JP7222289B2 - Coupling structure of shaft members and fluid machinery - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coupling structure for shaft members and a fluid machine having a coupling structure for shaft members.

US Pat. No. 6,300,009 describes a rotary compressor.
As shown in FIG. 7, the shaft 81 and the rotor 80 are coupled by press-fitting the shaft 81 into the press-fit hole 80a of the rotor 80. As shown in FIG.

JP-A-5-33788

In the joint structure of the shaft 81 (shaft member) and the rotor 80 (press-fitted member) of Patent Document 1, when the shaft 81 is press-fitted, the direction in which the pressure is applied tends to deviate. On the other hand, the axial center of the shaft 81 tends to be shifted. Aligning the center line of the press-fitting hole 80a with the axial center of the shaft 81 is an important factor in stabilizing the rotation of the rotor 80 and improving the performance of the rotary compressor.

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and an object of the present invention is to provide a shaft member that can be easily aligned with the center line of the press-fitting hole of the member to be press-fitted. An object of the present invention is to provide a coupling structure and a fluid machine having the coupling structure of the shaft member.

A joint structure for a shaft member for solving the above-mentioned problems is a joint structure for a shaft member and a press-fitted member having a press-fit hole into which the shaft member is press-fitted, wherein the shaft member is connected from one end to the other end. It has a first columnar portion, a second columnar portion, a third columnar portion, and a fourth columnar portion toward the side, the diameter of which increases in this order. It has a first inner diameter portion, a second inner diameter portion, and a third inner diameter portion toward the other end side, and is configured so that the inner diameter increases in this order, and the second cylindrical portion is the first inner diameter portion. the third cylindrical portion is press-fitted into the second inner diameter portion; the fourth cylindrical portion is press-fitted into the third inner diameter portion; is longer than the axial length B from the other end of the first inner diameter portion to the other end of the second inner diameter portion. The axial length C from one end of the second cylindrical portion to the one end of the fourth cylindrical portion extends from the other end of the first inner diameter portion to the third cylindrical portion. The gist is that each axial length is longer than the axial length D to the end on the other end side of the inner diameter portion, and each axial length satisfies the relationship of (AB)<(CD).

According to this configuration, the second cylindrical portion is press-fitted into the first inner diameter portion, the third cylindrical portion is press-fitted into the second inner diameter portion, and the fourth cylindrical portion is press-fitted into the third inner diameter portion, whereby the shaft member is inserted deeper into the press-fitting hole. Therefore, it is possible to suppress deviation in the direction of the pressure applied to the shaft member at the time of press-fitting. Further, since the axial length A is longer than the axial length B, and the axial length C is longer than the axial length D, immediately after the second cylindrical portion starts to be press-fitted into the first inner diameter portion, , the third cylindrical portion is not press-fitted into the second inner diameter portion, and the fourth cylindrical portion is not press-fitted into the third inner diameter portion. Further, each axial length satisfies the relationship of (AB)<(CD), so that immediately after the third cylindrical portion begins to be press-fitted into the second inner diameter portion, the fourth cylindrical portion 3 Not press-fitted into the inner diameter. Since the second cylindrical portion, the third cylindrical portion, and the fourth cylindrical portion are sequentially press-fitted, pressure can be applied to the shaft member in stages. Since the pressure at the initial stage of press-fitting can be made relatively low, deviation in the direction of the pressure can be suppressed. This makes it easy to align the axial center of the shaft member with the center line of the press-fitting hole of the press-fitted member.

In the coupling structure of the shaft member, it is preferable that the third columnar portion is formed with serrations. According to this configuration, plastic flow is generated when the third columnar portion is press-fitted into the second inner diameter portion, and the connection between the shaft member and the press-fitted member can be made stronger.

In the coupling structure of the shaft member, it is preferable that the first columnar portion is configured without protruding from the press-fitting hole. According to this configuration, since the first columnar portion does not protrude from the press-fitting hole, it is possible to reduce the size of the joint structure of the shaft member.

In the coupling structure of the shaft member, it is preferable that the axial length of the first columnar portion is half or less than the axial length of the second columnar portion. According to this configuration, it is possible to secure a larger press-fit region for the shaft member, so that the coupling force between the shaft member and the member to be press-fitted can be improved.

