US3828986A

US3828986A - Dispensing device with abrupt ejection terminating means

Info

Publication number: US3828986A
Authority: US
Inventors: Oscar Roth
Original assignee: Involvo AG
Current assignee: Involvo AG
Priority date: 1972-02-11
Filing date: 1973-03-20
Publication date: 1974-08-13
Anticipated expiration: 1991-08-13

Abstract

A piston rod extends longitudinally through a chamber of a cylinder, the latter being provided in one end wall with a dispensing nozzle. A piston surrounds and is slidable along the piston rod between a retracted position expelling matter through the nozzle, and a forward position. One or more passages are provided in the piston and/or piston rod and these passages connect opposite axial ends of the piston but are open only when the piston is in its forward position. A supply of material to be dispensed communicates with the chamber rearwardly of the piston. An arrangement is provided for assuring that material expelled from the nozzle will be expelled with at least substantially constant pressure at all times, and includes a means for abruptly terminating the ejection of the material.

Description

[451 Aug. 13, 1974 United States Patent 1191 Roth 1 1 DISPENSING DEVICE WITH ABRUPT 3,430,816 3/1969 Nadherny et a1. 222/387 EJECTION TERMINATING MEANS 222/387 X FOREIGN PATENTS OR APPLICATIONS [75] Inventor: Oscar Roth, Zurich, Switzerland Assignee: Involva AG, Buenzen, Switzerland 206,771 6/1955 Australia............................. 222/387 16,009 9/1900 Great Britain...................... 222/387 633,917 10/1927 222/387 France [22] Filed: Mar. 20, 1973 1211 pp 343,141 Primary Examiner-R0bert B. Reeves Related Application Dam Assistant ExaminerC. A. Marmor continuatiommpart of Sen N0 225,421, Attorney, Agent, or Fzrm-Mrchae1 S. Striker 1972. [5

Feb. 11,

7] ABSTRACT A piston rod extends longitudinally through a chamber of a cylinder, the latter being provided in one end wall with a dispensing nozzle. A piston surrounds and is slidable along the piston rod between a retracted posi- 137/522 222/380 tion expelling matter through the nozzle, and a forward position. One or more passages are provided in the piston and/or piston rod and these passages con- [51] Int.

[58] Field of Search nect opposite axial ends of the piston but are open 41/2 1 1 5 1 1 425/244 245 only when the piston 18 in 1115 forward position. A supply of material to be dispensed communicates with the chamber rearwardly of the piston. An arrangement is [56] References Cited UNITED STATES PATENTS 7 Claims, 4 Drawing Figures provided for assuring that material expelled from the nozzle will be expelled with at least substantially constant pressure at all times, and includes a means for abruptly terminating the ejection of the material.

new/22. Us

222/387 x Johnson 1,590,058 6/1926 1,716,504 6/1929 Pierce............

1,909,678 5/1933 Hi1lis..............

DISPENSING DEVICE WITH ABRUPT EJECTION TERMINATING MEANS BACKGROUND OF THE INVENTION The present invention is a continuation-in-part of my copending application Ser. No. 225,421, filed on Feb. ll, 1972 with the title DISPENSING DEVICE.

In that application I have disclosed a dispensing device, and in particular a device for dispensing a bonding agent. Devices of this type are used in the book-binding art and in other applications where an adhesive or a bonding agent must be dispensed and applied to a point of use. The bonding agent is usually accommodated in a supply vessel which can be heated and is supplied from this vessel via a similarly heatable connecting conduit under pressure to a spray or dispensing arrangement. The supply vessel itself is not part of a structural unit with the spraying arrangement. When a valve is actuated the bonding agent is expelled from the nozzle of the spraying arrangement.

