EP0082064B1 - Small-size manostat easy to put into operation and to assemble - Google Patents

Description

The invention relates to a pressure switch comprising in a housing, a device sensitive to a fluid pressure in which this causes the displacement of a movable control member, a compression spring having a first end which communicates a force to this member to balance the pressure and a second end cooperating with an adjustment device capable of modifying the compression of this spring, an electrical switch having a pusher and internal connection terminals for receiving ends of electrical conductors, a transmission lever which communicates the movements of the movable member to this pusher, an indicator member which is linked to the displacements of the second end of the spring or to the adjustment device and comprises an index moving opposite a set pressure scale, this housing having on its surface, on the one hand a pressure orifice connected internally to the sensitive device and externally to a source of pre ssion of fluid to be monitored, and a connection opening through which the electrical conductors pass, and on the other hand, a fixing face and a front face opposite thereto.

Such an apparatus is intended for example to start and stop a compressor group whose engine is controlled by the switch and whose air tank is connected to the sensitive device in order to maintain the pressure of this tank at a certain level.

There are already control devices with the general constitution mentioned above.

Thus, by patent FR 2380 590 there is known a control device capable of detecting pressure changes and comprising a support box, a switch carried by the box and comprising a movable control member urged by a return member, a device for pressure sensitive actuation and a lever system pivotally mounted on the housing and cooperating with the switch and actuation device, and a mechanism for adjusting the position of the lever according to the pressure detected.

Similarly, patent FR 1 224 907 describes a pressure switch controlled by a fluid pressure, in which said pressure acts in a closed enclosure on a movable wall against a calibrated spring whose state of compression can be adjusted by screwing a screw. This movable wall is, moreover, mechanically connected, by a lever, to a switch.

It turns out that in these devices the respective provisions of the elements which constitute them do not allow an easy assembly in the factory, nor a rational installation in the installations which implement them: these disadvantages become all the more important as the number of devices to be manufactured or installed side by side in facilities, becomes higher.

In addition, these devices are frequently subjected to significant vibration regimes, which subject their organs to internal stresses which are all the higher as these organs are large.

The invention therefore proposes to provide a compact pressure switch in which the measures taken will result in increasing robustness. to facilitate assembly in the factory, to reduce the space necessary for its installation and to facilitate the latter.

• un axe de mouvement d'un organe mobile de commande appartenant à un dispositif détecteur de pression,
• un axe de rotation d'un organe de réglage agissant sur un ressort d'équilibrage de pression placé dans le plan médian et relié à l'organe de commande,
• un axe de déplacement d'un poussoir d'interrupteur actionné par un levier de transmission du mouvement, mobile dans ce plan médian,
• un axe d'orifice de pression coaxial à l'axe de mouvement et un axe d'ouverture de raccordement électrique, ces axes étant parallèles entre eux et à la face de fixation,
• cet orifice et cette ouverture étant placés sur une même face de connexion perpendiculaire au plan médian et à la face de fixation.

It achieves these results thanks to a pressure switch comprising a housing having, on the one hand, a rear fixing face which is opposite and parallel to a front face carried by a closure cover, and having, on the other hand, a plane median which is parallel to two walls separated by a small width compared to the height and which contains:

• an axis of movement of a mobile control member belonging to a pressure sensing device,
• an axis of rotation of an adjustment member acting on a pressure balancing spring placed in the median plane and connected to the control member,
• an axis of movement of a switch pusher actuated by a movement transmission lever, movable in this median plane,
• a pressure orifice axis coaxial with the movement axis and an electrical connection opening axis, these axes being parallel to each other and to the fixing face,
• this orifice and this opening being placed on the same connection face perpendicular to the median plane and to the fixing face.

According to the invention, this pressure switch is more particularly characterized in that the fixing face is perpendicular to the median plane, while the front face has a movable indicator member parallel to the axis of movement, and that the associated balancing spring to a coaxial adjustment member accessible on said front face are placed in a region opposite to the connection face, the axis of rotation of this adjustment member being perpendicular to this fixing face.

