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
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
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
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
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
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
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
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
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
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
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
The ventilation apparatus described is advantageously lightweight
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
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.