WO2015193128A1

WO2015193128A1 - Retraction mechanism

Info

Publication number: WO2015193128A1
Application number: PCT/EP2015/062620
Authority: WO
Inventors: Angelo Michele CECCHI; Tim LIE; Martin Geelen; Pedro ROS-ZUAZUA; Mikel AGRELA GONZALES; Job GREEFHORST
Original assignee: Eaton Industries (Netherlands) B.V.
Priority date: 2014-06-16
Filing date: 2015-06-05
Publication date: 2015-12-23
Also published as: GB201410726D0

Abstract

The invention relates to a retraction mechanism (7) for extending and retracting an electrical contact (9) to a connected and a disconnected position, characterized by comprising - a drive shaft (20) with an external thread arranged to rotably drive the retraction mechanism; - a threaded collar (1008) with an internal thread arranged to engage with the outer thread of the drive shaft, the threaded collar being arranged to be moved along the drive shaft by rotation of the drive shaft; and - indicator means (2000,2001,2002,2003,2004,2005) to indicate the location of the collar.

Description

Retraction mechanism

The invention relates to a retraction mechanism for extending and retracting an electrical contact to a connected and a disconnected position.

US20100157512A1 discloses a subunit for connecting supply power to motor control components with moveable electrical contacts. The subunit is comprised in a frame. After the frame is secured into a compartment, the electrical contacts may be advanced to engage supply power buses. For disconnection, the electrical contacts may be retracted and isolated from the buses before the subunit itself is removed from the compartment. The electrical contacts are moved by a linear actuator and a stab assembly mounted on a drive shaft.

The subunit also comprises a set of control power contacts. In one case the position of set of control power contacts is fixed relative to the frame. In another case, they may be moveable in a similar manner to the electrical contacts.

Movement of the electrical contacts triggers an automatic latch such that the frame engages with the compartment. After triggering the automatic latch, the electrical contacts are extended further to finally engage with supply power conductors. When retracting, the electrical contacts are first retracted partly. The automatic latch will release from engagement again when the electrical contacts are retracted further. Only after the automatic latch disengages, the frame may be removed from the compartment.

A shutter or isolator assembly is disposed between the stab assembly and the exterior of the frame. The shutters of the shutter assembly either isolate or expose the electrical contacts form/to the supply power buses. A shutter arm is used to control a shutter indication mechanism that displays via a front panel indicator whether the shutters are open or closed.

A front panel is secured against a periphery of the compartment. The frame includes a number of latching mechanisms on the front panel to lock the frame into place when installed. A door with hinges allows access to components in the subunit when installed in the compartment.

US 5,337,210 discloses a drawout type switch gear, more particularly a drawout type circuit gear composed of a base frame and a circuit breaker movably mounted on the base frame.

DE10216594A1 discloses a drawer with a frame provided with a hooked part of a locking mechanism for securing the frame in a reception compartment in a switchgear cabinet. The locking mechanism is operated by 2 operating elements provided on a front panel of the drawer. One of the operating elements also indirectly drives a shutter rod for activating a shutter mechanism of the switchgear cabinet. The shutter rod is driven via a drive shaft between the operating element and the shutter rod. Each operating element drives a hooked part of the locking mechanism. In locked state, the hooked part engages with a lower horizontal rim of an opening in the switchgear cabinet. A first set of contacts (on the back side of the drawer) and a second set of contacts (on the side of the drawer) are each retractable between a connected position and a disconnected position. This is achieved by a retraction mechanism. The retraction mechanism is operated via a cylinder consisting of a first part and a second part at the front of the drawer. The rotation of the second part of the cylinder is transmitted via teeth to rods of a second part of the retraction mechanism to the second set of contacts. The rotation of the first part of the cylinder is transmitted via teeth to rods of a first part of the retraction mechanism to the first set of contacts.

The second part of the cylinder is operated by a short key. The first part of the cylinder is operated by a long key. When the first part of the cylinder is rotated, the second part is rotated as well.

The locking mechanism prevents access to the cylinder when the frame is not locked into the reception compartment. The long key and the short key must each be inserted against a spring force to prevent accidental operation of the first part of the cylinder and the second part of the cylinder.

The second part of the retraction mechanism locks the locking mechanism in the locked status when the second set of contacts is extended with a protrusion that extends and retracts together with the second set of contacts and engages with an opening in the mechanism that drives the hooked part.