Regarding the coupling structure of the shaft member, a fifth columnar portion having a diameter larger than that of the fourth columnar portion is provided on the other end side of the shaft member relative to the fourth columnar portion, and one end side of the fifth columnar portion is provided. is preferably in contact with an end face around the press-fitting hole in the press-fitting member. According to this configuration, it is possible to suppress scattering of chips generated in the press-fitting hole during press-fitting to the outside during use.

It is preferable that the fluid machine has the coupling structure of the shaft member. According to this configuration, it is possible to obtain a fluid machine that functions as a coupling structure for the shaft member.

According to the coupling structure of the shaft member and the fluid machine having the coupling structure of the shaft member of the present invention, it is easy to align the axis of the shaft member with the center line of the press-fitting hole of the member to be press-fitted. Become.

Sectional drawing of a fluid machine. Front view of rotor and shaft. Partial cross-sectional view of the rotor and shaft. Partial cross-sectional view of the rotor. Partial cross-sectional view of the shaft. 4(a) to 4(d) are diagrams for explaining a state in which the shaft is press-fitted into the rotor; FIG. 1 is a sectional view of a prior art rotor and shaft; FIG.

An embodiment of a fluid machine having a shaft member coupling structure and a shaft member coupling structure will be described.
An embodiment in which the fluid machine is embodied as a hydrogen circulation pump for a fuel cell, which is a roots type fluid machine, will be described below.

As shown in FIG. 1, a fuel cell hydrogen circulation pump 10 includes a housing 11, a first rotating shaft 40 as a shaft member rotatably held within the housing 11, and a shaft member rotatably held within the housing 11. and a second rotating shaft 41 as a shaft member. The first rotating shaft 40 is coupled to the first rotor 60 so as to rotate integrally therewith. The second rotating shaft 41 is coupled to the second rotor 61 so as to rotate integrally therewith. Specifically, one end side of the first rotating shaft 40 is press-fitted into the first press-fitting hole 70 of the first rotor 60 and both are coupled. Further, the two are coupled with one end side of the second rotating shaft 41 press-fitted into the second press-fitting hole 65 of the second rotor 61 . Since the first rotating shaft 40 is coupled to the first rotor 60 and the second rotating shaft 41 is coupled to the second rotor 61, the rotation of the first rotating shaft 40 and the second rotating shaft 41 causes the first rotating shaft 40 to rotate. The rotor 60 and the second rotor 61 are rotated to pump and circulate hydrogen.

The housing 11 will be explained.
As shown in FIG. 1 , housing 11 includes end housing 12 , rotor housing 13 , gear housing 14 and motor housing 15 . The end housing 12, rotor housing 13, and gear housing 14 are joined together by bolts (not shown). Gear housing 14 and motor housing 15 are joined by bolts 16 . An O-ring 17 is arranged between the end housing 12 and the rotor housing 13 . An O-ring 17 is also arranged between the rotor housing 13 and the gear housing 14 .

A rotor chamber 18 is formed by the end housing 12 and the rotor housing 13 . A gear chamber 19 is formed by the rotor housing 13 and the gear housing 14 . A motor chamber 20 is formed by the gear housing 14 and the motor housing 15 . A suction port and a discharge port (not shown) are formed in the rotor chamber 18 .

As shown in FIG. 1, the rotor housing 13 is formed with a first shaft hole 21 through which the first rotating shaft 40 is inserted and a second shaft hole 22 through which the second rotating shaft 41 is inserted. The first shaft hole 21 and the second shaft hole 22 pass through the rotor housing 13 .

A shaft seal device 21 a for the first rotating shaft 40 and a bearing device 21 b are provided in the first shaft hole 21 . The gear housing 14 is formed with a recess 14a into which the other end of the first rotating shaft 40 is inserted. A bearing device 14b is provided in the recess 14a. The first rotary shaft 40 is rotatably held by the shaft seal device 21a, the bearing device 21b, and the bearing device 14b.

In the second shaft hole 22, a shaft seal device 22a for the second rotating shaft 41 and a bearing device 22b are provided. A through hole 14c through which the second rotating shaft 41 is inserted is formed in the gear housing 14 . The center line of the through hole 14 c is coaxial with the center line of the second shaft hole 22 . A bearing device 14d and a shaft sealing device 14e are provided in the through hole 14c.

The motor housing 15 is formed with a recess 15a into which the other end of the second rotating shaft 41 is inserted. A bearing device 15b is provided in the recess 15a. The second rotating shaft 41 is rotatably held by the shaft sealing device 22a, the bearing device 22b, the bearing device 14d, the shaft sealing device 14e, and the bearing device 15b.

