CA1126315A - Self-extinguishing circuit breaker comprising gas pre-compression means - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
A hollow cylindrical member includes a compression chamber and a reservoir patitioned by a circumferential step disposed on its inner wall surface and filled with an arc-extinguishing fluid. A piston loaded with a spring forms stationary contact and is slidably fitted into the compression chamber while the reservoir is connected to the exterior of the cylindrical member through a flared hole in an electrically insulating nozzle. A movable contact loosely extends through the nozzle to engage separably the piston.
The stationary contact may be disposed in the reservoir while the piston serves as an arc contact. The spring may be replaced by a tulip-shaped member on the piston forced into a recess on the free end of the movable contact and leaving it upon the piston engaging the step.

Description

63~5 SELF-EXTINGUISHING CIRC~IT BR~AKER COMPRISING
GAS PRE-COMPRESSION MEANS

BA~KGROUND OF THE INVENTION

This invention relates to a gas-blast switch for interrupting an electric arc struck across a pair of station-ary and movable contact members by blowing an arc extinguish-ing fluid such as sulfurhexafluorlde (SF6) against the electric arc, and more particularly to a self-arc-extinguishing type switch utili~ing an arc-extinguishing fluid raised in pressure with an electric arc struck across a pair of stationary and movable contact members for extinguishing the electric arc.
Among puffer type switches for extinguishing the electric arc struck across the stationary and movable contact members by blowing the arc-extinguishing fluid such as sulfur hexafluoride against the electric arc, here have been known switches of the type including a pair of engageable contact members arranged to be separated from each other within an arc-extinguishing chamber of a predetermined volume to strike an electric arc thereacross and an amount of an arc-extinguish-ing fluid disposed in the arc-extinguishing chamber to be expanded with thermal energy of the electric arc thereby to increase in pressure after which the arc-extinguishing fluid from the arc-extinguishing chamber is delivered to the exterior thereof upon a spacing between both contact mernber reaching a predetermined magnitude whereupon the resulting stream of the arc-extinguishing fluid is operated to interrupt the electric arc.
Switches of the type referred to are called self-1~26315 extinguishing type switches because ti~e arc-extinguishincJ
operation is performed by utilizing the arc-ex-tinguishiny fluid having a pressure increased with its own arc energy. Those switches have eliminated the necessity of providing additionally means for pressurizing the arc-extinguishing fluid which have been required for conventional puffer type switches so that the resulting structure is simple and economical.
On the other hand, switches of the type referred to might not satisfactorily pressurize the arc-extinguishing fluid upon interrupting low currents because the resulting arc energy is low. In order to avoid this objection, Japanese laid-open patent publication No. 25,869/78, (corresponding to Japanese patent application No. 1,013,070/1976 filed on August 24, 1976 in the name of Mitsubishi Denki Kabushiki Kaisha and naming Koji Ibuki and Yoshihiro Ueda as inventors), for example, dis-closes a pressurizing piston disposed in an arc-extinguishing chamber to interlock with the operation of separating a pair of contact member from each other thereby to pressurize the arc-extinguishing fluid auxiliary. The piston is arranged to be moved over the entire volume of the arc-extinguishing chamber to compress the arc-extinguishing fluid. Therefore, upon interrupting a high current having high arc energy, the arc-extinguishing fluid has much increased in pressure while its temperature rises excessively resulting in the deteriora-tion of the interrupting performance. Also the arc-extinguish-ing chamber becomes extremely small in volume because of the movement of the piston as described above and therefore very high in fluid pressure. This has resulted in the necessity of using high-power operating means for operating the piston as well as the necessity of providing closing means having a high-power sufficient to overcome a force generated by the operating means.

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If the fluid pressure within the arc--extinyuishing chamber overcomes the force for operating the piston then the piston is moved toward its initial inoperative position.
This has resulted in a reduction in fluid pressure within the arc-extinguishing chamber and therefore in interrupting performance. With the piston made integrally with the stationary contact member, the movable contact member might repeat alternating engagement with and disengagement from the stationary contact member resulting in the occurrence of .
the chattering. Under these circumstances, if electric arcs strike across both contact members then there has been a fear that both contact members are fused to each other. h Accordingly, it is an object of the present invention to provide a new and improved self-extinguishing switch having 'che excellent interrupting performance by increasing a pressure of an arc-extinguishing fluid to be fit for interrupting currents within a wide range of from a ~r low to a high magnitude thereby to exert the puffer action on an electric arc struck across a pair of stationary and movable contact members. ~ ~, It is another object of the present invention to provide a new and improved self-extinguishing switch capable of interrupting efficiently a current even though would be low.
It is still another object of the present invention to provide a new and improved self-extinguishing type switch having a long time interval for which an arc-extinguishing fluid blown against an electric arc involved.

