EP1460273A1

EP1460273A1 - Ventilation apparatus

Info

Publication number: EP1460273A1
Application number: EP03425164A
Authority: EP
Inventors: Mario Chiaravalli; Stefano Regehellin
Original assignee: Rc Trasmissioni Srl
Current assignee: Rc Trasmissioni Srl
Priority date: 2003-03-17
Filing date: 2003-03-17
Publication date: 2004-09-22

Abstract

A ventilation apparatus (4) possesses a shaft (8) connected to a motor (7) and to a fan (6) in such a way as to rotate in a predetermined direction of rotation (S) in order to generate a fluid flow. The apparatus (4) also possesses an engagement and disengagement device (26) that allows the shaft to turn freely in the predetermined direction of rotation (S) and prevents contrarotation of the shaft in the opposite direction to the predetermined direction of rotation (S). The apparatus is lightweight and compact. Furthermore, the apparatus engages and disengages itself completely automatically, with no external intervention to activate or deactivate it.

Description

The present invention relates to a ventilation apparatus, that is to say an apparatus comprising ventilation means capable of generating a fluid flow when activated by suitable drive means, such as electric or hydraulic motors and the like.
In ventilation apparatuses it is known practice to use, for the drive means, electric motors that transmit the rotary motion to the ventilation means by, for example, belt, chain, gear and other such drives.
The ventilation means are usually turned in a predetermined direction of rotation in order to give rise to a desired fluid flow.
When not activated, the ventilation means must not turn in the opposite direction of rotation to predetermined direction of rotation.
This phenomenon can occur for various reasons, for example when the ventilation means are exposed, while off, to air currents which can cause them to rotate.
If, when the ventilation system is turned on, that is when the drive means are started in order to turn the ventilation means in the predetermined direction, the means are turning in the opposite direction, serious problems can occur.
For example, the gears of the drive carrying the motion from the drive means to the ventilation means may be damaged or broken, or the drive means may deliver insufficient starting torque to overcome the contrary rotation of the ventilation means to stop them and get them turning in the predetermined direction.
The prior art includes versions of braking systems that, by acting mechanically on the parts of the kinematic chain, such as gears or drive shafts, lock the ventilation means in a fixed position when they are not to be operated, to ensure that they cannot turn.
These braking systems are however bulky and, most seriously, have to be engaged or disengaged as required by some appropriate action. For this purpose, control systems are provided to activate them when the ventilation means are not to be activated, and deactivate them when the ventilation means are to be actuated.
Also, in the case of ventilation apparatuses comprising more than one fan, the prior art includes electronically controlled systems which continuously monitor the unused drive shafts and, if these shafts are turned in the contrary direction, they activate the drive means of these shafts either to stop them by the starting torque or to limit the speed of contrary rotation of the shafts to a low enough value so that the starting torque of the motors is enough to start them when necessary.
These control systems are very expensive and among other things require the consumption of electrical power to continuously actuate the motors of the fans.
An example an embodiment of such a control system is disclosed in US patent 3,789,284.
The problem addressed by the present invention is the provision of a ventilation apparatus that solves the disadvantages discussed with reference to the prior art.
These disadvantages and limitations are solved efficaciously by a ventilation apparatus in accordance with Claim 1.
Other embodiments of the ventilation apparatus according to the invention are disclosed in the succeeding claims.
Set out below is a preferred and non-restrictive example of an embodiment of the invention, illustrated in the appended drawings, in which:
Figure 1 is a longitudinal sectional view of a ventilation apparatus in one embodiment of the invention;
Figure 2 is a perspective view in separate parts of the ventilation apparatus of Figure 1;
Figure 3 is a view in partial section of the ventilation apparatus of Figure 1 seen in the direction of the arrow marked III in Figure 1;
Figure 4 is an enlarged detail of the apparatus of Figure 1; and
Figure 5 is an enlarged detail of the apparatus of Figure 1.
Parts or portions of parts common to the various embodiments described below will be denoted by the same reference numbers.