A stator 23 is fixed to the motor housing 15, and a current flows through the stator 23 through a harness (not shown). A motor rotor 24 is fixed to the other end of the second rotating shaft 41 in the motor housing 15 . The stator 23 and the motor rotor 24 are configured to apply rotational power to the second rotating shaft 41 .

As shown in FIG. 1 , in the gear chamber 19 , a first gear 19 a is fixed to the first rotating shaft 40 and a second gear 19 b is fixed to the second rotating shaft 41 . The first gear 19 a and the second gear 19 b are meshed with each other, and the rotational power applied to the second rotating shaft 41 is transmitted to the first rotating shaft 40 .
is configured to be transmitted to

The first rotor 60 and the second rotor 61 will be explained.
Since the first rotor 60 and the second rotor 61 are configured to have the same shape, the first rotor 60 will be described below, and the description of the second rotor 61 will be omitted.

As shown in FIGS. 2 and 3, the first rotor 60 is configured in a two-leaf shape having ridge teeth 60a and trough teeth 60b. The first rotor 60 has a rotor body 62 made of aluminum-based metal and a resin layer 63 formed on the outer periphery of the rotor body 62 . A first press-fitting hole 70 is formed in the central portion of the rotor body 62 so as to pass through the rotor body 62 in the thickness direction. The length of the resin layer 63 in the thickness direction of the rotor body 62 is slightly larger than the thickness of the rotor body 62 . Therefore, the resin layer 63 is formed in a state of protruding in the thickness direction of the rotor body 62 from both end portions in the thickness direction of the rotor body 62 . A plurality of inner diameter portions having different inner diameters are provided inside the first press-fitting hole 70 as will be described later. One end side of the first rotating shaft 40 is press-fitted into the first press-fit hole 70 , and the tip portion 40 a of the first rotating shaft 40 is positioned at the end portion 70 a on the one end side of the first press-fit hole 70 of the first rotor 60 . are doing.

As shown in FIG. 4, the first press-fit hole 70 of the first rotor 60 has a first inner diameter portion 71, a second inner diameter portion 72, and a third inner diameter portion 73 from one end side to the other end side. and the inner diameter increases in this order. An end portion 73 a on the other end side of the third inner diameter portion 73 is an end portion on the other end side of the first press-fitting hole 70 . A tapered connecting surface 74 is formed between the inner diameter portions in a vertical cross-sectional view of the first press-fitting hole 70 .

Here, the axial length from the end portion 71a on the other end side of the first inner diameter portion 71 to the end portion 72a on the other end side of the second inner diameter portion 72 is B, and the length on the other end side of the first inner diameter portion 71 is B. Let D be the axial length from the end portion 71a to the end portion 73a on the other end side of the third inner diameter portion 73 .

The 1st rotating shaft 40 and the 2nd rotating shaft 41 are demonstrated.
As shown in FIG. 1 , the first rotating shaft 40 and the second rotating shaft 41 are rotatably held within the housing 11 . In the rotor chamber 18 , one end side of the first rotating shaft 40 is press-fitted into the first press-fitting hole 70 of the first rotor 60 . Also, one end side of the second rotating shaft 41 is press-fitted into the second press-fitting hole 65 of the second rotor 61 . A portion of the first rotating shaft 40 press-fitted into the first press-fitting hole 70 (hereinafter also referred to as a “press-fitting portion”) and a portion of the second rotating shaft 41 press-fitted into the second press-fitting hole 65 (hereinafter referred to as a “press-fitting portion”). ) have the same shape, the press-fitting portion of the first rotating shaft 40 will be described below, and the description of the press-fitting portion of the second rotating shaft 41 will be omitted.

As shown in FIG. 3, the press-fit portion of the first rotating shaft 40 has a plurality of cylindrical portions with different diameters, as will be described later. The first rotating shaft 40 and the first rotor 60 are coupled by press-fitting the plurality of cylindrical portions into the plurality of inner diameter portions of the first rotor 60 . In a state in which the first rotating shaft 40 and the first rotor 60 are coupled, the tip portion 40a of the first rotating shaft 40 is positioned at the end portion 70a of the first press-fitting hole 70 of the first rotor 60 on the one end side. That is, the tip portion 40 a of the first rotating shaft 40 is configured without protruding from the first press-fitting hole 70 and is substantially flush with the end surface of the rotor body 62 of the first rotor 60 . The material of the first rotating shaft 40 and the second rotating shaft 41 is composed of ferrous metal, and is configured to have higher strength than the first rotor 60 and the second rotor 61 .

