CA1098381A - Desoldering tool - Google Patents

Abstract

ABSTRACT
A desoldering tool comprises a vacuum orifice (146) connected to a vacuum chamber (145) by a member (147) which incorporates an on-off valve operated by a push button (148). A hose connection (151) to a vacuum pump is also provided.

Description

1~8381 This invention relates generally to a desoldering tool for use in a vacuum system.
The present invention is a vacuum system comprising a desoldering tool having a vacuum orifice and a vacuum storage chamber connected to said orifice, a hose interconnecting the vacuum storage chamber and a vacuum source and an on-off valve controlling communication between the vacuum orifice and the vacuum source, said vacuum source including a plenum chamber to which said hose is connected, a venturi connected to a high pressure source and in communication with the plenum chamber whereby a flow of air from the high pressure source through the venturi creates the vacuum in the plenum chamber, and snap acting valve means responsive to the vacuum in the plenum chamber to control the flow of air from the high pressure source through the venturi.
Embodiments of the present invention will now be described, by way of example, with reference to the accompanying drawings, in which:
Figure 1 is a cross-sectional view of a preferred embodiment of a vacuum pump for use with the present invention;
Figure 2 is a cross-sectional view of another vacuum pump for use with the present invention;
Figure 3 is an elevational view of a desoldering tool which may be used with the vacuum pump of the present invention; and Figure 4 is an elevational view of a vacuum desoldering tip which may be used with a temperature-controlled desoldering instrument.

- 2 -8;~31 -Re~erri~g now to the dr~wings, the vacuum pump of Fig. 1 includes a housing generally designated at 10 within which moves a control element or plunger 11 a~d further including a venturi tube 12. The housing 10 may, as illustrated, be made in three parts and may include a plunger cap 14, a pl~nger housing 15 and a muffler portion 16. The purpose of the vacuum pump of Fig. 1 is to utilize compressed air to generate a vacuum. In addition, the compressed air having passed the ~enturi tube 12 is converted into a gas or air at a relatively low pressure so that both a ~acuum and a low pressure gas are available.
The pump is so arranged that it will automatically block the supply of high pressure air when a vacuum of predetermined pressure has been obtained. me pump is provided with an automatic control to apply compressed air again when the pressure in the vacuum reservoir has risen ' to another predetermined value. merefore, the vacuum is ¦ maintained between two limits by a demand action. ~hc operation may be described as a ~ariable pulse width modulation system, that is a system ~here the time duration of the on and off operation varies in accordance with demand.
Before further explaining the operation of the pump of the in~ention the structure of the pump of Fig. 1 will now be described in some detail.
m e plunger housing 15 consists of a generally cylindrical outer body haYing, for exa~pl~, four ~utlets 17, 18, 2~ and 21 connected to the interior ~h-ch forms a plenum 22~ The outlets 17, 1B, 20 and 21 are each provided with an outer serrated nipp~e for connection to a suitable hose

3~ such as a ~ose ~3 to provide a vacuum at a desired work place.
.

