GB2139815A - Lever operated switches - Google Patents

Abstract

An electrical switch for fixing to the side of a vehicle steering column, comprises a control lever (12) pivotally mounted in a box about two mutually perpendicular axes so that the lever can be rocked up and down about a substantially horizontal axis and forwards and backwards about a substantially vertical axis. Rocking the lever up and down moves movable contacts (52, 54) into and out of sliding engagement with fixed contacts (46a, b and c, and 48, b, and c). Rocking the lever forwards and backwards moves a slider 102, which pivots spring biassed contacts (78a and b) into and out of sliding engagement with further fixed contacts. The slider is constructed in such a manner that the rocking movements of the lever forwards and backwards will produce the sliding movement of the contacts (78a, b) relative to the fixed contacts irrespective of the angular position of the lever (12) about the horizontal axis (X). <IMAGE>

Description

SPECIFICATION Lever operated electrical switching unit for automobile steering column The present invention relates to electrical switching units of the kind which are fitted laterally to the steering column of an automobile for controlling the operation of parts of the vehicle, such units comprising a box which, in use, is fixed to the steering column, a control lever pivotally mounted in the box about two mutually perpendicular axes so that the lever can be rocked up and down about a substantially horizontal axis and forwards and backwards about a substantially vertical axis relative to the direction of travel of the vehicle, the lever having a longer arm extending outside the box to provide a free end accessible adjacent the periphery of the steering wheel and a shorter arm extending inside the box, mobile electrical contacts associated with the shorter arm of the lever and arranged to co-operate with fixed electrical contacts inside the box when the lever is rocked about its pivot axes, and means associated with the shorter arm of the lever and with the box for determining stable and/or unstable angular positions of the lever about its pivot axes.

The terms substantially horizontal axis and substantially vertical axis are used for simplicity, and it should be understood that these axes need not be truly horizontal and vertical. For example, it will be usual for the substantially horizontal axis to be parallel to the direction of the steering column, and for the substantially vertical axis to be substantially parallel to the general plane of the steering wheel, lying in a plane which is vertical and parallel to the direction of travel of the vehicle.

Electrical switching units of this type are commonly used in pairs, one on each side of the steering column, and according to a widely accepted practice the left-hand unit is used for operating the direction indicators by the upward and downward movement of the lever, and for controlling the lights by the rocking movement of the lever forwards and backwards. Similarly, the right-hand unit is used for controlling the front windscreen wipers by means of the upward and downward rocking movement of the lever, and for controlling the rear windscreen wipers and the front and rear windscreen washers by means of the movement of the lever forwards and backwards.

In these known units, for the most part, sliding contacts are used for controlling the functions associated with the rocking of the lever upwards and downwards, while frontal contacts are used for controlling the functions associated with the rocking of the lever forwards and backwards.

The frontal contacts, by their very nature, possess the double disadvantage of not being self-cleaning, and of providing, even when clean, an uncertain electrical connection. A bad electrical connection is accompanied by localized electrical resistance. This is not of great importance if the current flowing across the frontal contacts is small, as in the case of the current taken by the electrical pump of a windscreen washer. If, on the other hand, the frontal contacts energise a device with'a high current demand, such as the vehicle headlights (dipped or full beam) or the motor for a windscreen wiper, the localized resistance causes over-heating by the Joule effect. The boxes and other insulating components of the switching units are of plastics material, and the over-heating can result directly in softening and melting of these parts, accompanied by failure of the unit.Furthermore, in the case of the headlights, a bad electrical connection inevitably results in a reduction in the intensity of illumination due to the reduction in the supply voltage.

The aim of the present invention is to provide a switching unit of the kind described which does not suffer from the above disadvantages and which will be simple and economical to manufacture.

To this end, according to the invention, an electrical switching unit of the kind described is characterized in that at least one of the mobile contacts is a blade type contact which is movable in a direction substantially parallel to the direction of travel of the vehicle and is arranged to co-operate in a sliding manner with at least one fixed contact inside the box, the blade contact being mechanically connected to the shorter arm of the lever in such a way that rocking of the lever forwards and backwards about the substantially vertical axis produces the sliding co-operation between the blade contact and the fixed contact independently of the angular position of the lever about its substantially horizontal pivot axis.

With this arrangement, as will be explained later in more detail, it is possible to produce a switching unit incorporating sliding contacts for controlling at least those parts of the vehicle which have a high current demand, with all the advantages which derive therefrom.

