DOUBLE MEMBRANE ANTI-OVERFLOW DEVICE FOR ELECTRIC PUMPS OF WINDSHIELD WASHERS

Abstract: Said device is comprised of an adressing chamber CD which houses two membranes ( M1 , M2/ M3 , M4/ M5 , M6/ M7 , M8 ) of high flexibility which may be provided with means for compensating the loss of elasticity. In the absence of washing liquid pressure, the two membranes (M1 , M2/ M3 , M4/ M5 , M6/ M7 , M8 ) close permanently, by their proper elastic action and, in their case by the action of the means of compensation for the elasticity loss, the corresponding outlets ( 4a, 3a ) of the chamber ( C, D ). As a function of the rotation direction of the pump turbine, the washing liquid will cause elastic deformation of the corresponding membrane ( M1 , M2/ M3 , M4/ M5 , M6/ M7 , M8 ), allowing the passage of washing liquid through the associated outlet line (3, 4). When the turbine stops rotating, the aforesaid membrane reinstates the closing action on the outlet ( 3a, 4a) . Applicable to the car industry.

Description: Field of the Invention The object of the present invention is a double diaphragm leakproof sealing device for electric windscreen washer pumps which is applicable, in particular, to motor vehicles provided with equipment for cleaning the front and rear glazed surfaces. Background of the Invention It is well known that in motor vehicles provided with equipment for cleaning the said surfaces, such equipment is provided with an electric pump which is coupled to an auxiliary cleaning liquid reservoir and which may be operated at will by the vehicle user. Also known are double acting pumps, i.e. those which operate selectively, by rotating in one direction or the other to direct the liquid flow towards the front of the vehicle or towards the rear. In these cases, the user has available the corresponding control member to be able to select the surface(s) on which the cleaning liquid is to be sprayed and the corresponding operation of the wiper blades associated with said surfaces. By such selection, the user may spray the cleaning liquid on the windscreen and, even, simultaneously on the head-lamps or spray the cleaning liquid on the rear window of the vehicle. To such end, the known double acting pump embodiments are provided with a device for directing the cleaning liquid which is aspirated from the auxiliary reservoir by the suction and discharge impeller mounted in such pumps towards one or the other of such surfaces. This directing depends precisely on the direction of rotation applied by the electric drive motor to the suction and discharge impeller. The known directing devices essentially comprise, in general, a directing chamber housing a diaphragm acting as a sealing valve. The directing chamber is arranged close to the pumping chamber where the pump suction and discharge impeller is housed. Both the pumping and directing chambers are connected together by passages through which the cleaning liquid pumped by the said impeller flows alternately, depending on the direction of rotation of the suction and discharge impeller, with said directing chamber being provided with passages for the delivery of the cleaning liquid. The ports of said inlet and outlet passages are located, for each of the directions of rotation of the impeller in respective opposite sides of the directing chamber such as to define a chamber in which there is housed, intermediate said ports, a diaphragm which, as said above, acts as a stop valve. The said diaphragm is highly resilient and may be delected depending on the pressure exerted by the cleaning liquid pumped by the suction and discharge impeller so that, depending on the direction of rotation of said impeller, it stoppers one or the other of the ports of the cleaning liquid outlet passages, while the cleaning liquid may flow freely through the remaining outlet port towards the corresponding points of use. Exemplary of said embodiments of directing devices is Spanish utility model ES-U-287,059 for "Double directing device for electric windscreen washer pumps" which, further to the novel elements characterising it, comprises the operative members described in the foregoing paragraphs. In general, the known embodiments of directing devices described suffer, as main drawback, from the fact that their diaphragm occupies an intermediate position between the said cleaning liquid inlet and outlet passages. When not under pressure from the cleaning liquid, i.e., when the impeller is not in operation, the diaphragm does not stopper either of the ports of the outlet passages or stoppers only one of them, depending on the form it adopts after each use. Under these conditions, when the auxiliary cleaning liquid reservoir is at a higher level than the nozzles for spraying said liquid on the corresponding surfaces, said liquid flows freely and leaks out for a simple difference of head level, as happens for example, when transporting the vehicle from the works in a steeply inclined position. Another operative drawback of the known directing devices is that during the early moments of operation of the suction and discharge impeller, the diaphragm is in an indeterminate position and does not produce an effective seal, whereby the sealing of the corresponding discharge port is imperfect and a certain amount of liquid is discharged therethrough. This means that during the start up time of the pump