Split engagement flange for soap dispenser pump piston

A liquid soap dispenser having a permanent housing permitting simplified insertion and replacement of disposable fluid reservoirs. The housing includes an actuator assembly cycled by a lever between first and second positions. The actuator assembly is couple to a piston element of a piston pump carried on the reservoir so that when cycled, the piston element is actuated in sliding movement to dispense a quantity of fluid. The piston element includes resiliently deformable fingers which secure the piston element to the actuator assembly for sliding movement therewith. If, on insertion of a replacement reservoir, the reservoir is positioned uncoupled from the actuator assembly, on first cycling of the actuator assembly the fingers deform to permit movement of the actuator assembly relative to the piston element and move towards a coupled orientation. In the coupled orientation, the fingers return to an undeformed configuration securing the piston element to the actuator assembly.

SCOPE OF THE INVENTION

This invention relates generally to fluid dispensers and, more particularly, to a piston pump piston for a liquid soap dispenser which is adapted for simplified replacement of a liquid soap reservoir.

BACKGROUND OF THE INVENTION

Many of today's products sold in liquid form, such as liquid hand soap, are contained in disposable containers or reservoirs which incorporate a pump assembly. Typically, the pump assembly includes a reciprocally movable element which when moved dispenses a quantity of liquid soap from the reservoir. The reservoirs are generally fitted within a permanent housing which includes a movable actuator assembly which engages and reciprocally moves the movable element to dispense the fluid. This has been found to be both a convenient and economical means of fluid supply and dispensation. Since the fluid reservoirs are replaced once the fluid supply is exhausted, it is desirable to manufacture the dispenser and reservoir so as to make replacement of the fluid reservoir as easy and quick as possible.

Known fluid dispensers suffer the disadvantage in that replacement of the fluid reservoir is time consuming, as care must be taken to ensure the reservoir is placed in the permanent housing in the correct dispensing position to dispense fluids. If the reservoir is not placed in the correct dispensing position with the movable element coupled to the actuator assembly, the dispenser will be inoperative as the movement of the actuator assembly will not reciprocally move the movable element and no fluids will be dispensed. To achieve the proper dispensing configuration, the pump assembly must therefore be precisely aligned in the housing to ensure it is properly secured in or coupled to the actuator assembly.

Many known fluid dispensers suffer the further disadvantage in that to secure or couple the pump assembly to the actuator assembly of the housing, an adjustment of the position of the reciprocally movable element is often required.

Known fluid dispensers adapted to permit simplified replacement of the liquid soap dispenser provide for resilient fingers carried on the housing for complementary engagement with an engagement flange on the piston of a piston pump. The present inventors have appreciated that such arrangements suffer the disadvantage that the resilient members permanently on the housing must last the lifetime of the housing and, therefore, must be able to retain their resiliency for an extended period of time. While such resilient members may be made of resilient metal, they suffer the disadvantage that typically they are required to be separate parts for assembly at increased expense. Providing the resilient fingers to be of plastic has the disadvantage of requiring a plastic which will withstand its desired resiliency over a large number of cycles.

SUMMARY OF THE INVENTION

To at least partially overcome these disadvantages of known fluid dispensers, the present invention provides an improved arrangement for removably coupling a movable element of a piston pump to an actuator mechanism with resilient finger members circumferentially spaced about the movable element and extending from a radially inner end to a distal end for deflection by relative axial movement of the movable element and the actuator mechanism to assume a coupled orientation.

An object of the present invention is to provide a replaceable movable element in a pump mechanism with resilient coupling members.

The present invention provides in one aspect an improved fluid dispenser having a housing and a replaceable reservoir which incorporates as part of a fluid dispensing valve, a movable element. The housing includes a movable actuator assembly for coupling to the movable element. When the actuator assembly and movable element are coupled, the movement of the actuator assembly moves the movable element to dispense fluid from the reservoir. The actuator assembly is configured such that if the reservoir is inserted into the housing in a position uncoupled from the actuator assembly, the first activation of the dispenser moves the actuator assembly relative to the movable element to a position where the movable element and actuator assembly are secured together in a coupled orientation. The dispenser permits insertion of a replaceable reservoir therein regardless of the initial position of the movable element.