Two examples of the switching unit in accordance with the invention will now be described with reference to the accompanying drawings, in which: Figure 1 is a perspective view of the two switching units installed on opposite sides of the steering column of an automobile; Figure 2 is a section through the two units, taken along the broken line ll-ll in Figure 1; Figure 3 is a section in the plane indicated by the line Ill-Ill in Figure 2; Figures 4to 7are sections of the left-hand unit, respectively taken along the lines IV-IV, V-V, VI-VI and VII-VII in Figure 2; Figure 8 is an exploded perspective view of the left-hand switching unit; Figure 9 is a perspective view of the contacts only of the left-hand unit;; Figures 10, 11 and 12 are schematic representations, in three different positions, of the contacts controlled by means of upward and downward pivotal movement of the lever of the left-hand unit; Figures 13,14and 15 are schematic representa- tions, in three different positions, of the contacts controlled by forward and backward movements of the lever of the left-hand unit; Figures 16 and 17 are sections through the right-hand switching unit, respectively taken along the lines XVI-XVI and XVII-XVII in Figure 2; Figure 18 is an exploded perspective view of the right-hand switching unit; Figure 19 is a perspective view of the contacts only of the right-hand unit; Figures 20 to 23 are schematic views, in four different positions, of the contacts controlled by upward and downward movements of the lever of the right-hand unit; and, Figures 24 to 27are schematic views, in four different positions, of the contacts controlled by forward and backward movements of the lever of the right-hand unit.

Referring to Figure 1, reference W denotes the steering wheel of an automobile. The steering column, or the fairing which surrounds the shaft of the steering wheel W, is referenced C, and the fairing carries a support plate P at its end adjacent the hub of the steering wheel W.

A double electrical switching unit, which comprises a left-hand switching unit AL and a right-hand switching unit AR, iS associated with the steering column C. Each switching unit AL, AR comprises a box or box-shaped housing 1 0L, 1 OR, and the two boxes 1 0L, 1 OR are releasably fixed to the support plate P in the immediate vicinity of the steering wheel Wand on opposite sides of the column C.

From each box 1 0L, 1 OR there projects a longer arm 1 2L, 12R of a control lever. Each of these arms or levers, which is situated in front of the steering wheel W, possesses a free end accessible to the hands of the driver at the periphery of the steering wheel.

For simplicity, in the description which follows, the term "lever" will be used for designating each of these two longer arms 1 2L, 12R.

The left-hand switching unit AL, in the form of the embodiment shown, is intended for the control of the direction indicators, the parking lights, and the full and dipped beam headlights.

The right-hand switching unit AR, in the form of the embodiment shown, is intended for controlling the front windscreen wipers, the rear windscreen wiper, and the front and rearwindscreen washers.

The structure and functioning of the left-hand switching unit AL will be described as a whole. This description will be made with reference to Figures 2 to 15.

Referring in particular to Figures 2 to 7, the box 10L comprises a hollow box-shaped shell 14 of plastics material, a base wall 15 of which is provided with profiled zones which enable it to be fixed detachably to the support plate P (Figure 1). The body 14 is closed by a front cover 16, also of plastics material.

Inside the box 1 0L, there is mounted an oscillating block 18, also of plastics material. The block 18 possesses a pair of opposed pins 20, which define an axis XL of oscillation of the block itself relative to the box 14. The axis XL is substantially horizontal, or rather substantially parallel to the direction of the steering column C.

The lever 12 is, in turn, pivotally mounted in the block 18 by means of a pin 22. The pin 22 defines an axis ZL of oscillation for the lever 12 which is disposed transversely to the axis XL and is substantially parallel to the general plane of the steering wheel W (Figure 1).

The lever 12 is equipped with a shorter arm 24, situated beyond the pin 22 and extending inside the box 14.

The rotation of the lever 12L and of the block 18 about the axis XL serves for controlling the direction indicators.

On its face towards the steering column C, the box 14 possesses, internally, a shaped or cam surface which comprises a central seating or notch 26a and lateral ramps 26b and 26c.

The oscillating block 18 is equipped with a sliding tooth 28, which is thrust by a helical spring 30 into engagement, depending upon the case, with the bottom of the seating 26a or with the ramps 26b, 26c.

This is a system of the type known as "position marker".

When neither of the direction indicators is actuated, the tooth 28 is situated at the base of the notch or seating 26a, as illustrated in Figure 10, and the oscillating block 18 and the lever 12L are kept in a central, neutral angular position.

To bring the right-hand direction indicator into operation, the driver displaces the lever 12 upwards (arrow F1) and the tooth 28 moves along the ramp 26b (Figure 11).

To operate the indicator in the left-hand direction, the driver lowers lever 12 (arrow F2, Figure 1) and the tooth 28 moves into engagement with the ramp 26c, as illustrated in Figure 12.

The positions of the Figures 11 and 12 are stable provided that the steering wheel is not straightened after a turn into the direction corresponding to the indication chosen.

The oscillating block 18 is equipped, on its face towards the lid 16, with a mechanism referenced as a whole 32, for causing the return of the block itself to the neutral position when the steering wheel is straightened. This mechanism, which will not be described in detail, comprises amongst other things a pawl 34, with which is associated a helical tension spring 36 which tends to bias the pawl itself to the outside of the box 10, and towards the steering shaft S (Figure 3).

