EP2126360A1

EP2126360A1 - Sealed device for transmitting a rotational movement inside a chamber

Info

Publication number: EP2126360A1
Application number: EP08761880A
Authority: EP
Inventors: Guy Delaisse; Fabrice Bariau
Original assignee: Mouvex SAS
Current assignee: Mouvex SAS
Priority date: 2007-02-19
Filing date: 2008-02-13
Publication date: 2009-12-02
Also published as: FR2912788A1; CA2678578A1; US20100105487A1; WO2008116983A1

Abstract

The invention relates to a sealed device for transmitting a rotational movement inside a chamber (7) from a drive shaft (1) to a driven shaft (2), said drive shaft (1) including at least one input section (3) extending through a wall (14) of the chamber (7) and supported by two bearings, one (12) of which is located inside the sealed casing (8) very close to the output section (4), and intended to co-operate with a rotational drive means, and an output section (4) engaged with the driven shaft (2) and inclined by an angle α in relation to the input section (2). The inventive device includes a sealed casing surrounding the portion of drive shaft (2) located in the chamber (7). The sealed casing (8) includes at least: a bellows portion (9) conferring flexibility on the casing (8) at the intersection between the axis of the input section (3) and the axis of the output section (4) of the drive shaft (1); and a rigid sleeve (10) extending alongside the bellows portion (9) in the direction of the end of the output section (4) of the drive shaft (1). The invention also relates to a method for producing a sealed transmission device.

Description

SEALED DEVICE FOR TRANSMITTING A ROTATION MOVEMENT WITHIN A CHAMBER

The invention particularly relates to a device for transmitting a rotational movement to a pump shaft.

In the prior art, there are known sealed devices for transmitting a rotational movement inside a chamber.

Such devices are described in particular in the French patent application FR 2 746 452 in the name of the applicant.

The device described in this document comprises a motor shaft comprising an inlet section passing through a wall of the flow chamber of a pump and cooperating with a rotating drive means, and an inclined section with respect to the section of input whose end is engaged with a driven shaft to transmit the rotational movement. In order to guarantee the seal between the inside and the outside of the flow chamber, the portion of the motor shaft disposed in the flow chamber is covered with a non-rotating sealing sleeve comprising two metal bellows. The bellows are slidably mounted on the inclined section to ensure a sufficient life.

However, this type of device has disadvantages. Indeed, the maximum eccentricity of the end of the inclined section relative to the output section is limited because the exceeding of this maximum eccentricity leads to the buckling of the bellows. Indeed, in order to limit the stresses generated in the bellows waves due to wave deformation, the angle α of inclination between the inclined section and the input section must be limited. Thus, to increase the eccentricity, the length of the inclined section and therefore the bellows must be increased. Now, increasing the length of the bellows by the addition of several waves reduces the rigidity of the bellows until it becomes unstable in these movements. This instability can be called the buckling of the bellows. Thus, because of this impossibility of increasing the eccentricity under penalty of leading to the buckling of the bellows, the effort required to drive the driven shaft in rotation is relatively important.

The invention aims to remedy these problems by proposing a device for transmitting a rotational movement that is waterproof, resistant and allows to reduce the force required to actuate the driven shaft by increasing its lever arm.

For this purpose, and according to a first aspect, the invention proposes a sealed device for transmitting a rotational movement comprising:

- a room inside which the movement is transmitted

- a trained tree;

a motor shaft comprising at least one inlet section passing through a wall of said chamber and intended to cooperate with a rotation drive means and an output section engaged with said driven shaft and inclined at an angle α relative to at said entrance section; the device comprising a non-rotating sealed envelope covering the motor shaft inside said chamber.

The sealed envelope comprises at least:

a bellows portion ensuring the flexibility of said envelope at the intersection between the axis of the inlet section and the axis of the output section of the motor shaft, and a rigid sleeve extending the bellows portion in the direction of from the end of the output section of the motor shaft.