To avoid confusion, note that the expression "axial direction" is used here to mean a direction along which the ventilation apparatus predominantly extends, and a direction parallel to the axis of rotation of the shaft of the ventilation apparatus.
The expression "radial direction" is used to mean a direction perpendicular to the said axial direction and passing through the axis of rotation of the shaft of the ventilation apparatus.
The expression "tangential direction" is used here to mean a direction perpendicular to the axial direction and to the radial direction.
With reference to the abovementioned figures, the number 4 is a general reference to a ventilation apparatus designed to generate a fluid flow by the operation of ventilation means 6 such as fans, for example.
The ventilation apparatus 4 comprises a shaft 8 that extends in a predominant direction X and that is advantageously in the form of a circular-section cylinder.
The shaft 8 is designed to be connected to drive means 7, preferably electric motors, by direct connection or via belt, gear or other such drives. The shaft 8 is also designed to be connected to ventilation means 6 such as fans, to generate a fluid flow.
The shaft 8 is at least partly housed in a fixed housing or stator 12 that extends advantageously along the predominant direction X, surrounding and containing at least a portion of the shaft 8.
In an axial direction and at opposite ends in this direction, the housing 12 comprises a first and second end 13', 13''.
The shaft 8 is able to rotate inside the fixed housing 12. In other words it can rotate relative to the fixed housing 12.
In one embodiment, illustrated for example in Figure 1, the shaft 8 passes all the way through the housing 12 in the predominant direction X so as to project from it with a first shaft portion 14 and with a second shaft portion 16, these extending in opposite directions relative to the housing 12, along the predominant direction X.
At the first shaft portion 14, the shaft is preferably connected to the drive means 7, and at the second shaft portion 16 it is preferably connected to the ventilation means 6.
Inside the housing 12 are means of rotational support 18, such as rolling bearings, for the shaft 8. These give rotational support to the shaft 8 in the fixed housing 12, allowing the shaft 8 to rotate about the axis X.
Means of rotational support 18 comprise first support means 20, around the first shaft portion 14, and second support means 22 around the second shaft portion 16.
The fixed housing 12 advantageously comprises, around the first shaft portion 14, means of engagement and disengagement 26 which act between the shaft 8 and the fixed housing 12.
The means of engagement and disengagement 26 comprise an inner ring 30 coaxial with the shaft 8 and connected rigidly to it so as to rotate with it, for example by a pin 32.
The engagement and disengagement means 26 also comprise an outer ring 34 coaxial with the shaft 8 and with the inner ring 30.
The outer ring 34 is preferably mounted rigidly to the fixed housing 12, for example, as illustrated in Figure 1, at the first end 13' of the fixed housing 12.
Advantageously, as Figure 3 shows, the outer ring 34 and the inner ring 30 define a gap 38 essentially coaxial with the shaft 8. In other words the outside diameter De of the inner ring 30 is less than the inside diameter Di of the outer ring 34.
The inner ring 30 advantageously includes at least one seat 42, the seat or seats 42 being next to the gap 38 and to the outer ring 34.
The seat 42 is essentially bounded by a bearing surface 44 and a thrust surface 46. The bearing surface 44 is essentially tangential and the thrust surface 46 is essentially radial, that is essentially perpendicular to the bearing surface 44.
Advantageously, having defined a predetermined direction of rotation S, the thrust surface 46 is positioned so as to precede the bearing surface 44.
Preferably, as illustrated in Figure 3, the inner ring 30 comprises a plurality of seats 42 arranged circumferentially and preferably equidistant.
Each seat 42 is designed to contain one arrester body 50 capable of causing a condition of engagement between the inner ring 30 and the outer ring 34.
The arrester body 50 is advantageously axisymmetric with reference to at least one axis of symmetry Z, having at least one cylindrical form. The arrester body 50 is preferably housed in the seat 42 in such a way that the axis of symmetry Z is essentially parallel to the predominant direction X.
The seat 42 houses thrust means 52 interposed between the thrust surface 46 and the arrester body 50, the thrust means 52 tending to push the arrester body 50 away from the seat 42 and in particular from the thrust surface 46, in an essentially tangential direction parallel to the bearing surface 44. The thrust means 52 may for example comprise one or more helical springs.
