EP0251841B1 - Electrical contactor - Google Patents

Description

The present invention relates to an electrical contactor and, more particularly, to such a pressure-controlled contactor usable in fluid pressure systems such as hydraulic or pneumatic systems installed in a vehicle.

Fluid pressure systems often include pressure switches set to respond to different pressures to control the operation of devices such as pumps, solenoid valves, alarm or safety devices, or to control commissioning brake control systems, for example, found in particular in motor vehicles.

To reduce the number of pressure switches present in such systems, contactors capable of responding to several pressure values have been produced. French patent FR-A-2 300 408 describes such a contactor which comprises in particular a snap-action contact assembly of the "bi-stable" type, the tilting position of which does not correspond to the same displacement (and therefore pressure) values. for both directions of movement. The contactor described thus makes it possible to regulate the fluid pressure in a circuit between these two values, by controlling the starting and stopping of a pump inserted in the circuit, at the two ends of the differential pressure range thus defined.

Although such a contactor can give satisfaction in certain applications, it should be noted that the precision of the limits of the pressure range which it defines depends closely on the quality of the production of a spring of the "bi-stable" type in particular. its cut, its modulus of elasticity, etc. In other applications for which it is desired to precisely adjust the limits of the pressure range, independently of one of the other, it may not be possible to be satisfied with the possibilities of a contactor of the type described in the aforementioned patent.

German patent DE-A-1,690,393 discloses a double-break electrical contactor comprising at least one contact bridge movable in translation and in rotation so that the two contacts of the same bridge close successively. This contactor, designed to improve the closing and breaking powers of double-breaking electrical devices, is not designed to ensure the sequential closing of more than two pairs of contacts at separate times, according to three pressure levels. fluid for example.

The object of the present invention is therefore to produce an electrical contactor comprising at least three pairs of electrical contacts whose tilting conditions (from the open state to the closed state, or vice versa) can be adjusted with precision, according to a determined sequence. by the evolution of a physical quantity such as a fluid pressure, for example.

The present invention also aims to produce such a contactor associated with manometric means, for controlling a pump acting on the pressure of a fluid, so as to maintain the latter within a predetermined range, by switching the state of 'a pair of electrical contacts at each of the two limits of this range.

Another object of the present invention is to provide such a contactor capable of controlling not only a fluid pump so that the fluid pressure is maintained within a predetermined range, but also signaling members sensitive to the passage of the fluid pressure through a predetermined pressure value outside this range, to then emit in an alert signal.

These aims of the invention are achieved, as well as others which will appear below, with a contactor. electric, of the type comprising a control member movable in translation to pass through at least first, second and third positions each corresponding to the change of state of at least first, second, third and fourth pairs of electrical contacts which can be opened or closed, first and second bars which carry first and second, third and fourth, respectively, electrical contacts forming part of the first and second, third and fourth pairs of contacts, respectively, the control member cooperating with these bars to make each rotate around an axis of rotation perpendicular to the axis of translation of the control member, so that at each end of a rotational stroke, each bar changes the state of one of the pairs of electrical contacts associated with this strip, contactor characterized in that the control member comprises a one-piece interpo part between the two bars which are loaded towards each other and towards this part which has at least two bearing surfaces protruding axially from the control member and each arranged opposite one of the bars to act on it and cause it to tilt by a rotational stroke around an axis passing through a pair of contacts, the member being movable between these two bars to sequentially trigger the change of state of the four pairs of contacts, at the ends of the rotational travel of the bars, when it moves from one end to the other of its travel in translation, the surface of support cooperating with the contiguous part of the control member to receive the bar in a fixed position relative to this member, so as to allow movement in translation of the bar, beyond its rotational travel.

According to another characteristic of the invention, the position of the control member depends on the pressure of a fluid via a pressure member. The contactor according to the invention is then used to regulate the pressure of this fluid so that it remains within a predetermined pressure range, by an appropriate control of a pump for pressurizing this fluid.

The contactor also allows, in such a application, to control the commissioning or deactivation of a device, such as a computer, associated with a fluid pressure system.