. lQ~8381 The hose 23 may consist of a suitable plastic ~aterial which is flexible. It need not necessarily be able to withstand atmospheric pressure and may be allowed to collapse due to the ambient air pressure~ It will, of course, be obvious that more or less than the four nipples 17, 18, 20 and 21 may be provided~ The plunger housing 15 is also provided with an apertured conical inlet ~4 by means of which the high pressure a~r or gas may be supplied through a flexible hose 25. The hose 25 should be ~ble to withs~and the high pressure which ~ay amount to 80 - 100 psi (lbs. per square inch). '~he conical end 24 -may be threaded for recei~ing a coupler element 26 which turn is connected to the high pressure hose 25 and which may have a serrated nipple 27 to which the hose is secured.
me radially extending inlet 24 has a bore 3 which is connected to an axial bore 31 in the plunger , housing 15. The bore 30 is connected to the axial bore 31 ¦ through a reduced portion 32 which interconnects the high ¦ pressure hose 25 to the bore 31 and whic~ can be ope~ed and closed by the forward portion 33 of the plunger 11 which is ~ealed on either end by two 0-rings 34. The bore 31 connects to a conical opening 35 which has a much reduced central cylindrical opening 36 connected in t~rn to the Y~nturi 12.
me plunger housing 15 may ~e provi~ed at its rea~ end with suita~le internal holes not sho~n in ~ig. 1, ~or recei~ing ~el~tapping screws to secure the plunger cap 14 to the plunger housing 15. Finally, the plunger housing 1~ is provided with recesses 3~ which cooperate with corresponding projections 40 in the venturi 16 to provide a ~ayonet lock to lock the venturi or muffler housing 1& to the plunger ~'a83~
housing 15.
~rning now to the description of the muffler and ~enturi housing 12, it will be seen that this housing portion consists of a forwardly open cylindrical portion or manifold 4~ provided with a slot or hole 43 in its side wall.
The open end of the cylinder 42 is closed by a muffler material 44 ~o dampen noise created by the intermittent operation of the pump. me slot 43 serves the purpose to receive a portion of the muffler material 44 so as to prevent its ~eing blown out of the open cylin~er 42. me manifold 42 may be conno~ted to the outside of a room to ventilate the fumes and the like which may be sucked up by the vacuum.
Thls will keep the room clean and free of obnoxious gases.
me rear end of the muffler housing 16 is closed by , a disk-like structure 45 which in turn carries the venturi i -tube 12. The rearward end 46 of the venturi tube 12 is spaced from the front end 4'~ of the plunger housing 15 and ¦ from its ~ore 36 to provide an opening 48 through which air can escape from ?~ bore 50 to the venturi tube 12, thus ; 20 creating a vacuum in a manner well understood. In other words, the venturi tube 12 has a reduced portion or throat through which the compressed gas or air must flow at an increased speed and reduced pressure. This reduced pressure in turn will cause air to flow throlgh the opening 4B into the ~enturi tube 12 thus creat~ng a vacuum in the bore 50.
me bore 50 in turn has an enlarged cylindrical portion ~1 in which is proYided a check val~e 52 which is capable of sealing the ~ore ~0 against a connector element 53 by means of the 0-ring 54. The connector element 53 snaps over the out~ardly bulging ring ~ at the en~ of the 0 ~ 83U31 housing portion 16 and again has a serrated nipple 56 for connection to a hose 57. The hose 57 should also consist of a material capable of withstanding the air pressure, Hence the hose 57 whould be relativély rigid to resist collapse due to the air pressure and to provide a fast response time. It serves the purpose to interconnect the plenum 22 with the bore 50 so as to create a ~acuum in the -plenum 22. It will be understood that the proiections 40 at the rearward end of the muffler housing 16 which create ~ bayonet lock, extend on both sides through a predetermined angle so that the tw;o parts can be connected and locked by rotating one against the other.
; After the high pressure air has passed the venturi tu~e 12 it has a relatlvely low pressure such as say 2 - 6 psl. m~s air may be obtained through an aperture 60 in the cylinder 42 which connects to a connector 61 which may j be identlcal to the connector 53 and which is snapped over ¦ an outwardly bulging portion 62 of the housing 42. The connector 61 ~s provlded with a hole 63 ha~ing an eccentric ! 20 portion 64 which can be connected to the bore 60 by rotating ~t. This will permit to control the size of the opening between the $nterior of the cylinder 4~ and a flexible hose 65 from wh~ch the low pressure a~r can be obtained. This can be stored in a reservoir 66 sho~m schematically. This regula~ed output air c~ be utilized for many pu~poses.
Having now described the three housing portions ~4, 15, and 1~, the control piston or p~unge~ and its function w~ll now be described. As explained before, the plunger 11 has a forward or control portion 33 for either opening or . closing the opening 32 which connects to the compressed air lQ~83~1 supply. The plunger 11 is provided with a cylindrical central shaft 6~ which is integr~l with the control portion 33. The rearward portion 70 is provided with a small metal pin ?1 which oooperates with a trip cam 72. Finally the plunger 11 has a disk-like portion 73 which slides within the cylindrical opening 74 of the plunger housing 15 and is se~ed by an 0-ring 75. A main sprin~ 76 bears against one surface of the disk 73 and against the front wall 77 of the plunger housing 15.
. The trip cam 72 is of fork-like construction and has i a generally U-shaped opening 78 in both ~f its end portions ; ~n whlch the plunger shaft 71 can mo~e. It is provided on. its forward side with a semicircular detent 80 which helps , the snap action provided by the trip cam 72 and its spring load 81. The spring 81 is loaded in compression and disposed , , between the cylindrical wall 74 of the plunger cap 14 and the i top portion of trip cam 72. The spring 81 is pressed against i a ~houlder 82 in the plunger cap by a projection or ~etaining leg 83 forming part of the plunger cap 14 and which is . 20 secured to a semicircular disk 84. me disk 84 additionally has two rearwardly projectin~ retaining legs 85 spaced from retaining leg 83 and through which extend outwardly pro~ecting pins 86 about which the trip cam 72 is capa~le of , ~ p~ot~ng. --$he pins ~6 preferably form part of the trip cam 72 and are molded integ~al therewith.
A foam-like filter 88 of annular shape may ~e provided ~n t~e p~enum 22 for retaining particles such as solder which m~y haYe been suo~ed in by one of the hoses such as 23.
. ~y way of example, the muff~er housing 16 may consist o~ a clear plastic such as a polycarbonate which is sold in -- 7 -- .

