WO2014017550A1

WO2014017550A1 - Rotary joint

Info

Publication number: WO2014017550A1
Application number: PCT/JP2013/070078
Authority: WO
Inventors: 芳数三苫
Original assignee: リックス株式会社
Priority date: 2012-07-24
Filing date: 2013-07-24
Publication date: 2014-01-30
Also published as: JP5783964B2; CN104428572B; CN104428572A; JP2014025482A

Abstract

A lip seal (12) serving as a gap sealing part for selectively sealing only a flow of fluid in the downstream direction while a sliding gap (G1) in which a fixed shaft part (8a) fits into a fitting hole (7a) provided in a housing member (7) allows axial movement of the fixed shaft part (8a), is provided in said sliding gap (G1). A narrowing part (18) provided at a narrowing hole (18c) which has a flow path diameter (d2) smaller than the flow path inner diameter (d1) of a fixed flow path (8f) and is provided upstream of the end part of the fixed flow path (8f) is also provided in the sliding gap (G1). As a result, fluid flowing downstream through the narrowing part (18) generates a differential pressure, whereby the fluid within the sliding gap (G1) is made to flow to the fixed flow path (8f), and is discharged along with contamination (20) in the fixed flow path (8f).

Description

Rotary joint

The present invention relates to a rotary joint used for supplying fluid to a rotating part.

Fluid coupling for connecting a fixed fluid feed pipe to a flow path of a rotating part in a fluid feeding mechanism that feeds a coolant or other fluid to a rotating part that is in a rotating state during operation such as a spindle of a machine tool As a rotary joint is used. The rotary joint is a rotary seal that is coupled to the rotating portion and rotated, and a fixed shaft connected to the fluid supply pipe is arranged coaxially so as to face each other in the axial direction, and is attached to each facing end surface. These seal surfaces are in close contact with each other to prevent fluid leakage. A fluid having a predetermined pressure and a predetermined flow rate is continuously supplied from a fluid supply pipe to a rotating part in a rotating state via a rotary joint. In the rotary joint having such a configuration, it is necessary to move the fixed shaft side in the axial direction in order to bring the sealing surface into close contact. For this reason, the fixed shaft is slidably fitted into a fitting hole provided in the casing portion or the like, and a seal such as an O-ring interposed between the inner periphery of the fitting hole and the fixed shaft. The member prevents fluid leakage from the sliding gap.

Many fluids to be supplied by rotary joints contain foreign matter such as minute cutting waste, such as coolant that is circulated in machine tools. In such a case, it is inevitable that these foreign substances enter the sliding gap between the fixed shaft and the fitting hole in the process of continuously supplying the fluid. If these foreign substances enter repeatedly, they accumulate and adhere within the sliding gap, and the smooth sliding of the fixed shaft is obstructed. As a result, the rotary joint does not operate normally and a large amount of fluid leaks. Occurs. For this reason, a rotary joint having a structure for preventing foreign matter from entering the sliding gap between the fixed shaft and the fitting hole has been proposed for the purpose of preventing such problems (Patent Documents 1 and 2). reference).

In the prior art example shown in Patent Document 1, the sliding gap is filled with grease by constantly pushing the grease into the annular groove provided on the inner peripheral surface of the fitting hole, and foreign matter in the sliding gap is obtained. To prevent the intrusion. Moreover, in the prior art example shown in Patent Document 2, a bendable diaphragm is attached to the upstream end portion of the fixed shaft, and is sealed so that fluid does not flow other than the passage hole of the fixed shaft. This prevents foreign matter from entering the sliding gap.

JP 2007-218293 A Japanese Patent Laid-Open No. 06-241366

However, the above-described prior art has the following problems due to the structure of the mechanism that prevents foreign matter from entering. First, in the prior art example shown in Patent Document 1, since the grease filling the sliding gap is gradually dissolved in the fluid and the filling effect is reduced, it is difficult to stably secure the foreign matter intrusion preventing effect. . Further, in the prior art example shown in Patent Document 2, since the amount of movement of the fixed shaft cannot be secured sufficiently, the application to machine tools that require the amount of movement of the fixed shaft has been remarkably limited.