When the oscillating block 18 is situated in the neutral position, two pawls 38a, 38b provided on the cover 16 prevent the escape of the pawl 34.

When the block is brought to one or other of the positions of Figures 11 and 12, one or other of the pawls 38a frees the pawl 34 to project to the position indicated in broken line at 34a in Figure 3.

The shaft S is equipped with a pair of radial teeth T (Figure 3). When the steering wheel is straightened after a turn, one or other of the teeth T comes into engagement with the pawl 34, a rear cross-member 40 of which engages, depending upon the case, one or other of a pair of oscillating arms 42a, 42b, biased towards each other by a tension spring 44. By means of the pawl 34 and the corresponding arm 42a, the tooth T which engages the pawl 34 applies to the entire oscillating block 18 a rotation which brings it into the neutral position corresponding to Figure 10.

At the same time, the pawl 34 recedes and is held in its retracted position by the pawls 38a, 38b.

In the base wall 15 of the box 10L, or the wall adjacent to the support plate P (Figure 1), there are secured two series ofthree linear fixed contacts. The contacts of one of the series are indicated by 46a, 46b, 46c and those of the other series by 48a, 48b, 48c.

These fixed contacts are composed of metal strips secured across said base wall and which possess, outside same, respective projections 50 which function as electrical connection terminals.

The two series of contacts are disposed along arcs of circles concentric to the axis of oscillation X.

In seatings of the oscillating block 18 facing towards the bottom wall of the box 10 sliding contact staples 52 and 54 are mounted, of which one corresponds to the series of contacts 46 and the other to the series of contacts 48.

The mobile contacts constituted of the staples 52 and 54 are thrust into engagement with the respective fixed contacts by concealed helical springs 56 and 58.

The central fixed contacts 46a and 48a are supply contacts for the current and one of them (for example contact 46a) is normally kept energized for the purpose of actuating the direction indicators.

The central contact of the other series (for example contact 48a) can be energized, by means of a switch situated on the dashboard of the automobile, in replacement of the central contact of the preceding series, for the purpose of illuminating the right or left parking lights.

When the lever 12L and the oscillating block 18 are in the neutral position (Figure 10) the two staples 52 and 54 engage only the central fixed contacts 46a and 48a, through which the current is transmitted, depending upon the case, to the direction indicator system or to the parking lights supply system.

When the lever 12 is raised in the direction of arrow F1 in Figure 1, the two staples 52 and 54 are brought into engagement with the fixed contacts 46b, 48b (Figure 11), still maintaining engagement with the central contacts 46a, 48a. In this manner the supply is stabilized, depending upon the case, to the right blinking lamps or to the right parking lamps.

Correspondingly, when the lever 12 is lowered in the direction of arrow F2 of Figure 1, the staples, 52, 54 stabilize the connection of the central contacts 46a, 48a with the fixed contacts 46c, 48c (Figure 12).

In this manner, depending upon the particular case, the left-hand blinker lamps or the left-hand parking lamps are supplied with current.

As will be understood, the supply to the blinker lamps and parking lamps is advantageously realized by means of sliding contacts, kept in secure engagement by the springs 56 and 58. The use of sliding contacts, as already stated initially, is advantageous due to the fact that the contacts are self-cleaning and their ohmic resistance is completely negligible.

The shorter arm 24 of the lever 1 2L possesses, at its end remote from the pin 22, a hollow cylindrical seating 60, in which is housed a position ball 62, biased outwards by a helical spring 64, housed in the seating itself.

In its face towards the arm 24, the oscillating block 18 possesses a profiled surface, functioning as a cam, which comprises, amongst other things, two notches 66a and 66b, and also a ramp 66c. This cam and the ball 62 constitute a device known as a "position marker" for determining two stable angular positions and one unstable angular position of the lever 12 about the axis Z.

The stable positions are those in which the ball 62 is situated in the notch 66a (Figure 13) and in the notch 66b (Figure 14). The unstable position is that in which the ball 62 is situated in engagement with the ramp 66c (Figure 15). In this unstable position the spring 64 tends to bring the ball 62 to the base of the notch 66a.

In the base wall 15 of the box 10L, there are fixed two through strip conductors 68a, 68b, which possess extensions 70 outside the box functioning as terminals for the supply of the electrical current.

The parts of the conductors 68a, 68b situated inside the box possess respective V-notches 72a, 72b.

With these conductors 68a, 68b there are associated respective mobile conductors in the form of blades 74a, 74b, extending parallel to one another upwards.

These blades are composed of strip elements, produced by shearing and bending.

At its lower end, each blade 74a, 74b possesses a V-notch, respectively 76a, 76b, which is engaged in a cross-shaped or transverse manner in the corresponding notch 72a, 72b of the respective strip conductor 68a, 68b.