The present invention, in one preferred aspect, provides a fluid dispenser which includes a replaceable reservoir and a permanent housing. The housing is configured to support the reservoir in a dispensing position. The reservoir includes a chamber for holding fluids and a portioning valve which includes a reciprocally movable element, the movement of which dispenses a predetermined amount of fluid outwardly from the chamber. The housing includes an actuator assembly movable between first and second positions. The actuator assembly is adapted for coupling to the reciprocally movable element, wherein in a coupled orientation the movement of the actuator assembly moves the movable element to dispense fluid. The actuator assembly is further configured such that if the reservoir is inserted into the housing with the reciprocally movable element uncoupled, so that the movable element and actuator assembly may move independently, on first cycling of the actuator assembly, the actuator assembly is moved relative to the reciprocally movable element to secure it thereto. By cycling of the actuator assembly, it is generally meant the movement of the actuator assembly from the first position to the second position and back to the first position during the normal operation of the dispenser.

The dispenser of the present invention advantageously permits easy replacement of the reservoir, as it is not required to precisely align the reciprocally movable element with the actuator assembly to ensure the reservoir is inserted into the housing with the movable element and actuator assembly in a coupled orientation. Additionally, as there is no need to adjust the position of the reciprocally movable element on the insertion of the reservoir, the disadvantages of inoperative arrangement and/or premature dispensation or escape of fluids from the chamber are eliminated.

The reciprocally movable element includes a catch assembly. The catch assembly is configured to permit movement of the actuator assembly relative to the reciprocally movable element from a position where the actuator assembly and the reciprocally movable element are in an uncoupled orientation, to a position where the actuator assembly and the reciprocally movable element are in a coupled orientation. Once in the coupled orientation, the catch assembly prevents movement of the actuator assembly relative to the movable element to return to the uncoupled orientation.

Preferably, the reciprocally movable member is a piston element which, on insertion of the reservoir into the housing, is positioned coaxially aligned with the actuator assembly. The piston element includes a catch mechanism with at least one resilient member. A catch portion of the actuator assembly is to be engaged with the catch mechanism of the piston element to couple the piston element to the actuator assembly in a coupled orientation. However, in initial insertion of the reservoir into the housing, the piston element may be located relative to the catch portion of the actuator assembly in an uncoupled orientation, however, with the piston element in the uncoupled orientation located in a path of the catch portion of the actuator assembly through which the catch portion of the actuator assembly moves in the cyclical movement of the actuator assembly.

The resilient member on the piston element is deflectable on movement of the catch portion of the actuator assembly into the piston element to permit coupling of the catch portion of the actuator assembly with the piston element to assume the coupled orientation from the uncoupled orientation. With this arrangement the first cycling of the actuator assembly moves the actuator assembly relative to the piston element, deflecting the resilient member on the piston element to couple the piston element to the actuator assembly in the coupled orientation.

The catch mechanism on the piston element preferably comprises an annular engagement slot preferably between a pair of radially outwardly extending engagement flanges carried on the piston element with the catch portion of the actuator assembly to be received in the engagement slot. One of the engagement flanges preferably comprises the resilient member which extends radially of the piston element circumferentially about the piston element. Deflection of the resilient member permits the catch portion of the actuator assembly to move past the resilient member into coupled engagement within the slot yet with the resilient member on assuming its unbiased condition preventing removal of the catch portion of the actuator assembly from the slot by movement of the catch portion along the path the catch portion moves in the cyclical movement of the actuator assembly. The resilient member may comprise a set of resilient finger members disposed circumferentially about the piston element extending radially outwardly from inner ends of the finger member by which they are coupled to the piston element to a distal end, and sized to be deflected radially inwardly to pass through an opening in the actuator member then return to their unbiased positions larger than the opening to capture the actuator member.

Preferably, each finger member projects angularly from the piston element such that a leading surface of each finger member forms a camming surface. With the piston and actuator assembly in an uncoupled orientation, the first cycling of the dispenser moves the camming surfaces into contact with the actuator member to assist in moving the finger members to the biased position. When the actuator member is fully within engagement slot and the fingers members return to the unbiased position, a trailing edge or surface of the finger members engage the actuator member to couple the piston element to the actuator assembly.