The present invention has been made in view of such a problem, and it is possible to effectively solve a problem caused by foreign matter entering into a sliding gap between the fixed shaft portion and the fitting hole to be accumulated and solidified with a simple configuration. An object of the present invention is to provide a rotary joint that can be prevented.

The rotary joint of the present invention includes a rotating part (1a) provided with an axial rotation flow path (4e) and attached to the rotation shaft, and a fixed part (1b) provided with an axial fixed flow path (8f). ) Are coaxially arranged, and the fluid supplied from the fluid supply source is rotated around the axis (A) to the rotating channel (4e) of the rotating part (1a), and the fixed channel (8f) A rotary joint having a first seal surface (5b) provided at the end of the rotary joint (1a) with the rotary flow path (4e) open; The fixed flow path (8f) is formed so as to penetrate in the axial direction, and a predetermined sliding gap (G1) is maintained in a fitting hole (7a) provided in the holding member (7, 3), so that the shaft It has a fixed shaft part (8a) that fits in a state in which movement in the direction is allowed, and the front end face on one side A fixed seal portion having a second seal surface (9b) with an open fixed channel (8f) and the sliding gap are provided in the downstream direction while allowing the sliding gap to move in the axial direction. A gap seal portion that selectively seals only the flow of the fluid, and a flow path inner diameter (d1) at the upstream end of the fixed flow path (8f) and at the upstream end of the fixed flow path ) And a throttle part (18, 19) provided with a smaller flow path diameter (d2) than the fluid supply source to supply the fluid into the fitting hole, and the fixed shaft part (8a) Is pressed to the downstream side by a fluid force to bring the first seal surface (5b) and the second seal surface (9b) into close contact with each other to form a surface seal portion, and the throttle portion (18, 19) due to the differential pressure generated by the fluid flowing downstream, The body, characterized in that to flow into the fixed passage (8f).

According to the present invention, in the sliding gap in which the fixed shaft portion is fitted in the fitting hole provided in the holding member, the axial movement between the fitting hole and the fixed shaft portion is allowed and the downstream direction is allowed. A gap seal portion that selectively seals only the flow of the fluid is provided. Further, the throttle part is provided at the upstream end of the fixed flow path, and the flow path diameter of the throttle part is made smaller than the flow path inner diameter of the shaft end part on the upstream side of the fixed flow path. The fluid in the sliding gap can be caused to flow into the fixed flow path due to the differential pressure generated by the fluid flowing downstream. Thereby, it is possible to effectively prevent problems caused by foreign matters entering the sliding gap between the fixed shaft portion and the fitting hole to be accumulated and solidified with a simple configuration.

Sectional drawing of the rotary joint in one embodiment of this invention Operational explanatory diagram of a rotary joint in an embodiment of the present invention Structure and function explanatory diagram of a gap seal portion used for a rotary joint in an embodiment of the present invention Structure and function explanatory diagram of a gap seal portion used for a rotary joint in an embodiment of the present invention The fragmentary sectional view of the rotary joint in one embodiment of the present invention The fragmentary sectional view of the rotary joint in one embodiment of the present invention

Next, embodiments of the present invention will be described with reference to the drawings. First, the overall configuration of the rotary joint 1 will be described with reference to FIGS. In FIG. 1, a rotary joint 1 is used for a fluid supply mechanism for supplying a cooling fluid to a rotating shaft such as a spindle shaft of a machine tool. The rotary joint 1 is configured by coaxially arranging a rotating part 1a provided with an axial rotating flow path and a fixed part 1b provided with an axial fixed flow path.

The rotating part 1a is fastened to the flow path hole 2a of the spindle shaft 2 which is a rotating shaft. The spindle shaft 2 is driven to rotate by a motor built in the spindle to rotate around the axis A, and is moved forward and backward in the axial direction by a clamp / unclamp cylinder. The fixed portion 1b is fixedly mounted to a mounting hole 3a provided in the casing 3 so as to communicate with the flow path hole 3b via a housing member 7 serving as a holding member. The casing 3 is detachably fastened to a frame (not shown) through which the spindle shaft 2 is inserted by fastening means such as bolts, and the fixed portion 1b is disposed coaxially with the rotating portion 1a. A fluid such as a liquid coolant or cooling air is supplied to the flow path hole 3b from a fluid supply source (not shown).