The mutual engagement of the V-notches referred to above produces, for each blade 74a, 74b, a fulcrum or pivot point which permits it to pivot forwards and backwards (with respect to the direction of travel of the vehicle). The play of the pivots permits furthermore a certain transverse oscillation of the blades 74a, 74b, for a purpose which will be explained later.

At its upper end, each blade 74a, 74b, is shaped as a sliding contact plate. These plates are referenced respectively 78a and 78b. The contact faces of the plates are the external faces.

Through the bottom wall 15 of the box 10there are fixed in through manner the base or root portions of two strip conductors 80 and 82. Each of these conductors possesses, outside the base wall of the box, a projection, respectively 84 and 86, which functions as a connection terminal.

The conductor 80 is rectilinear and its end portion 88a situated inside the box can be engaged by sliding contact association with the external face of the plate 78a.

The other conductor, 82 is profiled so as to possess a strip end 88b coplanar with the fixed contact 88a and constituting another fixed contact.

In alignment with its extension 86, the conductor 82 possesses, still inside the box 10L, a flat contact portion 88c, which can be engaged in sliding contact association with the external face of the plate 78b.

Between the two plates 78a, 78b there is incorporated a helical compression spring 90, which tends to force these plates apart to produce a correct engagement of the plates themselves on the one hand with the fixed contacts 88a, 88b and on the other hand with the fixed contact 88c. The spring 90 acts upon the plate 78b through the interposition of an insulating washer 92.

The possibility of biasing the plates apart is permitted by the play of the above-mentioned pivots formed by the V-notches.

As will be explained in greater detail below, the plate 78a can engage alternatively with the single contact 88a and with the single contact 88b. The space between these contacts is less than the width of the plate 78a, so that during passage from one fixed contact to the other the force of the spring 90 is always resisted by one of the contacts or by both of them and the blade 74a is guided in its pivotal movement.

With regard to the blade 74b, its plate 78b is guided, against the force of the spring 90, by the fixed contact 88c when the blade 74b is pushed right forwards. For the remainder of the pivoting travel of the blade 74b, it is guided by a bar-shaped extension 94, which forms an integral part of the base wall of the box 10 or is fixed to that wall. The projection 94 extends parallel to the contact 88c. From the plate 78b there extends an upper tongue 96, the external face of which (the left face in Figures 4,8 and 9) engages the guide 94 to resist the force of the spring 90 when the plate 78b is not in engagement with the contact 88c.

The plates 78a, 78b are equipped with cheeks 98, to favourtheir entry into sliding engagement with the respective fixed contacts.

With each blade 74a, 74b, there is associated a helical buffer spring 100a, 100b, positioned between the blade itself and the base wall of the box 1 OL The buffer springs 1 00a, 1 00b tend to thrust the blades 74a, 74b angularly backwards with respect to the direction of travel of the vehicle, that is towards the shorter arm 24 of the lever 12L Between the shorter arm 24 and the blades 74a, 74b there is interposed a slider, generally referenced 102. The slider 102 is made from a piece of plastics material having a low co-efficient of friction.It comprises, amongstotherthings, a pair of guide arms 104 and 106, which are slidable in corresponding holes 108 and 110 of the base wall 15 of the box, In this manner, the slider 102 is guided substantially in the direction of movement of the mobile contacts or blades 74a, 74b which direction is substantially parallel to that of the steering column C and axis X.

The slider 102 is formed like two slide blocks in perpendicular arrangement, referenced 112 and 114.

The slide block 112 is in the form of a block elongated in a direction transverse to the shorter arm 24 of the lever 1 2L and engages this arm by means of a domed surface.

The slide block 114 has the form of a block elongated in a direction transverse to the blades 74a, 74b and possesses a convex surface, like the other block, which engages respectively rear edges 116a, 116b of the blades. The buffer springs 100a, 100b maintain the two slide blocks 112, 114 of the slider 102 constrained between the short arm 24 and the blades 74a, 74b.

As will be understood, the shorter arm 24 of the lever 12L remains in engagement with the slide block 112 independently of the angular position of the arm itself and of the pivoting block 18 about the axis XL.

Thus the slide block 114 remains constantly in engagement with the edges 11 6a, 11 sub.

As will be understood, the angular movements of the lever 12Lforwards (arrow F3, Figure 1) and backwards (arrow F4, Figure 1 ) cause corresponding inverse movements (backwards and forwards) of the blades 74a, 74b.

When the ball 62 is in the notch 66a, (Figure 13), the mobile contact 78b is not operative and the mobile contact 78a is in stable engagement with the fixed contact 88a. This condition corresponds to the supply to the lower beam headlights, which supply has been predetermined by the operating of a corresponding switch "positioning lights - headlights" on the vehicle dashboard.

When the lever 12v is moved forwards, the ball 62 moves into the notch 66b (Figure 14) and the mobile contact 78a comes into engagement with the fixed contact 88b. In this manner the full beam headlights are given a stable supply.