The inner ring 30 preferably comprises a recess 54 running from the thrust surface 46 tangentially away from the bearing surface 44. The recess 54 preferably forms a blind cylindrical hole pointing away from the bearing surface 44. The recess 54 is capable of housing a thrust member 56 of e.g. essentially cylindrical shape, and the thrust means 52.
The thrust member 56 is inserted between the arrester body 50 and the thrust means 52 and acts with the thrust means 52 to exert a thrust action on the arrester body 50.
In an advantageous embodiment, shown for example in Figure 4, the outer ring 34 serves the function of a cover closing an axial end of the fixed housing 12, such as the first axial end 13', a body 60 of the outer ring 34 being attached rigidly to the axial end of the fixed housing 12. The radial dimension of the body 60 preferably does not exceed the radial dimension of the axial end 13', 13" of the housing 12 to which the said body 60 is fixed and, with particular advantage, the body 60 is axially connected to one end of the housing 12 without exceeding the radial dimensions of the said housing.
The shaping of the body 60 is advantageously such as to assist the fluid dynamics of the fluid propelled axially by the ventilation means 6; in other words the axial profile of the body 60 of the outer ring 34 is configured in such a way as to promote an undisturbed flow of the fluid generated by the ventilation means in the axial direction.
The body 60 comprises an inner annular surface 61 that fits axially against the end of the housing, inside it.
The body 60 also includes an outer edge 60' designed to abut, when assembled, against a corresponding lateral edge 60" of the axial end of the housing 12.
The body 60 comprises an essentially cylindrical space 62 extending axially away from the said housing end. The space 62 is designed to coaxially house the inner ring 30. The said space 62 comprises an end face 63 that forms an axial stop for the inner ring 30. The axial length of the said space 62 is preferably equal to the axial thickness of the inner ring 30 in order that, when the inner ring 30 is assembled in the space 62 of the body 60, a surface of the said inner ring 30 and the inner annular surface 61 are axially level, that is, they form an axial bearing plane 63' that forms an essentially circular annulus coaxial with the shaft 8.
The body 60 advantageously has a preferably circumferential ridge 64 extending axially from the inner annular surface 61 and in the opposite direction to the said space 62.
The ridge 64 acts as a means of locating and centring the body 60 on the axial end of the housing. In another embodiment the said ridge is designed to engage with the means of rotational support 18 of the shaft 8, in that it forms for example a means of axial locking for the first means of rotational support 20 positioned at the first axial end 13'.
The housing 12 advantageously comprises a shoulder 76 which extends radially into the housing to form an axial end-of-travel to the first support means 20.
The shoulder 76 is preferably positioned axially in such a way that, when the first support means 20 are assembled in abutment against the shoulder and the body 60 against the lateral edge 60" of the housing 12, the said ridge 64 is positioned against the first support means 20.
The ridge 64 and the shoulder 76 therefore act as bilateral axial constraints on the said first support means 20. In another embodiment of the shaft 8, in the same axial position as the said shoulder 76, it comprises a circumferential edge 80 that functions as another stop means for the first support means 20.
The engagement and disengagement means 26 advantageously comprise a closing ring 84 connected rigidly to the body 60. In particular the closing ring 84 is constrained radially by the ridge 64; in other words the outer side diameter of the closing ring 84 is less than the inside diameter of the ridge 64, so that the closing ring 84 can be inserted into the volume defined inside the ridge 64.
Also, the closing ring 84 has an axial thickness less than the axial thickness of the ridge 64.
Advantageously, the closing ring 84 is in abutment against the bearing plane 63' in such a way as to be in abutment against both the inner ring 30 and against the inner annular surface 61. The closing ring 84 is also rigidly fixed, for example by threaded connection means, to the inner annular surface 61 of the body 60.
In other words the inner ring 30, in an axial direction, is constrained on both sides, by the end face 63 and by the closing ring 84. In other words the closing ring 84 tightly closes the inner ring 30 against the end face 63.
At its first end 13' the housing 12 is preferably at least partly filled with a lubricating substance such as oil or grease.