DETAILED DESCRIPTION OF THE DRAWINGS

Reference is made first toFIG. 1which shows a dispenser10in accordance with a preferred embodiment of the invention. The dispenser10comprises a reservoir12, and a housing14.

The reservoir12, only partially shown, comprises a chamber16for holding fluid18as, for example liquid soap, which is to be dispensed. An outlet20is provided through a lowermost wall17of the chamber16, across which is located a valve assembly22to regulate the flow of fluid18outwardly therethrough. Preferably the reservoir12is made entirely of plastic and is disposable once the supply of fluid18is exhausted.

FIG. 1shows the housing14in an open configuration ready for insertion of the reservoir12. The housing14includes a backplate21typically adapted for permanent attachment to a wall. A pair of side walls23extend vertically forwardly from each side of the backplate21. A support flange24is provided extending horizontally between the side walls23so as to define a cavity25above the flange24between the side walls23and backplate21to receive the reservoir12.

The flange24has an opening26vertically therethrough in the form of a U-shaped slot27closed at a rear blind end28and open forwardly to the front edge29of the flange24.

An actuator assembly30is provided on the housing14, movable relative to the housing. The actuator assembly30includes notably a pivoting lever31and an actuator plate32mounted to the housing to be vertically slidable. Pivoting of the lever31moves the vertically slidable actuator plate32linearly on a pair of vertically extending guide rods33against the bias of springs34disposed about the guide rods33. The actuator plate32has a downwardly directed lower surface35and an upwardly directed upper surface36, each extending normal to the linear path of movement of the actuator plate32.

The actuator plate32has a catch opening37vertically therethrough in the form of a U-shaped slot38closed at a rear blind end39and open forwardly to the front edge40of the actuator plate32.

The two parallel spaced locating rods33are fixedly secured at their upper ends41to flange24and extend downwardly to their lower ends42to which respective retaining ferrules43are secured. The actuator plate32has a pair of cylindrical bores44through which the rods33pass. The actuator plate32is disposed on the rods33above the ferrules43.

Springs34are provided about each of the locating rods33. The springs34have an upper end which engage the flange24and a lower end which engage the upper surface36of actuator plate32to resiliently bias the actuator plate32away from the flange24downwardly toward a fully extended position shown inFIGS. 1 to 3.

The actuator assembly30includes the lever31which is pivotally connected to the housing14for pivoting about a horizontal axis46. The lever30is U-shaped having a pair of side arms47connected at their front by a horizontal connecting bight48. A pair of horizontal stub axles49extend laterally outwardly from the side arms47and are received in holes50through the side walls23to journal the lever31to the housing for pivoting about an axis46.

A rear end51of the lever31engages the lower surface35of the actuator plate32. Manual urging of the bight48of the lever31rearwardly by a user moves the actuator plate32upwardly against the bias of the springs33from the extended position shown inFIG. 2to a retracted position shown inFIG. 4. On release of the lever31, the force of the springs33returns the actuator plate32to the extended position.

The opening26of the flange24is positioned to permit the reservoir12to be slid rearwardly inward into the housing14, in the manner illustrated inFIG. 1. The flange24is located such that when the reservoir12is slid into the housing14, the flange24abuts and supports the lowermost wall17of the fluid chamber16to assist in maintaining the reservoir12in fluid dispensing position. The flange24is received in a slotway52between the lowermost wall17of the fluid chamber16and an upwardly directed shoulder53on the valve assembly22such that the flange24is sandwiched between the wall17and the valve assembly22, thereby preventing axial sliding movement of the reservoir12as the dispenser10is used. The U-shape of the opening26of the flange24assists in guiding the reservoir12as it is inserted into and removed horizontally from the housing14.