Thus, according to the invention, the sealed envelope is stable because the bellows portion uses a small number of juxtaposed annular elements. In addition, the eccentricity of the end of the inclined portion can be increased in proportion to the length of the rigid sleeve because this portion of the envelope does not affect the rigidity of the envelope. Thus, the effort required for rotation of the driven shaft is decreased by the increase of the lever arm. Advantageously, the bellows portion extends an equal distance on either side of said intersection to describe a circular arc. Thus, the stresses are distributed equally over each wave.

Preferably, in order to obtain a large eccentricity, the length of the rigid sleeve is greater than half the length of the bellows portion.

Moreover, in the devices of the prior art, the bellows envelopes are subjected to deformations due to the pressure difference between the inside of the envelope and the chamber. Indeed, a bellows whose axis describes a circular arc goes in case of pressure change shape. In such circumstances, the shape of the bellows depends on the direction of the pressure difference. If the pressure inside the bellows is greater than that inside the chamber then said bellows will bend. On the contrary, if the pressure in the bellows is lower than the pressure in the chamber then the bellows recovers. The consequence of these deformations is an increase in the stresses in certain bellows waves, leading to a decrease in the life of said bellows.

Advantageously, in order to solve the aforementioned problem, the sealed envelope is filled with a liquid in order to balance the pressure between the inside of the chamber and the inside of the envelope. Filling the interior volume of a flexible and watertight cavity with a liquid is an effective solution to solve the problem mentioned above.

In a preferred embodiment, the liquid is a degassed lubricant. The degassed lubricant is advantageous in that it can, on the one hand, on our scale, be considered incompressible and on the other hand, on our scale, be considered insensitive to vacuum in the limit of its vapor pressure.

Advantageously, the sealed envelope is firstly fixed to the chamber and secondly mounted on the motor shaft by a sliding bearing. The sealed envelope thus has a degree of axial freedom at one of its ends. Thus, the casing is adapted to undergo expansions or contractions of the liquid as a function of the temperature changes inside the chamber.

Advantageously, the motor shaft is mounted in rotation by means of a bearing mounted on a support extending inside said chamber. Thus, the bearing of the motor shaft is close to the point of transmission of the torque which makes it possible to reduce the forces applied on said bearing.

Advantageously, the output section of the motor shaft is fixed on the input section via a support flange. Thus, the length of the input section is increased and the support bearing of the motor shaft can be arranged more closely to the torque transmission point.

In one embodiment, the device comprises a connection piece positioned at the end of the motor shaft, the driven shaft being provided with a cradle for receiving said connecting piece.

Advantageously, the sealed envelope is made of a stainless metal material or a composite material. Thus, the shell material is chemically compatible with all kinds of pumped liquid and is resistant to use at high temperatures.

According to a second aspect, the invention relates to a method of manufacturing a sealed transmission device according to the first aspect of the invention comprising a step of filling the sealed envelope with a liquid in order to balance the pressure between the chamber. and the inside of the envelope.

Preferably, said method further comprises a step prior to the filling step consisting in evacuating said sealed envelope.

Other objects and advantages of the invention will become apparent from the following description, made with reference to the appended drawings, in which: - Figure 1 is a schematic representation of the device for transmitting a rotation of a motor shaft to a driven shaft according to the invention;

- Figure 2 schematically illustrates the connection between the motor shaft and the driven shaft;

- Figure 3 is a sectional view of a motion transmission device according to a particular embodiment of the invention;

- Figure 4 shows the drive shaft of the transmission device of Figure 3;

FIG. 5 is a view of the device of FIG. 3, illustrating in more detail the sealed envelope and the connection between the motor shaft and the driven shaft;

FIG. 6 is an enlarged sectional view of the device of FIG. 3;

FIG. 7 is a sectional view of the bearing support of the motor shaft extending inside the chamber according to the embodiment of FIG. 3;

- Figure 8 is a perspective view of the receiving cradle of the connecting piece integral with the end of the motor shaft according to the embodiment of Figure 3; and

FIG. 9 is a sectional view in the plane IX-IX of FIG. 3.