1~8~1 the trade under the name Lexan.* The connector 53 may consist of polyethylene. The plunger housing 15 need not be transparent and may consist of a self-lubricating plastic such as Delrin* which is an acetal. The plunger cap 14 may again consist of Lexan. The trip cam 72 may also consist of Delrin.
If desired, a vacuum tank 90 may be connected to one of the vacuum hoses 23 as shown schematically and this in `~
turn may be connected to various work areas, for example by a hose 89.
Hexagonal bore holes 91 may be provided in the housing 15 and 16 for securing the pump to a fixed support.
The operation of the pump of Figure 1 will now be described. Initially the plunger 73 is in the position shown in Figure 1. In other words, the pressure of spring 76 pushes the plunger disk 73 rearwartly thus keeping the opening 32 free. Accordingly, air pressure applied through hose 2S flows through bore 30, opening 32, conical portion 35, reduced opening 36 into venturi 12. This will cause a reduced pressure at the point 48 thus opening check valve 52. The air is now capable of flowing from plenum 22 through hose 57 into the bore S0 and out of the venturi tube 12. The air at reduced pressure is available from hose 65 and may be stored in the low gas pressure reservoir 66 which may also be provided with a suitable chec~ valve such as shown at 52.
As the YaCUUm in the plenum 22 reaches a predetermined low pressure, the differential air pressure will be able to push the disk 73 of the plunger 11 forwardly, that is toward the right of Figure l and the control portion 33 will block opening 32 thus shutting off the air supply.

*Trademark r .._, lB~8381 This motion of the plunger ~1 is accelerated by the snap action created by spring 81 and trip cam 72. In other words, the initial motion of the plunger 68 ~ill eventually cause the spring to reach near dead center so that subsequent forward motion, toward the right of Fig. 1 is accelerated by the toggle action of the spring and cam.
me force of control spring 76 and the size of the disk 73 are so dimensioned that the plunger mo~es toward the right when a predetermined low air pressure has been reached in the plenum 22.
As the Yacuum is used up by operation of the tools connected thereto or simply by leakage, the pressure in the plenum 22 increases again. ~hen it has reached a predetermined upper value again determined by the force of spring 76 and the size of the disk 73, the reYerse action takes place, that is the plunger 11 moves rearwardly, that is toward the left of Fig. ~ because the air pressure differential has been reduced. Again the motion is accelerated by t~.e snap action or toggle action of spring 81 ~! 20 and trip cam 72. The off action, that is the movement of the plunger 68 into the position of Fig. 1, is helped by the provision of the semicircular recess 80 in the two legs of ~he c~m 72. This is so because the recess 80 tends to retain the pin 71 on the plunger 11.
It wi1l now be seen that the pump of Fig. 1 operates on demand and hence the compressed air is only used when it is needed. This helps to conserve the supply of compressed air and makes it possible for a person to carry a self-! contained system including a compressed air supply and a pump.
The pump will last for years. The system pro~ides not only _ g _ 1~!!98381 a vacuum but also a low gas pressure supply which may be used for other purposes. Since the system operates on demand the on and off times are variable; therefore the system becomes essentially a variable pulse width modulation control.
The snap action caused by spring 81 and trip cam 72 serves the purpose to prevent that the plunger 68 with its rontrol portion 33 keeps the opening 32 partially open and partially closed. mis would mean that the compressed air ~s wasted and that no positive control is obtained. mere-fore, in order to obtain the on-off action of the vacuum pump of the invention the snap action is essential.
" ~aving now described the construction and operation of the preferred vacuum pump of the invention, reference is 'i now made to Fig. 2 which shows a modified vacuum pump. mis ! vacuum pump has a different arrangement for providing the I re~uired snap action of the demand control plunger. The pump ¦ of F~g. 2 again may have a three-part housing including ~j plunger housing cap ~00, a plunger housing 101 and a muffler ~nd ~enturi housing 102. Thus the plunger cap 100 has a -cylindrical portion 103 and may be open to atmosphere at a reduced rearward portion 104. The plunger cap has a cylindrical radial extension 105 for housing a spring 106 w~ich urges a conical tip 107 against the plunger 110. Its operation will be subsequently described.
The plunger housing 101 has an outer cylindrical portion 111 for receiving the plunger 110. It has a dis~-¦ like forward portion 112 against which bears a main spring 114. It also has a central cylindrical portion 115 for the ; 3~ plunger 110 ~nd which has a reduced opening 116 for connection - 10 _ .