• les figures 1 à 4 sont des vues en coupe axiale du contacteur suivant l'invention, illustrant quatre états différents de ce contacteur,
• la figure 5 représente une partie d'un circuit de commande de pression de fluide qui comprend un contacteur suivant l'invention,
• les figures 6 à 8 sont des vues analogues à celle des figures 1 à 4, d'un deuxième mode de réalisation du contacteur suivant l'invention, et
• la figure 9 représente un circuit analogue à celui de la figure 5 et comprenant le contacteur des figures 6 à 8.

Other characteristics and advantages of the contactor according to the invention will appear on reading the description which follows, associated with the examination of the appended drawing in which:

• FIGS. 1 to 4 are views in axial section of the contactor according to the invention, illustrating four different states of this contactor,
• FIG. 5 represents a part of a fluid pressure control circuit which comprises a contactor according to the invention,
• FIGS. 6 to 8 are views similar to that of FIGS. 1 to 4, of a second embodiment of the contactor according to the invention, and
• FIG. 9 represents a circuit similar to that of FIG. 5 and comprising the contactor of FIGS. 6 to 8.

Referring to Figure 1 where it appears that the contactor according to the invention has a generally cylindrical shape with a longitudinal axis referenced 1. The contactor is composed of a housing 2 and an actuating cylinder 3 joined by a nozzle coupling 4. The housing 2 contains a one-piece control member 5 slidably mounted along the axis 1. The control member 5 is integral with an axial rod 6 which enters the coupling endpiece 4, where it is loaded towards the right by a compressed helical spring 7. The control member 5 acts on four pairs of electrical contacts 8, 9, 10 and 11. In the inactive position of FIG. 1, it appears that the pairs of contacts 8 and 11 are contact-work while the pairs of contacts 9 and 10 are contact-rest. Each of these pairs of contacts consists of an electrical contact secured to the housing 2 while the other contact is carried by a movable bar. The contactor comprises two such bars, referenced 12 and 13 respectively, each bar carrying each of its ends an electrical contact forming part of one of the four pairs of contacts. The contacts of the same strip are electrically connected to each other because each strip is made of an electrically conductive material. Compressed coil springs 14,15 load the bars 12,13 towards each other. An electrical contact 16 is centered on the axis of the control member 5, between the wall of the housing 2 and the spring 14, to be electrically connected to the bar 12 by means of the spring 14. Schematic adjustment screws in 17 and 18 allow to adjust the position of the integral contacts of the housing 2, in the pairs of contacts 9 and 10, respectively, for purposes which will be described later.

A metal part 19, pressed against the bottom of the housing, is electrically connected to ground. This part 19 has two protrusions, (19ʹ; 19ʺ) which each constitute one of the contacts of the pairs of contacts 10 and 11 (see Fig. 2).

As seen above, the control member 5 is movable in translation along the axis 1. It is moved to the left by the thrust of a piston 20 contained in the actuator cylinder 3, this piston 20 cooperating itself with a control rod 21 which pushes the piston to the left, from the point of view of FIG. 1. The position of this control rod on the axis 1 can be, for example, a function of the pressure of a fluid. In the position shown in Figure 1, the piston 20 is supported on the end of the control rod 21, under the action of a spring 22 operating in compression. In this position, the left end of the piston 20 remains separated from the right end of the rod 6, integral with the control member 5.

In FIG. 1, it is clear that a bearing surface 5ʹ of the control member pushes the strip 13, against the action of the spring 15 operating in compression, so as to prevent the closure of the pairs of contacts 8 and 11. It will be noted that, in this position, the strip 13 is inclined on the axis 1 so that the distance separating the contacts from the pair 8 is greater than the distance which separates the contacts from the pair 11. At the same time the bar 12 closes the contacts 9 and 10 under the action of the spring 14 operating in compression, the control member 5 then being moved away from the bar 12 so as to have no action thereon.

If from the state of the contactor shown in FIG. 1, the pressure in the fluid which controls the axial position of the rod 21 increases, the piston 20 comes to push the rod 6 integral with the control member 5 towards the left which separates the bearing surface 5ʹ formed on the control member, of the bar 13 which then begins to move to the left under the pressure of the spring 15. The pressure continuing to increase, the contacts 11 close , and, from this moment if the pressure continues to grow, the bar 13 pivots around a perpendicular axis in 19ʺ the axis 1, so that its other end 13 approaches, under the action of the spring 15, the fixed contact of the pair of contacts 8, until these contacts are closed (see Figure 2). The contacts 8 and 11 are thus earthed via the part 19. This grounding occurs at the moment when a predetermined pressure is reached in the fluid which controls the displacement of the rod 21. The closing of the contacts 8 and 11 can then be used to energize an electrical or electronic device associated with the fluid pressure system equipped with the connector according to the invention, as will be seen below in connection with FIG. 5.