As shown in FIG. 5, the press-fitting portion of the first rotating shaft 40 includes a first cylindrical portion 51, a second cylindrical portion 52, a third cylindrical portion 53, and a fourth cylindrical portion from one end side to the other end side. It has a portion 54, and the diameter increases in this order. The axial length of the first cylindrical portion 51 is less than half the axial length of the second cylindrical portion 52 . A fifth cylindrical portion 55 having a larger diameter than the fourth cylindrical portion 54 is provided on the other end side of the first rotating shaft 40 relative to the fourth cylindrical portion 54 . The outer diameter of the fifth cylindrical portion 55 is configured to be larger than the inner diameter of the end portion 73 a of the first press-fitting hole 70 on the other end side. As will be described later, the fifth cylindrical portion 55 is not press-fitted into the first press-fitting hole 70, so the fifth cylindrical portion 55 is located on the other end side of the press-fitting portion. A circumferentially extending groove 56 is formed between the cylindrical portions. The groove portion 56 functions as an accommodation portion for accommodating chips generated when each cylindrical portion is press-fitted into the first press-fitting hole 70 . Axially extending serrations 57 are formed along the entire outer periphery of the third columnar portion 53 .

The diameter of the first cylindrical portion 51 is smaller than the inner diameter of the first inner diameter portion 71, the diameter of the second cylindrical portion 52 is smaller than the inner diameter of the second inner diameter portion 72, and the diameter of the third cylindrical portion 53 is smaller than the inner diameter of the third inner diameter portion. It is configured to be smaller than the inner diameter of 73 . Therefore, when the first cylindrical portion 51 and the first inner diameter portion 71 overlap in the radial direction of the first rotating shaft 40 , the first rotating shaft 40 is between the first cylindrical portion 51 and the first inner diameter portion 71 . A gap is formed at a predetermined interval in the radial direction of the . Similarly, when the second cylindrical portion 52 and the second inner diameter portion 72 are positioned to overlap in the radial direction of the first rotating shaft 40, the first rotating shaft A gap is formed at a predetermined radial distance of 40 . Similarly, when the third cylindrical portion 53 and the third inner diameter portion 73 overlap in the radial direction of the first rotating shaft 40, the first rotating shaft A gap is formed at a predetermined radial distance of 40 . By forming these gaps, the first cylindrical portion 51 is loosely fitted into the first inner diameter portion 71, the second cylindrical portion 52 is loosely fitted into the second inner diameter portion 72, and the third cylindrical portion 53 is fitted into the third inner diameter portion 71. It is loosely fitted in the inner diameter portion 73 .

The diameter of the second cylindrical portion 52 is larger than the inner diameter of the first inner diameter portion 71, the diameter of the third cylindrical portion 53 is greater than the inner diameter of the second inner diameter portion 72, and the diameter of the fourth cylindrical portion 54 is the third diameter. It is configured to be larger than the inner diameter of the inner diameter portion 73 . As a result, when the second columnar portion 52 and the first inner diameter portion 71 overlap each other in the radial direction of the first rotating shaft 40 , the second columnar portion 52 is press-fitted into the first inner diameter portion 71 . Similarly, when the third cylindrical portion 53 and the second inner diameter portion 72 overlap in the radial direction of the first rotating shaft 40 , the third cylindrical portion 53 is press-fitted into the second inner diameter portion 72 . Similarly, when the fourth cylindrical portion 54 and the third inner diameter portion 73 overlap in the radial direction of the first rotating shaft 40 , the fourth cylindrical portion 54 is press-fitted into the third inner diameter portion 73 . Since the serrations 57 are formed on the outer circumference of the third cylindrical portion 53, the third cylindrical portion 53 and the second inner diameter portion 72 are press-fitted in a state in which plastic flow occurs.

Here, the first to fifth columnar portions 51 to 55 do not strictly mean only columnar shapes, but include, for example, shapes in which the outer diameter changes slightly along the axial direction. Examples of the shape in which the outer diameter changes slightly along the axial direction include, for example, a shape in which at least one of one end side and the other end side of each cylindrical portion is tapered, and a shape in which the central portion is reduced in diameter. . Also, the cross-sectional shape of each cylindrical portion includes a shape that is slightly deformed from a circular shape. Examples of the shape slightly modified from a circular shape include an elliptical shape.