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It is a different object of the present invontion ¦
to provide a self~extinguishing switch improved in in-terrupting characteristics concerning high currents while retaining the T~, good interrupting performance concerning low currents. , It is another object of the present invention to -provide a new and improved self~extinguishing type switch capable of reserving a proper amount of an arc-extinguishing fluid raised inpressure up to the interruption of an electric are involved.
It is another object of the present invention to provide a new and improved self-extinguishing type switch ineluding means for controlling a temperature rise of an are-extinguishing fluid and maintaining a pressure thereof as high as possible.
It is another object of the present invention to provLde a new and improved self-extinguishing type switch ;
preventing a pair of stationary and movable contact members from being fused to eaeh during the closing operation without the deterioration in interrupting performance.
It is a separate objeet of the present invention to provide a new and improved self-extinguishing type switch including simplified operating means and having the stabilized interrupting performance.

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'1 SUMMARY OF THE INVENTION ~' The present invention provides a self-extinguishing type switeh comprising, a hollow cylindrical member, an ii amount of arc-extinguihsing fluid accommodated in the hollo~
~i~ cyllnd al member, a pair of contact members disposed in _ 4 _ . .~, , . ,~, , 1~;263~S

the hollow cylindrical member to be relatively movable to engage and disengage from each other, a reservoir disposed in the hollow cylindrical member to accumulate the arc-extinguish-ing fluid increased in pressure due to an electric arc struck across the contact members separated from each other, a com-pression chamber disposed in the hollow cylindrical member to be connected in fluid communication with the reservoir, a piston movably disposed in the compression chamber and operable on separation OI the contact members from each other to compress the arc-extinguishing fluid with the compression chamber and deliver the compressed fluid to the reservoir, and a nozzle disposed to be connected in fluid communication with the reservoir, the nozzle delivering the arc-extinguishing fluid located in the reservoir and increased in pressure after contact members are separated by a predetermined distance.
In order to prevent the arc-extinguishing fluid with-in the reservoir from increasing in both pressure and tempera-ture, at least one of the contact members or the piston may be provided with an exhaust passageway permitting the reservoir to communicate with the exterior of the hollow cylindrical member therethrough after the separation of the contact members.
This measure is effective for exhausting a portion of the arc-extinguishing fluid at an elevated temperature into the exterior of the hollow cylinderical member after the separation of the contact members. Therefore the interrupting characteristics for high currents can be improved while those for low currents are retained.

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In order to prevent the arc-extinguishing fluid in the reservoir from rising in temperature abruptly thereby to cause the fluid put at a low temperature in the reservoir rS
to be remain therein till the interruption of an electric ,~
arc involved, an encircling member may be disposed in the hollow cylindrical member to encircle the movable contact .
member at its closed position over a predetermined length measured from a free end thereof. q In order to control the arc-extinguishing fluid ~, within the reservoir to a temperature as low as possible ~T
while maintaining a fluid pressure in the reservoir as high as possible, the exhaust passageway may extend through one of the contact members or the stationary contact member and communicate with at least one pair of radial holes disposed r:
on the stationary contact member to be selectively opened and ~
closed in accordance with a distance of movement of the ~r stationary contact member. This permits the reservoir to be selectively connected in fluid communication with the exterior of the hollow cylindrical member.
In order to stabilize the interrupting performance with a simple, inexpensive driving means, the switch may include a resilient member for causing the piston to tend ,;
to be forced in a direction of compression of the arc- , extinguishing fluid, the resilient member also imparting t~
a separation force to the movable contact member, closing ~i means for moving the movable contact member toward the ,`
stationary contact member to engage the latter, and locking ~' means for holding the movable contact member in engagement with the stationary contact member.
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11~6315 The movable contact member may be maintained in ,;
engagement with the sta~ionary contact member by coupling means disposed on free end faces of both contact members, to be enabled until a trip force with a predetermined magnitude ;
is applied to the coupling means. That trip force is preferably applied to the coupling means when the piston reaches its position where the piston completes the operation of compressing the arc-extinguishing fluid. This measure ;
prevents the piston from being returned bac~ to its initial inoperative position with the result that the puffer action is effectively exerted on an electric arc involved to ~s interrupt the particular current rapidly. Further, upon ;~
passing a current through the stationary contact member !
with the piston resiliently held at its initial inoperative j position, the stationary contact member is effectively "
prevented from being moved due to an electromagnetic ;
repulsion applied thereto.
The contact members may include a movable contact member and a stationary contact member fixedly disposed in !3 the hollow cylindrical member. The stationary contact ,7 member serves only to carry a current so that a mechanism for , operating the contact members can be simplified while the fusion and wear and tear of the contact members is reduced.
If desired, the movable contact member may be maintained in engagement with the piston by coupling means disposed on engaging portions of the two to be enabled until a trip force with a predetermined magnitude is applied to the coupling means. This measure is effective for preventing the fusion of the contact members without the deterioration f the interrupting performance. I

