Device for spraying or dispensing fluid product in which product contained in the outlet passage is aspirated at the end of actuation

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BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention concerns a device for spraying or dispensing fluid product in which product contained in the outlet passage is aspirated at the end of actuation.

2. Description of the Prior Art

Many fluid products are packaged in pump or valve dispensers which spray the product or dispense it without spraying it when a user presses a plunger. The product is discharged through an outlet passage usually incorporated in the plunger.

At the end of discharge of the product a certain quantity of product remains in the outlet passage. If the end part of the outlet passage is horizontal the product contained in this part of the outlet passage can then leak out of the passage in periods when the device is not used. In the case of a product that is not very volatile, such as a paste or a cream, the product escaping in this way from the outlet passage does not evaporate but runs or drips onto the bottle in which the product is stored or its surroundings, soiling said bottle or said surroundings.

Also, the end part of said outlet passage is usually of small diameter with the result that some of the product remaining in this end part for a long period of non-use can dry and block said end part.

An object of the present invention is to avoid these drawbacks.

SUMMARY OF THE INVENTION

The present invention consists in a pump for dispensing or spraying a fluid product comprising a pump body delimiting a pump chamber in which slides a piston, said pump comprising a hollow plunger-rod having an outlet passage, said plunger-rod being coupled to the piston to actuate said piston and to enable escape of the product, said pump further comprising an aspiration chamber which communicates with the hollow plunger-rod and which is reduced in volume when the plunger-rod is depressed and increased in volume when pressure is removed from the plunger-rod, wherein said aspiration chamber is delimited by the piston and the plunger-rod and the volume of said chamber is varied by relative sliding movement between the plunger-rod and the piston.

In one embodiment of the invention, the plunger-tube comprises a ring extended towards the pump chamber by a skirt inside which slides an upper annular part of the piston in fluid-tight contact with said skirt and said plunger-tube further comprises a solid cylindrical part on which a lower tubular part of the piston can slide to cut off communication between the pump chamber and the outlet passage, said pump chamber communicating with said outlet passage when said lower tubular part of the piston is above said solid cylindrical part of the plunger-rod.

Alternatively, an upper annular part of the piston slides in fluid-tight contact with a complementary part of the plunger-rod and said plunger-rod further comprises a solid cylindrical part on which a lower tubular part of the piston can slide to interrupt communication between the pump chamber and the outlet passage, said pump chamber communicating with said outlet passage when said lower tubular part of said piston is above said solid cylindrical part of the plunger-rod.

In another embodiment of the invention, the plunger-rod comprises a reduced cross-section lower part having a lateral orifice communicating with the outlet passage and the passage has an interior tubular part sliding in fluid-tight contact with the plunger-rod, said interior tubular part being extended by a reduced cross-section lower end sliding in fluid-tight contact with the reduced cross-section lower part of the plunger-rod, said aspiration chamber being delimited by the plunger-rod, its reduced cross-section lower part, the interior part of the piston and its reduced cross-section lower end. The reduced cross-section lower part of the plunger-rod comprises at least one groove extending in the axial direction from the lateral orifice away from the pump chamber. A first spring disposed in the pump chamber urges the piston towards the exterior of the pump and a second spring mounted between the plunger-rod and the piston urges the plunger-rod away from the piston towards the exterior of the pump.

Other features and advantages of the invention will emerge from the following detailed description of various embodiments of the invention given by way of non-limiting example with reference to the appended drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view in axial cross-section of a metering pump in a first embodiment of the invention, shown in the unoperated position.

FIG. 2 is a view in axial cross-section of the pump from FIG. 1 shown in the operated position.

FIG. 3 is a detail view showing part of the pump from FIG. 1.

FIG. 4 is a view in partial cross-section of a dispensing or spraying device in a first embodiment of the invention.

FIG. 5 is a view in axial cross-section of a metering pump in a second embodiment of the invention.

FIG. 6 is a view in axial cross-section of the pump from FIG. 5 shown in the operated position.

FIG. 7 is a view in axial cross-section of a metering pump in a third embodiment of the invention.

FIG. 7a is a view in axial cross-section of an alternative version of the pump from FIG. 7.

FIG. 7b is a view in axial cross-section of an alternative version of the pump from FIG. 7.

FIG. 8 is a view in axial cross-section of the pump from FIG. 7 shown in the operated position.