The lubricating substance therefore influences the engagement and disengagement means 26, a portion of the shaft 8 and the means of rotational support 18 of the shaft 8.
The ventilation apparatus 4 also has means for sealing the said lubricating substance in, such as seals 86 interposed in the zone of contact between the said outer edge 60' and the said lateral edge 60" and sliding-contact seals 88 between the shaft and body 60.
As can be seen, the means of engagement and disengagement 26 act on the shaft 8 and on the housing 12 in such a way that, in the engaged position, the shaft 8 and the housing 12 are connected rigidly to each other to immobilize the shaft 8 and prevent it contrarotating in the opposite direction to the predetermined direction of rotation S, while in the disengaged position the shaft 8 and the housing 12 are disconnected from each other to allow the shaft 8 to turn freely in the predetermined direction of rotation S.
What happens is that if the shaft is turned in the opposite direction to the predetermined direction of rotation S, the thrust surface 46, which is designed to act as a seat for the arrester body 50, rolls the arrester body 50 forwards, jamming it between the inner ring 30 and the outer ring 34 and preventing the shaft 8 turning. On the other hand if the shaft 8 is turned in the predetermined direction of rotation S, the thrust surface 46 does not roll the arrester body 50 forwards as it is moving ahead of the arrester body 50 during the rotation. The shaft 8 is therefore free to turn in the predetermined direction of rotation S but cannot turn in the opposite direction.
In other words the engagement and disengagement means 26 described here connect together the shaft 8 and the housing 12 in such a way as to release them when the forces applied to the shaft 8 produce a rotation of the shaft 8 in the predetermined direction of rotation S, and to lock them, so that the shaft 8 cannot move, when the forces applied to the shaft 8 tend to produce a contrarotation of the said shaft. Shaft 8 locking is the result of the wedging of the arrestor bodies 50 between the inner ring 30 and the outer ring 34, the wedging holding together the inner ring 30 (rigidly connected to the shaft 8) and the outer ring 34 (rigidly connected to the housing 12).
It will be realized from the above description that the ventilation apparatus according to the invention overcomes the drawbacks found in prior-art ventilation apparatuses.
The ventilation apparatus described is advantageously lightweight and compact.
It sits at one end of the apparatus, near a lateral cover, preferably in the vicinity of a shaft guide bearing, without increasing the radial dimensions.
Moreover, the presence of the proposed engagement and disengagement device does not prejudice the fluid dynamics of the flow generated by the ventilation means, particularly when the engagement and disengagement means are integrated into the body of the outer ring, which has a smaller radius than the housing. Advantageously the axial profile of the body of the outer ring is shaped in such a way as to limit the turbulence of the flow and optimize the fluid-dynamic efficiency of the ventilation means, in other words the body is aerodynamically shaped.
Another advantage of the device here proposed is the fact that the device described here can also be fitted to pre-existing ventilation systems: in a pre-existing system it is possible to replace the axial cover closing one end of the shaft housing with a cover comprising engagement and disengagement means according to the invention. An appropriate axial profile of the cover may also be selected in order to enhance the fluid dynamics of the pre-existing system.
During normal operation of the shaft in the predetermined direction of rotation, the system in practice exerts no torque against its rotation, partly owing to the fact that the opposing means are in an oil bath or at any rate immersed in a lubricant, preferably the same as the lubricant of the bearings.
The apparatus disclosed here furthermore engages and disengages itself completely automatically, that is with no external intervention to activate or deactivate it.
The apparatus disclosed here furthermore requires no control apparatus, of for example electrical or mechanical type, to engage or disengage the anti-rotation device of the ventilation means.
To fulfil any specific requirements which may arise, numerous modifications and alterations may be made to the apparatuses described above by those skilled in the art. For example the seats in which the arrestor bodies are housed may be formed in the outer ring, positioning the thrust surface to suit the predetermined direction of rotation as described.
This and other possible modifications all come within the scope of the invention as defined in the following claims.