As shown in FIG. 5, the axial length from the end 52a on the one end side of the second cylindrical portion 52 to the end portion 53a on the one end side of the third cylindrical portion 53 is A, and the one end side of the second cylindrical portion 52 C is the axial length from the end portion 52a of the fourth cylindrical portion 54 to the end portion 54a on the one end side. The axial length A is longer than the axial length B. The axial length C is longer than the axial length D. Each axial length is configured to satisfy the relationship (AB)<(CD).

The axial length A is the axial length from the point where the second cylindrical portion 52 is first press-fitted into the first inner diameter portion 71 to the point where the third cylindrical portion 53 is first press-fitted into the second inner diameter portion 72. can be rephrased as Similarly, the axial length C is the distance from the point where the second cylindrical portion 52 is first press-fitted into the first inner diameter portion 71 to the point where the fourth cylindrical portion 54 is first press-fitted into the third inner diameter portion 73. It can be rephrased as axial length.

The axial length B is the axial length from the first inner diameter portion 71 where the second cylindrical portion 52 is first press-fitted to the first inner diameter portion 72 where the third cylindrical portion 53 is first press-fitted. can be rephrased as Similarly, the axial length D is the distance from the first inner diameter portion 71 where the second cylindrical portion 52 is first press-fitted to the first inner diameter portion 73 where the fourth cylindrical portion 54 is first press-fitted. It can be rephrased as axial length.

A press-fitting mechanism for the first rotating shaft 40 and the first press-fitting hole 70 will be described.
As shown in FIG. 6A, the tip 40a of the first rotating shaft 40 is inserted into the first press-fitting hole 70 from the other end side. When part of the first cylindrical portion 51 is inserted into the first inner diameter portion 71 of the first press-fit hole 70 , the end portion 52 a on the one end side of the second cylindrical portion 52 is positioned inside the second inner diameter portion 72 . Then, the end portion 53 a on the one end side of the third columnar portion 53 is positioned inside the third inner diameter portion 73 . In this state, in the radial direction of the first rotating shaft 40, between the first cylindrical portion 51 and the first inner diameter portion 71, between the second cylindrical portion 52 and the second inner diameter portion 72, and between the third cylindrical portion A predetermined gap is provided between 53 and the third inner diameter portion 73 . By having a predetermined gap, the first cylindrical portion 51 is loosely fitted into the first inner diameter portion 71, the second cylindrical portion 52 is loosely fitted into the second inner diameter portion 72, and the third cylindrical portion 53 is fitted into the third inner diameter portion. 73 with a clearance fit. This makes it easy to insert the first rotating shaft 40 into the first press-fitting hole 70 with the axis of the first rotating shaft 40 aligned with the center line of the first press-fitting hole 70 .

As shown in FIG. 6B, when the first rotary shaft 40 is further inserted, the end 52a on the one end side of the second cylindrical portion 52 moves deeper into the first press-fit hole 70, It abuts on the end portion 71 a on the other end side of the inner diameter portion 71 . In this state, the first columnar portion 51 has a predetermined gap inside the first inner diameter portion 71 . Further, the end portion 53a on the one end side of the third cylindrical portion 53 is not in contact with the end portion 72a on the other end side of the second inner diameter portion 72. It has a predetermined gap. Further, the end portion 54 a on the one end side of the fourth cylindrical portion 54 does not contact the end portion 73 a on the other end side of the third inner diameter portion 73 . That is, since the axial length A is longer than the axial length B and the axial length C is longer than the axial length D, the second cylindrical portion 52 begins to be press-fitted into the first inner diameter portion 71. Immediately after, the third cylindrical portion 53 and the fourth cylindrical portion 54 are not press-fitted into the second inner diameter portion 72 and the third inner diameter portion 73, respectively. Therefore, the first cylindrical portion 51 and the third cylindrical portion 53 can be used as a guide member that moves while being fitted with a clearance. This makes it easy to press-fit the second columnar portion 52 into the first inner diameter portion 71 while aligning the axis of the first rotating shaft 40 with the center line of the first press-fitting hole 70 .