Figure 1 schematically illustrates a device for transmitting the rotational movement. The device comprises a drive shaft 1, a driven shaft 2 and a non-rotating chamber 7 filled with a fluid through which the movement is transmitted. The drive shaft 1 and the driven shaft 2 are rotatably mounted on the chamber by bearings 12, 13. The transmission device according to the invention is particularly intended for a pump. Thus, the chamber 7 may in particular be a flow chamber of a pump traversed by the product conveyed or a sealing chamber auxiliary to the flow chamber; the driven shaft 2 may in particular be a pump shaft on which is installed the pumping member of the pump.

The drive shaft 1 comprises an inlet section 3 and an outlet section 4 which is inclined at an angle α with respect to the inlet section 3. The inlet section 3 passes through a fixed wall 14 of the chamber 7 and cooperates with a rotating drive means placed outside the chamber, such as a motor, not shown. The inlet section 3 is coaxial with the driven shaft 2. The driven shaft 2 comprises a U-shaped cradle 5 to accommodate the eccentric end of the drive shaft 1. The eccentricity at the end of the drive shaft motor shaft 1 resulting from the inclination of the outlet section 4 is designated E. The force required to transmit the torque to the driven shaft 2 is inversely proportional to the eccentricity E.

The direction of rotation of the movement can be carried out in either the clockwise or counterclockwise direction. In addition, the direction of transmission of the movement can be reversed, the motor shaft 1 becoming the driven shaft 2 and vice versa. In order to guarantee the seal between the inside and the outside of the chamber 7, the portion of the motor shaft 1 disposed inside the chamber 7 is covered with a non-rotating tight envelope 8 around its axis. comprising two portions: a bellows portion 9 and a sleeve 10 extending said bellows portion 9 towards the outlet section 4. The envelope 8 is mounted on the one hand fixed relative to the chamber 7 and on the other hand mounted in rotation on the output section 4 of the drive shaft 1 by a sliding bearing 11. The sliding bearing 11 may in particular be a sliding bearing or a rolling bearing.

The bellows portion 9 makes it possible to ensure the flexibility of the casing 8 in the vicinity of the intersection I between the axis d1 of the inlet section 3 and the axis d2 of the outlet section. In the embodiment shown, the bellows consists of a series of annular elements 6. In order to limit the constraints in these annular elements 6, the bellows 9 describes a circular arc. For this purpose, the bellows 9 extends of a length equal to and a 'on either side of the intersection I.

The sleeve 10 is rigid and allows to extend the envelope 8 without increasing its instability. Advantageously, in order to obtain a sufficient eccentricity E, the increase in the eccentricity provided by the portion of the outlet section 4 covered by the sleeve 10 of length m is at least equal to the eccentricity e resulting from the portion of the section. 4, thus covered by the bellows 9. Thus, the length of the sleeve 10 is greater than 50% of the length of the bellows portion 9, and preferably greater than the length of the bellows portion 9.

The construction of the sealed envelope 8 must provide it with sufficient torsional rigidity to withstand the torsional torque to which it is subjected during operation.

In one embodiment, the sealed envelope 8 is made of stainless steel. However, it can be considered in any other material having physical and chemical characteristics suitable for this application, including ceramics.

In order to balance the pressure between the inside of the chamber 7 and the inside of the casing 8, the sealed casing 8 is filled with a liquid, preferably a lubricant. For this purpose, when the drive shaft 1 and the casing 8 are located inside the chamber 7, the method of manufacturing the device provides for evacuating the inside of the casing 8 via one or more orifices not shown. When the vacuum is carried out inside the casing 8, the mounting method provides for filling the casing 8, via the orifice or holes, with the lubricant.

Figures 3 to 8 described below illustrate a particular embodiment of the invention. The motor shaft illustrated in Figure 4 also has an inlet section 3 and an outlet section 4 inclined at an angle α. However, in this embodiment, the output section 4 is carried by a support flange 15 for laterally and angularly displacing said output section 4 with respect to the input section 3. Thus, the theoretical intersection I between the axis d1 of the inlet section 2 and the axis d2 of the outlet section 3 is located in an intermediate portion of the inlet section 3. The inlet section 3 and the outlet section 4 are arranged to have the lateral and angular displacement at the end of the motor shaft 1.