FIG. 9 is a detail view of part of the pump from FIG. 7.

FIG. 10 is a view in axial cross-section of a metering pump in a fourth embodiment of the invention.

FIG. 11 is a detail view of part of the pump from FIG. 10 shown in the unoperated position.

FIG. 12 is a view of the same parts as FIG. 11 but during dispensing or spraying of the product.

DETAILED DESCRIPTION OF THE INVENTION

First embodiment

FIG. 1 shows a metering pump in a first embodiment of the invention. The pump comprises a hollow cylindrical pump body 1 having an axis of revolution 2 and delimiting a pump chamber 6 which normally contains a fluid product to be dispensed. The pump body 1 comprises an open upper end 1c and a reduced cross-section lower end 1a extended downwardly by an inlet tube 1b. The inlet tube 1b communicates with a reservoir of product to be dispensed (not shown), directly or through the intermediary of a down-tube (not shown). The inlet tube 1b is provided with an inlet valve which opens when the pressure in the pump chamber 6 is reduced and closes when the pressure in said pump chamber 6 is increased. The inlet valve may be of any known form. For example, it may consist of a ball 15 that can be applied in a fluid-tight way to a valve seat 16 to close the inlet tube 1b when the pressure in the pump chamber 6 is increased and a plurality of arms 17 extending above the valve seat 16 which hold the ball 15 near the valve seat 16 when said ball 15 is raised off said valve seat 16 by reduction of the pressure in the pump chamber 6.

The pump body 1 may be snap-fastened to a cap 9 screwed to the neck of the product reservoir (not shown), for example. An annular gasket 30 may be disposed between the cap 9 and the neck of the reservoir. However, the pump body 1 could be fixed to the reservoir by any other known means without departing from the scope of the present invention.

In the specific embodiment shown in FIG. 1 the cap 9 has an inner ring 9a which extends a certain distance vertically down the inside perimeter of the pump body 1 from the open upper end 1c of said pump body.

A piston 3 slides in the pump body 1. As shown in FIG. 3, the piston 3 is a body of revolution about the axis 2 and comprises a tubular central part 4 extending between a lower end 4a and an upper end 4b. The piston 3 further comprises two peripheral outer lips 5a and 5b at its lower and upper ends, respectively, adapted to provide a seal between the pump body 1 and the piston 3 at least when said sealing lips 5a and 5b are in a part 1c of the pump body.

Referring to FIG. 3, the piston 3 slides with lost motion on a plunger rod 7, 8 consisting of a sleeve 7 force-fitted onto an inner core 8 so that the sleeve 7 and the inner core 8 are fastened together. The piston 3 slides on the sleeve 7 and the contact between the piston and the sleeve is fluid-tight. The sleeve 7 comprises at least one ring 7a forming an upper abutment for the upper end 4b of the tubular central part 4 of the piston. The inner core comprises an enlarged lower part 8a having a peripheral seat 8b forming a bottom abutment for the lower end 4a of the tubular central part 4 of the piston to which said lower end 4a can be applied in a fluid-tight manner.

The inner core 8 further has at lest one longitudinal groove 8f at its perimeter through which the pump chamber 6 communicates with the outside when said lower end 4a of the tubular central part 4 of the piston is not applied in a fluid-tight manner to the peripheral seat 8b of the inner core 8.

In the specific embodiment shown in FIG. 3 the enlarged lower end 8a of the inner core 8 is extended downwardly by a skirt 8c sliding in the pump body 1 which in particular contributes to guiding the plunger-rod 7, 8 and the piston in the pump body 1. The skirt 8c also serves to limit downward movement of the plunger-rod when it abuts the reduced cross-section lower end 1a of the pump body 1. Additionally, the skirt 8c comprises one or more openings 8d enabling communication between the pump chamber 6 and the groove 8c when the lower end 4a is not in fluid-tight contact with the peripheral seat 8b.

As an alternative, it would be possible to substitute for the skirt 8c vertical arms of the same height distributed around the perimeter of the increased cross-section lower end 8a of the core 8. The skirt 8c can even by totally dispensed with if the moving parts of the pump can be adequately guided by other means.

In the specific embodiment shown in FIG. 3 the sleeve 7 has on its interior a relief 7b enabling precise relative positioning of the sleeve 7 and the inner core 8: to assemble them together, these two parts are nested one inside the other with the piston 3 trapped between them and pushed towards each other until the interior relief 7b of the sleeve 7 abuts the inner core 8.