As shown in FIG. 6C, when the first rotating shaft 40 is further inserted, the end 53a on the one end side of the third cylindrical portion 53 contacts the end 72a on the other end side of the second inner diameter portion 72. . In this state, the end portion 54a on the one end side of the fourth cylindrical portion 54 is not in contact with the end portion 73a on the other end side of the third inner diameter portion 73 . That is, each axial length satisfies the relationship of (AB)<(CD), so that when the third cylindrical portion 53 contacts the second inner diameter portion 72, the fourth cylindrical portion 54 is not in contact with the third inner diameter portion 73 . In other words, the fourth cylindrical portion 54 is not press-fitted into the third inner diameter portion 73 immediately after the third cylindrical portion 53 begins to be press-fitted into the second inner diameter portion 72 .

As shown in FIG. 6(d), the first rotating shaft 40 is further inserted to position the tip 51a of the first cylindrical portion 51 at the end 70a of the first inner diameter portion 71 on the one end side. That is, the tip portion 40 a of the first rotating shaft 40 is substantially flush with the end surface of the rotor body 62 of the first rotor 60 . In this state, the fourth cylindrical portion 54 is press-fitted into the third inner diameter portion 73 . In addition, the end portion 55a on the one end side of the fifth columnar portion 55 comes into contact with the end surface 62a around the first press-fit hole 70 on the other end side of the rotor body 62, closing the first press-fit hole 70. .

The first rotating shaft 40 is press-fitted into the first press-fitting hole 70 by the above mechanism. A fuel cell hydrogen circulation pump equipped with the coupling mechanism of the present embodiment comprises a housing 11, a first rotating shaft 40 and a second rotating shaft 41 rotatably held in the housing 11, and coupled to the first rotating shaft 40. and a second rotor 61 coupled to the second rotating shaft 41 .

The action and effect of this embodiment will be described.
(1) The second cylindrical portion 52 is press-fitted into the first inner diameter portion 71, the third cylindrical portion 53 is press-fitted into the second inner diameter portion 72, and the fourth cylindrical portion 54 is press-fitted into the third inner diameter portion 73. , the press-fitting is performed at the stage where the first rotating shaft 40 is inserted deeper into the first press-fitting hole 70 . Therefore, it is possible to suppress deviation in the direction of the pressure applied to the first rotating shaft 40 during press-fitting. Further, since the axial length A is longer than the axial length B and the axial length C is longer than the axial length D, the second cylindrical portion 52 begins to be press-fitted into the first inner diameter portion 71. Immediately after, the third columnar portion 53 is not press-fitted into the second inner diameter portion 72 , nor is the fourth columnar portion 54 press-fitted into the third inner diameter portion 73 . Further, each axial length satisfies the relationship of (AB)<(CD), so that immediately after the third cylindrical portion 53 begins to be press-fitted into the second inner diameter portion 72, the fourth cylindrical portion 54 is not press-fitted into the third inner diameter portion 73 . The second columnar portion 52, the third columnar portion 53, and the fourth columnar portion 54 are configured to be press-fitted in sequence. Specifically, since A>B, the press-fitting start timings of the second cylindrical portion 52 and the third cylindrical portion 53 are shifted. Since C>D, the press-fitting start timings of the second cylindrical portion 52 and the fourth cylindrical portion 54 are shifted. Furthermore, since (AB)<(CD), the press-fitting start timings of the third cylindrical portion 53 and the fourth cylindrical portion 54 are shifted. Therefore, pressure can be applied to the first rotating shaft 40 in stages. Since the pressure at the initial stage of press-fitting can be made relatively low, deviation in the direction of the pressure can be suppressed. This makes it easier to align the axis of the first rotating shaft 40 with the center line of the first press-fitting hole 70 of the first rotor 60 .

(2) Since the second columnar portion 52, the third columnar portion 53, and the fourth columnar portion 54 are sequentially press-fitted, the chips generated immediately after each columnar portion starts to be press-fitted into the first press-fitting hole. It becomes possible to discharge to the outside of 70 . Since the chips generated during press-fitting can be discharged to the outside of the first press-fit hole 70 instead of being confined inside the first press-fit hole 70, more chips than necessary are allowed to enter the first press-fit hole 70. can be suppressed. Since it is possible to reduce the size of the grooves 56 provided between the cylindrical portions, the strength of the first rotating shaft 40 can be improved.

(3) The first rotary shaft 40 and the first rotor 60 can be coupled simply by press-fitting the press-fit portion, which is one end of the first rotary shaft 40 , into the first press-fit hole 70 of the first rotor 60 . Therefore, work efficiency can be improved.