FIG. 2best shows the reservoir valve assembly22as comprising a piston pump of the type described in U.S. Pat. No. 5,165,577 to Ophardt issued Nov. 24, 1992. The valve assembly22includes piston chamber forming member56and a piston element57. The piston chamber forming member56forms a dispensing chamber58having at an inwardmost end an inlet opening59opening into the chamber16. A one-way inlet valve60is provided across the inlet opening59which permits fluid18to flow outwardly from the chamber16into the dispensing chamber58but prevents flow from the dispensing chamber58to the chamber16. The reciprocally movable piston element57is slidably received within the dispensing chamber58and has an axially extending hollow stem61which carries a flexible inner flange62and an outer sealing flange63to engage the inner wall of the dispensing chamber58in a manner that reciprocal movement of the piston element57along a linear path axially in the dispensing chamber58causes fluid18to flow from the chamber16outwardly past the one-way valve60and out an outermost end64of the piston element57via an internal passageway65through the stem61.

The piston element57has on the stem61proximate its outermost end64a catch assembly comprising both an inner engagement member66and an outer engagement member67axially spaced from each other by an annular slotway68axially therebetween. The inner engagement member66a generally circular and radially extending flange presenting an outwardly directed shoulder69. The outer engagement member67comprises a plurality of circumferentially spaced resilient finger members70, each of which is coupled to the stem61at a radially inner end71and extend radially outwardly and axially inwardly to a distal end72. Each finger member70on the outer engagement flange67presents an axially outwardly and radially outwardly directed camming surface73. Each finger member70has at its distal end72an inwardly directed shoulder74. Each finger member70has an inherent bias to assume an extended position as seen inFIGS. 1 to 5but to be deflectable to have its distal ends deflected radially inwardly.

As seen in a coupled orientation inFIGS. 2 to 4, the piston element57is to be engaged with the actuator plate32with the actuator plate32disposed about the stem61within the slotway68sandwiched between the inner engagement member66and the outer engagement member67. In this regard the outwardly directed shoulder69of the inner engagement member66is of a greater diameter than the catch opening37such that the outwardly directed shoulder69is in opposition to the and engages the inwardly directed upper surface36of the actuator plate32. The finger members70of the outer engagement member67in the extended position are of a greater radius than the catch opening37such that the inwardly directed shoulder74is in opposition to and engages the outwardly directed lower surface35of the actuator plate32.

With the piston element57engaged with the actuator plate32as seen inFIGS. 2 to 4, reciprocal movement of the actuator plate32between the extended position and the retracted position results in corresponding movement of the piston element57to dispense fluid from the reservoir.

From the position shown inFIG. 1with the actuator plate32in the extended position and with the piston element57in the extended position, horizontal rearward sliding of the entirety of the reservoir12will permit the flange24to be received in the slotway52between the lowermost wall17of the fluid chamber16and the upwardly directed shoulder53and the actuator plate32to slide horizontally into the catch opening37of the actuator plate32with the actuator plate32in the annular slotway68between the inner engagement member66and the outer engagement member67. In this manner, the piston element57comes to be received with the catch opening37of the actuator plate and the piston element57is thus coupled to the actuator plate32in a coupled orientation as seen inFIGS. 2 to 4for movement of the piston element57with the actuator plate32.

Reference is made toFIG. 5which illustrates a situation which arises when the reservoir12is in inserted into the housing14with the piston element57in a fully retracted position. The flange24of the housing is received in the slotway52between the lowermost wall17and the upwardly directed shoulder53of the valve assembly22. However, with the piston element57in the retracted position, the outer engagement member67of the piston element57is disposed vertically above the catch opening37of the actuator plate32. From the position ofFIG. 5, in first operation of the dispenser, that is, as by manual movement of the lever31, the actuator plate32is moved from its position below the outer engagement member67vertically upwardly as indicated by the arrow inFIG. 6. The sides of the U-shaped slot38forming the catch opening37engage the resilient finger members70of the outer engagement member67. With such engagement, the resilient finger members70are deflected radially inwardly permitting the actuator plate32to move upwardly to above the resilient finger members70. Once the actuator plate32is disposed upwardly from the spaced resilient finger members70, the finger members70under their inherent bias expand radially outwardly to assume their unbiased position adopting a coupled configuration in the fully retracted position the same as that shown inFIG. 4.