As the pressure in the fluid continues to increase, the control rod 21 and the control member 5 continue to move to the left, from the point of view of the drawing, until a second bearing surface 5ʺ (see FIG. 2) of the control member 5 comes to push the bar 12, to a second determined pressure value, to open the contacts 10 without opening the contacts 9. According to the invention, this result is achieved by shaping the control member so that the bearing surface 5ʺ projects to the left (from the point of view of the drawing) of the left side of this organ (see Figure 3). Thus, when this bearing surface 5ʺ comes to bear on the strip 12 in the vicinity of the contacts 10, the control member rotates the strip 12 around an axis perpendicular to the axis 1 and centered on the pair of contacts 9 , to open the pair of contacts 10. This rotation of the strip 12 continues until this strip comes to rest in a stable manner on the left face of the control member 5, as shown in FIG. 3.

If the fluid pressure of the monitored system then continues to increase, the bar 12 then moves in translation parallel to the axis 1, carried by the control member 5, which causes the opening of the pair of contacts 9 to a third predetermined pressure value (see Fig. 4).

Conversely, if the pressure then begins to decrease, the contacts 9 and 10 will close successively. The closing of these contacts can be used to control the electrical supply of a pump placed in the fluid circuit of the monitored system, so as to maintain the fluid pressure within a pressure range whose limits are determined by the values for which the control rod 21 causes, through the control member 5, the opening or closing of the contacts 9 and 10. Similarly a significant pressure drop in the system, accidental for example, will cause the opening of the pairs of contacts 8 and 11 and therefore switching off the electrical or electronic device mentioned above.

According to the invention, adjusting screws 17 and 18 make it possible to adjust the position of the fixed contact of the pairs of contacts 9 and 10, by simple deformation of this fixed contact. This makes it possible to adjust, independently of one another, the pressure levels to which correspond a change of state of the pairs of contacts 9 and 10. It is thus possible to adjust the position and the width of the pressure range monitored. Of course, and although this is not apparent from the drawing, the fixed contact of the pair of contacts 8 could be equipped with the same adjustment means.

Referring now to Figure 5, where there is shown a portion of an electrical circuit for controlling a fluid pressure device which makes use of the contactor according to the invention. In this figure, the various electrical contacts bear the same numerical references as those appearing in FIGS. 1 to 4, which represent the contactor according to the invention, this to facilitate understanding of the operation of the circuit. The fluid pressure device can be, for example, used to apply the brakes of a motor vehicle. Such a device comprises a fluid circuit in which there is a pump actuated by an electric motor M supplied by the vehicle battery. The device further comprises an audible and / or visual alarm member 31 placed in series with a switch 32 controlled by the vehicle ignition key, a switch electrically connected to the vehicle battery. Pairs of contacts 8, 11 define a contact-work switch interposed between the alarm member and the earth.

The pump motor is controlled by a contact-work relay 33. The coil 33ʺ of the relay is connected on the one hand to the common point to the switch 32 and to the alarm device 31 and, on the other hand contact 16 common to the pairs of contacts 9 and 10 defining contact-rest switches. A diode 34 is interposed between the contacts 9 and the point common to the power supply wire of the motor M and to the controlled switch 33ʹ by the winding 33ʺ of the relay 33. This diode prevents the current from the motor M from flowing to earth through the pairs of contacts 9 and 10. It is clear that the contacts 8,11,9,10,16, are assembled in a contactor according to the invention, in accordance with the corresponding references in FIGS. 1 to 4.