Because the previously known constructions in the prior art had certain disadvantages, including the fact that it was not possible to precisely meter the quantity of bonding agent being dispensed during each use, I disclosed the device set forth in my aforementioned copending application wherein a cylinder was provided formed with an interior chamber in one end wall of which there is provided a dispensing nozzle. A piston rod extends longitudinally through this chamber and is surrounded by a piston that is slidable along the piston rod between a retracted position in which it expels matter through the nozzle, and a forward position. One or more passages are provided in this piston and/or the piston rod, and these passages connect opposite axial ends of the piston but are open only when the piston is in the forward position. A supply of material to be dispensed communicates with the chamber rearwardly of the piston. This construction provides for metering of the quantity of bonding agent which is dispensed during each use, and allows the discharge of a perfectly straight'streamof bonding agent so that the application of the bonding agent to a desired specific point is made easy. Moreover, the distances between the supply and the dispensing nozzle are small, so that heating of the material can be accomplished readily and without undue expenditure of energy.

However, I have found it desirable to further improve the aforementioned dispensing device, in order to assure that the stream of bonding agent or other matter which is ejected from the dispensing nozzle during each incident of use will be ejected under a pressure that is as uniform as possible from the beginning to the end of the ejection.

SUMMARY OF THE INVENTION It is, accordingly, a general object of the present invention to provide such an improved dispensing device.

More particularly it is an object of the invention to provide a dispensing device which not only has the advantages set forth with respect to the device disclosed in my aforementioned application, but in addition makes it possible for the stream of matter which is ejected from the dispensing nozzle of the device, to be ejected under a pressure which is at least substantially constant throughout the entire period during which ejection takes place.

In keeping with these objects, and others which will become apparent hereinafter, one feature of the invention resides in a dispensing device, particularly for applying a bonding agent, which briefly stated comprises cylinder means having an elongated internal chamber provided with two end walls, and dispensing nozzle means communicating with this chamber at one of the end walls. A piston rod extends longitudinally through the chamber and a piston surrounds and is slidable along this piston rod between an forward position closer to and a retracted position farther from the aforementioned one end wall. The piston divides the chamber into two compartments located at opposite axial sides of the piston. Passage means is provided which is open and connects the compartments when the piston is in its forward position, and is closed when the piston is in its retracted position. Supply means communicates with the chamber intermediate the piston and the other of the end walls for supplying material to be dispensed. Pressure control means is provided for assuring expulsion of material from the nozzle means with at least substantially constant pressure.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. I is a vertical section through one embodiment of a device according to the present invention;

FIG. 2 is a partly sectioned fragmentary detail view, on an enlarged scale, showing the piston of the device in FIG. 1 in its forward position;

FIG. 3 is a view analogous to FIG. 2 but showing the piston in its retracted position; and

FIG. 4 is an axial section through a further embodiment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Discussing the drawing in detail, and referring firstly to the embodiment illustrated in FIGS. l3, it will be seen that reference numeral 1 identifies a receptacle for material to be dispensed, for instance a bonding agent. The receptacle 1 has a cover 2 which closes it but of course is removable so that additional material may be admitted into it. At the lower end of the receptacle 1 there is provided an outlet portion 3 having an opening through which material can be dispensed. A heating element 4for instance a Calrod (TM) unit-- extends through this opening into the interior of the receptacle 1 so as to heat the contents thereof if they are of the type which require to be heated, as in the case of a bonding agent of requisite type. There is sufficient room for the material to flow through the opening about the heating element 4.

A thermally conductive member 5 is provided, serving as a support on which the receptacle 1 is mounted and being provided with a passage or conduit 6 which communicates with the opening of the receptacle 1 so as to receive material therefrom. A filter 7 and an additional heating element 8 with a thermostat 9 (all known to those skilled in the art) can be interposed in the conduit 6 or arranged in the support member for filtering and further heating the material to be dispensed.