• la figure 1 représente une vue schématique en perspective du manostat,
• la figure 2 montre schématiquement une vue de côté en coupe par le plan PP' de la figure 1, dans laquelle on aperçoit les principaux éléments,
• la figure 3 représente schématiquement une vue de face du manostat,
• la figure 4 illustre un mode de réalisation avantageux du manostat dans une vue de côté de coupe correspondant à celle de la figure 2,
• la figure 5 représente une vue avant en coupe partielle par le plan AA' d'une rondelle de l'organe de réglage,
• la figure 6 représente une vue avant d'un écrou de l'organe de réglage,
• la figure 7 illustre une vue avant de l'appareil, couvercle monté,
• la figure 8 montre en coupe partielle une vue de côté de l'appareil au cours du démontage ou du remontage du couvercle, et
• les figures 9 et 10 représentent deux variantes de réalisation du levier de transmission et de l'interrupteur.

Other complementary measures, as well as a preferred but nonlimiting embodiment, will appear better on reading the description below and on examining the figures among which:

• FIG. 1 represents a schematic perspective view of the pressure switch,
• FIG. 2 schematically shows a side view in section through the plane PP 'of FIG. 1, in which the main elements are seen,
• FIG. 3 schematically represents a front view of the pressure switch,
• FIG. 4 illustrates an embodiment advantageous of the pressure switch in a sectional side view corresponding to that of FIG. 2,
• FIG. 5 represents a front view in partial section through the plane AA ′ of a washer of the adjusting member,
• FIG. 6 represents a front view of a nut of the adjustment member,
• FIG. 7 illustrates a front view of the device, cover mounted,
• FIG. 8 shows in partial section a side view of the device during the disassembly or reassembly of the cover, and
• Figures 9 and 10 show two alternative embodiments of the transmission lever and the switch.

The pressure switch 1 visible in Figure 1 has been broken down into a number of elementary volumes each receiving one of the elements or group of elements necessary for the performance of its function, and is shown in a position corresponding to that which will be recommended because of the direction in which a pressurized fluid line and an electrical connection cable will be connected later. The pressure switch 1 comprises a prismatic housing 2 see also Figures 2 and 3, the width m, measured between two vertical parallel lateral faces 3, 4, is substantially less than the height h measured vertically. A rear face 5, rectangular like a front face 13 which is opposite to it, is used for fixing the housing to a frame or a support 6 having a vertical plane Q which contains this face 5, see FIGS. 1 and 2.

In a first volume 7 located in the vicinity of the rear face 5 and being in a lower region 8 of the housing, is placed a device 9 sensitive to the pressure in which the latter causes the displacement of a mobile control member 10; in a second volume 11 located in an upper region 12 of the housing, which extends from the fixing face 5 to the front face 13, are placed a compression spring 14 and an adjustment device 15, 15 'accessible on the front face; in a third intermediate volume 16, placed between the two preceding volumes, is disposed a transmission lever 17 which communicates the movements and the position of the control member 10 to the pusher 18 of a switch 19 which is itself located in a fourth volume 20 placed between the first volume 7 and the front face 13, finally, a fifth volume 21 placed between the second, third and fourth volumes on the one hand, and the front face 13 on the other hand, receives an indicator member 22 the index of which cooperates with a scale 23 visible from the side of the front face, see FIG. 3. The fifth volume 21 extends to the second volume 12, because of the connections which will be established between the indicating member and either the second end of the spring, or a part of the adjustment device, as will appear later.

Finally, on a lower face 24 of the housing 1 is placed a pneumatic connection orifice 25, accessible from the bottom up, which is placed in the vicinity of the fixing face 5 and must receive a pipe end 26 for driving a pressure external to the device sensitive 9, as well as a passage opening 27 through which a cable or electrical conductors 28 will have to be connected to terminals of the switch; the orifice 25 is, moreover, placed closer to the plane Q, and to the fixing face 5, than is the opening 27 which is itself closer to the front face 13.