It is appreciated that the engagement between the circumferential upper edge of the U-shaped slot and the outwardly directed camming surface73on each finger member70will with upward movement of the actuator plate32displace each finger member70such that its distal end72is displaced radially inwardly permitting the actuator finger members70to pass downwardly through the catch opening37until the upper distal ends72of the finger members70come to be below the lower surface35of the actuator plate32and then expand radially outwardly under their inherent bias.

In the actuator plate32moving upwardly as illustrated by the arrow inFIG. 6, the actuator plate32on first engagement with the finger members70will urge the piston element57upwardly, as possible, to place the piston element57in a fully retracted position in which upward movement of the piston element57relative to the piston chamber forming member56is prevented as by the inner engagement member66engaging an outwardly directed surface75on the piston chamber forming member56.

With the piston element57in the coupled orientation coupled to the actuator plate32, in a cycle of operation after manual release of the lever31, the springs33will return the actuator plate32and the piston element57together to the extended position.

Reference is made to a second embodiment of a dispenser10as illustrated inFIGS. 7 and 8in which similar elements to those in the first embodiment are referred to by similar reference numbers. The embodiment ofFIGS. 7 to 8is adapted for coupling of the reservoir12to the housing14by vertical sliding of the reservoir12relative to the housing14.

In this regard, the support plate24of the housing14is provided with an opening26vertically therethrough which is circular. The reservoir valve assembly22of the second embodiment is shown in pictorial end view inFIG. 10and pictorial side view inFIG. 11. The piston chamber forming member56has a stepped outer surface with a cylindrical portion76ending at its outer end at an enlarged radius axially directed shoulder77. The opening26through the flange24is closely sized to the outer cylindrical portion76and the reservoir12when inserted vertically down onto the flange24has the cylindrical portion76pass downwardly through the opening26with the shoulder77which is of a greater diameter than the opening26sit on the upper surface of the flange24. The actuator plate32has a catch opening37vertically through therefore in the shape of a U-shaped slot38closed at a forward blind end39and open rearwardly to the rear edge41of the actuator plate32. About the catch opening37is a camming chamfered surface77disposed to extend downwardly and radially inwardly. The cylindrical portion76of the piston chamber forming member56carries a radially outwardly extending boss78sized to be marginally smaller than the circular opening26through the flange24such that vertical downward insertion of the cylindrical portion76through the opening26requires downward forces to snap the boss78through the opening26and the boss78engages under the flange24resisting relative movement of the piston chamber forming member56upwardly other than by the application of some considerable manual force.

On insertion of the reservoir12, the pump assembly22is moved coaxially downwardly through the opening26in which case the piston element57is disposed above the catch opening37of the actuator plate32. To the extent the piston element57is in an extended position, engagement between the actuator plate32and the outer engagement member67will move the piston element57relative the piston chamber forming member56towards its retracted position. With the pump assembly22fixedly secured to the flange24, the piston element57is in an uncoupled orientation. With first manual movement of the lever31, the actuator plate32is moved upwardly with the outer engagement member67being engaged by the catch opening37. Engagement between the chamfered surface77of the actuator plate32about the catch opening37and the radially outwardly directed camming surface73on the finger members70biases the finger members70radially inwardly on moving of the actuator plate32upwardly until the finger members70clear the under surface35of the actuator plate32and the actuator plate32becomes captured between the inner engagement member66and the finger members70of the outer engagement67.

In an alternative manner of insertion, with the piston member57in a fully extended position, the reservoir12is inserted downwardly through the opening26of the flange24, however, tilted at an inclined angle such that the piston element57extends rearwardly towards the rear wall21and becomes located rearwardly of the open rear end of the U-shaped slot38of the catch opening37. Subsequently, the reservoir12is tilted from an inclined position to assume a vertical position thus pivoting the piston element57to move forwardly with the actuator plate32to become engaged between the inner engagement member66and the outer engagement member67thus assuming a coupled orientation.

Reference is made toFIG. 8which shows a top view of the actuator plate32upon which has been superimposed as a dashed circle a schematic representation of the relative coaxial location of the opening26of the flange24.