When the driver is driving with lower beam (dipped beam) headlights and desires to signal his presence by flashing the lower beam, he moves the lever 12, backwards. The ball 62 then leaves the base of the notch 66a and moves along the ramp 66c (Figure 15). The mobile contact 78b then moves into engagement with the fixed contact 88c and stabilizes the supply to the dipped beam headlights, while the full beam headlights remain supplied by means of the contacts 78a, 88a. This state continues so long as the driver holds the lever 12v pulled towards him.

When the driver releases the lever 1 2L, the cam action between the ball 62 and the ramp 66c, under the force of the spring 64, brings the system into the arrangement of Figure 12, or the condition of supply to the lower beam headlights.

As will be seen, all the contacts which supply the full beam and dipped beam headlights, that is devices with a high current demand, are of the sliding and self-cleaning type, the ohmic resistance of which is negligible, with all the advantages set out above.

A description will now be given of the structure and functioning ofthe right-hand switching units.

This description will be made with reference to Figures2,3and 16to27.

Referring in particular to Figures 2,3 and 16to 19, the box 10R comprises a hollow box-shaped shell 214 of plastic material, with a base wall 215 equip- ped with profiled zones enabling itto be releasably fixed to the support plate P (Figure 1). The body 214 is closed by a front cover 216, also of plastic material.

In the box 10Rthere is mounted an oscillating block 218, also of plastic material. The block 218 possesses a pair of opposed pins 220 which define a pivot axis XR of the block itself with respect to the box 214.

The lever 12R in turn is pivotally mounted in the block 218 by means of a pin 222. The pin 222 defines a pivot axis ZR for the lever 1 2R, which is disposed perpendicular to the axis XR and is substantially parallel to the general plane of the steering wheel W (Figure 1).

The lever 1 2R is equipped with a shorter arm 224 situated beyond the pin 222 and extending inside the box 10R Rotation of the lever 1 2R and of the block 218 about the axis XR serves for controlling the front windscreen wipers of the automobile.

On its side towards the steering column C, the box 10R possesses internally a profiled surface or cam surface which comprises a lateral or upper ramp 226a and a pair of notches 226b and 226c. The limit of the ramp 226a, on the side towards the notch 226b, is defined by a crest 226d.

The pivoting block 218 is equipped with a sliding tooth 228 which is thrust by a helical spring 230 into engagement, depending upon the case, with the ramp 226a or with the base of the notches 226b, 226c. In this case, also, we have a so-called "position marker" system.

When the front windscreen wipers are not actuated, the tooth 228 is situated towards the "lower" limit (the upper limit in Figure 20) of the ramp 226a and the pivoting block 218 and the lever 12R are maintained in a substantially horizontal position.

This position is stable, because the spring 230 tends to cause the tooth 228 to "descend" along the ramp 226a (or cause it to rise in Figure 19).

In the "bottom" wall of the box 1 OR, that is the wall adjacent to the support plate P (Figure 1), various fixed contacts are secured.

A first series of contacts comprises three linear contacts 246a, 246b and 246d, disposed along an arc of a circle concentric with the pivot axis XR. The same series comprises also a transverse contact 246c, which also forms part of a second series.

The second series of contacts comprises a linear contact 248 and a portion of the same transverse contact 246c.

All the aforementioned fixed contacts are composed of variously profiled strips which comprise a root or base portion fixed through said wall 215.

Outside this wall, the root portions possess respective projections or extensions 250 which function as terminals for electrical connection.

In seatings of the pivoting block 218 facing towards the base wall of the box 1 OR, there are slidably mounted contact staples 252 and 254. The staple 252 corresponds to the series of contacts 246a, 246b, 246c, 246d and the staple 254 corresponds to the series of contacts 248a, 248b, 248c.

The mobile contacts constituted of the staples 252 and 254 are thrust into engagement with the respective fixed contacts by concealed helical springs 256 and 258.

The fixed contact 246c is a supply contact for the current and is kept permanently energized.

The fixed contact 246a is connected to the circuit associated with the motor for the front windscreen wipers for stopping it at the end of its stroke. This fixed contact 246a is therefore energized during the stroke of the last cycle of the front windscreen wipers.

The fixed contact 246b is connected to the low speed winding of the motor for the front windscreen wipers. The fixed contact 246d is connected to the high-speed winding of the same motor.

The fixed contact 248 is also connected to the low-speed winding of the front windscreen wiper motor.

When the lever 1 2R is raised in the direction of arrow F5 of Figure 1, bringing the tooth 228 to the end of the ramp 226a and opposite the crest 226d (Figure 21), the staple 254 connects the contact 246c with the contact 248a. The front windscreen wipers are thus actuated so long as the driver holds the lever up. When the driver releases the lever, the system returns to the position of Figure 20, so that the staple 252 returns to connect the contacts 246a and 246b and the windscreen wipers stop at the end of one or more successive cycles.

