[0001] The present invention relates to a rotating drive apparatus, i.e. a device able to
impart rotation to doors, gates and similar elements.
[0002] Various types of rotating drive apparatuses are known. A traditionally known type
is one that uses an external telescopic arm that extends between a support and the
element to be rotated. This type of device is bulky and potentially dangerous and
can't therefore be used in many applications such as for instance in vehicles. To
resolve this problem, pneumatic or hydraulic rotating drive apparatuses have been
proposed comprising a stator and a coaxial rotor, in which an internal piston moves
a lug in one or more slots to rotate the rotor. Examples of these embodiments are
described in US-A-4838102; DE-A-2538529 and in EP-A-0823528 (in the name of the present
applicant).
[0003] The known coaxial drive apparatuses referred to above are compact and have many advantages
compared to telescopic actuators, but they have the disadvantage of being relatively
complex to produce and of being distorted by bumps or accidental knocks -- something
which is, however, very frequent when used in applications for machines or industrial
plants.
[0004] The purpose of the present invention is to produce a coaxial drive apparatus that
is simple and economical to produce, of reduced dimensions and also able to withstand
heavy use.
[0005] Such purpose is achieved by the present invention, which relates to a rotating drive
apparatus of coaxial type, comprising tubular guide means defining a longitudinal
axis, a stator consisting of a pair of fixed elements located along said guide means
with a space between them and comprising surfaces inclined with respect to the said
axis of the guide means, a rotor constituted by a piston located on the guide means
between said fixed elements, said piston comprising means for engaging the inclined
surfaces of both said fixed elements in a sliding way, and a jacket cooperating with
said piston and said fixed elements to define at least one chamber for feeding a fluid.
[0006] Preferably, the angle α formed between the inclined surface and the longitudinal
axis of the guide means is between 30° and 60°.
[0007] According to another preferential embodiment, the piston, too, has inclined surfaces
that are complementary to the inclined surfaces of the fixed elements and match up
with them at least at the end of the rotary movement of the piston.
[0008] According to a further aspect the invention, the stator comprises the tubular guide
means and the piston rotates together with the external jacket.
[0009] The drive apparatus according to the invention has many advantages with respect to
the preceding technique. In the first place, it has much reduced dimensions with respect
to known coaxial drive mechanisms, so that it can be used in a far wider range of
applications. Furthermore, it is simpler and less expensive to produce. Finally, it
is stronger and also stands up well to heavy use such as in gates of freight elevators
and similar, where it is subject to frequent bumps.
[0010] The invention will now be described in more detail by way of example and not of limitation,
with reference to the enclosed drawings, where:
- Fig. 1 is a plan view of the longitudinal section of an embodiment according to the
invention;
- Fig. 2 is a side view in section of the embodiment of fig. 1;
- Fig. 3 is a side view of the device of figures 1 and 2, without jacket;
- Fig. 4 is a side view of the device of fig. 3 after the piston has rotated; and
- Fig. 5 is a view in longitudinal section of a further embodiment of the device according
to the invention.
[0011] With reference first of all to figs. 1 and 2, the rotating drive apparatus 1 according
to the present invention comprises tubular guide means 2, such as the shaft shown
in fig. 1 and 2, defining a longitudinal axis A-A,' a stator constituted by the pair
of base-plates or similar fixed elements 3 and 4 located spaced from each other along
the A-A' axis of guide shaft 2. In the embodiment of figures 1-4 the fixed elements
3 and 4 are arranged at the extremities of guide means 2. As can be seen, fixed elements
3 and 4 are equipped with respective surfaces 5 and 6 inclined with respect to the
axis of guide means 2 and there is a rotor between the surfaces 5 and 6 constituted
by a piston located on guide shaft 2 between the two fixed elements 3 and 4. The piston
7 consists of a hollow cylinder inside which shaft 2 passes and comprises means for
engaging in a sliding way the inclined surfaces 5 and 6 of both the fixed elements
3 and 4. The piston 7 can rotate along and around the guide means constituted by the
shaft 2.