The sleeve 7 further comprises an exterior skirt 7c extending from the ring 7a towards the pump chamber 6 and surrounding the tubular part 4 of the piston. It slides inside the inner ring 9a of the cap 9, so contributing to the guiding of the plunger-rod 7, 8 in the pump body 1. The height of the exterior skirt 7c of the sleeve 7 is advantageously such that it abuts the piston 3 when the upper end 4b of the tubular central part 4 of the piston abuts the ring 7a of the sleeve. The exterior skirt 7c may comprise an exterior flange 7d in its lower part which contributes to the guiding of the piston 3 with respect to the plunger-rod 7, 8.

As an alternative, the exterior skirt 7c could be replaced by a plurality of arms the same height as the skirt 7c each comprising on its outside a peg replacing the exterior flange 7d of the ring.

Finally, the sleeve 7 comprises a tubular upper part 7e which fits within an axial tube 10 which is a body of revolution about the axis 2 of a plunger 11 (see FIG. 1). The tubular upper part 7e of the sleeve 7 and the axial tube 10 of the plunger 11 therefore delimit a chamber 19 referred to hereinafter as the aspiration chamber. The upper tubular part 7e can slide within the axial tube 10 with considerable friction. The axial tube 10 communicates with an outlet passage 12, a horizontal passage, for example, which discharges laterally from the plunger 11. The plunger 11 can have any known shape. It may comprise a spray nozzle.

A spring 13 bears on the plunger 11 and on the cap 9 so as to urge the plunger 11 upwards. To limit the upward movement of the plunger 11 the latter has a skirt 11a comprising in its lower part an exterior flange 11b which abuts a metal cup 14 crimped around the cap 9. The exterior flange 11b could be replaced with outwardly directed pegs.

The pump as previously described operates as follows:

1. When a user presses on the plunger 11, compressing the spring 13, the upper tubular part 7e of the sleeve 7 initially remains fixed relative to the axial tube 10 of the plunger 11 because of the high friction between said tubular part 7e and said axial tube 10. The combination of the sleeve 7 and the inner core 8 is therefore driven downwards by the plunger 11 which also moves the piston 3 downwards because of friction between said piston and the sleeve 7. This downward movement tends to reduce the volume of the pump chamber 6 and therefore increases the pressure in it which closes the inlet valve 15, 16, 17. The pump chamber 6 is then isolated: as the product contained in said pump chamber 6 is incompressible, the piston 3 remains immobile whereas the plunger-rod 6, 7 moves down into the pump body. During this movement the piston 3 therefore slides on the sleeve 7 and the inner core 8 until the upper end 4b of the tubular central part 4 of the piston abuts the ring 7a of the sleeve. The lower end 4a of the tubular central part of the piston is therefore lifted off the peripheral seat 8b to establish communication between the pump chamber 6 and the longitudinal groove 8f of the central core 8.

As soon as the upper end 4b of the tubular central part 4 of the piston abuts the ring 7a the piston 3 is in turn moved downwards.

As the piston moves down in the pump chamber 6 the product contained in it is ejected through the groove 8f of the inner core 8, the vertical tube 10 of the plunger and the lateral passage 12 of the plunger.

When the skirt 8c abuts the reduced cross-section lower end 1a of the pump body the downward movement of the plunger-rod 7, 8 and the piston 3 stops: because of the force exerted by the user on the plunger 11, the axial tube 10 slides downwards parallel to the axis 2 along the tubular upper part 7e of the sleeve 7, as shown in FIG. 2. This sliding movement reduces the interior volume of the aspiration chamber 19.

2. When the user releases the plunger 11 it is pushed up by the spring 13. Because of said high friction between the vertical tube 10 of the plunger and the upper tubular part 7e of the sleeve 7, said sleeve 7 first remains fixed relative to the plunger 11: the plunger-rod 7, 8 is therefore drawn upwards by the plunger 11.

Initially the piston 3 remains immobile because of the friction between said piston 3 and the pump body 1, during the upward movement of the plunger-rod 7, 8, until the lower end 4a of the tubular central part 4 of the piston comes into contact with the peripheral seat 8b of the inner core 8, cutting off communication between the pump chamber 6 and the groove 8f of the inner core 8. This isolates the pump chamber 6.