The circuit of FIG. 5 reacts to the passage of pressure, in the monitored fluid circuit, by three pressure values P₁, P₂, and P₃, increasing in this order. When the vehicle starts, the switch 32 closes and the coil 33ʺ of the relay is supplied to close the switch 33ʹ which places the pump motor under tension. The pressure in the fluid circuit then begins to increase under the action of the pump. When this pressure passes through the value P₁, the contacts 8,11 close to energize the alarm member 31. The pressure then continuing to increase up to the value P₂, the contact-rest switch 10 opens to disconnect the contact-rest switch 9 from the ground without disturbing the operation of the pump. Indeed, the current flowing through the coil 33ʺ of the relay can flow to ground via the switch 9 and the diode 34 as well as by the switch 33ʹ of the relay itself. The pressure continuing to increase the switch 9 opens when this pressure reaches the value P₃. Relay 33 is then de-energized and switch 33ʹ opens to cut the power to the pump motor. The pressure in the fluid circuit then begins to drop and when this reaches the value P₂, the switch 10 closes again to energize the winding 33ʺ of the relay 33, which has the effect of closing the switch 33ʹ and power the pump again. This supply causes the pressure to rise to the value P₃ where again the switch 9 opens so that this pressure drops again and thus remains in the pressure range bounded by the values P₂ and P₃.

As we saw above, we can adjust independently the values of P₁, P₂ and P₃ by acting on the position of the contacts, for example using adjusting screws.

It will be noted that with the circuit of FIG. 5 and the contactor of FIGS. 1 to 4, if the pressure in the fluid circuit drops, for example accidentally, below the value P₁, the computer is automatically put out of service and the driver is only warned of this fact by the extinction of the lamp, phenomenon which can escape him because it is not a positive signal, that is to say a signal perceived by an emission of energy, sound or light, for example, likely to attract the driver's attention. The decommissioning of the computer is an event which must however be brought to the attention of the driver for safety reasons because the behavior of the vehicle during braking period is modified. In general, a drop in the fluid pressure in the brake circuit below a certain level must be signaled to the driver because it can be indicative of a breakdown, for example a leak, which requires a stop emergency.

According to the present invention, the driver is informed as to the commissioning of the computer in an even more perceptible manner thanks to the contactor of FIGS. 6 to 8, as incorporated in the circuit of FIG. 9. This contactor makes it possible to control the supply of two signaling or alarm members and no longer of a single one, the supply switching from one member to the other when the pressure passes by the value P₁. Thus the transition is marked by the emission of two different and successive positive signals, which is likely to attract the attention of an observer.

In most of their arrangements the contactors of Figs. 1 to 5 and 6 to 9 are identical or very similar. We will only describe below the parts of the contactor of FIGS. 6 to 9 which are not found in the description of the contactor of FIGS. 1 to 5, the Identical or very similar members of these two contactors being identified by the same reference numeral. Reference will be made to the preceding description of the contactor of FIGS. 1 to 5 with regard to these contactor members of FIGS. 6 to 9.

The latter essentially differs from the previous embodiment with regard to the shape of the strip 13ʹ which replaces the strip 13 and the contacts associated therewith. It will also be noted in FIG. 6 that a bearing surface 5 ‴ of the control member pushes the strip 13 against the action of the spring 15 operating in compression, so as to prevent the closure of the pair of contacts 8.

According to the present invention, the bar 13 'has an end 13ʺ shaped so as to bypass a fixed contact 23 of the pair of contacts 11, end which rests on the left face (from the point of view of FIGS. 6 to 8) of this fixed contact. Thus, in the position occupied by the bar 13ʹ in FIG. 6, inclined on the axis of translation of the member 5, the pair of contacts 8 is open while the pair of contacts 11 is closed. It will be noted that the line of action of the bearing surface 5 ‴ on the bar 13ʹ is spaced vertically (from the point of view of FIG. 1) from the line of action of the reaction of contact 23 on the end 13ʺ of this bar. Thus is exerted on this bar a couple oriented in a clockwise direction, which exceeds the force exerted by the spring 15 on this bar, force which would tend to rotate the bar in the opposite direction, around an axis perpendicular to the plane of FIG. 1 and passing through the contacts 11.

At the same time, the strip 12 closes the pairs of contacts 9 and 10 under the action of the spring 14 operating in compression, the control member 5 then being moved away from the strip 12 to be without action on the latter.