The drawer also comprises a switch for switching on and off electronic components in the drawer. A further locking system locks the retraction mechanism when the electronic

components are on line.

The rods of the first part and require relatively large amount of space to move in. The rods of the second part include a pivoting arm and also require a relatively large amount of space to move in and a relatively large amount of parts.

In addition, two different keys are needed to be able to distinguish between tree states of the retraction mechanism. The three states are:

1 both the first set of contacts (12) and the second set of contacts (14) are retracted

2 the second set of contacts (14) is extended but the first set of contacts is retracted

3 both the first set of contacts (12) and the second set of contacts (14) are retracted. A user may by mistake use the wrong key and extend both the first set of contacts and the second set of contacts instead of only extending the second set of contacts. Moreover, by using the long key when both the first set of contacts and the second set of contacts are extended to retract the first set of contacts, the second set of contacts is retracted as well. This option is considered to be less safe and undesirable. Preferably the states can only change from first to second and from second to third and vice versa. Changes between the first state and the third state in either way are undesired.

It is an object of the invetion to provide an alternative retraction mechanism of which the state can be indicated.

According to a first embodiment of the invention, there is provided a retraction mechanism for extending and retracting an electrical contact to a connected and a disconnected position, characterized by the retraction mechanism comprising

- a drive shaft with an external thread arranged to ratably drive the retraction mechanism; - a threaded collar with an internal thread arranged to engage with the outer thread of the drive shaft, the threaded collar being arranged to be moved along the drive shaft by rotation of the drive shaft; and

- indicator means to indicate the location of the collar.

Driving the drive shaft ratably causes the collar to move along the drive shaft and drives the retracton mechanism. A collar with internal thread is easy to produce and requires little space to move. As both the collar is moved by rotation of the drive shaft and the retraction mechanism is driven by roation of the drive shaft, the orientation of the drive shaft couples the position of the collar to the status of the retraction mechanism. By using the position of the collar, the status of the retraction mechanism can be indicated.

According to a second embodiment of the invention there is provided a retraction mechanism according to the first embodiment, wherein the drive shaft is supported by a frame in a fixed position relative to the frame and wherein the location of the threaded collar relative to the frame is used for indicating the retraction status of the retraction mechanism.

Since the position of the drive shaft is fixed relative to the frame, the collar moves relative to the frame when the drive shaft rotates. Therefore the position of the collar relative to the frame can be used to indicate the state of the retraction mechanism.

This is advantageous as the drive shaft may be partly hidden by the frame and therefore not visible to a user. This for example may be the case when the drive shaft runs from a front side of the frame where a user may operate the retraction mechanism, to a back side of the frame.

According to a third embodiment of the invention there is provided a retraction mechanism according to the second embodiment, wherein the indicator means comprise a pivotable arm and coupling means to couple the location of the threaded collar to a pivoting orientation of the pivotable arm.

By using a pivotable arm, a movement of the collar can be scaled. For instance, the movement of the collar is magnified when the movement of the collar is coupled to the pivotable arm at a shorter distance than the distance of the part of the pivotable arm used to indicate the position. The movement of the collar is minified when the movement of the collar is coupled to the pivotable arm at a larger distance than the distance of the part of the pivotable arm used to indicate the position.

According to a fourth embodiment of the invention there is provided a retraction mechanism according to the third embodiment wherein the indicator means comprise a cable and wherein a first end of the cable is attached to the threaded collar and a second end of the cable is attached to an anchor having a fixed position relative to the frame, the cable arranged to make a loop around a pulley mounted on the pivotable arm. The advantage of using a cable is that the pivotable arm does not need to be at the collar. The position of the pivotable arm can be optimized for indicating the status of the retraction mechanism, while the space in which the collar moves can be optimized for another function, such as being directed away from a user accessible side of the retraction mechanism providing a safety distance between a user and supply conductors.

According to a fifth embodiment of the invention there is provided a retraction mechanism according to the fourth embodiment, wherein the cable forms the inner cable of a Bowden cable.

Because the cable forms the inner calbe of a Bowden cable, the cable can travel a distance and change direction without the need for pulleys or flexible joints. Therefore, the application is kept simple, with a mimimum of moving parts. Having less moving parts is advantageous for preventing malfunctions.

