GB2029529A

GB2029529A - Movement-damping arrangements

Info

Publication number: GB2029529A
Application number: GB7836097A
Authority: GB
Original assignee: Marconi Co Ltd
Current assignee: BAE Systems Electronics Ltd
Priority date: 1978-09-08
Filing date: 1978-09-08
Publication date: 1980-03-19
Also published as: DE2850444C2; DE2850444A1; GB2029529B

Abstract

An arrangement for damping the movement of a primary member such as a moving member of a waveguide switch. A linear rate dashpot damping system (not shown) is provided to resist the movement of a pivotable mounted arm 15 the opposite side surfaces of which are arranged to be contacted by posts 13, 14 upstanding from a drive plate 8 which moves clockwise or counter-clockwise with the moving member (not shown) of the switch (not shown). The surfaces of the arm contacted by the posts are profiled so that the ratio of movement of the arm to the movement of the drive plate increases with progressive movement of the drive plate. <IMAGE>

Description

SPECIFICATION Improvements in or relating to movement damping arrangements This invention relates to movement damping arrangements and in particular to damping arrangements provided to control the decelaration of a moving member.

Whilst not limited thereto the invention is particularly concerned with providing a damping arrangement for rotary switching mechanisms such as waveguide switches.

Typically a waveguide switch consists of a cylindrical rotor incorporating one or more waveguide sections which, depending upon the rotational position of the rotor, connect different ports provided in a surrounding stationary portion of the switch. Such a waveguide switch will commonly be used to select main or standby channels in a ground communications station in the event of a fault condition arising and clearly the changeover in the event of failure should be made as quickly as possible in order to afford the minimum of interruption of traffic flow. Thus it is required to accelerate the rotor with a high angular acceleration from rest and thereafter to bring this to a stop rapidly with a relatively low level of mechanical shock and with relatively little "bounce" at the end of the switching movement.

Typically the drive and damping arrangement for a waveguide switch consist of a d.c.

torque motor and a linear rate viscous rotary dashpot which is engaged over a finite deceleration angle prior to the moving rotor being finally stopped by a mechanical stop arrangement. When switched, the rotor is held in alignment by an arrangement of permanent magnets. The angular velocity characteristics of such a typical arrangement is exponential in both the acceleration and deceleration phases and a basic disadvantage of such an arrangements is the mechanical shock associated with the high rate of deceleration as the dashpot is engaged. Indeed the level of shock at the point of engagement of the dashpot may well be higher than that occurring as the mechanical stop is engaged at the end of rotor movement.

The present invention seeks to provide an improved damping arrangement for controlling the deceleration of a moving member and in particular an improved damping arrangement for a rotary switching mechanism such as a waveguide switch in which the above disadvantages are reduced.

According to this invention an arrangement for damping the movement of a primary member comprises damping means provided to resist the movement of an intermediary member, a drive member coupled with or provided for coupling to, said primary member so as to move therewith and means for causing movement of said drive member to effect movement of said intermediary member resisted by said damping means, and wherein the arrangement is such that the relationship between said movement of said drive member and the resulting movement of said intermediate member is non-linear.

Normally said damping means itself is substantially linear that is to say that the resistance offered is substantially independent of the position of said intermediary member over a range of movement thereof.

Preferably the relationship between said movement of said drive member and the resulting movement of said intermediary member is such that the ratio of the latter to the former increases with increasing movement of said drive member.

Preferably said drive member is a driving plate having an abutment thereon which is arranged to engage with a surface of said intermediary member to effect movement of the latter which surface is. profiled to provide the required relationship between said movement of said drive member and the resulting movement of said intermediary member.

Preferably said intermediary member is a pivotably mounted arm coupled to said damping means and having one side surface engageable by said abutment carried by said drive plate which side surface is profiled in order to provide the required non-linear relationship between said movement of said drive member and the resulting movement of said intermediate member.