lQ~83~
to a ~enturi. A bore 116 connects to the venturi.
T~e muffler portion 102 has a forward end 118 with external openings 120 and which serves as a muffler. It may be provid~d with sound deadening material not shown. Its main body 121 forms a ~enturi 119 in the manner previously ; ~ explained and connects to the bore 116 of the plunger housing. It has a first outlet 122 from which the ~racuum is available. A check valve 123 may be provided in a connector 124 similar to those previously described. The connector in ~urn connects to a hose 125 which interco.~nects the outlet , 122 uith the outlet 117 forming a serr~d nipple so as toc~eate a vacuum in the plenum 126 formed in the cylindrical ~, portion 111. A filter 129 may be provided in the plenum !; 126. me ~ompressed air is applied to the inlet 127.
e air at reduced pressure is a~ailable from an air outlet 128 which may be closed by a check ~alYe 130.
; The plunger 110 may be some~hat similar to tnat of ~ ~ig~ 1 and again has a forward portion 131 sealed by two! 0-rings 132 for opening or closing the air inlet opening 133.
The forward portion 131 of the plunger 110 is made integral ¦ -~with a circular disk 134 sealed by an 0-ring 135 against the cylindrical portion 111 of the plunger housing. Its rearward portion 13~ has a dis~-like termination 137 ~rhich cooperates w~th the spring biased detent 107.
The p~mp of ~ig. 2 differs primarily from that of Fig. 1 by ~ts di~ferent snap action provided by the detent 107 and the spring ~06. Tts operation may be described as follows. Due to the force o~ spring ~14 acting against the plun~er disk 134 the plunger is initially in its rearward 3 position, that is in the left-hand position as ~iewed in ~q8381 Fig. 2. ~.~en compressed air having a pressure of say 80 - 100 psi is applied to the inlet 127 a vacuum is cre~ted at the outlet bore 122 in the manner previously described. This reduced pressure is applied by the hose 125 to the plenum 126. At the same time air at reduced pressure is available from the outle~ 128 as long as the check ~alve 130 is open.
Eventually the pressure in the plenum 126 decreases *o a predetermined value. This will now per~it the disk 134 : to mo~e toward the right against the pressure of the main spring 114. me snap action is obtained by the enlarged disk-like port~on 137 of the plunger being forced past the detent 107. This will now permit the control portion 131 to seal off the bore 133 thus cutting off the air supply. At that time the check valve 1~0 closes so as to preserve the ~ low pressure air ~hi~h may be maintained in the reservoir I sim~lar to the one shown in 66 in Fig. 1. At the same time the check valve 123 closes. The regulated vacuum output llne 140 may also be connected to a vacuum tank such as shown at 90 in Fig. 1. As the vacuum is used up the pressure in the plenum 126 will slowly rise until it reaches a predetermined value. This is again determined by the force of main spring 114, the size of the plunger disk 134 and the -force--of the -spring biased detent 07. Eventually, however, -the plunger 110 will be able to snap rea~ardly, that is to the left of Fig. 2 thus opening the bore 133 and the pre~iously describe~ action repeats again.
It should be noted that the embodiment of Fig~ 1 has certain advantages over that of Fig. 2. In other words, the plunger 11~ of the embodiment of ~ig. 2 must overcome the re3atively stron~ force of the spring bi~sed detent 107 to ;