According to a sixth embodiment of the invention there is provided a retraction mechanism according to any of the previous embodiments, arranged to extend and retract a further electrical contact to a connected position and a disconnected position.

As the drive shaft is arranged to drive the retraction mechanism, it also drives the extension and retraction of the further electrical contact. The position of the collar therefore not only indicates the retraction state of the electrical contact, but also of the further electrical contact. Therein, the electrical contact and the further electrical contact do not have to be in the same state (i.e. both in retracted state or both in extended state) but may be in different states. Thus a simple, cheap and space efficient indication of the retraction state is obtained. According to a sixth embodiment of the invention there is provided a retraction mechanism according to the sixth embodiment, arranged to extend and retract the further electrical contact only when the electrical contact is in disconnected position and to extend the electrical contact only when the further electrical contact is in connected position.

This is advantageous as either the electrical contact is moved between a retracted and an extended position, i.e. a connected and a disconnected position, or the further electrical contact is moved between a retracted and an extended position, i.e. a connected or disconnected position. Therefore, in use either the electrical contact or the further electrical contact connects or disconnects from a circuit at any given moment.

Examples of embodiments the invention will now be described with reference to the

accompanying schematic drawings. Corresponding reference symbols in the schematic drawings indicate corresponding parts. The schematic drawings are not necessarily to scale and certain features may be exaggerated to better illustrate and explain the present invention. Further, the examples are not intended to be exhaustive or otherwise limit or restrict the invention to the precise configurations shown in the drawings and disclosed in the following detailed description.

Figure 1 cabinet of a low voltage distribution system comprising a drawer with a retraction mechanism according to the invention

Figure 2 drawer comprising a retraction mechanism according to the invention

Figure 3 schematic overview of the retraction mechanism, locked in the first state

Figure 4 schematic overview of the retraction mechanism, locked in the second state For the purpose of explaining the invention, use is made of an x-direction, a y-direction and a z- direction, which are all perpendicular and chosen in right-handed orientation. A corresponding Cartesian coordinate system is used as well.

In the following examples of the invention, the positive z-direction is a vertical upward direction, i.e. the negative z-direction is the direction of the force of gravity.

In an example of the invention, there is a housing comprising switchgear for a low voltage distribution system. The housing comprises a number of cabinets (1) placed side by side against each other (figure 1). Each cabinet has a front side (parallel to the x-direction) that is accessible for personnel.

The cabinets (1) each comprise a main bus bar compartment (2). The main bus bar

compartments of neighbouring cabinets are connected by openings (3). Four main bus bars (4) are housed in a main bus bar compartment. The four main bus bars run parallel to the x-direction and are connected to four distribution bus bars per cabinet. The four distribution bus bars are vertically placed (i.e. they run parallel to the z-direction) in an insulated bus bar chamber at the backside of the cabinets. Each of the four distribution bus bars is housed in a separate glass-fibre reinforced polyester bus bar duct running parallel to the z-direction. The four distribution bus bars are each connected to one of the horizontal main bus bars by connection bars.

The cabinets (1) comprise multiple switchgear and control gear compartments aligned to the left walls of the compartments. On the right side of the cabinets (1) is a cable connection

compartment (5).

One of the switchgear compartments is occupied by a drawer (6) framing a retraction mechanism (7) according to the invention (figure 2). In figure 2 parts of the retraction mechanism (7), such as a sliding door (1017) and a switch (2008) have been left out for clarity. The retraction mechanism comprises four contacts (9) fixedly mounted in a first contact housing (8). The four contacts (9) are isolated from each other by walls of glass-fibre reinforced polyester. The first contact housing (8) can be extended and retracted along the y-direction thereby extending and retracting the four contacts (9) to connect or disconnect the four contacts (9) with the four distribution bus bars. The connected state of a contact (9) corresponds to the extended state wherein the contact has a maximum value for the y-coordinate. The disconnected state corresponds to the retracted state wherein the contact (9) has a minimum value for the y- coordinate.