some cleaning liquid is discharged over a surface or surfaces which the user had not selected for cleaning. DE-U-8 620 253.7 reveals a double feed pump comprising a directing chamber with two valve elements formed by diaphragms. Said diaphragms control the supply of two liquid discharge passages in such a way that upon applying a pressurized liquid each diaphragm may open against the force of a spring disposed intermediately between the two diaphragms scaling the conduit between an inlet and the discharge passage. Upon a pressure drop in the passing liquid the diaphragms will close the pasage and seal it under the force of the intermediate spring. The diaphragms according to this document, however, disadvantageously comprise holes or cavities in the center thereof for accommodating the spring. As can be seen from figure 1 the connection portion 232 of the diaphragms is furthermore weak and therefore not able to reconstitute the sealing state without the force of the intermediate spring. The assembly of the diaphragms with a spring between them is, however, a complicated operation which on the other hand renders the production process expensive. Lastly the weakened portions of these proposed diaphragms influence the sealing properties thereof in a negative way. From the British patent application GB-A-2 202 133 a windscreen washer pump and valve assembly is known, which comprises a pumping chamber and a directing chamber with two inlets and outlets for cleaning liquid and a valve system comprised of two diaphragms between which a spring is interposed. The working principle of this valve system essentially resembles the one of DE-U-8 620 253.7 having therefore the same disadvantages concerning low rigidity of the diaphragms and high production and assembling expenses. As can be derived from the sole figure of this document and the corresponding description, it is the intermediate spring which presses the diaphragms onto the outlet ports of the pumping chamber. Since pot shaped housings for the spring are needed, it is impossible for the diaphragm under liquid pressure to transmit the force of said pressure directly to the other diaphragm and thereby reinforce the sealing action on the closed outlet port. This means that, as there is furthermore a small distance between the inner ends of the two parts of the pot shaped spring housing, neither a direct transmission of a reinforcing sealing pressure nor a self-reconstitution of the diaphragm with good sealing properties can be achieved without a variety of component parts including a spring. It is therefore the object of the present invention to propose a double-diaphragm leak-proof sealing device which overcomes the above-mentioned drawbacks of the prior art and which, in particular, provides a self-reconstituting valve element using diaphragms with excellent sealing properties. This object is obtained by a double-diaphragm leak-proof sealing device of the type disclosed e.g. in GB-A2 202 133 or DE-U-86 20 253.7 and showing the features as presented in the characterizing part of claim 1. The fact that the axial sealing extensions of both diaphragms mounted in the leakproof sealing device of the invention permanently bear against the ports of the discharge passages when the suction and discharge impeller is not operating prevents the cleaning liquid from flowing by simple difference of head level from the auxiliary reservoir to the liquid spray nozzles for the corresponding surfaces. Furthermore, the action of the cleaning liquid pumped by the suction and discharge impeller on the diaphragms of the device depends on the direction of rotation of said impeller. When the suction and discharge impeller rotates in one direction, the cleaning liquid is forced into one of the two half chambers defined by the diaphragms of the device according to the invention, which causes the corresponding diaphragm to free the respective cleaning liquid discharge port by resilient deformation from the axial sealing extension formed on the convex surface side of the said diaphragm so that the cleaning liquid can flow through the corresponding discharge passage. Simultaneously, the other diaphragm continues to press against the corresponding discharge port by way of the axial sealing extension thereof, the said sealing action being reinforced by the resilient deformation of the diaphragm under the pressure of the cleaning liquid. When the suction and discharge impeller ceases to operate and, thus, the cleaning liquid ceases to act on the diaphragm the latter resiliently recovers the original position thereof, sealing the discharge port. Rotation of the suction and discharge impeller in the opposite direction to the one described above causes a symmetrical operation of the device leading to the same results, but relating to the other diaphragm and to the corresponding discharge passage. In this way, operation of the suction and discharge impeller has no effect on the cleaning liquid contained in the discharge passage still stoppered by the corresponding diaphragm, thereby preventing said cleaning liquid from being pumped towards surfaces not selected by the user. According to trials that have been performed, the embodiment constructed according to the new features described above is fully satisfactory, but has the drawback of having a rather limited life, which may be negative when it