If, from the state of the contactor shown in Figure 6, the pressure in the fluid which controls the axial position of the rod 21 increases, the piston 20 pushes the rod 6 integral with the control member 5 to the left, which moves the bearing surface 5 ‴ formed on the control member to the left, the bar 13 then begins to rotate counterclockwise around the contacts 11, under the pressure of the spring 15. As the pressure continues to increase, the contacts 8 close (Fig 2), and, at from this moment, if the pressure continues to grow, the bar 13ʹ pivots clockwise around an axis perpendicular at 8 to axis 1, so that its other end 13ʺ moves away, under the action of the spring 15, of the fixed contact 23 of the pair of contacts 11, until the opening of these contacts (see FIG. 3). This rotation of the bar is stopped by a stop 24.

Fig. 7 therefore represents the contactor according to the invention at the time of the transition between the closing of the contacts 8 and the opening of the contacts 11, which results from the tilting of the rotation of the strip 13 'from one direction of rotation to the opposite direction . This tilting has the effect of connecting the contacts 8 to ground via the bar 13ʹ and of the spring 15 and cutting the connection to this same ground of the fixed contact 23 of the pair of contacts 11.

According to the invention, this tilting is used to cut off the supply to a first electrical or electronic member or device and to energize a second electrical or electronic member or device, when the pressure in a fluid, which determines the axial position of the control member 5, passes through a predetermined value. We will describe below, in conjunction with FIG. 9, a fluid pressure regulation circuit which takes advantage of this characteristic of the contactor according to the present invention.

Reference is therefore now made to FIG. 9, where a part of an electrical circuit for controlling a fluid pressure device which uses the contactor of Figs. 6 to 8. In this figure, the various electrical contacts bear the same numerical references as those appearing in Figures 6 to 8, this to facilitate understanding of the operation of the circuit. The fluid pressure device can be, for example, used to apply the brakes of a motor vehicle. Such a device comprises a fluid circuit in which there is a pump actuated by an electric motor M supplied by the vehicle battery. According to an essential characteristic of the present invention, the device further comprises two electrical signaling members 31 and 35, by audible and / or visual alert, each connected in series with a switch 32 controlled by the vehicle ignition key, switch electrically connected to the vehicle battery. Pairs of contacts 8, 11 define a rocker switch interposed between the signaling members 31, 35 and the ground, respectively. An apparatus 36, such as an electronic computer used in an anti-skid braking device for a motor vehicle, is placed in series with the display member 31. This computer modulates the pressure in a circuit for using a fluid brake forming part of the device.

The pump motor is controlled by a contact-working relay 33. The coil 33ʺ of the relay is connected on the one hand to the common point with the switch 32 and the signaling members 31 and 35 and, on the other hand to the contact 16 common to the pairs of contacts 9 and 10 defining contact-rest switches. This part of the circuit is identical to the corresponding part of the circuit in fig. 5 and will not be described further.

The circuit of FIG. 9 like that of FIG. 5, reacts to the passage of pressure, in the monitored fluid circuit, by three pressure values P₁, P₂, and P₃, increasing in this order and corresponding to the switchings of the switches (8,11,13ʹ), 10 and 9 respectively .

According to the invention if, accidentally, the pressure of fluid leaves the range (P₂, P₃) to descend below P₁, for example due to a pump failure or a leak in the brake fluid circuit, the driver perceives, when passing the pressure at the value P₁, not only the extinction of the emission of the member 31 but also the triggering of an emission by the member 35. If these emissions are bright, it will be possible to provide different colors for the emissions of the organs 31 and 35, constituted for example by light bulbs or light-emitting diodes arranged on the dashboard of a motor vehicle as indicator lights. Thus, will the driver be alerted to the drop in pressure below the level P₁, with the computer being deactivated, by a positive signal that is easier to perceive than the simple disappearance of the signal emitted by the device 31 , as was the case in the control circuit of FIG. 5. This arrangement improves the safety of the driver in that it allows him to be more surely alerted of the drop in pressure in the braking circuit in order to react by result.

As indicated for the contactor in FIGS. 1 to 4, the values P₁, P₂ and P₃ can be adjusted independently by acting on the position of the contacts, for example using adjusting screws.

The contactor according to the invention performs several switches with precision, using a single contactor allowing a reduction in manufacturing costs.

Of course the embodiment described and shown has only been described by way of example.

Thus, the pairs of contacts 8, 11 on the one hand, 9, 10 on the other hand, could be made completely independent of one another by producing the support strips for the conductive contacts in a material not electrically conductive, and by providing between these contacts and the connection circuits electrical connections by flexible wires, for example.