The motor shaft 1 is mounted on the chamber via two bearings 12, 16 (see Figure 3). A first bearing 16 is carried by a bearing support 17 extending outwardly of the chamber 7 and a second bearing 12 is carried by a bearing support 18 extending inside the chamber 7. bearing supports 17, 18 are mounted integral with the chamber 7, not shown in FIGS. 3 to 9. In order to reduce the force exerted on the bearings 12, 16 during the transmission of the movement, it is sought to place the second bearing 12 as close as possible to the point of transmission of the movement between the two shafts 1, 2. The second bearing 12 is thus placed close to the end of the inlet section 3 adjacent to the outlet section 4.

This embodiment is therefore particularly advantageous because the design of the motor shaft 1 illustrated in Figure 4 associated with a bearing support 18 extending inside the chamber 7 allows to have the second bearing 12 very close to the end of the motor shaft 1.

Figure 7 illustrates in detail said bearing support member 18. The bearing support 18 extends inside the sealed envelope 8. At a first end, the support 18 comprises a fastening flange 19 on the chamber 7, provided with orifices 20 intended to receive fasteners not shown. A cylindrical bore 21 extends from the fastening flange 19 inwardly of the chamber 7 and allows the passage of the drive shaft 1. In operation, the bore 21 is also filled with lubricant. At its second end, the bore 21 comprises a housing 22 for receiving the second bearing 12.

Moreover, the sealed envelope 8, illustrated in detail in FIG. 6, is on the one hand integral with a fastening collar 23 secured to the bearing support 19 itself attached to the chamber 7 and on the other hand mounted in rotation on the outlet section 3 of the drive shaft 1 by a sliding bearing 11.

The drive shaft 1 is provided at its end with a connecting piece 24, shown in detail in FIGS. 6 and 9. Said connecting piece

24 is received in a cradle 5 U, shown in Figures 8 and 9, secured to the end of the driven shaft 2. The connecting piece 24 has a cylindrical housing 25 for receiving the end of the shaft motor and a double bearing 11, 26. The sealed casing 8 is fixed to the intermediate piece 27 of said double bearing 11, 26. The intermediate piece 27 is slidably mounted on the drive shaft 1. Thus, as we have seen previously, the envelope

9 is mounted on the motor shaft 1 via a sliding bearing 11. The double bearing

11, 26 allows the envelope 8 to be non-rotating on itself while the connecting piece 24 and the motor shaft 1 are driven in a rotational movement.

The cradle 5 has a motion transmission function, comparable to the function of a crank, and is attached to one end of the driven shaft 2.

In the embodiment shown, the connecting piece or endpiece 24 and the cradle 5 have support walls 28a, 29a, 28b, 29b substantially planar. However, the bearing areas between the walls 28a and 28b of the connection piece 24 and the walls 29a, 29b of the cradle 5 are limited to a portion of the zones facing each other so as to provide a clearance which allows deformations. of construction or operation without causing blockage of the movement transmission.

In the embodiment shown, the driven shaft 2 is supported by two bearings 13, 30 extending on either side of the flow chamber 31 of the pump (see Figure 3) and comprises pumping members for circulating the liquid through the chamber 31.

The invention is described in the foregoing by way of example. It is understood that the skilled person is able to achieve different embodiments of the invention without departing from the scope of the invention.