is expected that the windscreen washer device will be subjected to intensive continuous use, in view of the environmental conditions of the places where the vehicle is to be used. In fact, when the device diaphragms reach approximately 3,000 or 4,000 work cycles, the loss of resilience or fatigue of the material forming the diaphragms may prevent correct operation of the said device. This deterioration is caused by using as constituent material of the diaphragms one of those considered to be the most suitable among those currently known, such as among others: silicone rubber; NBR (butadiene-nitrile-acrylic rubber); and, EPDM (ethylene-propylene-diene terpolymer) rubber. To overcome this operational limitation, the invention also relates to embodiments specially designed to ensure a long average life for the two diaphragms of the device. Consequently, according to an embodiment of the invention, the device comprises means for compensating the loss of resilience of the two diaphragms of the device. Such compensating means is formed by pressure extensions of preferably essentially cylindrical form which, arranged coaxially relative to the axial sealing extensions of the convex surface sides are formed symmetrically with the concave surface sides of both diaphragms. At the free ends thereof, such pressure extensions are separated apart so that when the cleaning liquid is pumped by the suction and discharge impeller in one direction or the other, the resilient deformation or opening stroke of the corresponding diaphragm during the opening of the associated discharge port is limited by the pressure extension of the other diaphragm opposite thereto and, when the suction and discharge impeller is stopped, the resilient deformation or closing stroke of said diaphragm stoppering the said discharge port is reinforced by the action of auxiliary recovery means. According to one embodiment, the auxiliary recovery means comprises, on the axial sealing extensions of the convex surface sides of both diaphragms, respective large axial recesses. According to another embodiment, the auxiliary recovery means comprises an O-ring arranged in the intermediate central chamber of the directing chamber, between the inner edges of both diaphragms. The O-ring is provided with through holes which through corresponding holes provided for the purpose in the pump body member act as an inlet for the atmospheric pressure, establishing a direct communication between the said intermediate central chamber and the environment. It is obvious that the provision of the resilience loss compensating means described does not alter the essential mode of operation of the leakproof sealing device of the invention. In fact, the start up of the suction and discharge impeller and the consequent pressure of the cleaning liquid will cause the resilient deformation or opening stroke of one or the other of the two diaphragms of the leakproof sealing device, thereby freeing the corresponding discharge port through which the cleaning liquid will freely flow. The said resilient deformation or opening stroke is limited by the pressure extension of the other diaphragm opposite thereto,whereby said resilient deformation is smaller than the resilient deformation produced in the absence of compensating means and, consequently, the constituent material of the diaphragm is subject to less fatigue, lengthening its average life to a great extent. On the other hand, stoppage of the suction and discharge impeller and the consequent lack of cleaning liquid pressure will cause the resilient deformation or closing stroke of the said diaphragm. The closing action will be reinforced by the operation of any of the auxiliary recovery means whose features have been described in the foregoing paragraphs and, consequently, as happens during the opening stroke, the constituent material of the diaphragm is subject to less fatigue. In this way, the above described resilience loss compensating means provides the two diaphragms with an average life which is much longer than the average life obtained with such diaphragms when no compensating means is used. Brief Description of the Drawings The double diaphragm leakproof sealing device for electric windscreen washer pumps of the invention is represented in the sheets of drawings of the present specification. In the drawings: Figure 1 is a cross-section view of one embodiment of the device of the invention. Figure 2 is a cross-section view of the embodiment of the device of the invention shown in Figure 1 illustrating the action of the cleaning liquid on one of the device's diaphragms. Figure 3 is a cross-section view of a further embodiment of the device of the invention. Figure 4 is a cross-section view of the embodiment of the device of the invention shown in Figure 3 illustrating the action of the cleaning liquid on one of the device's diaphragms. Figure 5 is a cross-section view of a further embodiment of the device of the invention incorporating compensating means. Figure 6 is a cross-section view of the embodiment of the device of the invention shown in Figure 5 illustrating the action of the cleaning liquid on one of the device's diaphragms. Figure 7 is a cross-section view of a further embodiment of the device of the invention incorporating compensating means. Figure 8 is a cross-section view of the embodiment of the device of the