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Engaging means may be disposed at a position where the piston completes the compressing operation and abuts against the engaging means. This measure is effective ~or i, preventing the fusi.on of the contact members upon their closure without the deterioration of the interrupting , performance.
In order to prevent the piston from being returned ~;
back to its initial inoperation position and interrupt rapidly the particular current by exerting more effectively the puffer action on an associated electric arc, a back pressure chamber for the piston may be disposed in the compression chamber to be connected in fluid communication with the exterior of the hollow cylindrical member through a communication passageway, and a check valve is disposed on the communication passageway to permit the arc-extinguishing i' fluid to flow into the back pressure chamber only from the exterior of the hollow cylindrical member.

BRIEF DESCRIPTION OF THE DRAWINGS
The present invention will become more readily apparent from the following detailed desdription taken in i,~
conjunction with the accompanying drawings in which: t Figures l and 2 are longitudinal sectional views of a conventional puffer type switch illustrated at its i1 closed and tripped positions respectively with parts omitted;
Figures 3 and ~ are views similar to Figures l and

2 respectively but illustrating another puffer type switch; b Figure 5 is a longitudinal sectional view of one embodiment according to the self-extinguishing type switch 8 Il .
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of the present invention illustraed at its closed position r with parts omitted;
Figure 6 is a view similar to Figure 5 but ~, illustrating the arranyement of Figure 5 at its tripped position;
Figures 7 and 8 are views similar to Figures 5 and 6 respectively but illustrating a modification of the arrangement shown in Figures 5 and 6; f~
Figures 9 and 10 are views similar to Figures 5 and 6 respectively but illustrating another modification of the arrangement shown in Figures 5 and 6; `.
Figures 11 and 12 are longitudinal sectional views of a modification of the coupling as shown in Figures ~ and . 10 illustrated at its closed and tripped positions respectively;
: Figures 13 and 14 are views similar to Figures 11 !, and 12 respectively but illustrating another modification i~
of the coupling shown in Figures 9 and 10; .
Figures 15 and 16 are views similar to Figures 9 and 10 respectively but illustrating still another modification of the coupling shown in Figures 9 and 10; !, Figures 17 a~d 18 are views similar to Figures 9 and 10 respecti-~ely but illustrating a modification of the r' arrangement shown in Figures 9 and 10;
Figure 19 is a view similar to Figure 17 but illustrating at its closed position a modification of the arrangement shown in Figures 17 and 18; K
Figure 20 is a longitudinal sectional view of a r modification of the present invention illustrated at its closed position with part omitted; R
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¦ Figure 21 is a view similar to Figure 20 bllt ¦ illustratiny the arrangement of Figure 20 illustrated at its tripped position;
¦ Figure 22 is a view similar to Figure 8 but ,.
¦ illustrating a modification of the arrangement as shown in :s ¦ Figures 20 and 21 applied to the arrangement sohwn in Figures !C

