Ejecting Device

Abstract

A piston is reciprocable in a cylinder between a suction position and an expulsion position, and a drive is provided for reciprocating the piston. The drive includes a speed regulating arrangement which can be used to make the piston move faster during its retraction from the expulsion position to the suction position than vice versa.

Description

BACKGROUND OF THE INVENTION

The present invention relates generally to ejecting devices, and more particularly to devices for ejecting putty and analogous materials.

Devices for ejecting putty and analogous materials, including more or less liquid substances, are known. It is also known to provide these devices with a cylinder and a piston which is reciprocable in the cylinder for drawing in and subsequently ejecting the material in question. The drive can be produced by means of an electro-motor. The problem with the prior art is that the operation and the manner in which these prior-art devices must be handled, are not entirely satisfactory. In particular, both the expulsion or working stroke and the retraction or suction stroke of the piston take place at identical speeds in the prior art, so that the retraction stroke of the piston requires an unnecessarily long period of time. If for any reason it is necessary or desired to retract the piston by hand, this is difficult to do in the prior art devices.

SUMMARY OF THE INVENTION

It is, accordingly, a general object of the present invention to overcome the disadvantages of the prior art.

More particularly, it is an object of the present invention to provide a device of the character in question which avoids these disadvantages.

Still more particularly, it is an object of the present invention to provide such a device which is reliable in its operation, simple in its construction, and rapid in performing its intended functions.

In keeping with these objects, and others which will become apparent hereafter, one feature of the invention resides, in a device of the character in question, in a combination which comprises a cylinder, a piston reciprocable in the cylinder between a suction position and an expulsion position, and drive means for reciprocating the piston. In accordance with the invention the drive means includes speed regulating means operable for moving the piston from the expulsion position to the suction position at a higher speed than vice versa. This makes it possible to have the piston move during its expulsion stroke to the expulsion position at a speed which is the most advantageous for the expulsion of the material, such as the putty or the like, whereas the drawing-in of the material can be carried out at a higher retraction speed which may be double or a multiple of that of the expulsion speed.

The motor is advantageously an electromotor whose torque becomes automatically adjusted in dependence upon the resistance encountered by the piston during its expulsion stroke. In other words, the higher the resistance --for instance because of higher viscosity of the material to be expelled-- the greater will be the torque supplied by the electromotor for advancing the piston during its expulsion stroke. The motor may be a direction-reversible motor, for instance a direct current reversible motor, and an electronic regulating device can be provided which regulates the torque and therefore the force exerted upon the piston, largely independently of the RPM setting of the motor.

One of the problems of the prior-art devices has always been that after the completion of an expulsion stroke there was a tendency for additional material to drip from the interior of the device, under the influence of the still existing pressure therein. In many instances this was undesirable because of the aesthetically displeasing appearance resulting from such dripping. A manual withdrawal of the piston was not able to overcome this problem. In accordance with the present invention, this problem is avoided by providing an arrangement which, when the drive is shut off upon the piston reaching its expulsion position, will automatically retract the piston by a short distance in order to prevent the undesirable dripping.

The cylinder as well as the ejection nozzle are advantageously readily removable, for instance by being threadedly connected with a portion of the housing, so that the device can be readily accommodated for different uses as well as to the particular material which is to be ejected. Generally speaking, the piston is to be advanced at speeds of up to 1/2 cm/sec. during its expulsion stroke.

Another feature of the present invention is that the novel device is particularly easily usable, that is it can be readily handled. In particular, it is advantageous that in accordance with the present invention the arrangement for controlling the operation of the drive means is such that the same hand which holds the device can also control this arrangement, for which case the device advantageously has a housing provided with a pistol grip.