lQ98;~1 move left o~ riGht. miS additional force is wasted, that is it re~uires an additional supply of compressed air. Otherwise, however, the operation of the vacuum pump of Fig. 2 ~s basically identical with that of Fig.
1. It is again controlled by demand and provides variable on and off periods analogous to a variable pulse width modula~ion system.
The parts of the pump of Fig. 2 may consist of the same materials as corresponding parts of the pump of Fig. 1.
Turning now specifically to Fig. 3, there is illustrated ~ desoldering tube for use with the vacuum pump described. The desoldering tube of Fig. 3 is characterized by its extremely fast reaction. It includes a cylinder 145 which preferably is transparent and consists of a plastic material capable of with-standing high impact. Disposed within or connected to the cylinder 145 is an operating tip 146 having a central opening for applying the vacuum. me tip 146 is connected to a connector member 147 having an on-off valve therein of conventional construction which ~ is operated ~y depressing a button 148 which preferably ¦ is spring loaded. Hence when the button 148 is I depressed, the valve is open to permit a vacuum to be ¦ app~ied to the tip 146 through an inner cylinder 150 ¦ connected thereto.
The ~acuum may be applied ~y a hose 151 connected to a cap 152 which fits over the cylinder 145 and is sealed thereto. The hose 151 in turn ~o is connected by a flexible I

l~Ql~;~Bl cylinder 153 to a nipple 154 forming part of the cap 152.
The cylinder 145 provides a storage space for the vacuum and a filter material 155 may be disposed at its rear end for filtering, for example, solder drops that may be sucked in by the tool. Some of the solder may additionally be trapped inside the cylinder 150.
The operation of the desoldering tube of Figure 3 will now be evident. The solder to be removed is first heated by a soldering instrument. After the solder has become liquid it is sucked in by the desoldering tube which can readily be held in one hand with the index finger operating the push button 14~ by depressing it. Since the vacuum or the low pressure is stored in the cylinder 145 the action is extremely fast because as soon as the button 148 is depressed the liquid solder is sucked in in the usual manner. It should be noted that the desoldering tube of Figure 3 is a strap-down system which is mainly suited for production work.
Thus while the tool is very efficient and features a snap action switch it needs a permanent connection to a vacuum pump of the type previously disclosed.
Turning now to Figure 4, this illustrates again a desoldering tip controlled by one hand and which may be attached to a soldering instrument such as a temperature controlled soldering instrument disclosed and claimed in ~nited States Patent No. 3,8~3,716 to the Applicant which issued on May 13, 1975.
Thus referring again to Figure 4, the soldering tool is generally shown at 15~ and may be provided with a special desoldering tip 160 having a suction orifice at 161. The portion 160 may consist of stainless steel and a filter for ~ .,.

lQ9~3~3i retaining the sucked in solder. The hose 162 connects to the vacuum pump previously described and may be secured to the soldering tool 158 by a band or tape 163.
The attachment 164 through which the hose 162 extends includes an on-off valve which may again be operated by a spring biased button 165. It will again be evident that th~
! oldering tube 168 may be held with one hand with the index finger operating the spring biased button 165. This instrument operates basically in the same m~nner as does ~0 that described in Fig. 3. lt will be evident that the vacuum i desoldering tip 160 may be removed when not needed. Also, it will be e~ident that the on-off valve and push button 165 may be detachably secured to the soldering instrument 158 b~ a snap action connector 166. The vacuum available from the ' hose 162 may also be used to exhaust the fumes due to the j soldering or desoldering operation. This is one reason why ! lt may be desir ble to exhaust the mariiold 42 to the outside.

I) .

r ' ~ - 15 -.

Claims (4)

THE EMBODIMENTS OF THE INVENTION IN WHICH AS EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A vacuum system comprising a desoldering tool having a vacuum orifice and a vacuum storage chamber connected to said orifice, a hose inter-connecting the vacuum storage chamber and a vacuum source and an on-off valve controlling communication between the vacuum orifice and the vacuum source, said vacuum source including a plenum chamber to which said hose is connect-ed, a venturi connected to a high pressure source and in communication with the plenum chamber whereby a flow of air from the high pressure source through the venturi creates the vacuum in the plenum chamber, and snap acting valve means responsive to the vacuum in the plenum chamber to control the flow of air from the high pressure source through the venturi.

2. A vacuum system as claimed in claim 1, wherein said storage chamber is transparent.

3. A vacuum system as claimed in claim 2, wherein a filter is provided in said transparent storage chamber.

4. A vacuum system as claimed in claim 1, wherein a solder trap is provided between said on-off valve and said storage container.