Next, the detailed structure of each part will be described. The rotating part 1 a is mainly composed of a rotor 4 mounted on the spindle shaft 2. The rotor 4 has a shape in which a flange portion 4b having an outer diameter larger than that of the rotation shaft portion 4a is provided at one end of the rotation shaft portion 4a, and a rotation flow path 4e is provided in the axial direction in the axial center portion. Yes. A male screw portion 4d is provided on the outer surface of the rotating shaft portion 4a, and a female screw portion 2b is provided on the inner surface of the flow path hole 2a. By screwing the male screw portion 4d into the female screw portion 2b, the rotor 4 is screwed to the spindle shaft 2, and the screw fastening portion is sealed by the O-ring 6. As a result, the rotating flow path 4 e communicates with the flow path hole 2 a of the spindle shaft 2.

A circular recess 4c is formed on the end surface of the rotor 4 on the right side (the side facing the fixed portion 1b) so as to surround the opening surface of the rotating flow path 4e. A first seal ring 5 is fixed to the recess 4c. The first seal ring 5 is formed by molding a hard material rich in wear resistance such as ceramic into an annular shape having an opening 5a in the center, and the first seal surface 5b finished to a smooth surface. Is fixed to the recess 4c in a state in which is on the outer surface side. In this state, the rotating flow path 4e communicates with the opening 5a and opens to the first seal surface 5b. In the above configuration, the rotor 4 to which the first seal ring 5 is fixed is provided in the rotating portion 1a, and constitutes a rotating seal portion having a first seal surface 5b having an opening on the end surface of the rotating flow path 4e. ing.

Next, the structure of the fixing portion 1b attached to the casing 3 will be described. The fixed portion 1 b is configured such that the floating sheet 8 is attached to the housing member 7. A mounting hole 3 a provided in communication with the flow path hole 3 b is opened in the mounting surface 3 c of the casing 3. A cylindrical housing member 7 constituting the main body of the fixing portion 1b is fitted into the mounting hole 3a. The housing member 7 is bolted to the mounting surface 3 c (screw holes provided in the mounting surface 3 c are not shown), and the fitting portion to the mounting hole 3 a is sealed by the O-ring 11.

The floating sheet 8 is provided with a disk-shaped flange portion 8b on one side (the side facing the rotating portion 1a in the figure), and on the other side, a fixed flow path 8f (flow path inner diameter d1) penetrates in the axial direction. Thus, the fixed shaft portion 8a is formed. On the downstream side of the fixed flow path 8f, a stepped portion 8g having an inner peripheral surface 8e narrowed to the flow path diameter d3 is formed. Here, the flow path diameter d3 is set so as to be larger than the flow path diameter d2 of the throttle hole 18c of the throttle section 18 described later.

A second seal ring 9 is fixed in a convex portion 8c projecting in an annular shape on the left side of the flange portion 8b (the end surface facing the rotating portion 1a). The second seal ring 9 is formed by molding a hard material similar to that of the first seal ring 5 into an annular shape having an opening 9a at the center. The second seal ring 9 is fixed to the flange portion 8b with the second seal surface 9b finished as a smooth surface facing the outer surface. In this state, the fixed flow path 8f communicates with the opening 9a and opens to the second seal surface 9b.

The fixed shaft portion 8a is fitted in a fitting hole 7a provided in the center portion of the housing member 7 so as to penetrate in the axial direction in a state where movement in the axial direction is allowed. That is, the sliding gap G1 (with a predetermined clearance dimension) between the inner peripheral surface 7b of the fitting hole 7a and the outer peripheral surface 8d of the fixed shaft portion 8a is determined by setting the shape and dimensions of the fitting hole 7a and the fixed shaft portion 8a. 3, 4, and 5) are secured. A seal groove (circumferential groove) 7c is formed on the inner peripheral surface 7b of the fitting hole 7a, and a lip seal 12 which is an annular seal member having a V-shaped cross section is formed in the seal groove 7c. It is installed.