Claims

Ventilation apparatus (4) comprising a shaft (8) connected to ventilation means (6), the said shaft (8) being at least partly housed in a fixed housing (12) and capable of being connected to drive means (7) for rotating the shaft (8) in a predetermined direction of rotation (S), the said apparatus (4) being characterized in that it also comprises means of engagement and disengagement (26) which act on the said shaft (8) and the said housing (12), such that in the position of engagement the said shaft (8) and the said fixed housing (12) are connected rigidly together to lock the shaft (8) in terms of rotation and prevent contrarotation of the shaft (8) in the opposite direction to the predetermined direction of rotation (S), while in the disengaged position the said shaft (8) and the said housing (12) are disconnected from each other to let the shaft (8) turn freely in the predetermined direction of rotation (S).
Ventilation apparatus (4) according to Claim 1, in which the said means of engagement and disengagement (26) comprise at least one inner ring (30) rigidly connected to the said shaft (8) and at least one outer ring (34) rigidly connected to the said fixed housing (12), the said inner and outer rings (30, 34) engaging together, when in the engaged position, to prevent contrarotation of the shaft, and disconnecting from each other, when in the disengaged position, to allow the shaft to rotate in the predetermined direction of rotation (S).
Ventilation apparatus (4) according to Claim 2, in which the said outer ring (34) and the said inner ring (30) are coaxial with the said shaft (8) and define a gap (38) that is essentially coaxial with the said shaft (8).
Ventilation apparatus (4) according to Claim 3, in which the said inner ring (30) comprises at least one seat (42), adjacent to the said gap (38) and to the said outer ring (34), and at least one arrester body (50) housed in the said seat (42) and capable of becoming wedged between the inner ring and the outer ring to prevent the shaft (8) turning in the opposite direction to the predetermined direction of rotation (S).
Ventilation apparatus (4) according to Claim 4, in which the said arrester body (50) is axisymmetric with respect to an axis of symmetry Z and is housed in the said seat (42) in such a way that the said axis of symmetry Z is essentially parallel to the said shaft (8).
Ventilation apparatus (4) according to Claim 4 or 5, in which the said seat (42) comprises a thrust surface (46) against which the said arrester body or bodies (50) can sit in such a way that, when the shaft (8) turns in the predetermined direction of rotation (S), the said thrust surface (46) pushes the said arrester body (50) around, whereas when the shaft (8) is turned in the opposite direction to the predetermined direction of rotation (S), the said thrust surface (46) is free to rotate with respect to the said arrester body (50).
Ventilation apparatus (4) according to Claim 6, in which the said seat (42) houses thrust means (52) interposed between the said thrust surface (46) and the said arrester body (50), and capable of pushing the said arrester body (50) away from the said seat (42).
Ventilation apparatus (4) according to Claim 7, in which the said thrust means (52) comprise at least one helical spring.
Ventilation apparatus (4) according to any one of the preceding claims, in which the said fixed housing (12) comprises means of rotational support (18) for the said shaft (8).
Ventilation apparatus (4) according to any one of the preceding claims, in which the said shaft (8) comprises a first shaft portion (14) and a second shaft portion (16), these extending from opposite ends of the fixed housing (12) in such a way that the said first shaft portion (14) of the shaft (8) is connected to the said drive means (7), and the second shaft portion (16) of the shaft (8) is connected to the said ventilation means (6).
Ventilation apparatus (4) according to Claim 9 or 10, in which the said means (18) of support for the rotation of the shaft (8) are positioned at at least one axial end (13', 13") of the said fixed housing (12).
Ventilation apparatus (4) according to any one of the preceding claims, in which the said outer ring (34) acts as a cover closing one axial end (13') of the fixed housing (12), with a body (60) of the said outer ring (34) being fixed rigidly to the said fixed housing (12).
Ventilation apparatus according to Claim 12, in which the radial dimension of the said body (60) is contained within the radial dimension of the fixed housing (12).
Ventilation apparatus according to Claim 12 or 13, in which the axial profile of the said body (60) is such as to promote the axial flow generated by the ventilation means (6).
Ventilation apparatus (4) according to any one of Claims 12 to 14, in which in a configuration in which the said body (60) is mounted on the said fixed housing (12), the said body (60) comprises a ridge (64) suitable for axial engagement with the said means (18) of support for the rotation of the shaft (8).
Ventilation apparatus (4) according to Claim 15, in which the said ridge (64) restrains, in the direction of the axis of rotation (X) of the said shaft (8), the said means (18) of support for the rotation of the shaft (8) against a shoulder (76) on the said housing (12).
Ventilation apparatus (4) according to any one of Claims 12 to 16, in which the said means of engagement and disengagement (26) comprise a closing ring (84) coaxial with the said body (60) and connected rigidly to the said body (60) in such a way as to connect the said inner ring (30) axially to the said body (60).
Ventilation apparatus (4) according to Claim 17, in which the said closing ring (84) is restrained radially by the said body (60).