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. 1 is a somewhat diagrammatic longitudinal section through a device according to the present invention, with the control arrangement being diagrammatically shown;

FIG. 2 is a view analogous to FIG. 1, but of a further embodiment of the invention; and

FIG. 3 is a section taken on line 3--3 of FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Discussing the drawing now in detail, and firstly the embodiment illustrated in FIG. 1 thereof, it will be seen that reference numeral 10 identifies the device in toto. It has a drive housing portion 11 which may be of synthetic plastic material, or of another material, and a cylindrical housing portion 12 which is advantageously of steel. The portion 12 is connected with the portion 11, advantageously in a manner so that they can be readily separated, for instance by means of a sleeve 13 or a screw threaded connection. The free front end of the portion 12 is provided with an injection or spray nozzle 14 which is also readily releasably connected with it, in the illustrated embodiment by means of a screw connection 15. The housing portions 11 and 12 together have a somewhat pistol-shaped configuration, with the housing portion 11 constituting a pistol grip which is to be surrounded and engaged by a hand of a user and which can be further adapted in a shape to more effectively fit the hand.

The housing portion 11 is essentially of two-part construction and has a motor component 16 and a gear component 17 which can be connected with one another or constitute a common housing. The motor component 16 accommodates the diagrammatically illustrated electromotor 18, which is too well known to require a detailed description. This motor 18 may for instance be a reversible direct current motor which drives, via a step-down drive 19, a pinion 20. The latter is in mesh with a toothed rack 21 which is displaceable transversely to the axis of the motor drive in the direction of the arrows x.sub.1, x.sub.2. The rack 21 at the same time constitutes the piston rod of the piston 22 which is reciprocably accommodated in the housing portion 12. At opposite sides of the pinion 20 the rack 21 is journalled at 23 and 24 in the side walls of the housing portion 17 for sliding displacement in the direction of the aforementioned arrows. Thus, in the illustrated position of the piston 22, the free end 25 of the rack 21 projects from the housing at the side which is opposite or away from the piston 22, but the rack 21 is still guided in the housing. It is advantageous, but not absolutely necessary, that a sealing or cover arrangement 26 be provided (shown in broken lines) which may for instance be in form of a bellows, so that when the piston 22 and the rod or rack 21 are displaced in the direction of the arrow x.sub.2, the free end 25 which moves out of the housing portion 11 is covered by the arrangement 26. This not only provides for a seal but also provides for a protection against the possibility that the user might be injured, for instance by having a finger clamped between the rack 21 and the housing.

The piston 22 itself can be removably mounted on or connected with the rack 21. Because of this, the rack 21 is provided with a plate 22a having a smaller diameter than the piston 22. With this arrangement it is possible to be able to use in the device according to the present invention so-called cartridges which each have a cylindrical container and can be inserted into the cylinder 12, and each of which contains not only the material to be ejected but also its own piston. Evidently, with this arrangement the piston 22 is not required and can be unthreaded from the rack 21, whereupon in use the plate 22a presses against and operates the piston of the cartridge.

An electronic control device 27 is advantageously arranged separately of the remainder of the device and connected with the drive thereof by a flexible cable 28 which may have any desired length. As indicated at 29 the device 27 can be connected with an external source of electrical energy, identified with reference numeral 30, for instance a net of 220 volts, or as indicated at 31 with a battery 32. Of course, the arrangement can be such that the device can be connected at will either with the battery or with the power source, that is with an energy-supplying net. A transformer and a rectifier for transforming the net voltage to the necessary mode of voltage, for instance of 12 volts, can be made a part of the electronic control device 27. The battery 32 is advantageously of the type supplying the voltage required by the motor, for instance 12 volts, without needing further adjustment of the voltage.

A speed regulating device 33 is provided in the housing 11. It is advantageously provided on the upper side of the housing portion 17, that is on that side of the drive 20, 21 which is located away from the housing portion 16. It may be operated by a control element 34, for instance in form of a turnable knob. The device 33, in conjunction with the electronic control unit 27, permits an adjustment of the RPM setting of the electromotor 18. Switches 35 and 36 can be operated by the fingers of a user whose hand grasps the housing portion 11. Thus, the switch 35 may serve to energize the drive in a sense causing the piston 22 to advance to its expulsion or forward position in the direction of the arrow x.sub.1, and the switch 36 may serve to energize the drive to cause the piston to be retracted from expulsion position to suction or retracted position in the direction of the arrow x.sub.2. It is advantageous if the arrangement is such that the drive motor is switched on only when one of the two switches 35 or 36 is depressed. The electronic control unit 27 can control the motor, for instance via the speed regulating device 33, in such a manner that when the switch 36 is operated to retract the piston 22, the latter will retract at increased speed (for instance double or a multiple) as compared to the advancement in the direction of the arrow x.sub.1 to its expulsion position. The device 27 can also be constructed for so controlling the electromotor 16 --or the latter can be so constructed-- that when the piston 22 encounters increased resistance during its movement to expulsion position, for instance because a different type of material is to be expelled, the motor will supply a correspondingly higher torque and be in turn supplied for this purpose with a correspondingly increased amount of electrical energy.