invention shown in Figure 7 illustrating the action of the cleaning liquid on one of the device's diaphragms. Detailed Description of the Embodiment Figures 1 and 2 and Figures 3 and 4 show, as stated above, respective embodiments of the double diaphragm leakproof sealing device for electric windscreen washer pumps according to the invention. In both embodiments, the leakproof sealing device of the invention comprises a directing chamber CD and two diaphragms, which are identical to one another, and referenced for differentiation as M1 and M2 in said Figures 1 to 4. Figures 1 and 2 show one embodiment of the directing chamber CD , said embodiment corresponding to cases in which the diaphragms M1 and M2 work vertically. Figures 3 and 4 show another embodiment of the directing chamber CD , in which said embodiment corresponds to cases in which the diaphragms M1 and M2 work horizontally. Both embodiments of the directing chamber CD of the device of the invention are provided with equivalent elements which, for purposes of a clearer explanation, will be identified, both in the description and in the drawing sheets, with the same reference symbol, the elements of the embodiment of the directing chamber CD shown in Figures 3 and 4 being differentiated with the prime (') notation. Figures 1 and 2 show how the directing chamber CD is formed in the interior of one of the ends of the pump body CB which has been shown in part in said Figures. The directing chamber CD is connected, by way of the inlet passages 1 and 2, to the pumping chamber 3 containing the pump suction and discharge impeller which, for a clearer understanding of the description, has not been shown in the drawings. The passages 1 and 2 are tangential to the pumping chamber 3 and, in this embodiment shown in Figures 1 and 2, they are located on the same side of the directing chamber CD where they form respective inlet ports 1a and 2a . The cleaning liquid pumped by the suction and discharge impeller may flow through said passages 1 and 2. In one of the directions of rotation of the impeller, the cleaning liquid will be forced through one of the passages, 1 or 2, and in the opposite direction of rotation of the impeller, the cleaning liquid will be forced through the other passage. In this way, the cleaning liquid pumped by the suction and discharge impeller may enter the directing chamber CD through one of the inlet ports, 1a or 2a , but never through both at the same time. In this embodiment, as shown in Figures 1 and 2, the pump body CB is formed with the discharge passages 3 and 4 which are longitudinally aligned. The said discharge passages 3 and 4 are extended longitudinally over approximately the same distance into the directing chamber CD by the tubular portions marked 3p and 4p , the respective ends of which define corresponding discharge ports 3a and 4a . The discharge ports 3a and 4a which, as may be seen in the Figures, are opposite each other, have the front edge thereof perpendicular to the longitudinal axis of the discharge passages 3, 4. Figures 1 and 2 show how the arrangement of the inlet ports 1a and 2a and of the discharge ports 3a and 4a define in the mid-portion of the directing chamber CD a central chamber CC in which the diaphragms M1 and M2 of this embodiment of the device of the invention are located. The tubular portion 3p of the discharge passage 3 and the tubular portion 4p of the discharge passage 4 are concentric in the directing chamber CD with the tubular extensions 5 and 6 formed on the pump body CB and acting as structural reinforcement for said pump body CB . According to the embodiment of the directing chamber CD shown in Figures 3 and 4, the chamber CD is also formed on one of the ends of the pump body CB' which has been shown in part in said Figures. The directing chamber CD is connected to the chamber containing the suction and discharge impeller, which have not been shown in said Figures 3 and 4 for the same reasons as given above, by the inlet passages 1' and 2' formed in said directing chamber CD on the opposed top and bottom sides thereof. Like in the embodiment of the directing chamber CD shown in Figures 1 and 2, the cleaning liquid pumped by the suction and discharge impeller may flow through said passages 1' and 2' . Depending on the direction of rotation of said impeller, the cleaning liquid will be pumped through one or other of said passages, but never through both at the same time. In this embodiment of the directing chamber CD shown in Figures 3 and 4, the discharge passages 3' and 4' formed in the pump body CB' are provided with respective discharge ports 3a' and 4a' which are opposite each other and are longitudinally aligned. Figures 3 and 4 show how the inlet passages 1' and 2' and the discharge ports 3a' and 4a' are arranged in such a way as to define in the mid-portion of the directing chamber CD the central chamber CC' in which the diaphragms M1 and M2 of this embodiment of the device of the invention are located. According to the embodiment of the directing chamber CD shown in Figures 1 and 2, the cleaning liquid pumped by the suction and discharge impeller follows, for one of the directions of rotation of the impeller, the path determined by the inlet passage 1, the chamber CD and the discharge passage 4 and, for the other direction of rotation of the impeller, the path determined by the