Claims

1. Sealing device for transmitting a rotational movement, comprising: - a chamber (7) inside which the movement is transmitted;

a driven shaft (2);

a driving shaft (1) comprising at least one inlet section (3) passing through a wall (14) of said chamber (7) and intended to cooperate with a rotating drive means and an output section (4) engaged with said driven shaft (2) and inclined at an angle α with respect to said inlet section

(2); and a non-rotating sealed envelope (8) covering the drive shaft (2) within said chamber (7);

said device being characterized in that the sealed envelope (8) comprises at least:

a bellows portion (9) ensuring the flexibility of said envelope (8) at the intersection I between the axis (d1) of the inlet section (3) and the axis (d2) of the output section (4). ) of the motor shaft (1), and

- A rigid sleeve (10) extending the bellows portion (9) towards the end of the output section (4) of the drive shaft (1).

2. A sealed rotational transmission device according to claim 1, wherein the bellows portion (9) extends an equal distance on either side of said intersection I to describe an arc of rotation. circle.

3. Rotational transmission sealing device according to any one of claims 1 or 2, wherein the length of the rigid sleeve (10) is greater than the length of the bellows portion (9).

4. Rotational transmission sealing device according to any one of claims 1 to 3, wherein the sealed envelope (8) is filled with a liquid to balance the pressure between the chamber (7). and the inside of the envelope (8).

The sealed rotational transmission device according to claim 4, wherein said liquid is a degassed lubricant.

6. Sealing device for transmitting a rotational movement according to any one of claims 1 to 5, wherein the sealed envelope (8) is firstly fixed to the chamber (7) and secondly mounted on the motor shaft (1) by a sliding bearing (11).

7 sealed device for transmitting a rotational movement according to one of claims 1 to 6, comprising a bearing support (18) extending inside the chamber (7) and carrying a bearing (12) supporting the motor shaft (1).

8. Rotational transmission sealing device according to claim 7, wherein the bearing support (18) extends inside the sealed envelope (8).

A sealed rotational transmission device according to claim 7 or 8, wherein the bearing support (18) comprises a fastening flange (19) on the chamber (7).

10. Rotational transmission sealing device according to one of claims 7 to 9, wherein the bearing (12) extending inside the chamber (7) is disposed near the end of the inlet section (3) adjacent to the outlet section (4).

A rotational transmission impervious device according to claim 10, wherein the bearing support (18) comprises a cylindrical bore (21) extending from the attachment flange (19) to the interior of the chamber (7) and allowing the passage of the motor shaft (1).

12. Sealing device for transmitting a rotational movement according to one of claims 9 to 11, wherein the sealed envelope (8) is secured to a fastening collar (23) integral with the bearing support (18). .

13. Rotational transmission sealing device according to one of claims 1 to 12, comprising a bearing support (17) extending outside the chamber (7) and carrying a bearing (16) supporting the motor shaft (1).

14. Impermeable transmission device of a movement according to one of claims 1 to 13, wherein the output section (4) of the drive shaft (1) is fixed on the inlet section (3) by the intermediate a support flange (15) to move laterally and angularly the output section (4) relative to the inlet section (3).

15. A sealed motion transmission device according to one of claims 1 to 14, characterized in that the input section (3) and the output section (4) are arranged to have the lateral and angular displacement at the end of the motor shaft (1).

16. A rotational transmission sealing device according to any one of claims 1 to 15, comprising a connecting piece (24) secured to one end of the drive shaft (1), the driven shaft ( 2) being provided with a receiving cradle (5) of said connecting piece (24).

17. Rotational transmission sealing device according to claim 16, wherein the connecting piece (24) has a cylindrical housing (25) for receiving the end of the drive shaft (1) and a double bearing (11, 26) having an intermediate piece (27), the sealed envelope (8) being fixed to said intermediate piece (27).

18. Sealing device for transmitting a rotational movement according to one of claims 1 to 17, wherein the sealed envelope (8) is made in a material compatible with surrounding fluids and resistant to induced bending and twisting forces.

19. A method of manufacturing a sealed transmission device according to one of claims 1 to 18, characterized in that it comprises a step of filling the sealed envelope (8) with a liquid to balance the pressure. between the interior of the chamber (7) and the inside of the envelope (8).

20. The manufacturing method according to claim 19, characterized in that it comprises a step prior to the filling step of evacuating said sealed envelope (8).