Mounted on the support member 5, in communication with the conduit 6 thereof, is a dispensing unit having a cylinder 10 which is connected coaxially with a pneumatic cylinder 11. A piston 12 is displaceably accommodated in the cylinder 11 which latter has two

openings

13 and 14 for the admission and evacuation of compressed air. A piston rod 16 is rigidly connected with the piston 12, and a further piston surrounds and is slidable along the piston rod 16.

The lower end of the cylinder 10 is closed by a oneway valve 17 which discharges into the dispensing nozzle 18.

A set screw 19 is provided at the upper end of the cylinder 1 1, coaxially with the piston rod 16, so that it can be adjusted to thereby limit the extent to which the piston rod 16 can be axially displaced. It will be seen that the piston rod 16 has a conical portion 21 and a cylindrical portion 24, the piston 15 surrounding the latter and being slidable along the same between a lower forward position which is shown in FIG. 2, and an upper retracted position which is shown in FIG. 3. As the latter Figure also shows, an axial bore 22 in the piston 15, which bore diverges conically in upward direction, accommodates the conical portion 21 of the piston rod 16 when the piston 15 is in the retracted position. In addition, the piston 15 is provided with channels 25 which communicate (when the piston 15 is in the forward position shown in FIG. 2) the

compartments

20 and 23 into which the interior of the cylinder 10 is divided by the presence of the piston 15. The channels also communicate with the conical portion of the bore 22 and are blocked when the piston 15 is in the position shown in FIG. 3.

In operation of the novel device, material to be dispensed such as a bonding agent will flow from the receptacle 1 around the heating element 4 into the conduit 6, to pass through the filter 7. The thermostat 9 as sures that the material will be maintained at a precisely preselected temperature.

From the conduit 6 the material, for instance the heated bonding agent, flows into the space 20 above the piston 15. At this time it is assumed that the piston 12 is in its upper position by admission of compressed air into the cylinder 11 and in its forward position with respect to the piston rod 16. This position is shown in FIGS. 1 and 2 and it will be seen that the conical portion 21 of the piston rod 16 is out of contact with the conical portion of the bore 22 of the piston 15. Thus, the bonding agent can flow through the opening 22 and the channels 25 into the space 23 between the nozzle 18 and the piston 15. If compressed air is now admitted above the piston 12 through the inlet 13, then the piston 12 and thereby the piston rod 16 will be displaced downwardly (in FIG. 1). In so doing the piston rod 16 will slide in the piston 15 until the conical portion 21 contacts the piston 15 as shown in FIG. 3. This closes thebore 22 of the piston 15 so that no further bonding agent can enter, and the piston 15 together with the piston rod 16 now continues to move in downward direction, opening the one-way valve 17 and ejecting the bonding agent through the nozzle 18. When the piston rod 16 is subsequently retracted again, a vacuum will develop between the piston 15 and the nozzle 18, so

that a renewed charge of bonding agent can be rapidly aspirated into this space. When the piston rod 16 is retracted, the conical portion of the bore 22 becomes immediately opened again.

The stroke or displacement of the piston rod 16 can be adjusted by requisite setting of the set screw 19, and thus the quantity of bonding agent to be dispensed during the expulsion stroke of the piston 15 can be varied at will. The more rapid the operation of piston 15, the more quickly bonding agent must be able to enter into the space between the piston 15 and nozzle 18, and the necessary rapidity is assured by the suction effect resulting from the movement of the piston 15 towards the upper position.

It is also possible, although not illustrated in the drawing, for the piston rod 16 to be provided with a downwardly open axial connecting channel which upwardly communicates with a conical portion of the bore 22 when the piston 15 is in the forward position thereof. In this case the channels 25 could be omitted from the piston 15.

Coming now to the embodiment in FIG. 4 it will be seen that the member 5 and the receptacle 1 with their associated structures have been omitted for the sake of clarity. Thus, only the actual dispensing arrangement is illustrated. In FIG. 4 the parts which are the same as or equivalent to the parts in the embodiment of FIGS. 1-3 are identified with like reference numerals having a prime symbol.