inlet passage 2, the chamber CD and the discharge passage 3. According to the embodiment of the directing chamber CD shown in Figures 3 and 4, the cleaning liquid pumped by the suction and discharge impeller follows, for one of the directions of rotation of the impeller, the path determined by the inlet passage 1' , the chamber CD and the discharge passage 4' and, for the other direction of rotation of the impeller, the path determined by the inlet passage 2' , the chamber CD and the discharge passage 3' . The above described operation of the directing chamber CD is known and said chamber CD may take on any other shape appropriate for the needs that may arise in each particular application of the leakproof sealing device of the invention. Each of the diaphragms M1 and M2 of both embodiments of the leakproof sealing device of the invention, shown in Figures 1 and 2 and 3 and 4, respectively, is essentially cylindrical. Both longitudinal ends are formed with respective recesses defining, at one end, a convex surface 7 and, at the other of said ends, a concave surface 9. The convex surface 7 of the diaphragms M1 and M2 is formed with an axial sealing extension 9 which is cylindrical and is dimensioned functionally to mate with the discharge ports 3a and 4a , in the embodiment illustrated in Figures 1 and 2 and with the discharge ports 3a' and 4a' in the embodiment shown in Figures 3 and 4. In the embodiment of the device of the invention shown in Figures 1 and 2, the diaphragms M1 and M2 are arranged in the central chamber CC in such a way that the concave surfaces 8 thereof are longitudinally aligned opposite to each other and the respective axial sealing extensions 9 thereof resiliently bear permanently on the discharge ports 3a and 4a , respectively, as shown in Figure 1. The perimetral slot 10 formed in the central chamber CC partly houses and retains both diaphragms M1 and M2 so that these define two half chambers SC1 and SC2 which are not in fluid communication with each other through the directing chamber CD , as shown in Figures 1 and 2. In the embodiment of the device of the invention shown in Figures 3 and 4, in a similar way as described above for the embodiment shown in Figures 1 and 2, the diaphragms M1 and M2 are arranged in the central chamber CC' in such a way that the respective concave surfaces 8 thereof are longitudinally aligned opposite to each other and the axial sealing extensions 9 thereof resiliently bear permanently on the discharge ports 3a' and 4a' , respectively as shown in detail in Figure 3. The central chamber CC' is formed with the perimetral slot 10' which partly houses and retains both diaphragms M1 and M2 so that these define two half chambers SC1' and SC2' which are not in fluid communication with each other through the directing chamber CD , as shown in Figures 3 and 4. The operation of the embodiment of the leakproof sealing device of the invention according to Figures 1 and 2 is as follows: Figure 1 shows how, when the suction and discharge impeller is stopped, the axial sealing extensions 9 of the diaphragms M1 and M2 resiliently bear against the discharge ports 3a and 4a , respectively. In this way, it is impossible for the cleaning liquid contained in the auxiliary liquid reservoir to flow by simple head level difference to the discharge passages 3 and 4, since it is prevented by the diaphragms M1 and M2 stoppering said discharge ports 3a and 4a ; Figure 2 shows how the cleaning liquid pumped towards the half chamber SC2 by the suction and discharge impeller in one of the directions of rotation thereof acts on the diaphragm M2 , which action is resiliently to deform said diaphragm M2 so that the cleaning liquid may flow through the discharge port 4a and flow along the passage 4 to the corresponding points of use; simultaneously, the resilient deformation of the diaphragm M2 compresses the diaphragm M1 so that the latter has an increased sealing action on the discharge port 3a . In this way, the cleaning liquid contained in the passage 3 is not subjected to any pressure caused by operation of the impeller, thereby avoiding the uncontrolled projection of cleaning liquid on surfaces which have not been selected by the user for cleaning; when the suction and discharge impeller stops rotating and, consequently, the action of the cleaning liquid on the diaphragm M2 ceases, the latter resiliently recovers the position shown in Figure 1, with the initial service state of the device being recovered; rotation of the suction and discharge impeller in the opposite direction to the one described above produces a symmetrical operation of the leakproof sealing device, i.e. in this case it will be the diaphragm M1 which is subjected to the action of the cleaning liquid pumped by the impeller, so that said liquid will leave the directing chamber CD through the discharge passage 3 and the diaphragm M2 will be compressed so as to increase the sealing action thereon against the port 4a of the discharge passage 4. When the impeller stops rotating, the diaphragm M1 will return resiliently to the position shown in Figure 1. The operation of the embodiment of the leakproof sealing device of the invention according to Figures 3 and 4, in which the diaphragms M1 and M2 work horizontally, is as follows: Figure 3 shows the position adopted by the diaphragms M1 and M2 when the suction and discharge