Reference is made toFIG. 9which shows an alternative actuator plate32for replacement of the actuator plate shown inFIGS. 7 and 8. The actuator plate32inFIG. 9has a catch opening37therethrough in the form of a U-shaped slot38closed at a front blind end39and open rearwardly. A chamfered surface77which tapers radially inwardly and downwardly is disposed about the U-shaped slot38. At the rear of the catch opening37, an access opening79is provided through the actuator plate32. The access opening79is in the form of a U-shaped slot80closed at a blind end81and opening forwardly into the catch opening37. The access opening79is sized to permit the inner engagement member66and the outer engagement member67to pass therethrough rearward of the catch opening37and subsequent movement forwardly with piston element57to become engaged with the catch opening37.

Reference is made toFIGS. 10 and 11which best show the resilient finger members70. In the preferred embodiment, six finger members70are provided each representing an equal segment about a central axis81through the piston element57and each disposed uniformly spaced from each other by a slot82.

The slot82is of a circumferential extent that the distal ends72of the finger member70may be deflected radially a sufficient extent for the finger members70to pass through the catch opening37without circumferential side portions of the distal ends72of adjacent finger members70engaging. Providing the finger members70to extend circumferentially about the outer end of the piston element57permits the piston element57to have fingers70which will engage with the periphery of the U-shaped slot38of the catch opening37irrespective of the relative rotational position of the piston element57within the piston chamber forming member56.

Reference is made toFIG. 14which is a cross-sectional side view similar toFIG. 12, however, showing a third embodiment of a piston element57with a reversed arrangement in which the outer engagement member66is a relatively rigid inflexible disc and the inner engagement member67comprises the plurality of spaced resilient finger members70. The configuration ofFIG. 14is useful in the situation in which the piston element57may be inserted into an uncoupled orientation in which the actuator member32is disposed inwardly of the inner engagement member67, for example, with a stem61inwardly from the inner engagement member67passing through the catch opening37.

Reference is made toFIG. 15which is a cross-sectional side view similar toFIG. 12, however, showing a fourth embodiment of a piston element57, however, in which both the inner engagement member66and the outer engagement67comprise a plurality of spaced resilient finger members70with the configuration ofFIG. 15permitting the piston element57to be in unconfigured conditions either above or below catch opening37of the actuator plate32in initial positioning and with which an axial sliding of the piston element57axially through the catch opening37the one of the inner engagement member66and the outer engagement member67engaging the catch opening37will have its finger members70deflect inwardly so that the actuator plate32becomes secured in the annular slotway68.

The preferred embodiments illustrated, for example, in each ofFIGS. 12,14and15is preferably injection moulded from a plastic material as a unitary element. The entirety of the reservoir12and its pump assembly22is disposable as a unit after the contents of the reservoir have been dispensed. The resilient fingers70of the piston element57therefore merely need to have resiliency which permits coupling with the actuator plate32once or at least not more than a few times since an individual reservoir22with its disposable pump assembly22is typically only expected to be coupled to the housing a single time. Thus, the plastic materials from which the resilient fingers70are constructed need not be capable of being deflected any significant number of times and still retain their resiliency. Thus, the resilient fingers70may be formed from a relatively inexpensive plastic material which while having some inherent resiliency need not maintain that resiliency over repeated cycles of deflection. The piston element57or at least substantial portions thereof including the inner and/or engagement members66,67which carries the resilient fingers70may preferably be formed as a substantially unitary element from plastic material as by injection moulding.

The piston element57permits the sliding insertion of the reciprocally movable piston element57into the catch opening37of the actuator plate32either into an orientation where the catch opening37and piston element57are coupled for movement together, as shown inFIGS. 2,3and4, or an uncoupled orientation where the piston element may move independently from the actuator plate32shown inFIG. 5.

