a small value, and the durability of the bolt 7 is enhanced.

Alternatively, as shown in FIG. 3, knock holes 3a and bolt holes 5a that match each other at the pump operating temperature are formed in the body 3 and the cover 5 at positions that are offset from each other during processing to correspond to the body 3 of the countersunk bolt 11. The portion to be knocked is the knock size (inner diameter size of the knock hole 3a). Then, the body 3 and the cover 5 may be fastened by a countersunk bolt 11 inserted into the knock hole 3a and the bolt hole 5a formed therein. When the body 3 and the cover 5 are fastened with the countersunk bolts 11 in this way, the misalignment between the knock holes 3a and the bolt holes 5a formed in the body 3 and the cover 5, respectively, is corrected by the countersunk bolts 11.

<Embodiment 2>
Next, Embodiment 2 of the present invention will be described below with reference to FIG.

FIG. 4 is a diagram showing a temperature change in the amount of thermal expansion of the body and cover of the pump assembled by the assembly method according to the second embodiment of the present invention. In the following, the same reference numerals are given to those shown in FIG. Will be described using.

In the method of assembling the pump 1 according to the present embodiment, the body 3 is cooled to a temperature lower than room temperature (20 ° C.) (-30 ° C. in the present embodiment), and the cooled body 3 and the cover at room temperature are covered. 5 and 5 are fastened with bolts 7. Here, the temperature of -30 ° C for cooling the body 3 is such that when the temperature of the cover 5 is room temperature (20 ° C) and only the body 3 is cooled, the heat shrinkage amount δ _{-30 of the} body 3 is the body in the operating state. The temperature is equal to the difference in thermal expansion amount Δδ ₁₀₀ between 3 and the cover 5 (δ _-30 = Δδ ₁₀₀ ).

As described above, when the body 3 is cooled to −30 ° C. and the cooled body 3 and the cover 5 at room temperature are fastened with bolts 7, the body 3 has a temperature of −30 ° C. as shown in FIG. Starting from c (thermal expansion amount = 0), thermal expansion is performed along the broken line A', and the thermal expansion amounts of the cover 5 and the body 3 become equal at the operating temperature (100 ° C.) of the pump 1 (broken line A'and The straight line B intersects at the point d), and the difference in the amount of thermal expansion between the cover 5 and the body 3 Δδ ₁₀₀ becomes 0 (Δδ ₁₀₀ = 0). The difference Δδ in the amount of thermal expansion between the body 3 and the cover 5 at each temperature is shown by diagonal lines in FIG.

As described above, when the difference in thermal expansion amount Δδ ₁₀₀ between the body 3 and the cover 5 at the operating temperature (100 ° C.) of the pump 1 becomes 0 (Δδ ₁₀₀ = 0), the cover 5 and the rotor in the operating state of the pump 1 The side clearance with 10 becomes equal to the design value and can be kept small. As a result, also in the present embodiment, it is possible to prevent a decrease in the discharge performance (discharge pressure and flow rate) of the pump 1 due to an increase in the side clearance.

By the way, also in this embodiment, the actual assembly of the pump 1 may be performed as follows. That is, the body 3 and the cover 5 have a knock hole (body side knock hole) 3a of the body 3 and a knock hole (cover side knock hole) 3b of the cover 5 that match each other at the operating temperature (100 ° C.) of the pump 1 (FIG. 1) and are formed at positions that are offset from each other during processing. Then, the sleeve-shaped knock member 12 is driven into the knock hole 3a of the body 3 and the knock hole 3b of the cover 5 which are displaced from each other to deform the cover 5 at the time of assembly, and the knock hole 3a and the cover 5 formed in the body 3 are formed. The knock holes 3b formed in the above are matched with each other. Then, the body 3 and the cover 5 are fastened by the bolts 7 inserted into the knock hole 3a, the knock hole 3b, the bolt hole 5a, and the knock member 12.

When the body 3 and the cover 5 are fastened in the same manner as described above, the knock holes 3a formed in the body 3 and the knock holes 3b (bolt holes 5a) formed in the cover 5 coincide with each other during the operation of the pump 1. The shearing force acting on the bolt 7 inserted into the knock hole 3a and the knock hole 3b (bolt hole 5a) is suppressed to a small value, and the durability of the bolt 7 is enhanced.