impeller is stopped. In this position, the axial sealing extensions 9 of the diaphragms M1 and M2 stopper, respectively, said discharge ports 3a' and 4a' ; Furthermore, Figure 4 shows how, when the suction and discharge impeller is rotating in one direction thereof, the inflow of the cleaning liquid through the passage 1' into the half chamber SC2' causes resilient deformation of the diaphragm M2 and consequently the cleaning liquid flows through the discharge passage 4' to the corresponding points of use; When the suction and discharge impeller stops, the diaphragm M2 resiliently recovers the position shown in Figure 3; rotation of the suction and discharge impeller in the opposite direction to the one described above produces a symmetrical operation of the leakproof sealing device, i.e. the inflow of the cleaning liquid into the half chamber SC1' will cause the resilient deformation of the diaphragm M1 and, consequently, the cleaning liquid will flow through the discharge passage 3' and the diaphragm M2 will be compressed so as to increase the sealing action thereof against the discharge port 4a and when the suction and discharge impeller stops rotating, the diaphragm M1 will return resiliently to the position shown in Figure 3. As stated above, Figures 5 to 8 of the drawings show other embodiments of the double diaphragm leakproof sealing device for electric windscreen washer pumps of the invention which, complementing the embodiments of the device of the invention shown in Figures 1 to 4, incorporate compensating means for the loss of resilience of the two constituent diaphragms. In the following description of the embodiments of the leakproof sealing device of the invention shown in Figures 5 to 8, said devices are applied to the embodiment of the directing chamber CD shown as an example in Figures 1 and 2. This embodiment of the directing chamber CD corresponds to the cases in which the two constituent diaphragms of the device of the invention operate in the vertical position. Logically, the embodiments of the device of the invention shown in Figures 5 to 8 are equally applicable without any loss of operativeness to those cases in which the constituent diaphragms of the device according to the invention operate horizontally, i.e. in directing chambers CD such as the one detailed as embodiment in said Figures 3 and 4. The embodiment of the device of the invention shown in Figures 1 and 2 and the embodiments of the device shown in Figures 5 to 8 are provided with equivalent means whereby, for the purposes of a clearer understanding, both in the following description and in said Figures 5 to 10, such equivalent means will bear the same reference numbers. Even where differences of structure or shape not affecting the invention are to be appreciated, the same reference numbers are maintained. Figures 5 and 6 show another embodiment of the leakproof sealing device of the invention in which, the same as described in the preceding embodiments, the two vertical constituent diaphragms, referenced with M5 and M6 , are housed in the intermediate central chamber CC of the directing chamber CD of the lower end of the pump body CB . According to this further embodiment of the device of the invention shown in Figures 5 and 6, the resilience loss compensating means comprises the two pressure extensions 17 which are formed respectively and symmetrically on the concave surface sides 18 of the diaphragms M5 and M6 and the two large axial recesses 19 which are formed respectively on the axial sealing extensions 20 of the convex surface sides 21 of the diaphragms M5 and M6 . As shown in Figures 5 and 6, the pressure extensions 17 are essentially cylindrical in shape and are arranged coaxially relative to the axial sealing extensions 20 formed on the convex surface sides 21 of both diaphragms M5 and M6 . The large axial recesses 19 formed on the axial sealing extensions 20 of the diaphragms M5 and M6 are essentially frustoconical in shape and the smaller ends are opposite, respectively, the cleaning liquid discharge ports 4a and 3a . Figures 7 and 8 show a further embodiment of the leakproof sealing device of the invention in which, like has been described for the preceding embodiments, the two constituent diaphragms thereof, which are referenced as M7 and M8 , are housed in the intermediate central chamber CC of the directing chamber CD at the lower end of the pump body CB . According to this further embodiment of the device of the invention shown in Figures 7 and 8, the resilience loss compensating means comprises the two pressure extensions 22 which are respectively and symmetrically formed on the concave surface sides 23 of the diaphragms M7 and M8 , and the O-ring 24 which is located between the inner edges of both diaphragms M7 and M8 . As shown in Figures 7 and 8, the pressure extensions 22 are essentially cylindrical are are arranged coaxially relative to the axial sealing extensions 25 which are formed on the convex surface sides 26 of both diaphragms M7 and M8 . In this embodiment, the O-ring 24 is directly compressed by the inner edges of the diaphragms M7 and M8 although, logically, it may occupy any other intermediate position between both diaphragms M7 and M8 , without this affecting the operativeness thereof. Figures 9 and 10 show how the O-ring 24 has two radial through holes 27 which, through corresponding