Preferably where the motion of said drive plate may be in either direction preferably an opposite surface of said intermediary arm is correspondingly profiled and a second abutment carried by said drive plate is arranged to engage said opposite correspondingly profiled surface whereby over a range of movements in either direction by said drive member the resulting movement of said intermediary member is non-linear.

Said surface or surfaces of said arm may be integral with said arm. However, said surface or surfaces may be provided by a roller carried at one end of said arm.

Preferably final arresting of movement by said drive member is effected by means of a mechanical stop arrangement.

Preferably said mechanical stop arrangement comprises a stop plate provided to be engaged by one of said abutments when said other abutment is in engagement with a profiled surface of said intermediary arm and vice versa.

Preferably said primary member comprises a moving member of a rotary switch such as a waveguide switch.

Preferably said or each abutment is a pillar of circular cross section upstanding from said drive plate.

The invention is illustrated in and further described with reference to the accompanying drawing in which, Figure 1 illustrates schematically a typical waveguide switch, Figure 2 illustrates one example of move ment damping arrangement in accordance with the present invention as applied to the waveguide switch in Fig. 1 and Figure 3 illustrates a modification.

In Figs. 2 and 3 like references are used to denote like parts.

Referring to Fig. 1 the waveguide switch consists of a stationary housing 1 having an input port 2 and two output ports 3 and 4. A rotor 5 having a transfer port 6 is moveable, by means of a motor represented at 7, from the position in which it is shown in which input port 2 is connected to output port 3 to an alternative position in which input port 2 is connected with output port 4. Typically output port 3 would be connected to a main communications channel in a ground station whilst output port 4 would be connected to a standby channel provided to replace the main channel should this latter become faulty.

In order to provide a minimum of interruption of traffic in the event of a change from main to standby channels motor 7 is provided to be capable of generating a high acceleration. At the end of its required travel the rotor 5 should be brought to rest as rapidly as possible with a mimimum of shock and "bounce". It is for this reason that the damping arrangement provided by the present invention is applied to the waveguide switch of Fig. 1.

Referring to Fig. 2 the waveguide switch itself is not represented but the rotor 5 of Fig.

1 may be considered to be connected to a driving plate 8 so that rotor 5 and driving plate 8 are coupled for rotary motion about the axis 9. The driving plate 8 carries a stop plate 10 which is provided to abut at the limit of desired angular movement in one direction an end stop 11 and at the limit of desired angular movement in the opposite direction an end stop 1 2. The positions of the end stops 11 and 1 2 are such that the maximum permissible arc through which rotation may occur is 120 . In one extreme position as shown with stop plate 10 abutting end stop 11 rotor 5 of the waveguide switch shown in Fig. 1 is in one extreme position with port 2 connected to port 4.In the other extreme position with stop plate 10 engaged with end stop 12 the rotor 5 of the waveguide switch shown in Fig. 1 is in a position with port 2 connected to port 3 (as illustrated in fact).

The driving plate 8 is provided with two upstanding posts 1 3 and 14 which are provided to connect respective side surfaces of an arm 1 5 which is pivoted about a point 1 6.

The arm 1 5 is linked to a mechanical linear rate dashpot damping system which is not separately shown so that rotational movement of the arm 1 5 about the pivot point 1 6 is damped by the dashpoint in either direction.

The side surfaces of the arm 1 5 which are contacted by the posts 1 3 and 14 respectively are profiled as shown so that as either post 1 3 or 14 engages the arm 1 5 to rotate the same the mechanical advantage ratio progressively increases so that a progressively increasing deceleration torque is applied to the drive plate 8 and thus the switch rotor 5.

With the drive plate 8 in the position shown in Fig. 2 and with rotor 5 of the waveguide switch shown in Fig. 1 correspondingly in a position in which port 2 is connected to port 4 post 14 is in a position remote from the arm 1 5 whilst post 1 3 is in contact therewith.

If motor 7 of Fig. 1 is now activated to drive the drive plate 8 in an anti-clockwise direction as viewed post 1 3 disengages arm 1 5 without disturbing the angular position of this. The rotor 5 of the waveguide switch shown in Fig.