If we refer to Figure 2, we see that the control member 10 moves along an axis XX ', that the compression spring 14, which is constituted by a helical spring, has an axis of symmetry YY ', that the pusher 18 moves along an axis ZZ', that the index of the indicator member 22 moves along an axis TT ', that the orifice 25 has an axis VV' and that the opening 27 has an axis SS '.

The axis YY 'is substantially perpendicular to the plane Q, to the fixing face 5 and to the front face 13, and the axes XX', TT ', VV' and SS ', are substantially parallel to each other and to the front face , see figure 2; moreover, all of these axes are substantially contained in a median plane PP ', which passes equidistant from the parallel lateral faces 3 and 4 and which is perpendicular to the plane Q, see FIG. 3.

A transmission lever 17, contained in the third volume 16, oscillates for example around an axis RR 'which is substantially perpendicular to the median plane P.

In an advantageous embodiment visible in FIG. 4, the elements having the same functions as above will be defined by the same references.

The housing 2 comprises a hollow body 29 which has an interior space closed by a substantially flat cover 30, placed at the front of the housing to form the front face 13 oppo-. attached to the fixing face 5.

The pressure-sensitive device 9 comprises a control member constituted by one end 10 of a cylindrical rod 31 sliding along the axis XX 'in a bore 32 of the body. This rod is associated with a concentric pusher 33, a portion 34 of which passes through an opening 35 of an annular seat 36 which is placed in a second bore 37 of the body concentric with the first; one end of the pusher, opposite to the control member 10, has a head 38 of revolution which is placed in a first chamber 39 of the annular seat; this chamber is closed by a flexible membrane 40, the periphery of which is applied to the seat by an annular surface 41 of a plug 42 having a second chamber 43 opposite the first and connected by a channel 44 to the pneumatic connection orifice 25 whose axis is VV '. This plug 42 is fixed to the body 29, for example using screws such as 45.

When a pressure P is present at the orifice 25, a force, directed towards the top of the figure, is applied to the head 38 by the membrane, and tends to lift the control member 10.

The movement of this control member 10 is communicated to a support piece 47 belonging to a second lever 46, which is pivoted around a cylindrical pin 48 of axis WW ', perpendicular to the plane of the figure which is the median plane PP'; this lever also comprises, a lug 49 substantially parallel to the axis WW ', which is, in the rest position shown in this figure, supported on a boss 50 forming part of the bottom 51 of the body opposite the rear fixing face 5.

This boss has a threaded hole 52 into which is screwed and blocked a first end 53 of a threaded rod 54 whose axis YY 'is perpendicular to the rear faces 5 and front 13.

On the end 55 of this threaded rod opposite the first, is engaged a thread belonging to a nut 56 which also has a cylindrical housing 57 opposite the rod and an external shoulder 58. This nut constitutes an adjustment piece which will be moved by an adjustment member identified by 15 'in Figures 2 and 3 and. described later.

Against one face 59 of this shoulder, directed towards the end 53, is placed a washer 60 which has a radial extension 61 and a diametrically opposite notch 62, see in particular FIG. 5. This notch cooperates with an internal rib 98 of the body which is parallel to YY '. A helical spring 14 is placed concentrically at YY 'around the threaded rod and in such a way that a first end 14' is supported on the tab (49) and that a second end 14 "is supported on the washer 60 .

The compression of this spring, which is communicated via the first lever 46 to the control member 10, can therefore balance a force imparted to the latter by the fluid pressure.

This compression of the spring can be adjusted by communicating to the nut 56 a rotation in one direction or the other; during this rotation, the washer 60 moves parallel to the axis YY 'and without rotating on itself. The rotation of this nut is obtained by virtue of the presence thereon of surfaces 63 parallel to the axis YY ', on which bear opposite ends of a pin 64 placed diametrically in one end 65 of a member adjustment 15 which enters the housing 57. These surfaces 63 may for example be carried by a notch 66 which passes through the wall 67 of the nut surrounding the housing 57, the end 65 then being placed coaxially in the housing, see also figure 6.