(4) Serrations 57 are formed on the third cylindrical portion 53 . Therefore, plastic flow occurs when the third cylindrical portion 53 is press-fitted into the second inner diameter portion 72, and the coupling between the third cylindrical portion 53 and the second inner diameter portion 72 can be made stronger. Further, since the press-fitting of the third columnar portion 53 is started after the press-fitting of the second columnar portion 52 is started, the direction of the pressure deviates when high pressure due to plastic flow is applied to the third columnar portion 53. can be suitably suppressed.

(5) The tip portion 40 a of the first rotating shaft 40 is positioned at the end portion 70 a on the one end side of the first press-fitting hole 70 . Therefore, it is possible to reduce the size of the connecting structure of the shaft members compared to the case where the tip portion 40a of the first rotating shaft 40 protrudes from the first press-fitting hole 70 . In particular, in the roots type fluid machine, the first rotor 60 is held in a cantilevered state by the first rotating shaft 40, which contributes to downsizing of the fluid machine.

(6) The axial length of the first cylindrical portion 51 is less than half the axial length of the second cylindrical portion 52 . Therefore, since a larger press-fit region for the first rotating shaft 40 can be ensured, the first
The coupling force between the rotating shaft 40 and the first rotor 60 can be improved.

(7) A fifth cylindrical portion 55 having a larger diameter than the fourth cylindrical portion 54 is provided on the other end side of the first rotating shaft 40 relative to the fourth cylindrical portion 54, and the end of the fifth cylindrical portion 55 on the one end side The portion 55 a contacts the end surface 62 a around the first press-fitting hole 70 on the other end side of the first rotor 60 . Therefore, it is possible to suppress scattering of chips generated in the first press-fitting hole 70 during press-fitting to the outside during use.

This embodiment can be implemented with the following modifications. This embodiment and the following modified examples can be implemented in combination with each other within a technically consistent range.
O In the present embodiment, the serrations 57 are formed on the third columnar portion 53, but the serrations 57 may be omitted. Further, the serrations are not limited to the third columnar portion 53, and at least one of the second columnar portion 52 and the fourth columnar portion 54 may be formed with serrations. Serrations may be formed on all of the second cylindrical portion 52 , the third cylindrical portion 53 , and the fourth cylindrical portion 54 .

In the present embodiment, when the first rotating shaft 40 and the first rotor 60 are connected, the tip 51a of the first cylindrical portion 51 is positioned at the end 70a on the one end side of the first press-fitting hole 70. However, it is not limited to this aspect. That is, the tip portion 51a of the first cylindrical portion 51 may protrude from the end portion 70a on the one end side of the first press-fit hole 70, or may protrude from the end portion 70a on the one end side of the first press-fit hole 70. It may be located on the other end side of the hole 70 .

O The axial length of the first cylindrical portion 51 is not limited to half or less of the axial length of the second cylindrical portion 52 . The axial length of the first cylindrical portion 51 may be longer than half the axial length of the second cylindrical portion 52 . Since it is longer than half of the axial length of the second columnar portion 52, the function as a guide member can be improved by fitting the first columnar portion 51 with a clearance.

○ In the present embodiment, when the first cylindrical portion 51 and the first inner diameter portion 71 are positioned to overlap in the radial direction of the first rotating shaft 40, there is a A gap was formed at a predetermined interval in the radial direction of the one-rotation shaft 40 . Similarly, a predetermined interval is provided between the second cylindrical portion 52 and the second inner diameter portion 72 and between the third cylindrical portion 53 and the third inner diameter portion 73 in the radial direction of the first rotating shaft 40. Although a gap was formed, it is not limited to this aspect. That is, there are gaps between the first cylindrical portion 51 and the first inner diameter portion 71, between the second cylindrical portion 52 and the second inner diameter portion 72, and between the third cylindrical portion 53 and the third inner diameter portion 73. The two may be in contact with each other to the extent that they are not press-fitted. Even if they are in contact with each other, they can be used as guide members by moving the first cylindrical portion 51 and the third cylindrical portion 53 within the first press-fitting hole 70 .

(circle) the 5th cylinder part 55 may be abbreviate|omitted.
O In the present embodiment, the grooves 56 are formed between the cylindrical portions of the first rotating shaft 40, but the grooves 56 may be omitted. For example, the cylindrical portions may be connected in a stepped manner via a connecting surface extending in the radial direction, or the cylindrical portions may be connected via a connecting surface that is tapered in a vertical cross-sectional view. Further, instead of forming the groove portion 56 in each cylindrical portion of the first rotating shaft 40 , a groove portion may be formed in the inner circumference of the first press-fitting hole 70 .