In the coupled orientation, the pivotal movement of the lever31axially moves the catch plate32and piston element57between the first rest, extended position and the second fully retracted position to dispense a quantity of fluid18. If the reservoir12is inserted with the piston element57in the uncoupled orientation ofFIG. 5, the first movement of the lever31moves the catch plate32relative to the piston element57until the piston element57engages the catch plate32and assumes the coupled orientation ofFIG. 5. In this manner, the dispenser10is operative to dispense fluid18regardless of whether the piston element57is initially inserted into the housing14either coupled or uncoupled to the catch plate32.

To dispense fluid18, the actuator assembly30is cycled by the pivotal movement of the lever31moving the piston element57from the first rest, extended position shown inFIG. 2to the second retracted position shown inFIG. 3and released with the springs34returning the actuator plate32back to the first rest, extended position to complete the cycle.

The dispenser10of the present invention advantageously permits insertion of the reservoir12into the housing without the requirement of ensuring the piston element57is in a particular position relative to its piston chamber forming member57or the catch plate32.

Reference is made toFIG. 16which is a cross-section similar to that shown inFIG. 12, however, showing a fifth embodiment of a piston element57in which a single outer engagement member66is provided comprised of resilient finger members70. Each finger member70carries a short radially inwardly extending, circumferential portion of an annular slotway68disposed between an axially outwardly and radially outwardly directed outer camming surface73and an axially inwardly and radially outwardly directed inner camming surface84. If the finger members70are above the activation plate32, then on moving the piston element57downwardly coaxially into the catch opening37, the outer camming surface73engages the perimeter of the catch opening37and is biased radially inwardly until the an inner shoulder85of the slotway68is above the upper surface36of the activation plate32and the finger members70may then snap outwardly under their bias to capture the activation plate32in the slotway68. If the finger members70are below the activation plate32, then on moving the piston element coaxially upwardly into the catch opening37, the inner camming surface84engages the perimeter of the catch opening37and is biased radially inwardly until an outer shoulder86of the slotway68is below the lower surface35of the activation plate32and the finger members70may then snap outwardly under their bias to capture the activation plate32in the slotway68. InFIG. 16, the finger members70are coupled to the stem61at an inner end71axially outwardly from their distal end72with the resilient fingers70extending radially outwardly and axially inwardly to their distal end.

Reference is made toFIG. 17which is a cross-section similar toFIG. 12, however, showing a sixth embodiment of a piston element57substantially the same as inFIG. 16but with the resilient fingers70coupled to the stem61at their inner ends71axially inwardly from their distal ends72and the finger members70extending radially outwardly and axially outwardly to their distal ends72.

Reference is made toFIG. 18which is a schematic cross-sectional side view similar to that shown inFIG. 12, however, showing a sixth embodiment of a piston element57and a modified actuator plate32. The actuator plate32is shown to include about the catch opening37an upwardly extending tube86. The tube86has an inner end with a hook-like configuration which has a radially outwardly and axially inwardly directed camming surface87which extends radially outwardly as it extends axially outwardly. A radially outer end of the camming surface87ends at an undercut outwardly directed catch shoulder88. The actuator plate and its tube86is formed to be relatively rigid.

The piston element57carries a plurality of resilient finger members70which are adapted to be deflected radially outwardly. On movement of the piston element57downwardly relative to the actuator plate32, end surfaces74and/or camming surfaces89on each resilient finger member70engage the camming surfaces87on the actuator plate32biasing the resilient finger members70outwardly. The resilient finger members70have a hook-like configuration with a radially inwardly directed catch shoulder90which is adapted after the catch shoulder90has moved downwardly past the catch shoulder88on the actuator plate32to snap radially inside the catch shoulder88on the actuator plate32to secure the piston element57to the actuator plate32in the coupled orientation shown inFIG. 18. Each finger member70carries an outer end surface74. Engagement between the outer end surface74and the upper surface36of the actuator plate32prevents relative movement in one axial direction and engagement between the actuator plate's catch shoulders88and the piston's catch shoulders90prevents relative movement in the other axial direction. In the embodiment ofFIG. 18, an annular slotway92is effectively carried on the tube86between the catch shoulder88and upper surface36.

While the invention has been described with reference to preferred embodiments, it is not so limited. Many variations and modifications will now occur to persons skilled in the art. For a definition of the invention, reference may be made to the appended claims.