The retraction mechanism (7) also comprises a second contact housing (108) with four further electrical contacts (109) that are isolated from each other by walls of glass-fibre reinforced polyester. The second contact housing (108) can be extended and retracted along the y-direction to thereby extending and retracting the four further electrical contacts (109) to connect or disconnect the four further electrical contacts (109) with corresponding cables of an auxiliary circuit. The drawer (6) comprises a switch (2008) for switchably connecting each of the four contacts (9) to one of the four further electrical contacts (109) over internal cables. Internal here means that the cables run inside the drawer (6). The extension and retraction motion of the contacts (9) and the further electrical contacts (109) is driven by a threaded drive shaft (20). The threaded drive shaft is cylindrical and has an external thread with a helical shape. The threaded drive shaft (20) extends the y-direction from the front of the drawer (6) to the back of the drawer (6). A gear wheel is concentrically mounted on the threaded drive shaft (20). The gear wheel engages with a further gear wheel to transmit the rotational motion of the threaded drive shaft (20) to a rotational motion of a threaded transmission shaft running in x-direction. The further gear wheel is concentrically fixed to the threaded transmission shaft. The threaded transmission shaft is supported by two bearings in a support frame (14). The positions of the threaded transmission shaft and the two bearings are stationary, the orientation of the threaded transmission shaft changes in use by rotation around an axis in x-direction.

The support frame (14) supports a transport member (11). The first contact housing (8) is fixed to the transport member (11) by screws. The transport member (11) comprises a retraction slot (12) with a part parallel to the threaded transmission shaft and a part at an angle to the threaded transmission shaft. The transport member (11) is slidably arranged in the support frame (14) such that it may be moved in y-direction to extend or retract the four contacts (9). The edge of the retraction slot (12) in the transport member (11) engages with a retraction collar arranged around the threaded transmission shaft. The retraction collar comprises an internal thread that engages with the thread of the threaded transmission shaft. The retraction collar therefore moves along the threaded transmission shaft upon rotation of the threaded transmission shaft. When the retraction collar is in use in the part of the retraction slot (12) angled to the threaded transmission shaft, rotation of the threaded transmission shaft and therefore the movement of the retraction collar along the threaded transmission shaft moves the transport member (11), i.e. it either extends the transport member (11) or retracts the transport member (11). When the retraction collar is in the part of the retraction slot (12) parallel to the threaded transmission shaft, rotation of the threaded transmission shaft (and therefore the movement of the retraction collar along the threaded transmission shaft) does not move the transport member (11).

The support frame (14) also supports a further transport member (111). The second contact housing (108) is fixed to the further transport member (111) by screws. The mechanism for extending and retracting the further electrical contacts (109) is similar to that of the contacts (9). The further transport member (111) comprises a further retraction slot (112) with a part parallel to the threaded transmission shaft and a part at an angle to the threaded transmission shaft. The further transport member (111) is slidably arranged in the support frame (14) such that is may be moved in y-direction to extend or retract the four further electrical contacts (109). The edge of the further retraction slot (112) in the transport member (11) engages with a further retraction collar (113) arranged around the threaded transmission shaft. The further retraction collar (113) comprises an internal thread that engages with the thread of the threaded transmission shaft. The further retraction collar (113) therefore moves along the threaded transmission shaft upon rotation of the threaded transmission shaft. When the further retraction collar (113) is in use in the part of the retraction slot (112) angled to the threaded transmission shaft, rotation of the threaded transmission shaft and therefore the movement of the further retraction collar (113) along the threaded transmission shaft moves the further transport member (111), i.e. it either extends the further transport member (111) or retracts the further transport member (111). When the further retraction collar (113) is in the part of the further retraction slot (112) parallel to the threaded transmission shaft, rotation of the threaded transmission shaft and therefore the movement of the retraction collar along the threaded transmission shaft does not move the transport member (111).

The retraction slot (12), the further retraction slot (112), the retraction collar (13) and the further retraction collar (113) are arranged such that when the retraction collar is in the part of the retraction slot (12) parallel to the threaded transmission shaft, the further retraction collar (113) is in the part of the further retraction slot (112) at an angle to the threaded transmission shaft. In addition, when the retraction collar is in the part of the retraction slot (12) at an angle to the threaded transmission shaft, the further retraction collar (113) is in the part of the further retraction slot (112) parallel to the threaded transmission shaft. This arrangement ensures that upon rotation of the treaded transmission shaft either the four contacts (9) or the four further electrical contacts (109) are moved between extended and retracted positions.