The cylinder 11' here is connected with the cylinder 10, the latter being composed of an upper portion 101 and a lower portion 102 which is threadedly connected with the upper portion 101. The piston 15' is axially displaceably accommodated in the cylinder 10' and subdivides the interior thereof into an upper space 20 and a lower space 23'. Piston 15' is provided at its upper end with a funnel-shaped recess 103 in the wall of which there is provided a pin 104 which extends transversely of the recess 103. The lower end of the recess 103 communicates with a connecting channel 25' which is split up into individual smaller channels in the region towards the lower space 23. Screws 105 connect a hardened steel plate 106 to the lower cylinder portion 102. A nut 108 connects the dispensing nozzle 18 having the outlet bore 109 to the plate 106.

A valve chamber 110 for the one-way valve 17' is also provided in the cylinder portion 102, and the valve chamber 110 has an opening 111 communicating with the lower cylinder space 23, which opening 1 11 is provided on the side facing the valve chamber 110 with a valve seat for engagement of a corresponding seating surface of the valve body 112 which latter is pressed against the valve seat by the biasing spring 113. A further opening 107 is provided in the steel plate 106 and communicates the valve chamber 110 with the bore 109 and the steel plate 106 is provided on the side facing the valve chamber 1 10 with an additional valve seat for cooperation with a corresponding further seating surface of the valve body 112. The latter is provided with an abutment 114 which extends through the opening 111 into the lower cylinder space 23'.

A contact face 115 is provided on the piston 15' for contact and cooperation with the abutment 114 so that, when the piston 15 moves from its upper into its lower end position, the contact face 115 will engage the abutment 114 as the piston approaches its lower position and will thus displace the valve body 112 downwardly towards the nozzle 18. As soon as the sealing surface of the valve body 112 contacts the valve seat of the opening 107 which communicates the chamber 110 with the bore 109, the abutment 114 will limit the further displacement of the piston The lower conical portion 24 of the piston rod 16 extends into the recess 103. Above the conical portion 24' the piston rod 16 is provided with a diametrical slot 116 through which the pin 104 extends. The latter is thus displaceable in the slot 116 in axial direction of the piston rod 16. Thus, when the piston rod 16 is displaced axially upwardly in FIG. 4, the conical portion 24 will be lifted away from the recess 103 and a space will develop between piston rod 16' and the recess 103. When the lower end 117 of the slot 116 moves into contact with the pin 104, the piston rod 16' will take along the piston 15' in upward direction. At this time the piston 15 will be in its forward position so that a connection is established via the recess 103 and the channel 25 between the upper cylinder space and the lower cylinder space 23'.

In operation of this embodiment, the material to be dispensed (such as liquid glue or other bonding agent) enters through the conduit 6' into the upper cylinder space 20 and fills the same. When the piston rod 16 now moves upwardly the piston 15 initially remains in the position shown in FIG. 4. A communication develops between the upper cylinder space 20' and the lower cylinder space 23 via the recess 103 and the channel As soon as the lower end 117 of the slot 116 moves into abutment with the pin 104, the piston rod 16' takes along the piston 15' in upward direction. At this time, the piston 15' is in its forward position as seen with reference to its relative displacement on the piston rod 16. During the upward movement of the piston 15', the valve body 112 engages the seat associated with the opening 111, closing the latter and thus closing the valve chamber 110 with respect to the lower cylinder space 23 so that a suction develops in the latter, with the result that the material in the upper cylinder space 20' is now drawn by this suction through the channel 25' into the lower cylinder space 23.