Because it is in contact with the peripheral seat 8b, the piston 3 is then drawn upwards by the plunger-rod 7, 8. The volume of the pump chamber 6 therefore increases, which reduces the pressure in it, which opens the inlet valve 15, 16, 17 and enables the fluid product contained in the reservoir to enter the pump chamber 6 as the piston 3 rises.

When the upper lip 5b of the piston 3 comes into contact with the inner ring 9a of the cap 9 this upward movement halts.

The plunger 11 then continues to rise on its own due to the action of the spring 13; it slides upwards, parallel to the axis 2, along the upper tubular part 7e of the sleeve 7. The effect of this is to increase the volume of the aspiration chamber 19. As the aspiration chamber 19 is isolated from the pump chamber 6 by the contact between the upper end 4a and the peripheral seat 8b, this increase in volume creates suction in the outlet passage 12: the product in said outlet passage 12 is therefore aspirated into the aspiration chamber 19. The increase in the volume of the aspiration chamber 19 is preferably such that after this aspiration the level of the product in the vertical tube 10 is below the outlet passage 12, so that outlet passage 12 contains no more product.

In the example shown in FIGS. 1 and 2 the pump body 1 comprises a familiar air inlet orifice 18 at the side, to enable air to enter the product reservoir as the product that it contains is consumed by the pump. It is obvious that this orifice 18 could be dispensed with, so that the pump operates without ingress of air, without departing from the scope of the present invention.

Similarly, the pump shown does not comprise any internal spring to push the actuator assembly 7, 8 and the piston upwards, as the return to the raised position is effected by the spring 13, whose upward thrust is transmitted to the assembly 7, 8 by the friction-fit of the vertical tube 10 of the plunger onto the upper tubular part 7e of the sleeve 7. Thus one advantage of this device is that it does not comprise any spring or any other metal part in contact with the product to be dispensed: this can avoid pollution of the product by substances contained in the steel of the spring or by oxidation of the spring.

However, it goes without saying that, without departing from the scope of the present invention, a spring could be provided in the pump chamber 6, in addition to the exterior spring 13, to facilitate the upward movement of the plunger-rod 7, 8.

It is also necessary to point out that this first embodiment of the invention can be applied to any type of metering pump or valve for dispensing or spraying the product under gas pressure, as shown in FIG. 4. These dispensing or spraying devices 21 always have a hollow plunger-rod 20 with an axis of symmetry 2 onto which can be sleeved an axial tube 10 of a plunger 11 which in this example discharges laterally to the outside of the plunger 11 through an outlet passage 12, a horizontal passage, for example. It goes without saying that the plunger 11 could have any other shape without departing from the scope of the present invention.

The hollow plunger-rod 20 enables the product to escape when it is depressed. The axial tube 10 of the plunger 11 is mounted to slide on the plunger-rod 20: the axial tube 10 and the plunger-rod 20 therefore delimit an aspiration chamber 19. The travel of the plunger 11 relative to the plunger-rod 20 in the downward direction is limited by a lower abutment on the rod 20, for example an exterior shoulder 20a on the rod 20. Also, the plunger 11 is urged upwards by a spring 13 bearing on the plunger 11 and directly or indirectly on the spraying or dispensing device 21.

In FIG. 4 the spring 13 bears indirectly on the device 21 through the intermediary of a cap 9 into which the device 21 is snap-fastened and which can be screwed onto the neck of a product reservoir (not shown): it goes without saying that the device 21 could be mounted on the product reservoir in a different way without departing from the scope of the present invention.

The upward travel of the plunger 11 is limited by any known means: for example, as shown in FIG. 4, the plunger 11 has a skirt 11a comprising an exterior flange 11b at its lower end, or possibly exterior pegs instead of the flange, which abuts a metal cup 14 crimped around the cap 9 and therefore fastened to the spraying or dispensing device 21.

When a user depresses the plunger 11 the plunger-rod 20 is depressed to discharge the product and during this movement the axial tube 10 of the plunger is pushed all the way down onto the plunger-rod 20 until it abuts the exterior shoulder 20a of said plunger-rod 20: this reduces the interior volume of the aspiration chamber 19. When the user releases the plunger 11, the latter is pushed upwards by the spring 13. The plunger-rod 20 is moved to a raised position either by the action of spring means internal to the device 21 or by the action of the spring 13 transmitted to said plunger-rod 20 by friction between the axial tube 10 and said plunger-rod 20. During this movement the plunger 11 moves upwards relative to the plunger-rod 20 by virtue of sliding of the axial tube 10 on said plunger-rod 20, the effect of which is to increase the interior volume of the aspiration chamber 19 and cause suction in the outlet passage 12, aspirating the product contained in said outlet passage 12 towards the aspiration chamber 19.