[0012] Furthermore, there is a jacket 8 cooperating with piston 7 and with fixed elements
3 and 4 to define two chambers 9 and 10 fed by fluid from a pneumatic or, preferably,
hydraulic system. The hydraulic or pneumatic systems are of known type and are not
shown. The fluid is fed (alternatively) to the chambers 9 and 10 through two pipes
respectively 11 and 12 that cross the fixed base-plates 3 and 4 and part of the guide
shaft 2; gaskets 20 located on the piston 7 and on the shaft 2 guarantee the seal
between the two chambers 9 and 10.
[0013] The surfaces 5 and 6 of fixed elements 3 and 4 are inclined with respect to the longitudinal
axis A-A' of the shaft at an angle α, such as to impart a rotation to the piston when
this moves; in other words, the surfaces of the fixed elements are such as to transform
part of the axial push given to the piston in a transversal push and thus have the
piston to rotate. Preferably, the angle α is between 20° and 75° and more preferably
between 30° and 60°; in fig.2 the angle is shown with reference to the external surface
of the jacket 8 (parallel to the A-A' axis) for better clarity and simplicity of the
drawing.
[0014] The means present on the piston for engaging surfaces 5 and 6 of base-plates 3 and
4 in a sliding way could be of various types, provided that they carry out the function
of following said surfaces and of forcing the piston-rotor to rotate when it moves
following the admission of the fluid into one of the two chambers. For instance, such
means could be constituted by one or more fingers extending from the piston and engaging
with the corresponding base-plates.
[0015] Preferably, as shown in the figures, the means for engaging the inclined surfaces
5 and 6 of fixed elements 3 and 4 in a sliding way consist of inclined surfaces 13
and 14 of the piston 7, that is complementary to inclined surface 5 and 6, respectively,
of fixed elements 3 and 4. Since surfaces 13 and 14 are of complementary form to those
of the surface 5 and 6 of the base-plates, at the end of the movement of rotation
of piston the surfaces 13 and 14 match up with the surfaces 5 and 6 and, in this way,
supply high resistance to any knocks. According to this embodiment, as shown in the
figures, one of the surfaces of the piston matches with the corresponding surface
of the base-plate only at the end of the piston run, i.e. when the piston has rotated
completely. During the rotation, there is no significant matching. If better resistance
to knocks during rotation of the piston is desired, the surfaces of piston and base-plates
can be so shaped that they are constantly at least partially matched up.
[0016] In the embodiment of figs. 1-4 the guide means, i.e. the shaft 2, isa integral with
fixed elements 3 and 4 that constitute the stator of the device. The piston 7, i.e.
the rotor of the device, engages with jacket 8 and rotates with it; jacket 8 is in
its turn locked to the element to be rotated (not shown) in a known way. A slot and
key system is preferably used to lock piston 7 to jacket 8; the piston 7 has a pair
of slots 15 that engage in a sliding way with a corresponding pair of keys 16 that
engage in their turn slots 17 cut into the jacket 8. The length of slot 15 is equal
to the stroke of the piston plus the length of the key; bigger keys require longer
slots but give better structural strength.
[0017] As an alternative to embodiment described above, the jacket 8 could be fixed and
locked to elements 3 and 4 and constitute the stator of the device (fig. 5), while
the shaft 2 could rotate.
[0018] In such an embodiment, the guide shaft 2 is engaged through at least one key 18 and
slot 19, with the piston 7 and it can rotate with it and with the door, gate or other
element to be rotated to which the guide shaft is fixed. Preferably, there will be
one or two slots on guide means 2 whose length is determined in the way described
above for the embodiment of figs. 1-4.
[0019] As above mentioned, the stator comprises two fixed elements, or base-plates, 3 and
4 located to the sides of the piston 7 and comprising inclined surfaces 5 and 6 that
are engaged in a sliding way with the piston 7 so as to cause its rotation when the
piston is moved. In the preferential embodiments of figs. 1-5 surfaces 5 and 6 of
the fixed elements are equal and are arranged as mirror images with respect to a median
plane transversal to the device; in this disposition the means for engaging the inclined
surface in a sliding way are rotated with respect to each other by an angle that corresponds
to the angle through which it is desired to rotate the element (door, gate or other).