The shape and sealing characteristics of the lip seal 12 will be described with reference to FIG. FIG. 3A shows a state in which the lip seal 12 is mounted in the seal groove 7c in a state where the fixed shaft portion 8a is fitted in the fitting hole 7a. The lip seal 12 has a cross-sectional shape in which two lip portions of the inner peripheral lip portion 12b and the outer peripheral lip portion 12c extend in a V shape from the connecting ring portion 12a that contacts the groove wall surface of the seal groove 7c. is doing. In a state where the lip seal 12 is mounted in the seal groove 7c, the inner peripheral lip portion 12b is pressed against the outer peripheral surface 8d of the fixed shaft portion 8a, and the outer peripheral lip portion 12c is pressed against the bottom surface of the seal groove 7c. It becomes a state. In this state, the axial movement of the fixed shaft portion 8a is allowed.

FIG. 3B shows the sealing characteristics of the lip seal 12 when the fluid flows (arrow f) in the sliding gap G1 with the lip seal 12 mounted. That is, the pressure of the fluid reaching the seal groove 7c via the sliding gap G1 acts on the inter-lip gap 12d, so that the inner peripheral lip portion 12b and the outer peripheral lip portion 12c have the outer peripheral surface 8d and the seal respectively. It is pressed against the bottom surface of the groove 7c (arrow g). With this pressing force, the fluid flow in the downstream direction in the sliding gap G <b> 1 is sealed by the lip seal 12.

On the other hand, FIG. 3C shows the sealing characteristics of the lip seal 12 when the fluid flows upstream in the sliding gap G1 (arrow h) when the lip seal 12 is mounted. . That is, the pressure of the fluid that has reached the seal groove 7c via the sliding gap G1 acts on the inner peripheral lip portion 12b from the upper surface side, so that the inner peripheral lip portion 12b is close to the outer peripheral lip portion 12c. Deflection in the direction (arrow i). As a result, a gap is generated between the inner peripheral lip portion 12b and the outer peripheral surface 8d, and the fluid from the downstream side flows upstream via the sliding gap G1 (arrow j).

That is, the lip seal 12 is a gap seal portion that selectively seals only the flow of fluid in the downstream direction through the sliding gap G1 while allowing the movement of the fixed shaft portion 8a in the axial direction. By using the gap seal portion having such sealing characteristics, the fluid supplied to the flow path hole 3b is prevented from leaking through the sliding gap G1, and the fluid for discharging foreign matter in the sliding gap G1. In other words, the fluid is allowed to flow upstream in the sliding gap G1.

As described above, an example of using the lip seal 12 in which the lip is mounted in the seal groove 7c opened in the sliding gap G1 with the lip facing upstream is shown as the form of the gap seal portion. The seal form that can be used as the gap seal portion is not limited to the lip seal 12. Various seals can be adopted as long as it is a circumferential seal that can selectively seal only a flow in one direction, such as the example shown in FIG.

For example, FIG. 4A shows an example of a gap seal portion configured by pressing the O-ring member 121 downstream by a biasing member 122 such as a spring in the seal groove 7c opened in the sliding gap G1. It is shown. In this case, the fluid flow (arrow f) in the downstream direction in the sliding gap G <b> 1 is sealed by the O-ring member 121. On the other hand, when the fluid flows in the upstream direction in the sliding gap G1 (arrow h), the O-ring member 121 is displaced upstream against the biasing force of the biasing member 122. Fluid flow in the upstream direction is allowed (arrow j).

FIG. 4B shows an example in which a plurality of bent seals 123 are stacked and installed in the seal groove 7c. In this case, the fluid flow (arrow f) in the downstream direction in the sliding gap G 1 is sealed by the bent seal 123. On the other hand, when the fluid flows in the upstream direction in the sliding gap G1 (arrow h), the bending seal 123 is displaced in a direction in which a gap is formed between the outer peripheral surface 8d and thereby in the upstream direction. Is allowed to flow (arrow j).

Further, FIG. 4 (c) shows an example of a gap seal portion in which an O-ring member 124 is mounted in a seal groove 7c 'having a tapered bottom surface whose groove depth is shallower toward the downstream side. In this case, the fluid flow (arrow f) in the downstream direction in the sliding gap G1 moves to the downstream side where the groove depth is the shallowest in the seal groove 7c ′ and is pressed against the O-ring member 124. Sealed by. In contrast, when the fluid flows in the upstream direction in the sliding gap G1 (arrow h), the O-ring member 124 moves to the upstream side having the deepest groove depth in the seal groove 7c '. As a result, a gap is created between the O-ring member 124 and the outer peripheral surface 8d, and fluid flow in the upstream direction is allowed (arrow j).