Further, the retraction slot (12), the further retraction slot (112), the retraction collar (13) and the further retraction collar (113) are arranged such the transport member (11) and the further transport member (111) can simultaneously be in an retracted position, corresponding to a first state (figure 3) of the retraction mechanism (7) or can simultaneously be in an extended position corresponding to a third state of the retraction mechanism (7). In a second state (figure 4) the further transport member (111) is in an extended position, whereas the transport member (11) is in a retracted position. As the retraction collar (13) and the further retraction collar (113) move along the threaded transmission shaft linearly, the only possible transitions are from the first state to the second state, from the second state to the third state, from the third state to the second state and from the second state to the first state.

The drawer (6) forms a withdrawable frame for the retraction mechanism (7). The threaded drive shaft (20) is supported by a bearing on each end of the threaded drive shaft (20) (figures 3 and 4). A bearing close to the front side of the drawer (6) is supported by the drawer (6). The position of the threaded drive shaft (20) is stationary with respect to the drawer (6), the orientation of the threaded drive shaft (20) changes in use the orientation of the threaded drive shaft (20) changes in use when the threaded drive shaft (20) rotates around an axis parallel to the y-direction.. A threaded collar (1008) is arranged around the threaded drive shaft (20) between the front side of the drawer (6) and the support frame (14). The threaded collar (1008) has an internal thread engaging with the external thread of the threaded drive shaft (20). The threaded collar (1008) protrudes into a slot (1001) of a locking member (1000). The locking member (1000) is a sheet of metal fixed onto an arm of a pivotably arranged locking element (1009). The locking element (1009) is arranged to pivot around a pivot (1019) extending in x-direction. The pivot (1019) is mounted in a sidewall of the drawer (6), the sidewall extending in y-direction. The slot (1001) comprises an edge (1002). In an orientation of the locking element (1009), the edge (1002) of the slot (1001) is parallel to the direction in which the threaded drive shaft (20) extends, i.e. parallel to the axis around which the threaded drive shaft (20) in use rotates.

A spring is mounted between the bottom of the drawer (6) and the arm of the locking element (1009) in compressed state. The spring therefore pushes the edge (1002) against the threaded collar (1008), in this example in clockwise direction when seen from the positive x-direction. The edge comprises a first recess (1011), a second recess (1012) and a third recess (1013). Each recess (1011, 1012, 1013) has a shape suitable to receive the threaded collar (1008). When the threaded collar (1008) reaches a recess, say the first recess (1011) a spring pushes the arm upward so that it pivots in clockwise direction (when seen from the positive x-direction). When the arm of the locking element (1009) pivots, the locking member (1000) pivots with it. The threaded collar (1008) is received in the first recess (1011).

The first recess (1011) is at a first end of the slot (1001); the third recess (1013) is at a second end of the slot (1001). The first recess (1011) and the third recess (1013) correspond to the first state and the third state of the retraction mechanism (7). The second recess (1012) corresponds to the second state of the retraction mechanism (7) and is situation in between the first recess (1011) and the third recess (1013).

The retraction mechanism (7) further comprises a lever (1014). The lever (1014) is pivotably connected to the locking element (1009) and extends along the sidewall of the drawer (6) to the front of the drawer (6), i.e. it extends in the y-direction. The lever (1014) is slidable in the y- direction. An end of the lever (1014) is curved. The curved end is accessible through the front of the drawer (6) forming a hook so that it may be pulled. The pivotable connection between the lever (1014) and the locking element (1009) is at a smaller y-coordinate and a larger z- coordinate than the pivot (1019) around which the locking element (1009) pivots. By pulling the lever (1014), the locking element (1009) pivots in counter clockwise direction (again seen from the positive x-direction), i.e. against the spring force. As the locking element (1009) pivots in counter clockwise direction, the locking member (1000) pivots as well including the slot (1001). If the threaded collar (1008) was received in the first recess (1006), the recess is moved away from the threaded collar (1008) and the threaded collar (1008) can move along the threaded drive shaft (20). The similar effects take place if the threaded collar (1008) was received in either the second recess (1012) or the third recess (1013).

The slot (1002) comprises a further edge (1004) comprising a further recess (1005). The further edge (1004) is parallel to the edge (1002), obviously except at the first recess (1011), the second recess (1012), the third recess (1013) and the further recess (1005). The further recess (1005) is arranged to partially receive the threaded collar (1008). The location of the further recess (1005) is opposite to the second recess (1012).