Likewise, quantities other than a fluid pressure could be regulated by a circuit comprising a contactor according to the invention. Various transducers well known to those skilled in the art make it possible to convert such a physical or electrical quantity, for example, into a displacement of the control member of the contactor.

Claims (11)

1. Electrical contactor of the type including a control member which moves in translation in order to pass through at least first, second and third positions each corresponding to the change of state of at least first 8, second (9), third (10) and fourth (11) pairs of electrical contacts which can be open or closed, first and second bars (12, 13) which carry first and second, and third and fourth pairs of contacts, respectively, the control member (5) working in conjunction with these bars (11, 12) in order to make each of them turn about an axis of rotation perpendicular to the axis of translation (1) of the control member in such a way that at each of the ends of a rotational travel, each bar changes the state of one of the pairs of electrical contacts associated with this bar, the contactor being characterized in that the control member (5) includes a monobloc part interposed between the two bars (12, 13) which are weighted towards each other and towards this part which includes at least two bearing surfaces (5', 5"; 5", 5"') projecting axially from the control member and each placed facing one of the bars in order to act on the latter and to make it swing through a rotational travel about an axis passing through a pair of contacts, the member (5) being movable between these two bars in order to sequentially trigger the change of state of the four pairs of contacts, at the ends of the rotational travels of the bars, when it moves from one end to the other of its translational travel, and in that the bearing surface (5") works in conjunction with the adjacent part of the control member in order to receive the bar (12) in a fixed position with respect to this member, in such a way as to allow a translational displacement of the bar, beyond its rotational travel.
2. Contactor according to Claim 1, characterized in that the bearing surface (5") axially protrudes from the control member in order to receive the bar (12) in a position inclined to the translation axis of the control member, beyond the rotational travel of the bar.
3. Contactor according to Claim 1, characterized in that the control member passes through first, second and third successive positions on its translation axis, respectively corresponding to the closing of the contacts of a pair of contacts forming a first make-contact electrical switch and to the opening of the contacts of second and third break-contact switches.
4. Electrical contactor according to Claim 1, characterized in that the first and second pairs of contact (sic) of a bar (13') include first and second fixed contacts respectively which work successively in conjunction with the bar (13') in order to make the latter turn in first and second opposite directions of rotation respectively about axes passing through the first and second fixed contacts respectively in order to change the state of the second and first pairs of contacts respectively.
5. Contactor according to claim 4, characterized in that the bar is electrically conducting and connected to ground through the body of the contactor, this bar (13') constituting with the first and second pairs of contacts (8, 11) a changeover switch connected to ground through the bar.
6. Contactor according to either of Claims 4 or 5, characterized in that the control member passes through first, second and third successive positions on its translation axis, the first position corresponding with the closing of one of the first and second pairs ...(sic) contacts (8, 11) and with the opening of the other, the second and third positions corresponding with the change of state of third and fourth pairs of contacts (9, 10) associated with the other bar (12).
7. Contactor according to any of the preceding claims, characterized in that the contacts of a same bar are electrically connected.
8. Contactor according to any of the preceding claims, characterized in that it includes means of adjustment of the change of state positions of the pairs of electrical contacts.
9. Application of the contactor according to either of Claims 3 or 4, to the regulation of a fluid pressure established by a pump driven for (sic) an electric motor, characterized in that the axial position of the control member is adjusted by the fluid pressure, and in that the pairs of contacts (9, 10) of the bar (12) are included in a circuit (33, 34) controlling the power supply to the motor in order to maintain the pressure of the fluid between two predetermined values (P₂, P₃).
10. Application according to Claim 9 of the contactor according to Claim 4, to the switching of the power supplies to two electrical signalling elements for a predetermined value (P₁) of the fluid pressure, characterized in that the switch (8, 11, 13') is associated with two electrical power supply circuits for the two electrical signalling elements designed to emit positive distinct signals, to switch off the power of one of them and switch on that of the other when the fluid pressure passes through this predetermined value.
11. Application according to Claim 10, characterized in that the changeover switch (8, 11, 13') switches off the power supply to a computer controlling the value of the fluid pressure in an operational circuit, when the pressure in the pump circuit drops below the said predetermined value (P₁), this switch also controlling the switching on of the computer when the pressure in the pump circuit rises above this predetermined value.

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