Second embodiment

The second embodiment of the invention shown in FIGS. 5 and 6 consists in a metering pump whose various parts are substantially the same shape as in the pump of FIGS. 1 through 3. For this reason they will not be described in detail again. In the remainder of this description of the second embodiment of the invention the reference numbers of identical or similar parts of the pump will therefore be the same as those for the pump from FIGS. 1 through 3.

Unlike the pump from FIGS. 1 through 3, the sleeve 7 is not fastened to the inner core 8 but slides on said inner core 8. On the other hand, the axial tube 10 of the plunger 11 is force-fitted onto the tubular upper part 7e of the sleeve 7 with the result that the plunger 11 is fastened to the sleeve 7.

Also, the pump chamber 6 contains a spring 100 which bears on the reduced cross-section lower end 1a of the pump body and on the wider lower end 8a of the inner core 8 of the plunger-rod 7, 8 so as to urge said inner core 8 upwards.

Finally, the exterior flange 11b on the plunger 11 and the metal cup 14 crimped to the cap 9 are no longer needed as they are in the first embodiment.

When a user depresses the plunger 11 the sleeve 7 attached to the plunger 11 is moved downwardly until the interior relief 7b abuts the inner core 8. The inner core 8 is then moved down and the piston 3 is moved down because of friction between the sleeve 7 and said piston 3. This downward movement tends to decrease the volume of the pump chamber 6 and therefore increases the pressure in it which closes the inlet valve 15, 16, 17. The pump chamber 6 is then isolated. As the product contained in pump chamber 6 is incompressible the piston 3 initially remains immobile whereas the plunger-rod 7, 8 moves down in the pump body 1. This relative movement between the piston 3 and the plunger-rod 7, 8 lifts the lower end 4a of the tubular part of the piston off its seat 8b which establishes communication between the pump chamber 6 and the groove 8f of the core 8. When the upper end 4b of the tubular central part of the piston contacts the ring 7a of the sleeve 7 the piston 3 is in turn moved downwards.

As the piston 3 moves downwards in the pump chamber 6 the product contained in said pump chamber is therefore ejected from said pump chamber through the groove 8f of the inner core 8, the axial tube 10 and the outlet passage 12.

This downward movement ends when the skirt 8c of the inner core 8 contacts the reduced cross-section lower end 1a of the pump body 1, as shown in FIG. 6.

When the user releases the plunger 11 the inner core 8 of the plunger-rod 7, 8 is pushed upwards by the spring 100 whereas the piston 3 initially remains immobile because of the friction between said piston 3 and the pump body 1. The lower end 4a of the tubular part 4 of the piston is therefore applied to its seat 8b on the increased cross-section lower end 8a of the core 8, so isolating the pump chamber 6.

The piston 3 is then driven upward in its turn, which tends to increase the volume of the pump chamber 6 and so reduce the pressure in said pump chamber. Because of this reduction in pressure the inlet valve 15, 16, 17 opens and the product can enter the pump chamber 6 as the piston 3 and the plunger-rod 7, 8 rise due to the action of the spring 100.

When the top lip 5b of the piston 3 contacts the inner ring 9a of the cap 9 the movement of the piston ceases. The inner ring 8 of the plunger-rod 7, 8 is therefore also immobilized against the lower end 4a of the tubular central part 4 of the piston 3. The peripheral seat 8b of the core 8 is held against the lower end 4a by the spring 100: communication between the pump chamber 6 and the groove 8f of the core therefore remains cut off.

The sleeve 7 attached to the plunger 11 then continues to move upwards, due to the action of the spring 13, until the exterior flange 7d at the bottom of the exterior skirt 7c of the sleeve 7 contacts the inner ring 9a of the cap 9.

Because of the fluid-tight contact between the central tubular part 4 of the piston and the sleeve 7 and between the lower end 4a of said tubular central part 4 of the piston and the core 8, the plunger-rod 7, 8 and the piston 3 define an aspiration chamber 119 which communicates with the outside only through the axial tube 10 and the outlet passage 12: during the upward movement of the sleeve 7 relative to the inner core 8 and the piston 3 the volume of the aspiration chamber 119 increases which causes suction in the outlet passage 12. The product contained in the outlet passage 12 is therefore aspirated into the axial tube 10.