In use, the lever (1014) may be pulled while the threaded collar (1008) is moved by driving the threaded spindle (20) to rotate. The threaded collar may therefore engage with the further edge (1004) and not with the edge (1002). In such a case the user will be alerted when the second state is reached. This is because the threaded collar (1008) is received in the further recess (1005). By releasing the lever (1014) the locking element (1009) and therefore the locking member (1000) will pivot in clockwise direction (again seen from the positive x-direction) and the threaded collar (1008) will leave the further recess (1005) and be received in the second recess (1012).

The drive shaft (20) can be driven by a user from the front of the drawer (6) by inserting a drive tool (1015) into an end of the drive shaft (20) through an opening in the front of the drawer (6). The drawer (6) comprises a sliding door (1017) arranged to slide in the x-direction. When the position of the door has a minimum value for the x-coordinate the sliding door (1017) blocks the opening. When the opening is blocked, the drive tool (1015) cannot be used to drive the drive shaft (20). The switch (2008) comprises a rotable knob arranged on the front of the drawer (6). The rotable knob is mounted on a switching axle extending in the y-direction. The switching axle has a cross section with a square shape.

The sliding door (1017) comprises a recess corresponding to the switching axle. When the position of the sliding door (1017) has maximum value for the y-coordinate, the switching axle is received in the recess. The recess engages with the switching axle, preventing the switching axle to rotate, thus locking the state of the switch (2008).

An end of an inner cable (2000) of a Bowden cable (2001) is clamped onto the threaded collar (1008). The Bowden cable (2001) further comprises a hollow outer cable housing (2002). One end of the hollow outer cable housing (2002) is attached to a first cable support (2003) arranged in the drawer (6), the drawer (6) thus functioning as a frame. The other end of the hollow outer cable housing (2002) is attached to a second cable support (2004) near the front of the drawer (6). The position and orientation of the second cable support (2004) are stationary within the drawer (6). A part of the inner cable (2000) runs from the other end of the hollow outer cable housing (2002) to a pulley (2005) and back to a clamp on the second cable support thereby running in a U-shaped loop. The clamp forms a stationary anchor for the inner cable (2000). The pulley (2005) is mounted on an end of a pivotable arm. The other end of the pivotable arm indicates the state of the retraction mechanism (7) and is visible through a window (2006) in the front of the drawer (6). On the front of the drawer (6) there is a sticker with status indicators at positions corresponding to the position of the other end of the pivotable arm.

A torsion spring forces the pivotable arm to rotate such that the pulley (2005) remains in contact with the inner cable (2000) when the threaded collar (1008) moves towards the first cable support (2003).

Claims

1. Retraction mechanism (7) for extending and retracting an electrical contact (9) to a connected and a disconnected position, comprising

- a drive shaft (20) with an external thread arranged to rotably drive the retraction mechanism;

- a threaded collar (1008) with an internal thread arranged to engage with the outer thread of the drive shaft, the threaded collar being arranged to be moved along the drive shaft by rotation of the drive shaft; and

- indicator means (2001,2002,2003) to indicate the location of the collar,

characterized in that,

the indicator means comprise a pivotable arm (2007) and coupling means (2001) to couple the location of the threaded collar (1008) to a pivoting orientation of the pivotable arm, and a cable (2000) and wherein a first end of the cable is attached to the threaded collar (1008) and a second end of the cable is attached to an anchor (2004) having a fixed position relative to the frame (6), the cable arranged to make a loop around a pulley (2005) mounted on the pivotable arm (2007).

2. Retraction mechanism (7) according to claim 1, wherein the drive shaft is supported by a frame (6) in a fixed position relative to the frame and wherein the location of the threaded collar (1008) relative to the frame is used for indicating the retraction status of the retraction mechanism.

3. Retraction mechanism (7) according to claim 1, wherein the cable (2000) forms the inner cable of a Bowden cable (2001).

4. Retraction mechanism (7) according to any of the claims 1, 2, and 3 arranged to extend and retract a further electrical contact (109) to a connected position and a disconnected position.

5. Retraction mechanism (7) according to claim 4, arranged to extend and retract the further electrical contact (109) only when the electrical contact (9) is in disconnected position and to extend the electrical contact only when the further electrical contact is in connected position.