In the above configuration, the floating sheet 8 to which the second seal ring 9 is fixed has a fixed shaft portion 8a, and becomes a fixed seal portion having a second seal surface 9b having a fixed flow path 8f opened at the end surface. Yes. The fixed shaft portion 8a is fitted in a fitting hole 7a provided in the housing member 7 which is a holding member having a fixed flow path formed in the axial direction in a state where movement in the axial direction is allowed. In the present embodiment, an example is shown in which the floating sheet 8 is attached to the casing 3 via the housing member 7 as a holding member, but the floating sheet 8 may be directly attached to the casing 3. Good. In this case, the fixed shaft portion 8a is fitted in a fitting hole provided in the casing 3 as a holding member in a state where movement in the axial direction is allowed.

A throttle portion 18 is attached to the end of the fitting convex portion 7e where the housing member 7 is fitted into the fitting hole 3a. The restricting portion 18 includes a cylindrical cylindrical portion 18b extending in the axial direction from a circular plate-shaped annular portion 18a. The throttle portion 18 is provided with a throttle hole 18c having a flow path diameter d2 that passes through the annular portion 18a and the cylindrical portion 18b in the axial direction. The throttle portion 18 is mounted by inserting the cylindrical portion 18b into the fixed flow path 8f and fixing the annular portion 18a to the end of the fitting convex portion 7e. At this time, the dimensions of each part are set so that a predetermined annular gap G2 (see FIG. 5) is secured between the inner peripheral surface 8e of the fixed flow path 8f and the outer peripheral surface 18d of the cylindrical portion 18b. Yes.

That is, in the above-described configuration, the throttle portion 18 is provided on the upstream side of the end portion of the fixed flow path 8f. The restricting portion 18 is a restricting hole having a flow passage diameter d2 that is smaller than the flow passage inner diameter d1 of the upstream shaft end portion of the fixed flow passage 8f and smaller than the downstream flow passage diameter d3 of the downstream stepped portion 8g. 18c. The throttle part 18 provided with the throttle hole 18c penetrating is fixed to the housing member 7 as a holding member and extended in the inner diameter direction of the fitting hole 7a, and the annular part 18a. A cylindrical portion 18b extending downstream and inserted into the fixed flow path 8f with a predetermined annular gap G2. As will be described later, the throttle portion 18 has a function of causing the fluid in the sliding gap G1 to flow into the fixed flow path by the differential pressure generated by the fluid flowing downstream through the throttle hole 18c.

Next, the operation of the rotary joint 1 will be described with reference to FIG. The fluid to be supplied is fed into the throttle hole 18c through the flow path hole 3b, and further flows into the fixed flow path 8f, whereby the fluid pressure of this fluid is provided on the downstream side of the fixed flow path 8f. It acts on the end face of the stepped portion 8g (arrow F). As a result, the fixed shaft portion 8a slides toward the rotating portion 1a in the fitting hole 7a, and the second seal ring 9 is fluidized to the projected area of the end surface of the stepped portion 8g with respect to the first seal ring 5. It is pressed by a fluid force F having a magnitude multiplied by the pressure. The fluid force F causes the second seal surface 9b and the first seal surface 5b to be in close contact with each other, thereby leaking the fluid fed from the fixed channel 8f to the rotating channel 4e in a rotating state around the axis. A face seal portion 10 is formed to prevent this.

When the floating sheet 8 is slid in the axial direction, a bolt 16 screwed to the flange portion 8b and a cylindrical collar 17 surrounding the bolt 16 are placed in a guide hole 7d provided in the housing member 7 in the axial direction. Slide. As a result, the movement of the floating sheet 8 in the axial direction is guided and the rotation around the axis is prevented.

In the operating state of the rotary joint 1, the sealing surface of the face seal portion 10 is contacted and separated by the advancement of the floating sheet 8 due to the pressure of the supplied fluid and the advancement / retraction operation of the spindle shaft 2. That is, when the floating sheet 8 is moved backward and the first seal surface 5b and the second seal surface 9b are separated from each other, the fluid is supplied to the flow channel hole 3b, whereby the fixed flow channel 8f. Inside, the fluid force F acts on the end surface of the stepped portion 8g and presses it in the axial direction. As a result, the floating sheet 8 moves forward (in the direction of the arrow a), the first seal surface 5b and the second seal surface 9b come into contact with each other, and the face seal portion 10 in close contact with each other is formed. Thereafter, the fluid is supplied from the fixed flow path 8f to the rotating flow path 4e in the rotating state.