When the lever 12R is raised further in the direction of arrow F5 in Figure 1, to bring the tooth 228 into the notch 226b, the staple 252 comes into engagement with the fixed contacts 246b and 246c (Figure 22), so that the front windscreen wipers are actuated at low velocity. In these conditions the staple 254 is situated on fixed contact 248b without any effect.

When the lever 1 2R is again raised further, according to arrow F5 of Figure 1, to bring the tooth 228 into the notch 226c, the staple 252 is disposed in engagement with the fixed contacts 246c and 246d (Figure 23), so that the front windscreen wipers are actuated at high speed. In this case also, the staple 254, which is in engagement with the fixed contact 248b, has no effect, the fixed contact 248b having the sole function of supporting it against the force of the spring 258.

When the driver wishes to stop the windscreen wipers, he lowers the lever 12R according to arrow F6 of Figure 1, to bring the tooth 228 onto the ramp 226a. Once the tooth 228 has arrived at the start of the ramp 226a beyond the crest 226d, the same spring 230 will bring the pivoting block 218 and the lever 12R to the at-rest position corresponding to Figure 20. In this position of Figure 20, the staple 252 supplies the motor of the front windscreen wipers at low speed, from the fixed contact 246a, until the windscreen wipers are stopped at their limit stop.

As will be understood, the supply to the motor for the front windscreen wipers is advantageously realized by means of sliding contacts, kept in secure engagement by the spring 256 (and also by the spring 258 in the case of intermittent actuation). The use of sliding contacts, as was stated earlier, is advantageous due to the fact that these contacts are self-cleaning and their ohmic resistance is quite negligible.

The shorter arm 224 of the lever 1 2R possesses, at its end remote from the pin 222, a cylindrical seating 260, in which there is housed a positioning ball 262 biased outwards by a helical spring 264 housed in the same seating.

In one of its faces towards the arm 224, the pivoting block 218 possesses a profiled surface, functioning as a cam, which comprises, amongst other things, in succession (Figure 2) a ramp 266a, two successive notches 266b and 266c and a ramp 266d. The two opposite ramps 266a, 266b constitute the "outermost" flanks of the notches 266d and 266c.

This cam and the ball 262 constitute, in the present case also, a device known as a "position marker" for determining two stable angular positions and two opposite unstable angular positions of the lever 12R about the axis ZR.

The stable positions are those in which the ball 262 is situated in the notch 266b (Figure 24) and in the notch 266c (Figure 26). The unstable positions are those in which the ball 262 is situated in engagement with the ramps 266a (Figure 25) and 266d (Figure 27).

In these unstable positions, the spring 264 tends to bring the ball 262, depending upon the particular case to the bottom of the notch 266b or of the notch 266c.

In the base wall of the box 1 OR, there is fixed a through strip conductor 268 which possesses, outside the box, an extension or projection 270 functioning as a terminal for the supply of the electrical current. The part of the conductor 268 situated inside the box possesses a V-notch 272.

With the conductor 268 there is associated a mobile contact in the form of a blade 274, which extends upwards. This blade is constituted of a strip element produced by shearing and bending.

At its lower end, the blade 274 possesses a V-notch, referenced 276, which is in transverse or cross-shaped engagement with the notch 272 of the strip conductor 268.

The mutual engagement of the aforementioned V-notches produces, for the blade 274, a fulcrum or pivot which permits it to pivot forwards and backwards (with reference to the direction of travel of the vehicle). The play of the fulcrum also permits a certain transverse pivoting of the blade 274, for a purpose which will be explained below.

At its upper end, the blade 274 is profiled like a sliding contact plate, referenced 278. The contact face of the plate is that towards the right in Figures 16,18 and 19.

Through the base wall of the box 10R, there are secured in through manner the root portions or end portions of two strip conductors 280 and 282. Each of these conductors possesses, outside the base wall 215 of the box, an extension or projection, respectively 284 and 285, which functions as a connecting terminal.

The conductor 280 is rectilinear and its end portion 288a situated inside the box can be engaged by sliding contact with the corresponding face of the plate 278.

The other conductor, 282, is profiled in such a way as to possess a strip end 288b coplanar with the fixed contact 288a and constituting another fixed contact.

The fixed contact 248a forms part of a profiled strip conductor 289, which extends above the blade 274 and possesses an end 288c situated towards the lid 216 of the box 10R The end 288c constitutes a further fixed contact in connection with the contact 248a.

The plate 278 is biased into alternative engagement with the contacts 288a and 288b by a helical compression spring 290, which in turn bears against a member which will be described below.

The possibility of transverse oscillation or pivoting of the plate 274 offered by the fulcrum constituted of the V-notches, enables a good electrical contact to be obtained as a result of the spring 290.