through holes 28 formed in the lower end of the pump body CB , act as communication with the atmosphere, setting up direct communication between the intermediate central chamber CC and the environment. The embodiment of the leakproof sealing device of the invention shown in Figures 5 and 6 is as follows: Figure 5 shows how, when the suction and discharge impeller is stopped the axial sealing extensions 20 stopper the cleaning liquid discharge ports 4a and 3a , respectively, by the resilient action of the diaphragms M5 and M6 ; Figure 6 shows the action exerted by the cleaning liquid pumped into the half chamber SC2 by the suction and discharge impeller in one direction of rotation thereof on the diaphragm M5 . This action consists of a resilient deformation or opening stroke of the diaphragm M5 , freeing the discharge port 4a through which and through the passage 4 the cleaning liquid is directed to the points of use, the opening stroke of the diaphragm M5 being limited by the pressure extension 17 of the diaphragm M6 ; the presence of the axial recesses 19 confers a semi-articulated structure on the axial sealing extensions 20 of the diaphragms M5 and M6 , with a tendency to flex in the weaker areas thereof when sujected to external actions, such as the deformation caused by the action of the cleaning liquid, and it is precisely the tendency to recover the position of least effort that will help effectively in the recovery of the sealing position of the diaphragm when the cleaning liquid ceases to flow and, therefore, the pressure against the diaphragm is relieved; when the suction and discharge impeller stops and the pressure of the cleaning liquid against the convex surface 21 of the diaphragm M5 is freed, the latter resiliently recovers the initial position illustrated in Figure 5. This resilient recovery or closing stroke is reinforced by the action of the axial frustoconical recess 19 formed on the sealing extension 20 of the diaphragm M5 ; rotation of the suction and discharge impeller in the opposite direction to the one described above causes a symmetrical operation of the leakproof sealing device, i.e., to summarize, the opening stroke of the diaphragm M6 will be restricted by the pressure extension 17 of the diaphragm M5 and the closing action on the discharge port 3a will be reinforced by the axial frustoconical recess 19 formed on the axial sealing extension 20 of the diaphragm M6 . The operation of the embodiment of the leakproof sealing device of the invention shown in Figures 7 and 8 is as follows: Figure 7 shows how, when the suction and discharge impeller is stopped the axial sealing extensions 25 of the diaphragms M7 and M8 stopper the discharge ports 4a and 3a , respectively, by their own resilient action; Figure 8 shows the action exerted by the cleaning liquid pumped into the half chamber SC2 by the suction and discharge impeller in one direction of rotation thereof on the diaphragm M7 . This action consists of a resilient deformation or opening stroke of the diaphragm M7 , freeing the discharge port 4a through which and through the passage 4 the cleaning liquid is directed to the points of use and of the partial expulsion of the air contained in the intermediate central chamber CC to the environment through the through holes 27 and 28 of the O-ring 24 and of the pump body CB respectively, the opening stroke of the diaphragm M7 being limited by the pressure extension 22 of the diaphragm M8 ; when the suction and discharge impeller stops and the pressure of the cleaning liquid against the convex surface 26 of the diaphragm M7 is relieved, the latter resiliently recovers the initial position illustrated in Figure 7. This resilient recovery or closing stroke is reinforced by the entry of air in the intermediate central chamber CC through the said through holes 27 and 28 caused by the depressing action of the resilient recovery of the diaphragm M7 ; rotation of the suction and discharge impeller in the opposite direction to the one described above causes a symmetrical operation of the leakproof sealing device, i.e., to summarize, the opening stroke of the diaphragm M8 will be restricted by the pressure extension 22 of the diaphragm M7 and the closing action on the discharge port 3a will also be reinforced by way of the depressing action of the diaphragm M8 . According to the tests performed, the embodiments of the leakproof sealing device of the invention shown in Figures 1 to 4, i.e. the embodiments of the device in which the diaphragms M1 and M2 do not have resilience loss compensating means, the number of working cycles that said diaphragms M1 and M2 attain without loss of operativeness of the device is approximately 3,000, as stated above. On the other hand, in tests performed with the embodiments of the leakproof sealing device of the invention shown as example in Figures 5 to 8, i.e. the embodiments of the leakproof sealing device in which the constituent diaphragms comprise resilience loss compensating means, the number of working cycles which said diaphragms attain, in any of the embodiments, without loss of operativeness of the device is at least 30,000, this result being far superior to the 3,000 working cycles attained by the diaphragms M1 and M2 of the embodiments of the leakproof sealing device shown in Figures 1 to 4 which do not have resilience loss compensating means.