When the piston 15 has reached its upper end position, the piston rod 16 is again displaced in downward direction. As this takes place, the piston 15 initially remains in its upper end position until the conical portion 24' of the piston rod 16 engages the recess 103 and thus closes the channel 25'. Now, the piston 15' is taken along in downward direction by the piston rod 16' and the material in the lower cylinder space 23' is ejected through the valve chamber 110 and the opening 107 and finally out of the nozzle 18'. The excess pressure which thus develops in the space 23 causes the valve body 112 to be displaced downwardly against the effect of the spring 113, and as soon as the surface 115 moves into engagement with the abutment 114, the valve body 112 is displaced further downwardly and moved into sealing engagement with the valve seat associated with the opening 107, so that the latter is suddenly closed. Appropriate dimensioning of the spring 113 on the one hand, and closing of the opening 107 via the piston 15 and the valve body 112 on the other hand, assure that the material ejected in the form of a stream out of the nozzle 18 will be ejected under a substantially constant pressure for the entire time period during which the ejection lasts. Of course, it will be understood that the valve body 112 must close the opening 107 before the piston 12 in the pneumatic cylinder 11 has reached its lower end position, so that the contact face of the piston 15' can engage the abutment 114 at relatively high speed in order to assure a sudden closing of the opening 107.

It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of constructions differing from the types described above.

While the invention has been illustrated and described as embodied in a dispensing device particularly suitable for dispensing a bonding agent, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims:

1. A dispensing device, particularly for applying a bonding agent, comprising cylinder means having an elongated internal chamber; a piston rod member extending longitudinally through said chamber; a piston member surrounding and slidable along said piston rod member between a forward position and a retracted position with respect thereto, said piston member dividing said chamber into a first and a second compartment located respectively at opposite axial sides of said piston member; supply means communicating with said first compartment for supplying material to be dispensed thereinto; passage means communicating said first and said second compartments when said piston member is in said forward position thereof so as to permit passage of the material from said first into said second compartment and preventing communication betwen said compartments when said piston member is in said retracted position thereof; dispensing nozzle means; a valve chamber provided in said cylinder means intermediate said second compartment and said nozzle means; a first opening communicating said valve chamber with said second compartment and having a first sealing surface; a second opening communicating said valve chamber with said nozzle; a valve body accommodated in said valve chamber and having a side facing said first opening and provided with a first contact surface; biasing means normally urging said first contact surface into sealing contact with said first sealing surface and permitting yieldable displacement of said valve body away from said first opening when the pressure in said second compartment exceeds the pressure in said valve chamber, whereby the material being expelled from said second compartment is admitted into said valve chamber to be ejected therefrom through said nozzle means; and means for abruptly terminating the ejection of the material through said nozzle means and including a first abutment surface on one of said members, a second abutment surface provided on said side and extending into the path of movement of said first abutment surface, a second sealing surface surrounding said second opening, and a second contact surface on an additional side of said valve body facing said second opening and sealingly engaging said second sealing surface when said valve body is further displaced against the action of said biasing means upon abutment of said first abutment surface against said second abutment surface, whereby the ejection of the material through said nozzle means is terminated due to the sealing engagement between said second contact surface and said second sealing surface.

2. A device as defined in claim 1, said piston rod member having a conical end portion and said piston member having a corresponding recess receiving said end portion, said conical end portion tightly engaging in said recess when said piston member is in said retracted position and being spaced out of engagement with said recess when said piston member is in said forward position; and an axial channel connecting said recess with said second compartment.

3. A device as defined in claim 2; further comprising a transversely extending pin provided in a wall bonding said recess, said piston rod member having a diametrical longitudinally extending slot into which said pin extends so as to be slidable therein axially of said piston rod member to determine said forward position of said piston member.

4. A device as defined in claim 2, wherein said channel widens in direction toward said second compartment.

5. A device as defined in claim 1, wherein said passage means is provided in said piston member.

6. A device as defined in claim 1; and further comprising filter means for filtering the material to be dis-' pensed prior to such dispensing.

7. A device as defined in claim 1; and further comprising heating means for heating the material to be dispensed prior to such dispensing.

Claims

6. A device as defined in claim 1; and further comprising filter means for filtEring the material to be dispensed prior to such dispensing.