The adjusting member 15 ′ has an external head 68 provided for example with a screwdriver slot 69 which will facilitate its operation, and a cylindrical surface 70 which is pivoted in a bearing 71 of the cover 30. Retaining means, such as 'a circlip, 72 make the adjustment member secured to the cover. The nut 56 and the adjustment member together constitute the adjustment device 15, 15 '.

• une première pièce de guidage 75 ayant une portion transparente 76 externe qui remplit cette fenêtre et une première surface d'appui 82 interne,
• une seconde pièce de guidage 77 qui est placée contre la première pièce de guidage le long d'une seconde surface d'appui 78 ayant comme la première surface d'appui une première portion plane 79 parallèle à la face avant 13 du couvercle, une seconde portion courbe 80 et une troisième portion plane 81 sensiblement perpendiculaire à la première portion.

The cover also has a vertical window 73, see also FIG. 7, and receives on its internal face 74 elements belonging to a pressure indicator member 22, namely:

• a first guide piece 75 having an external transparent portion 76 which fills this window and a first internal bearing surface 82,
• a second guide piece 77 which is placed against the first guide piece along a second bearing surface 78 having, like the first bearing surface, a first planar portion 79 parallel to the front face 13 of the cover, a second curved portion 80 and a third flat portion 81 substantially perpendicular to the first portion.

Between this first bearing surface 78 and the second bearing surface 82 of the same outline belonging to the second part, there is a corridor 83 which follows the same path and has an inlet 84 at the end of the third portion 81. L entry 84 could possibly be placed at the end of the curved portion if the latter was located substantially opposite the extension 61.

These two guide parts are made integral with the cover by simple means which are not illustrated in the figure, such as for example an adhesive or elastic hooking means.

A flexible strip 85 is arranged in the corridor 83 in such a way that its end 86 which leaves the entry 84, is associated with the extension 61 of the washer 60 placed opposite, for example by virtue of an opening 87; the second end 88 of the ribbon which is placed in the first portion 79 carries an index 89 cooperating with the graduations 90 of a scale 23, see FIG. 7; this can either be engraved on the transparent portion, or preferably, carried by a self-adhesive label 91 which takes for example the shape of a rectangular frame whose periphery 92 covers the edges of the window and those of the portion transparent 76, thus ensuring sealing, see FIGS. 7 and 4.

A second lever 93 extending substantially parallel to the axis YY 'and pivoting around a pin 94 of axis RR' perpendicular to the median plane P, has a first fulcrum 95 applied to a shoulder 96 of the control member and a second support point 97 opposite the first.

This second movable fulcrum in a direction ZZ of the plane PP 'substantially parallel to the axis XX' is placed opposite a pusher 18 belonging to a switch 19 having connection terminals preferably directed towards the cover and suitable receiving ends of conductors 26.

These conductors, possibly protected by a sheath, pass through a passage opening 27 of the body and of axis SS ′, which can be fitted with a cable gland, not shown.

The pneumatic connection orifice 25 is placed like the pressure-sensitive device, in the vicinity of the fixing face 5, while the passage opening 27 is placed, as the switch, in the vicinity of the cover 30, this orifice and this opening opening onto the lower face 24.

This arrangement which facilitates access to the terminals of the switch, nevertheless requires that the. cover is separated from the body to make the electrical connection; during this separation, see FIG. 8, which takes place parallel to the axis YY ′, the pin 64 of the adjusting member 15 emerges from the notch 66 of the nut 56 after having run a stroke d 'a certain length P, and the flexible tape 85 which remains attached to the washer 60, 61, escapes from the corridor 83, when the cover has made a stroke q parallel and greater than p.

The choice of these p and q values makes it possible, at the time of replacing the cover (dotted position), to first engage the end 88 of the ribbon 85 in the inlet 84 before engaging the pin 64 in the notch 66, the latter engagement being more convenient to perform than the previous one.