As will be explained in more detail later, the plate 278 can engage alternatively the contact 288a alone and the contact 288b alone. The space between these contacts is less than the width of the plate 278, so that in passing from one fixed contact to the other the force of the spring 290 is always opposed by one of the contacts or by both, and the blade 274 is guided in its pivoting movement.

From the base wall 215 ofthe box 1OR there extends a projection 294 in the form of a bar, which forms an integral part of said base wall or is fixed to it. The projection 294 extends parallel to the fixed contacts 288a and 288b. From the plate 278 there projects an upper tongue 296, the outerface of which (the face to the right in Figure 16,18 and 19) engages the guide 294 in order to resist the force of the spring 290 when the plate does not engage either one or the other of the contacts 288a and 288b.

The tongue 296 constitutes a mobile contact, adapted for engaging the fixed contact 288c, for a purpose which will be explained below.

The plate 278 is provided with checks 298 to promote entry into sliding engagement with the respective fixed contacts 288a and 288b.

With the blade 274 there is associated a helical buffer spring 300, which acts between the blade itself and the base wall of the box 1 OR The buffer spring 100 tends to thrust the blade 274 angularly backwards with respect to the direction of travel of the vehicle, that is towards the shorter arm 224 of the lever 12R.

Between the shorter arm 224 and the blade 274 there is incorporated a slider, referenced generally 302. The slider 302 is composed of a piece of plastic material having a low coefficient of friction. It comprises, amongst other things, a pair of guide arms 304 and 306, which are slidably guided in corresponding bores 308 and 310 of the base wall of the box 10R. In this way, the slider 302 is guided substantially in the direction of motion of the mobile contact or blade 274, a direction which is substantially parallel to that of the steering column C and the axis XR.

The slider 302 is formed like two mutually perpendicular slide blocks referenced 312 and 314. The slide block 312 is in the form of a block elongated in a direction transverse to the shorter arm 224 of the lever 12R and engages this arm by means of a convex surface.

The plate 314 has the form of a block elongated in a direction transverse to the blade 274 and possesses a convex surface, like the preceding one, which engages the edge 316 of the blade. The buffer spring 300 keeps the two slide blocks 312,314 of the slider 302 constrained between the shorter arm 224 and the blade 274.

As will be understood, the shorter arm 224 of the lever 12R remains in engagement with the slide block 312 independently of the angular position of the arm itself and of the pivoting block 218 about the axis XR.

In this way, the slide block 314 remains continually in engagement with the edge 316.

From the slider 302 there projects an extension 315, which functions as abutment for the compression spring 290. Although the slider 302 executes a rectilinear movement and the plate 278 executes a curved movement, the radius of the latter curve is sufficiently large and the curved travel is sufficiently small for the path of the plate 278 to be considered rectilinear and parallel to the path of the extension 315. The distortions of the spring 290 are therefore negligible.

As will be understood, the angular movement of the lever 12R forwards (arrow F8, Figure 1) and backwards (arrow F7 in Figure 1) cause corresponding inverse movements (backwards and forwards) of the blade 274.

When the ball 262 is situated in the notch 266b (Figure 24) the mobile contact 278 is not operative.

When the lever 12R is displaced backwards, the ball 262 moves along the ramp 266a (Figure 25) and the mobile contact 278 comes into engagement with the fixed contact 288a, which is connected with the electrical pump of the front windscreen washer. This state continues as long as the driver keeps the lever 12R pulled towards himself. When the driver releases the lever 12R, the cam action between the ball 262 and the ramp 266a, under the force of the spring 264, brings the system into the arrangement of Figure 24, or the neutral condition.

When the driver, starting from the arrangement of Figure 24, displaces the lever 12R forwards in the direction of arrow F8, the ball 262 comes into the notch 266c and the mobile contact 278 comes into engagement with the fixed contact 288b (Figure 26).

In this situation, the motor of the rear windscreen wiper is continuously supplied from the fixed contact 288b.

If, however, the driver pushes the lever 1 2R further forwards in the direction of arrow F8, the tongue 296 of the mobile contact 278 engages the fixed contact 288c (Figure 27) from which the electrical pump of the rear windscreen wiper is supplied.

The ball 262 is then brought onto the ramp 266d.

The condition of Figure 27 persists as long as the driver keeps the lever 12R pushed forwards. When the driver releases the lever 12R, the cam action between the ball 262 and the ramp 266d, under the force of the spring 264, brings the system into the arrangement of Figure 26 and the rear windscreen wiper continues to function.

In the case of the right-hand unit AR also, the presence of the blade 274 enables sliding contacts to be obtained, in particular for the supply to the motor of the rear windscreen wiper.

The only frontal contact is that estalished between the tongue 296 and the end 288c of the conductor 289, but this contact supplies a device having a low current demand.

As will be seen, in the switching groups according to this invention, the pressure of the contacts is assured by springs as well as by the elasticity of the material of the contacts. It is therefore possible to use, for all the strip elements which constitute the mobile and fixed contacts, a material of relatively low cost, with the economic advantage which derives therefrom.