When the spindle shaft 2 moves forward (arrow d direction) relative to the fixed portion 1b, the floating seat 8 moves backward (arrow b direction), and the flange portion 8b returns to a position close to the housing member 7. . By relatively retreating the spindle shaft 2 from this state (in the direction of the arrow c), the first seal surface 5b and the second seal surface 9b are returned to the separated state.

Next, the foreign matter discharging function in the rotary joint 1 having the above-described configuration will be described with reference to FIG. FIG. 5 shows a case where the fluid fed through the flow path hole 3b and flowing into the fitting hole 7a (arrow k) flows downstream in the fixed flow path 8f of the fixed shaft portion 8a toward the rotating portion 1a. Indicates the state. In this case, the fluid to be supplied often includes foreign matter 20 such as minute cutting waste such as coolant that is circulated and used in the machine tool. A part of these foreign substances 20 enters the sliding gap G1 together with the fluid flowing into the sliding gap G1. And if the penetration | invasion of these foreign materials 20 repeatedly accumulates and fixes in the sliding gap G1, it will result in the smooth sliding of the fixed shaft part 8a being inhibited.

Even in such a case, in the rotary joint 1 shown in the present embodiment, the fluid flow in the sliding gap G1 is induced by the differential pressure generation effect by the throttle portion 18 described below, that is, the so-called ejector effect. be able to. Thereby, the foreign material 20 in the sliding gap G1 can be discharged. That is, when the fluid supplied through the flow path hole 3b passes through the throttle hole 18c with a reduced flow path diameter (arrow k), the flow velocity increases, and as a result, the fitting hole 7a and the sliding gap G1 are increased. , A static pressure difference corresponding to the increase in the flow velocity occurs between the annular gap G2.

This differential pressure induces an upstream flow in the sliding gap G1 (arrow 1), and the fluid in the sliding gap G1 passes through the annular gap G2 together with the foreign matter 20 by this flow, and the fixed flow path. It is discharged into 8f (arrow m). At this time, the lip seal 12 as a gap seal portion provided in the sliding gap G1 has a sealing property that allows fluid flow (arrow n) from the downstream side to the upstream side. The foreign matter 20 existing on the downstream side of the lip seal 12 in the gap G1 can be discharged by the above-described differential pressure.

Thereby, foreign matter adhesion in the sliding gap G1 can be prevented over the entire range of the fitting hole 7a and the fixed shaft portion 8a. In addition, by appropriately setting the gap amount for fitting the cylindrical portion 18b into the fixed flow path 8f, even if the required operation stroke differs depending on the model of the target machine tool, the operation is always good. It may be possible to ensure the state.

In the above-described embodiment, the example in which the throttle portion 18 configured to insert the cylindrical portion 18b into the fixed flow path 8f is used as the throttle portion for generating the differential pressure has been described. It is not limited to. That is, it is provided on the upstream side of the end of the fixed flow path 8f, and is provided with a flow path diameter smaller than the flow path inner diameter of the fixed flow path 8f, and has an effect of restricting the flow of fluid from the upstream side. For example, any type of aperture may be selected. For example, as shown in FIG. 6, a simple disk-shaped throttle part 19 with a hole can be used.

In this example, the throttle part 19 is provided with a throttle hole 19b having a flow path diameter d2 smaller than the flow path inner diameter d1 of the fixed flow path 8f at the center, and the outer edge part 19a of the throttle part 19 is a fitting convex of the housing member 7. It is fixed to the part 7e. The fluid from the upstream side passes through the throttle hole 19b and flows into the fixed flow path 8f. At this time, a differential pressure corresponding to an increase in the flow velocity when passing through the throttle hole 19b is generated, and a flow is generated that sucks the fluid in the sliding gap G1 together with the foreign matter 20 into the fixed flow path 8f ( Arrow o). Thereby, the same effect as the example shown in FIG. 5 is acquired.