Alternatively, as shown in FIG. 3, knock holes 3a and bolt holes 5a that match each other at the pump operating temperature are formed in the body 3 and the cover 5 at positions that are offset from each other during machining, and correspond to the body 3 of the bolt 11. The portion has a knock size (inner diameter size of the knock hole 3a). Then, the body 3 and the cover 5 may be fastened by the knock hole 3a formed therein and the countersunk bolt 11 inserted into the bolt hole 5a. When the body 3 and the cover 5 are fastened with the countersunk bolts 11 in this way, the misalignment between the knock holes 3a and the bolt holes 5a formed in the body 3 and the cover 5, respectively, is corrected by the countersunk bolts 11.

<Embodiment 3>
Next, Embodiment 3 of the present invention will be described below with reference to FIGS. 5 and 6.

FIG. 5 is a partial cross-sectional view of a pump to which the assembly method according to the third embodiment of the present invention is applied, and FIG. 6 is a thermal expansion of the body and cover of the pump assembled by the assembly method according to the third embodiment of the present invention. It is a figure which shows the temperature change of the quantity, and in FIG. 5, the same element as the one shown in FIG. 1 is given the same reference numeral, and the description about them again will be omitted below.

In the pump 1 shown in FIG. 5 assembled by the method according to the present embodiment, the flange portion 5A is integrally formed on the outer circumference of the cover 5 over the entire circumference, and the other configurations are the implementation shown in FIG. The configuration is the same as that of the pump 1 according to the first embodiment.

In the method of assembling the pump 1 according to the present embodiment, the flange 5A of the cover 5 is clamped, and the cover 5 is subjected to a radial outward load F at room temperature (20 ° C.). The body 3 at room temperature is fastened with a plurality of bolts 7. As a result, at room temperature, a tensile stress outward in the radial direction is generated in the cover 5, and a compressive stress is generated in the axial direction. Therefore, as shown in FIG. 6, the cover 5 is shown in the axial direction. (only shrinkage [delta] ₂₀₎ to [delta] ₂₀ by expansion.

Here, the magnitude of the load F applied radially outward to the cover 5 at room temperature (20 ° C.) is determined by the axial contraction amount δ ₂₀ of the cover 5 at room temperature, which is the operating temperature (100 ° C.) of the pump 1. by setting the thermal expansion amount difference equal value to _{Δδ 100 (δ 20 = Δδ 100} ) between the body 3 and the cover 5 in the cover 5, the broken line B "with an increase in temperature starting from the point e shown in FIG. 6 When the temperature of the pump 1 reaches the operating temperature (100 ° C.), the thermal expansion amounts of the cover 5 and the body 3 become equal (broken line B "and the straight line A are points. (Intersect at f), the difference in the amount of thermal expansion between the cover 5 and the body 3 Δδ ₁₀₀ becomes 0 (Δδ ₁₀₀ = 0). The difference Δδ in the amount of thermal expansion between the body 3 and the cover 5 at each temperature is shown by diagonal lines in FIG.

As described above, when the difference in thermal expansion amount Δδ ₁₀₀ between the cover 5 and the body 3 at the operating temperature (100 ° C.) of the pump 1 becomes 0 (Δδ ₁₀₀ = 0), the cover 5 and the rotor in the operating state of the pump 1 The side clearance with 10 becomes equal to the design value and can be kept small. As a result, also in the present embodiment, it is possible to prevent a decrease in the discharge performance (discharge pressure and flow rate) of the pump 1 due to an increase in the side clearance.

By the way, also in the present embodiment, the actual assembly of the pump 1 may be performed as follows. That is, the body 3 and the cover 5 have a knock hole (body side knock hole) 3a of the body 3 and a knock hole (cover side knock hole) 3b of the cover 5 that match each other at the operating temperature (100 ° C.) of the pump 1 (FIG. 1) and are formed at positions that are offset from each other during processing. Then, the sleeve-shaped knock member 12 is driven into the knock hole 3a of the body 3 and the knock hole 3b of the cover 5 which are displaced from each other to deform the cover 5 at the time of assembly, and the knock hole 3a and the cover 5 formed in the body 3 are formed. The knock holes 3b formed in the above are matched with each other. Then, the body 3 and the cover 5 are fastened by the bolts 7 inserted into the knock hole 3a, the knock hole 3b, the bolt hole 5a, and the knock member 12.