That is clearly visible in fig. 3, where it can be seen that vertices 21 and 22 of
inclined surfaces 14 and 13 are rotated through an angle of around 90° with respect
to each other. Alternatively, the vertices of surfaces 5 and 6 can be rotated through
the required angle and the piston presents surfaces or means of engagement that are
mirror images of each other (zero angle).
[0020] The device according to the invention could furthermore be provided with means of
retention to maintain the fluid in the chamber (9 or 10) into which it has been introduced
and in this way prevent the door or gate fixed to the device being rotated manually.
Means of retention of this type are known in the art of hydraulic circuits and are
available commercially; such means are not an object of the present invention and
are not illustrated in the enclosed drawings. In some applications the means of retention
are not necessary; particularly, in applications such as elevators the means of retention
are missing and the door (when at the floor) can be rotated manually and therefore
opened also in case of failure of electric power.
[0021] In operation, oil is introduced for instance through the channel 12 in the chamber
10, forcing the piston toward the left side of fig. 2. The piston is initially in
the position shown in fig. 1, 2 and 3. The piston engages surface 6 of fixed element
4 with the vertex 21 of its own surface 14 and the linear movement is thus transformed
partially into rotation of piston 7 around guide 2, according to arrow
F of fig. 3; the movement finishes when the surface 14 comes to rest completely on
surface 6, in the position shown in fig. 4. To return to the position of figs. 2 and
3 oil is fed to chamber 9 through the channel 11 and the piston rotates accordingly
in the reverse direction to that of the preceding rotation, coming to rest on fixed
element 3.
1. A coaxial rotating drive apparatus, characterized by comprising tubular guide means (2) defining a longitudinal axis (A-A'), a stator
comprising a pair of fixed elements (3,4) located with a space between them along
said guide means (2) and comprising surfaces (5, 6) inclined with respect to said
axis of the guide means, a rotor comprising a piston (7) located on said guide means
(2) between said fixed elements (3, 4), said piston comprising means for engaging
the inclined surfaces (5, 6) of both said fixed elements (3, 4) in a sliding way,
and a jacket (8) cooperating with said piston (7) and with said fixed elements (3,
4) to define at least one chamber (9, 10) for feeding of a fluid.
2. A drive apparatus according to Claim 1, characterized by the angle α formed between said inclined surface (5, 6) and said longitudinal axis
(A-A') of the guide means (2) being within the range of 20° to 75° and preferably
30° to 60°.
3. A drive pparatus according to Claim 2, characterized by said guide means (2) being secured to said fixed elements (3, 4) and said piston
(7) being engaged with said jacket (8) and able to rotate with it.
4. A drive apparatus according to Claim 2, characterized by said jacket (8) being secured said fixed elements (3, 4) and said guide means (2)
being engaged with said piston (7) and rotating with it.
5. A drive apparatus according to any of the preceding Claims, characterized by there being two chambers (9, 10) provided on opposite sides of said piston (7).
6. A drive apparatus according to any of the preceding Claims, characterized by said means for engaging the inclined surfaces (5,6) of both said fixed elements (2,
3) in a sliding way being constituted by inclined surfaces (13, 14) of the piston
(7), that are complementary to said inclined surfaces (5, 6) of said fixed elements
(3, 4) and matching up with them at least at the end of the rotational movement of
the piston.
7. A drive apparatus according to any of the preceding Claims, characterized by said fixed elements (3, 4) being arranged as mirror images of each other.
8. A drive apparatus according to Claim 7, characterized by said means for engaging said inclined surfaces in a sliding way being arranged rotated
with respect to each other.
9. A drive apparatus according to an any of the preceding Claims characterized by said piston (7) being engaged with said jacket (8) or with said guide means (2) through
a key (16) sliding in a slot (17).