As described above, in the rotary joint 1 shown in the present embodiment, the fixed shaft portion 8a is fitted into the fitting hole 7a provided in the housing member 7 which is a holding member. For the sliding gap G1 between the fitting hole 7a and the fixed shaft portion 8a, only the flow of fluid in the downstream direction is selectively performed while allowing the sliding gap G1 to move in the axial direction of the fixed shaft portion 8a. A lip seal 12 is provided as a gap seal portion. A throttle portion 18 is provided upstream of the end portion of the fixed flow path 8f, and the throttle portion 18 is provided with a throttle hole 18c having a flow path diameter smaller than that of the fixed flow path 8f. As a result, the fluid in the sliding gap G1 can be caused to flow into the fixed flow path 8f by the differential pressure generated by the fluid flowing downstream through the throttle portion 18, and the fixed shaft portion 8a and the fitting hole 7a. Thus, it is possible to effectively prevent a problem caused by the foreign matter 20 entering and solidifying into the sliding gap G1 with a simple configuration.

The rotary joint of the present invention is characterized in that it is possible to effectively prevent problems caused by foreign matter entering into the sliding gap between the fixed shaft portion and the fitting hole and being solidified by a simple configuration. It is useful for applications in which fluid such as liquid coolant or air is fed to a rotating part such as a spindle of a machine tool.

DESCRIPTION OF SYMBOLS 1 Rotary joint 1a Rotating part 1b Fixed part 2 Spindle shaft 3 Casing member 4 Rotor 4e Rotating flow path 5 1st seal ring 5b 1st seal surface 8 Floating sheet 8a Fixed shaft part 8f Fixed flow path 9 2nd seal ring 9b Second seal face 10 Face seal part 12

Lip seal

18, 19

Restriction part

18c, 19b Restriction hole G1 Sliding gap G2 Ring gap

Claims

The rotating part (1a) provided with the axial rotation flow path (4e) and attached to the rotation shaft, and the fixed part (1b) provided with the axial fixed flow path (8f) are arranged coaxially. The rotary which comprises and supplies the fluid supplied from a fluid supply source to the rotation flow path (4e) of the said rotation part (1a) rotating around an axis (A) via the said fixed flow path (8f). A joint,
A rotary seal portion having a first seal surface (5b) provided on the rotary portion (1a) and having an end surface provided with the rotary flow path (4e);
The fixed flow path (8f) is formed so as to penetrate in the axial direction, and a predetermined sliding gap (G1) is maintained in a fitting hole (7a) provided in the holding member (7, 3), so that the shaft A fixed seal portion having a fixed shaft portion (8a) that fits in a state in which movement in the direction is allowed, and having a second seal surface (9b) in which the fixed flow path (8f) is opened on one end surface. When,
A gap seal portion that is provided in the sliding gap and selectively seals only the flow of fluid in the downstream direction while allowing the sliding gap to move in the axial direction;
A throttle part (d2) provided on the upstream side of the end of the fixed channel (8f) and having a channel diameter (d2) smaller than the channel inner diameter (d1) of the shaft end on the upstream side of the fixed channel. 18, 19), and
By supplying the fluid from the fluid supply source into the fitting hole and pressing the fixed shaft portion (8a) to the downstream side by a fluid force, the first seal surface (5b) and the second seal surface (5b) The seal surface (9b) is brought into close contact with each other to form a surface seal portion,
A rotary joint characterized in that the fluid in the sliding gap is caused to flow to the fixed flow path (8f) by the differential pressure generated by the fluid flowing downstream through the throttle portions (18, 19).
The throttle part is fixed to the holding member and extends in the inner diameter direction of the fitting hole (7a), and extends from the annular part (18a) to the downstream side. The rotary joint according to claim 1, further comprising a cylindrical portion (18b) inserted into the fixed flow path with a predetermined annular gap (G2).
The gap seal portion is a lip seal (12) mounted in a circumferential groove (7c) opened in the sliding gap with the lips (12b, 12c) facing upstream. Item 3. The rotary joint according to Item 1 or 2.
The clearance seal portion is configured by urging an O-ring member (121) downstream by an urging member (122) in a circumferential groove (7c) opened in the sliding clearance. The rotary joint according to claim 1 or 2.