The preferred embodiment of the invention which has just been described may undergo adjustments which do not modify the general arrangement of the main elements.

Thus the removable coupling established between the nut and the adjustment member could be obtained by equivalent means, or by an obvious reversal of the position of the pin, which could come on the nut, and of the notch which could be practiced on the control member.

One could also use only one lever simultaneously performing the functions of the first and second lever. This latter variant would not, however, give the device the advantageous independence between the pressure balancing function and the control function of the electric switch which is provided by the preferred embodiment of FIG. 4.

The latter makes it possible in particular to give the levers different transmission ratios to satisfy their own function and above all makes it possible to prevent the wear appearing on the pin 48, which is heavily loaded by the spring, modifying the point of engagement and tripping of the switch. Finally, the position of the switch in the housing remaining unchanged, it is possible to use switches whose pusher is oriented differently. Thus, in the variant visible in FIG. 9, the pusher 100 of the movable switch along TT 'in the plane P is placed between the pressure-sensitive device 9 and the switch 101 and that in the visible variant in FIG. 10, the push-button 102 of the movable switch, also along TT ′, is placed between the switch 103 and the cover 30. In these two cases, the transmission levers 104 respectively 105 must include a bent branch 106 respectively 107 to communicate to the pusher the movements of the control member; in order to obtain in FIG. 9 a movement of the branch 106 of the lever 104, capable of causing the push-button 100 to be pushed in, it may for example be necessary to place a pivot 108 of this lever 104 between the bottom 51 of the body and the control unit 10.

The respective provisions of the parts constituting this pressure switch as well as their embodiment make it possible to obtain the desired results in full and at low cost.

In an alternative embodiment not shown, the adjusting nut could be extended outwards by a cylindrical rod passing through an opening in the cover; this embodiment would however deprive the device of the benefit provided by a substantially flat front face, since this rod would exceed, depending on the set pressure selected, by a greater or lesser amount. However, such a variant falls within the scope of the invention, as well as that where the flexible strip carries a movable ladder and where the fixed index is placed on the cover or on the window.

Claims (3)

1. A manostat comprising a case having, on the one hand, a rear securing surface (5) opposite and parallel to a front surface (13) borne by a closing lid, and having, on the other hand, a median plane (PP') parallel to two walls which are separated by a small width with respect to the height and which contains :

an axis of movement (XX') of a movable control member (10) belonging to a pressure detection device (9),

an axis of rotation (YY') of a setting member (15, 15') which operates a pressure balancing spring (14) which is located in the median plane (PP') and connected to the control member (10),

an axis (ZZ') of movement of the pusher (18) of a switch (19) operated by a motion transmitting lever (17) which moves in said median plane (PP'),

an axis (VV') of a pressure orifice (25) coaxial to the axis of movement (XX') and the axis (SS') of an electric connection aperture (27), these axes being mutually parallel and parallel to the securing surface (5),

this orifice (25) and this aperture (27) being located on the same connection surface (24) perpendicular to the median plane (PP') and to the securing surface (5),

characterized in that the securing surface (5) is perpendicular to the median plane (PP'), whereas the front surface (13) has a display member (22) moving parallel to the axis of movement (XX') and in that the balancing spring (14), together with a coaxial setting member (15) accessible on said front surface, are located in a region (12) opposite the connection surface (24), the axis of rotation (YY') of said setting member being perpendicular to said securing surface (5).

2. A manostat according to claim 1, characterized in that a second lever (46), which pivots in the median plane (P) transmits the movements of the movable controll member (10) to one end (14') of the balancing spring (14) adjacent to the bottom (51) of the rear surface (5).

3. A manostat according to one of claims 1 or 2, characterized in that the case (2) comprises a hollow body (29) which has the connection aperture (27) and a plug (42) which comprises the pressure orifice (25) and which is secured on the connection surface (24).

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