Claims: A double diaphragm leakproof sealing device for electric windscreen washer pumps comprising: a directing chamber ( CD ) arranged at a short distance from a pumping chamber (3) containing a cleaning liquid suction and discharge impeller driven by the electric windscreen washer pump, both chambers ( CD , 3) being in communication over preferably two passages (1, 2; 1' , 2' ), the respective ends (1a, 2a) of which debouch independently in the directing chamber ( CD ), the ports of the preferably two cleaning liquid discharge Passages ( 3a , 4a ; 3a ', 4a' ) being arranged in the directing chamber ( CD ) in such a way that, in correspondence with the respective inlet ports (1a, 2a), they define, an intermediate central chamber ( CC ); wherein said intermediate central chamber ( CC ) houses and retains two diaphragms ( M1 , M2 ; M5 , M6 ; M7 , M8 ), arranged one adjacent to the other so as to define in the directing chamber ( CD ) two half chambers (SC1, SC2; SC1' , SC2' ) in each of which there are located one of the inlet passage (1, 2) ports (1a, 2a) and the port ( 3a , 4a ; 3a' , 4a' ) of the corresponding cleaning liquid discharge passage (3, 4; 3a , 4a ) in such a way that there is no fluid communication between said half chambers ( SC1 , SC2 ; SC1' , SC2' ) across said diaphragms ( M1 , M2 ; M5 , M6 ; M7 , M8 ), each of said diaphragms( M1 , M2 ; M5, M5 ; M7 , M8 ) having, on one side thereof, a convex surface (7, 21, 26) and, on the other side, a concave surface (8, 18, 23), characterized in that the convex surface sides (7, 21, 26) are formed with respective axial sealing extensions (9, 20, 25) dimensioned in functional correspondence with the respective ports ( 3a , 4a ; 3a ', 4a ') of the discharge passages (3, 4; 3' , 4' ) which they face and against which they permanently bear when the cleaning liquid is not pumped by the suction and discharge impeller, that both diaphragms ( M1 , M2 ; M5 , M6 ; M7 , M8 ) are arranged in the intermediate central chamber ( CC ) in such a way that the respective concave surfaces (8, 18, 23) thereof are mutually opposite a relatively short distance apart, that the two diaphragms ( M1 , M2 ; M5 , M6 ; M7 , M8 ) are made of highly resilient materials, and that the sealing action of the diaphragm pressing against its corresponding port (3a , 4a , 3a' , 4a' ) of the discharge passage (3, 4, 3', 4') in one of the two half chambers (SC1, SC2) is reinforced by the resilient deformation of the other diaphragm under pressure of the cleaning liquid as it is pumped towards the other half chamber (SC2, SC1). A double diaphragm leakproof sealing device for electric windscreen washer pumps according to claim 1, characterized in that the two constituent diaphragms thereof comprise means for compensating the loss of resilience, said compensating means consisting of pressure extensions (17, 22) of preferably essentially cylindrical form which, arranged coaxially relative to the axial sealing extensions (20, 25) of the convex surface sides (21, 26) are formed symmetrically with the concave surface sides (18, 23) of both diaphragms ( M5 , M6 ; M7 , M8 ), said pressure extensions being spaced apart at the free ends thereof, so that when the cleaning liquid is pumped by the suction and discharge impeller in one direction or the other of rotation, the resilient deformation or opening stroke of the corresponding diaphragm ( M5 , M6 ; M7 , M8 ) during the opening of the associated discharge port ( 3a , 4a ) is limited by the pressure extension (17, 22) of the other diaphragm opposite thereto and, when the suction and discharge impeller is stopped, the resilient deformation or closing stroke of said diaphragm ( M5 , M6 ; M7 , M8 ) stoppering the said discharge port ( 3a , 4a ) is reinforced by the action of auxiliary recovery means. A double diaphragm leakproof sealing device for electric windscreen washer pumps according to claim 2, characterized in that the auxiliary recovery means comprises, on the axial sealing extensions (20) of the convex side (21) of both diaphragms ( M5 , M6 ), respective large axial recesses (19). A double diaphragm leakproof sealing device for electric windscreen washer pumps according to claim 2, characterized in that the auxiliary recovery means comprises an O-ring (24) arranged in the intermediate central chamber ( CC ) of the directing chamber ( CD ), between the inner edges of both diaphragms ( M7 , M8 ), said O-ring (24) being provided with through holes (27) which through corresponding holes (28) provided for the purpose in the pump body member ( CB ) act as an inlet for the atmospheric pressure, establishing a direct communication between the said intermediate central chamber ( CC ) and the environment.

Inventors: MORALES GARCIA JOSE LUIS, MOTA LOPEZ MIGUEL, MORALES GARCIA, JOSE, LUIS, MOTA LOPEZ, MIGUEL, MORALES GARCIA, José, Luis
Applicants: FICO TRANSPAR SA, FICO TRANSPAR, S.A.
Application year: 1991
Main classification: B60S1
IPC codes: B60S1, F04D15