The increase in volume of the aspiration chamber 119 is preferably such that after this aspiration the level of the product in the axial tube 10 is below the outlet passage 12, so that the outlet passage 12 contains no more product.

Third embodiment

The pump shown in FIGS. 7 through 9 comprises a hollow cylindrical pump body 201 similar to that from FIGS. 1 through 3 having an axis of revolution 202. The pump body 201 has an open upper end 201c and a reduced cross-section lower end 201a which is extended downwardly by an inlet tube 201b which communicates with a reservoir of product to be dispensed (not shown) directly or via a down-tube (not shown).

The pump body 1 delimits a pump chamber 206 which normally contains the product to be dispensed. The inlet tube 201b is provided with an inlet valve which may, for example, comprise a ball 215 adapted to be applied in a fluid-tight manner to a valve seat 216 and shut off the inlet tube 201b when the pressure in the pump chamber 206 is increased. On the other hand, if the pressure in the pump chamber 206 is reduced the ball 215 is lifted off its seat 216 to open the inlet tube 201b although it is held near its seat 216 by arms 217 which extend from the reduced cross-section lower end 201a of the pump body. The inlet valve could be of any other known form without departing from the scope of the present invention.

As shown in FIG. 7, the pump body 201 may be snap-fastened into a cap 209 of which a central part 209a in which there is a central hole 209b caps the upper end 201c of the pump body. The cap 209 may, for example, be screwed onto the neck of the reservoir of product (not shown) and an annular gasket 230 may be disposed between the cap 209 and the neck of the reservoir. It goes without saying that the pump body 201 could be fixed by any other known means to the reservoir, for example by crimping a metal cup.

A piston 203 slides in the pump body 1. As shown in FIG. 9, the piston 203 is a body of revolution about the axis 202 and advantageously has at least one peripheral exterior sealing lip 205 and an interior lower tubular part 204. The piston 203 is extended upwardly by an upper annular part 203a to an upper end comprising an exterior peripheral sealing lip 203b.

The piston 203 slides with lost motion on a plunger-rod 207, 208 comprising a sleeve 207 force-fitted onto an inner core 208 so that said sleeve 207 and said inner core 208 are fastened together. The sleeve 207 comprises a ring 207a which defines a lower shoulder 207f and an upper shoulder 207d. The ring 207a is extended downwardly on the outside by a skirt 207c surrounding the sleeve 207. The upper annular part 203a of the piston slides inside the skirt 207c, the peripheral sealing lip 203b being in fluid-tight contact with the skirt 207c.

From the ring 207a the sleeve 207 is extended vertically upwards by an upper tubular part 207e. The sleeve 207 further comprises an interior relief 207b enabling precise relative positioning of the sleeve 207 and the inner core 208 when they are assembled together by inserting the inner core 208 into the sleeve 207 until it abuts the interior relief 207b.

The inner core 208 has an increased cross-section lower end 208a provided with a peripheral seat 208b forming a lower abutment for the lower tubular part 204 of the piston 203: the piston 203 is therefore trapped between an upper abutment formed by the lower shoulder 207f of the sleeve 207 and a lower abutment formed by the peripheral seat 208b of the inner core 208, whereby the piston 203 can slide with lost motion between these two abutments.

Above the peripheral seat 208b the inner core 208 comprises a cylindrical part 208g on which slides the lower tubular part 204 of the piston 203. An axial groove 208f is formed in the solid cylindrical part 208g of the core 208 starting a certain distance above the peripheral seat 108b and extends upwardly over all the length of the inner core 208 to discharge into the upper tubular part 207c of the sleeve 207. Thus when the tubular lower part 204 of the piston 3 slides on a solid cylindrical part 208h of the core between the peripheral seat 208b and the groove 208f said lower tubular part 204 isolates the pump chamber 206 from the groove 208f. On the other hand, when said lower tubular part 204 is above the solid cylindrical part 208h of the core the groove 208f communicates with the pump chamber 206.