1 is then accelerated through an angle + until post 14 engages the profiled surface of arm 1 5 which imparts a low rate of initial acceleration to the damped dashpot due to the very low mechanical advantage at this point. As the post 14 progresses in an anti-clockwise direction the mechanical advantage ratio increases due to the profiling to apply a progressively increased deceleration torque to the rotor 5. Eventually stopplate 10 closes end stop 1 2 and post 14 will have moved the arm 1 5 through a small angle 8 in a clockwise direction to place this into the correct position to receive the post 1 3 should the motor 7 of Fig. 1 be activated to cause clockwise rotation of the rotor 5 and the drive plate 8.

Referring to Fig. 3 in the modification illustrated therein the integral profiled surfaces of arm 1 5 are dispensed with and instead a relatively large diameter roller 1 7 is rotatably mounted towards the end of the arm 1 5 the effect achieved is somewhat similar to that achieved by the arrangement of Fig. 2 except that since the contoured surfaces contacted by the posts 1 3 and 14 are the surfaces of a roller, friction and consequent wear between the posts and the contoured surfaces is reduced. However, this arrangement is not preferred since it imposes practical limitations on the range of mechanical advantage ratio which may be obtained.

Claims

1. An arrangement for damping the movement of a primary member comprising damping means provided to resist the movement of an intermediary member, a drive member coupled with or provided for coupling to, said primary member so as to move therewith and means for causing movement of said drive member to effect movement of said intermediary member resisted by said damping means, and wherein the arrangement is such that the relationship between said movement of said drive member and the resulting movement of said intermediate member is non-linear.

2. An arrangement as claimed in claim 1 and wherein said damping means itself is substantially linear.

3. An arrangement as claimed in claim 1 or 2 and wherein the relationship between said movement of said drive member and the resulting movement of said intermediary member is such that the ratio of the latter to the former increases with increasing movement of said drive member.

4. An arrangement as claimed in any of the above claims and wherein said drive member is a driving plate having an abutment thereon which is arranged to engage with a surface of said intermediary member to effect movement of the latter which surface is profiled to provide the required relationship between said movement of said drive member and the resulting movement of said intermediary member.

5. An arrangement as claimed in claim 4 and wherein said intermediary member is a pivotably mounted arm coupled to said damping means and having one side surface engageable by said abutment carried by said drive plate which side surface is profiled in order to provide the required non-linear relationship between said movement of said drive member and the resulting movement of said intermediate member.

6. An arrangement as claimed in claim 5 wherein the motion of said drive plate may be in either direction and wherein an opposite surface of said intermediary arm is correspondingly profiled and a second abutment carried by said drive plate is arranged to engage said opposite correspondingly profiled surface whereby over a range of movements in either direction by said drive member the resulting movement of said intermediary member is non-linear.

7. An arrangement as claimed in claim 5 or 6 and wherein said surface or surfaces of said arm is integral with said arm.

8. An arrangement as claimed in claim 5 or 6 and wherein said surface or surfaces of said arm is or are provided by a roller carried at one end of said arm.

9. An arrangement as claimed in any of the above claims and wherein final arresting of movement by said drive member is effected by means of a mechanical stop arrangement.

10. An arrangement as claimed in claim 9 as dependent upon claim 6 and wherein said mechanical stop arrangement comprises a stop plate provided to be engaged by one of said abutments when said other abutment is in engagement with a profiled surface of said intermediary arm and vice versa.

11. An arrangement as claimed in any of the above claims and wherein said primary member comprises a moving member of a rotary switch such as a waveguide switch.

1 2. An arrangement as claimed in claim or 6 or any of claims 7 to 11 as dependent upon claim 5 or 6 and wherein said or each abutment is a pillar of circular cross-section upstanding from said drive plate.

1 3. An arrangement for damping the movement of a primary member applied to a waveguide switch and substantially as herein described with reference to Fig. 2 of the accompany drawing.

14. An arrangement for damping the movement of a primary member applied to a waveguide switch and substantially as herein described with reference to Fig. 3 of the accompanying drawing.