The device 27 can be made to form a housing unit with the housing 11, if desired, and as an alternative the device 27 can form a portable unit together with the battery 32.

I have found in actual practice that it is advantageous if the cylinder 12 has a diameter of approximately 5 cm and a length of approximately 35 cm, although these are of course exemplary figures.

In order to fill the cylinder with the substance to be expelled, the nozzle 14 is unscrewed and the piston 22 is retracted, while the open front end of the cylinder is immersed in or otherwise connected with a source of supply containing the material. This causes material to be drawn into the cylinder 12. Thereupon, the nozzle 14 is threaded back into place and the piston 22 is then made to advance to its expulsion position, causing the expulsion of the material through the nozzle 14. When the piston has reached its expulsion position the piston is briefly retracted for instance by brief operation of the switch 36 or automatically, so that dripping of the material from the cylinder is avoided.

The embodiment in FIGS. 2 and 3 is analogous to that of FIG. 1, and like reference numerals identify like elements except that in FIGS. 2 and 3 each reference numeral has been given a 100 prefix.

Reference numeral 110 identifies the device in toto, and reference numeral 111 identifies a drive housing portion which may be of synthetic plastic material. A cylindrical housing portion 112 is advantageously of steel and is again removably connected with the housing portion 111 by threaded means or by the sleeve 113. A threaded connection 115 is provided by means of which the nozzle 114 is connected with the housing portion 112.

The housing portion 111 is of several parts and is provided with a rearward motor portion 116, a gear portion 117 and a handgrip portion 116a which in the illustrated embodiment is of one piece with a portion of the gear portion 117. The handgrip portion 116a is a part of the housing, and a portion 116a' of the handgrip 116a is configurated as a cover via which the interior of the handgrip portion is accessible from outside. The entire device is again of substantially pistol-shaped configuration, and the handgrip portion 116a extends transversely of the elongation of the device, as illustrated.

A piston rod 121 is configurated as a screw spindle or provided with helical threads 121a, and a piston 122 is reciprocable in the housing portion 112. The piston rod 121 is driven by a stepdown gear 119a, 119b by the electromotor 18 which is accommodated in the housing portion 116 and arranged in parallel with the piston rod 121a. The stepdown gear comprises a first gear unit 119a and a spur gear drive having gears 120a and 120b which are accommodated in the housing portion 127 in such a manner that they cannot be displaced axially. The gear 120b is in mesh with the threads 121a of the piston 121. End switches 137 and 138 (also known as limit switches) shut off the drive for the piston rod 121 and thereby the piston 122 as soon as the piston 122 has reached either its expulsion position or its suction position, respectively. A toggle switch 135 is provided that may for instance assume three positions. It may operate the drive so as to cause the piston 122 to advance to the forward or expulsion position when in position indicated by the arrow x.sub.1, to move the piston 122 to the retracted or suction position when in the position indicated by the arrow x.sub.2, and to switch off the electromotor 118 when the switch is in an intermediate position. The retraction of the piston 122 can be effected in that the motor 118 is a reversible motor. The limit switches 137 and 138 can be so arranged that before the electromotor 118 is switched off, a brief retraction of the piston 122 from its expulsion position towards its suction position is carried out, so as to prevent dripping of material from the device. A relay with a time switch can be provided in the electronic system for this purpose, and advantageously the time during which the piston is so retracted, or the distance through which it is retracted, can be made adjustable, for instance in dependence upon the viscosity of the material being expelled. The retraction can be between 1 and 5 cm, to name an advantageous range. It is also possible to construct the arrangement in such a manner that the piston 122 is retracted briefly and part of the way towards the suction position, when the switch 135 is released by the fingers of a user who grips the handgrip portion 116a.