O In the present embodiment, between the inner diameter portions of the first press-fitting hole 70, a tapered connection surface 74 is formed in a vertical cross-sectional view, but the present invention is not limited to this aspect. Each inner diameter portion may be connected in a stepped manner via a connecting surface extending in the radial direction.

○ The fluid machine of the present embodiment is not limited to a hydrogen circulation pump for a fuel cell, which is a Roots-type fluid machine. It may be a roots-type fluid machine other than the hydrogen circulation pump for the fuel cell, and may be, for example, a roots-type fluid machine used for air conditioners, dehumidifiers, and the like. Further, the fluid machine may be of a type other than the Roots type, and may be, for example, a scroll type, reciprocating type, or vane type. Further, the coupling structure of the shaft member of the present embodiment is applicable to coupling structures of shaft members other than fluid machinery as long as it is a coupling structure of a shaft member and a press-fitted member having a press-fitting hole into which the shaft member is press-fitted. can also

A cylindrical portion having a smaller outer diameter than the first cylindrical portion 51 may be provided on the first rotating shaft 40 on the one end side of the first cylindrical portion 51 .
○ In this embodiment, both the connection between the first rotating shaft 40 and the first rotor 60 and the connection between the second rotating shaft 41 and the second rotor 61 are configured to have the shaft member coupling structure of this embodiment. However, it is not limited to this aspect. Even if either one of the coupling between the first rotating shaft 40 and the first rotor 60 and the coupling between the second rotating shaft 41 and the second rotor 61 is configured to have the shaft member coupling structure of the present embodiment. good.

51... First columnar part 51a... End part on one end side of first columnar part 52... Second columnar part 52a... End part on one end side of second columnar part 53... Third columnar part 53a... Third columnar part 3 end on one end side of cylindrical part 54... fourth cylindrical part 54a... end on one end side of fourth cylindrical part 71... first inner diameter part 71a... end on the other end side of first inner diameter part , 72 . . . second inner diameter portion 72 a .

Claims (6)

A coupling structure between a shaft member and a press-fitted member having a press-fitting hole into which the shaft member is press-fitted,
The shaft member has a first columnar portion, a second columnar portion, a third columnar portion, and a fourth columnar portion in order from one end side to the other end side, and the diameter increases in this order. is,
The press-fit hole has a first inner diameter portion, a second inner diameter portion, and a third inner diameter portion from one end side to the other end side, and is configured so that the inner diameter increases in this order,
The press-fitting hole has a tapered connecting surface or a stepped connecting surface extending in the radial direction that connects an end portion on the other end side of the first inner diameter portion and an end portion on the one end side of the second inner diameter portion. and a tapered connection surface or a radially extending stepped connection surface that connects the end of the second inner diameter portion on the other end side and the end portion of the third inner diameter portion on the one end side have
The second cylindrical portion is press-fitted into the first inner diameter portion,
The third cylindrical portion is press-fitted into the second inner diameter portion,
The fourth cylindrical portion is press-fitted into the third inner diameter portion,
The axial length A from the end on the one end side of the second cylindrical portion to the end on the one end side of the third cylindrical portion is equal to the length A from the end on the other end side of the first inner diameter portion to the second inner diameter portion. longer than the axial length B to the end on the other end side of
The axial length C from one end of the second cylindrical portion to the end of one end of the fourth cylindrical portion is from the other end of the first inner diameter portion to the third inner diameter portion. longer than the axial length D to the end on the other end side of
A connecting structure of shaft members, wherein each axial length satisfies the relationship of (AB)<(CD). 2. The connecting structure of the shaft member according to claim 1, wherein the third cylindrical portion is formed with serrations. 3. The joint structure of the shaft member according to claim 1, wherein the first columnar portion is configured so as not to protrude from the press-fitting hole. 4. The coupling structure for shaft members according to claim 1, wherein the axial length of said first columnar portion is half or less of the axial length of said second columnar portion. A fifth cylindrical portion having a larger diameter than the fourth cylindrical portion is provided on the other end side of the shaft member relative to the fourth cylindrical portion,
5. The coupling structure of the shaft member according to claim 1, wherein the end of the fifth cylindrical portion on the one end side abuts on the end face around the press-fitting hole of the press-fitting member. A fluid machine comprising the shaft member coupling structure according to any one of claims 1 to 5.

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