By doing so as described above, the knock holes 3a formed in the body 3 and the knock holes 3b (bolt holes 5a) formed in the cover 5 coincide with each other during the operation of the pump 1, so that the knock holes 3a and these knock holes 3a The shearing force acting on the bolt 7 inserted into the knock hole 3b (bolt hole 5a) is suppressed to a small value, and the durability of the bolt 7 is enhanced.

Alternatively, as shown in FIG. 3, knock holes 3a and bolt holes 5a that match each other at the pump operating temperature are formed in the body 3 and the cover 5 at positions that are offset from each other during machining, and the body portion of the bolt 11 has a knock size. (Inner diameter of the knock hole 3a), the body 3 and the cover 5 may be fastened with the knock hole 3a formed therein and the countersunk bolt 11 inserted into the bolt hole 5a. When the body 3 and the cover 5 are fastened with the countersunk bolt 11 in this way, the misalignment between the knock hole 3a and the bolt hole 5a formed in the body 3 and the cover 5 during pump operation is corrected by the countersunk bolt 11.

In the above embodiment, the room temperature is set to 20 ° C. and the operating temperature of the pump 1 is set to 100 ° C. However, the room temperature changes depending on the season and the operating temperature of the pump 1 differs depending on the specifications of the pump 1. , These should be set according to the situation.

In addition, although the above three examples are given as embodiments of the method of the present invention, both are in a state where the internal stresses of the body and the cover are corrected so that the thermal expansion amounts of the body and the cover are equal in the operating state of the pump. Any other method can be adopted as long as it is a method of concluding.

In addition, the present invention is not limited to the embodiments described above, and various modifications can be made within the scope of claims and the technical ideas described in the specification and drawings.

1 Pump 2 Pump housing 3 Body 3a Body knock hole (body side knock hole)
3b Cover knock hole (cover side knock hole)
4 Spacer 5,6 Cover 5A Cover flange 5a Cover bolt hole 7 Bolt 8 Pump shaft 9 Bush 10 Rotor 10A Inner rotor 10B Outer rotor 11 Countersunk bolt 12 Knock member F Radial outward load S Pump chamber

Claims (6)

A method of assembling a pump in which a body and a cover having a coefficient of thermal expansion larger than that of the body are fastened, and a rotor rotationally driven by a pump shaft is housed in a pump chamber defined by the body and the cover. And
A pump characterized in that both are fastened in a state where the internal stresses of the body and the cover are corrected so that the thermal expansion amounts of the body and the cover are equal in the operating state of the pump. Assembly method. The method for assembling a pump according to claim 1, wherein the cover is heated to a temperature higher than room temperature and lower than the pump operating temperature, and the heated cover is fastened to the body at room temperature. The method for assembling a pump according to claim 1, wherein the body is cooled to a temperature lower than room temperature, and the cooled body is fastened to the cover at room temperature. The method for assembling a pump according to claim 1, wherein the cover and the body are fastened at room temperature in a state where a load outward in the radial direction is applied to the cover at room temperature. The body and the cover are fastened with bolts, and body-side knock holes and cover-side knock holes that match each other at the pump operating temperature are formed in these bodies and covers at positions that are offset from each other during assembly. A knock member is passed through the displaced body-side knock hole and the cover-side knock hole, and the body or the cover is deformed at the time of assembly to match the body-side knock hole formed in both and the cover-side knock hole. The method for assembling a pump according to any one of claims 1 to 4, wherein the body and the cover are fastened with bolts inserted into the body-side knock hole and the cover-side knock hole. The body and the cover are fastened with bolts, and knock holes and bolt holes that match each other at the pump operating temperature are formed in these bodies and covers at positions that are offset from each other at the time of assembly, and the body and the cover are formed from these. The method for assembling a pump according to any one of claims 1 to 4, wherein the knock hole is fastened with a countersunk bolt inserted into the bolt hole.