Reference numeral 128 designates a connecting cable which can lead to an external battery, or else to a socket of a current supply net, in which case a transformer and a rectifier will have to be interposed. The electronic control device may be mounted directly on the novel device itself. A potentiometer is identified diagrammatically at reference numeral 139 and may serve for the slower advancement of the piston during its movement to expulsion position, and for faster retraction during movement toward suction position.

As in the case of the embodiment in FIG. 1, the embodiment of FIGS. 2 and 3 provides for a bellows 126 or analogous cover which surrounds the end portion 125 of the piston rod which extends rearwardly out of the housing portion 111.

The device according to the present invention is highly versatile and can be used with almost all plastically flowable materials.

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 an injecting device, 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.

Claims

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

1. A device of the character described, comprising a cylinder having an interior at least partially filled with a substance to be expelled; a piston mounted in said interior of said cylinder for reciprocation with respect thereto between a plurality of positions delimited by a forward position and a retracted position and adapted to expel the substance from said interior of said cylinder during its movement toward said forward position and to draw a medium into said interior of said cylinder during its movement toward said retracted position; nozzle means connected to said cylinder and communicating with said interior thereof for dispensing the substance expelled therefrom; drive means for reciprocating said piston; and retracting means for limited retraction of said piston toward said retracted position subsequently to the termination of each movement toward said forward position to thereby retract the substance present in said nozzle means into said interior of said cylinder and prevent dripping.

2. A device as defined in claim 1, and further comprising speed regulating means operable for moving said piston toward said forward position at a first speed and for moving said piston toward said retracted position at a second speed higher than said first speed.

3. A device as defined in claim 1, wherein said drive means further comprises an electromotor having a torque which is self-adjusting in dependence upon the resistance encountered by said piston during movement to said forward position.

4. A device as defined in claim 1; and further comprising switching means for controlling movement of said piston between said positions thereof, and for stopping and starting said drive means in dependence upon such movements.

5. A device as defined in claim 1, said retracting means comprising regulating means for regulating the extent of such retraction.

6. A device as defined in claim 1, wherein said retracting means comprises an arrangement for retracting said piston by between substantially 1 and 5 cm.

7. A device as defined in claim 1; said nozzle means comprising an ejection nozzle; and further comprising mounting means mounting said nozzle for ready removal and installation.

8. A device as defined in claim 1; further comprising a housing; wherein said drive means comprises an electromotor in said housing; and wherein said speed regulating means is mounted on an upper side of said housing which is opposite said electromotor.

9. A device as defined in claim 1; further comprising a housing having a pistol grip; and switch means in said pistol grip for engagement by the hand of a user and associated with said drive means for controlling the operation of the same.

10. A device as defined in claim 1; further comprising a housing; and said piston having a piston rod which extends in part from said housing; and cover means covering the region where said piston rod extends from said housing.

11. A device as defined in claim 10, wherein said piston rod extends from said housing to a variable extent depending upon the position of said piston; and wherein said cover means surrounds said piston rod exteriorly of said housing and is extensible and retractable in dependence upon the extent to which said piston rod extends from said housing.

12. A device as defined in claim 1; further comprising a housing; and an electronic control unit for controlling the operation of said drive means, said control unit having a casing which is unitary with said housing.

13. A device as defined in claim 1; further comprising a housing having a handgrip portion; said piston having a piston rod; and said drive means including an electromotor adjacent said piston rod outside said handgrip portion and operative for effecting reciprocation of said piston rod.

14. A device as defined in claim 13, said drive means further comprising a gear drive including a gear surrounding said piston rod, and helical threads on said piston rod and meshing with said gear.

15. A device as defined in claim 1; further comprising a housing having one end region provided with a handgrip portion, and an opposite end region provided with said nozzle means; and wherein said drive means comprises an electromotor mounted in said housing intermediate said end regions.

16. A device as defined in claim 15; further comprising limit switches arranged in said handgrip portion and positioned so as to be operated in dependence upon reciprocatory movement of said piston to the respective position thereof.

17. A device as defined in claim 1; further comprising a housing having a pistol grip portion and being at least in part composed of two connected shell sections.