The inner core 208 may further comprise a skirt 208c which extends the increased cross-section lower part 208a downwardly and slides in the pump body 1. The skirt 208c therefore contributes to guiding the plunger-rod 207, 208 in the pump body 1 and limits the downward movement of the plunger-rod 207, 208 by contacting the reduced cross-section lower end 201a of the pump body 1. The skirt 208c comprises one or more openings 208d enabling communication between the pump chamber 206 and the groove 208c of the core 208 when the lower tubular part 204 of the piston is above the part 208h of the core 208.

As shown in FIG. 7, an axial tube 210 which is a body of revolution about the axis 202 of a plunger 211 is force-fitted over the upper tubular end 207e of the sleeve in contact with the upper shoulder 207d. The axial tube 210 is extended by an outlet passage 212, a horizontal passage, for example, which discharges laterally from the plunger 211. The plunger 211 could be of any other known form and may incorporate a spray nozzle.

A spring 200 bears on the reduced cross-section lower end 201a and on the increased cross-section lower end 208a of the cord 208 and urges the plunger-rod 207, 208 upwards. Upward movement of the plunger-rod 207, 208 is limited by the skirt 207c of the sleeve 207 contacting the central part 209a of the cap 209. An annular gasket 231 is advantageously provided below the central part 209a of the cap 209, sandwiched at its outer perimeter between said central part 209a and the cap 209 and the upper end 201c of the pump body 201. The spring 200 presses the skirt 207c elastically against the gasket 231 to isolate the interior of the pump body 201 when the pump is not operated.

When a user depresses the plunger 211 the plunger-rod 207, 208 is pushed down and compresses the spring 200. This downward movement tends to move the piston 203 downwards and so decreases the volume of the chamber 206: this increases the pressure in the pump chamber 206 which closes the inlet valve 215, 216, 217. The pump chamber 206 is therefore initially isolated. As the product contained in the pump chamber 206 is incompressible the piston 203 initially remains immobile whereas the plunger-rod 207, 208 moves down in the pump body until the upper annular part 203a of the piston contacts the bottom shoulder 207f of the sleeve 207. During this sliding movement, as soon as the lower tubular part 204 of the piston 203 is above the part 208h of the core 208 the pump chamber 206 communicates with the groove 208f of the core 208 which itself communicates with the exterior through the upper tubular part 207e of the sleeve 207, the axial tube 210 and the outlet passage 212. The product contained in the pump chamber 206 therefore leaves the pump by this route while the piston 203 moves down in the pump body with the plunger-rod 207, 208 until the skirt 208c contacts the reduced cross-section lower end 201a of the pump body 201, as shown in FIG. 8.

When the user releases the pressure, the plunger-rod 207, 208 is pushed up by the spring 200. Because of the friction between the sealing lip 205 and the pump body 201, the piston 203 initially does not move. The core 208 therefore slides upwards relative to the lower tubular part 204 of the piston, which initially moves said lower tubular part 204 to the level of the part 208h of the core 208 where it interrupts communication between the pump chamber 206 and the groove 208f of the core 208. The part 208h of the core 208 then continues to slide upwards in the lower tubular part 204 of the piston, the effect of which is to increase the volume of an annular aspiration chamber 219 delimited by the sleeve 207, the core 208 and the piston 203 and which communicates only with the groove 208f because the exterior sealing lip 203b of the upper annular part 203 of the piston is in fluid-tight contact with the skirt 207c of the sleeve and the tubular lower part 204 of the piston is in fluid-tight contact with the solid part 208h of the core 208. The increased volume of the annular aspiration chamber 219 aspirates product in said chamber. The product contained in the outlet passage 212 is therefore aspirated towards said chamber 219.

The increase in the volume of the annular chamber 219 is preferably such that after this aspiration the level of the product in the axial tube 210 is below the outlet passage 212 so that said outlet passage 212 contains no more product.

When the tubular lower part 204 of the piston contacts the seat 208b of the core 208 the piston 203 is in turn moved upwards which decreases the pressure in the pump chamber 206. The inlet valve 215, 216, 217 therefore opens which enables product to enter the pump chamber 206 via the inlet tube 201b as the plunger-rod 207, 208 and the piston 203 rise in the pump body 201 until the skirt 207c of the sleeve contacts the gasket 231 under the central part 209a of the cap 209.

As in the first two embodiments of the invention, the pump body 201 may comprise an air inlet orifice 218, situated in this example above the rest position of the sealing lip 205 of the piston 203, to establish communication between the interior of the product reservoir and the atmosphere via the central hole 209b of the cap 209 when the skirt 207c of