Claims (12)

1. An electrical switching unit for fitting laterally to the steering column of an automobile for controlling the operation of parts of the vehicle, the unit comprising a box which, in use, is fixed to the steering column, a control lever pivotally mounted in the box about two mutually perpendicular axes so that the lever can be rocked up and down about a substantially horizontal axis and forwards and backwards about a substantially vertical axis relative to the direction of travel of the vehicle, the lever having a longer arm extending outside the box to provide a free end accessible adjacent the periphery of the steering wheel and a shorter arm extending inside the box, mobile electrical contacts associated with the shorter arm of the lever and arranged to co-operate with fixed electrical contacts inside the box when the lever is rocked about its pivot axes, and means associated with the shorter arm of the lever and with the box for determining stable and/or unstable angular positions of the lever about its pivot axes, characterized in that at least one of the mobile contacts is a blade type contact which is movable in a direction substantially parallel to the direction of travel of the vehicle and is arranged to co-operate in a sliding manner with at least one fixed contact inside the box, the blade contact being mechanically connected to the shorter arm of the lever in such a way that rocking of the lever forwards and backwards about the substantially vertical axis produces the sliding co-operation between the blade contact and the fixed contact independently of the angular position of the lever about its substantially horizontal pivot axis.

2. A switching unit according to claim 1, in which the blade contact possesses an edge facing towards the shorter arm of the lever, and is mechanically connected to the shorter arm through a slider which is mounted in the box to slide in the direction of movement of the blade contact and which possesses two slide blocks substantially at right angles to each other, one slide block extending transversely with respect to the edge of the blade contact and being in sliding engagement with the edge, and the other slide block extending transversely with respect to the shorter arm of the lever and being in sliding engagement with the arm, there being a buffer spring which acts on the blade contact to maintain the sliding engagements of the slider with the blade contact and the shorter arm of the lever.

3. A switching unit according to claim 1 or claim 2, in which the blade contact is pivotally mounted at one end in the box and has a contact plate at its other end for engagement with the fixed contact or contacts, and resilient lateral pressure means is provided for biassing the contact plate towards the fixed contact or contacts to ensure engagement therewith when the blade contact is moved.

4. A switching unit according to claim 3, in which the blade contact comprises two parallel, pivoted blades each with a contact plate at its end opposite the pivoted end of the blade contact for engagement with oppositely spaced fixed contacts, and the resilient lateral pressure means comprises a compression spring interposed between the contact plates of the two blades, each blade being pivoted with play sufficient to permit rocking movement in the direction of thrust of the compression spring to ensure engagement of the contact plates with the fixed contacts.

5. A switching unit according to claim 3 when dependent on claim 2, in which the blade contact comprises a single pivoted blade and the resilient lateral pressure means comprises a compression spring interposed between the contact plate and an abutment extension on the slider situated alongside the contact plate, the blade being pivoted with play sufficient to permit rocking movement in the direction of thrust of the compression spring to ensure engagement of the contact plate with the fixed contacts.

6. A switching unit according to claim 4 or claim 5 when dependent on claim 2, in which the pivoted end of the blade or of each blade is flat and possesses a V-shaped notch engaging in a corresponding V-notch in a flat transversely extending member which is fixed in the box, the engagement of the V-notches being maintained by the buffer spring.

7. A switching unit according to any one of claims 4 to 6, in which the blade or one of the blades can occupy at least one position in which its contact plate does not engage a fixed contact, and in which position or positions a guide tongue at the free end of the blade is in sliding engagement with an insulating guide integral with the box to support the blade against the action of the resilient lateral pressure means.

8. A switching unit according to claim 7, in which the tongue is engageable by means of one of its lateral edges with a further fixed contact in a stop position.

9. A switching unit according to any one of the preceding claims, in which the box contains at least one series of fixed contacts situated in a plane substantially perpendicular to the substantially horizontal pivot axis of the lever and arranged along an arc of a circle concentric with the said horizontal pivot axis, and movable with the lever about the said horizontal axis is a pivoting block in which is mounted at least one contact staple so that it is slidable relative to the pivoting block in a direction substantially parallel to the said horizontal axis into sliding engagement with the series of fixed contacts under the action of a compression spring interposed between the staple and the pivoting block.

10. Switching apparatus for controlling the operation of parts of an automobile, comprising a pair of electrical switching units according to any one of the preceding claims arranged to be disposed on opposite sides of the steering column of the vehicle, the units being mounted on a single support element which is to be connected integrally with the steering column, and the boxes of the two units possessing profiled zones by which they are releasably mounted on the support element.

11. A switching unit according to claim 1, substantially as described with reference to Figures 1 to 15, or to Figures 1 to 3 and 16 to 27 of the accompanying drawings.

12. Switching apparatus according to claim 10, substantially as described with reference to the accompanying drawings.