¦ 7 and 8; rY
¦ Figure 23 is a longitudinal sectional view of ¦ another modification of the present invention illustrated at ¦ its closed position with parts omitted; ..
¦ Figures 24 and 25 are views similar to Figure 23 ¦ but illustrating the arrangement of Figure 23 at two different ¦ tripped positions thereof; ~¦
¦ Figure 26 is a view similar to Figure 23 but I illustrating a modification of the arrangement as shown in ¦ Figures 23, 24 and 25 applied to the arrangement shown in ¦ Figures 7 and 8;
¦ Figures 27 and 28 are views similar to Figure 26 ¦ but illustrating the arrangement of Figure 26 at different r~
tripped positions thereof; il Figures 29 and 30 similar to Figures 20 and 21 respectivel~ but illustrating another modification of the :!
arrangement shown in Figures 20 and 21; :;
Figure 31 is a view similar to Figure 22 but t illustrating a modification of the arrangement as shown in ,i Figure 22 at its closed position; s;
Figures 32 and 33 are views similar to Figure 31 but illustrating the arrangement of Figure 31 at different tripped positions thereof; u ll l~
1~63.15 ,1 Figures 34 and 35 are views similar to Figure 31 but illustrating different modiEica-tions of the arranc3ement i!
of Figure 31 at their closed position; ,, Figure 36 is a v.iew similar to Figure 23 bu-t "
illustrating still another modification of the present ~-invention;
Figure 37 is a view similar to Figure 36 but illustrating the arrangement of Figure 36 at its tripped position; i~
Figure 38 is a view similar to Figure 9 but illustrating at its closed position a modification of the arrangement as shown in Figures 36 and 37 applied to the arrangement shown in Figures 9 and 10; t~
Figure 39 is a view simialr to Figure 17 but ~.~
illustrating at its closed position another modification of ~.
the arrangement of ~igure 38 applied to the arrangement shown .
in Figures 17 and 18; ~-i Figure 40 is a view similar to Figure 9 but illustrating at its closed position another modification of the arrangement shown in Figures 9 and 10;
Figures 41 and 42 are views similar to Figure 40 but illustrating the arrangement of Figure 40 at different tripped positions thereof; .
Figure 43 is a view similar to Figure 40 but illustrating at its tripped position a modification of the arrangement shown in Figures 40, 41 and 42; !~
Figures 44 and 45 are views similar to Figure 9 but i~
illustrating at their closed position different embodiment .: I;
of the arrangement shown in Figures 9 and 10;

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Figure 46 is a longitudinal sectional view of a different modification of the present invention illustrated r at its closed position with parts omitted; ,~
Figures 47 and ~8 are views similar to Figure 46 but illustrating the arrangement of ~igure 46 at its tripped and open positions respectively;
Figure 49 is a view similar to Figure 46 but , illustrating its closed position a modification of the '!
arrangement shown in ~igures 46, 47 and 43; and Figures 50 and 51 are views similar to Figure 49 Li but illustrating the arrangement of Figure 49 at its tripped ,~
and open positions respectively. ~!
Throughout the Figures like reference numerals designate the identical or corresponding components. ,`

DESCRIPTION OF THE PREFERRED E~BODI~1~.NTS 9 Referring now to Figure 1 of the drawings, there is illustrated a conventional single-pressure puffer type switch. The arrangement illustrated comprises a puffer ~`
cylinder 1 operatively coupled to a operating mechanism h (not shown), a movable contact member 2 fixedly disposed in .
an axial portion of the cylinder 1 and an annular puffer ,!
piston 3 slidably fitted into the puffer cylinder 1 to form ;
an annular compression chamber 4 with an apertured bottom of D
the cylinder 1. The piston 3 is fixed at its position illustrated in Figure 1 b~ means of a supporting member (not shown). The puffer cylinder 1 has an electrically insulating nozzle 5 screw threaded into the bottom portion thereof to defin hereln an arc-extinguishing chamber 6 that, in turn,

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communicates with the compression chamber ~ through a plurality of communlcating holes 7 extending through the bottom of the puffer cylinder 1. A stationary contact member 8 is supported to a supporting member (not shown) and includes a free end portion loosely extending through the nozzle 5 until its free end is normally contacted by the free end of the movable con.
tact member 2 as shown in Figure 1.
When a command trip signal-is received the operating mechanism (not shown) is operated to move the cylinder 1 and the movable contact member 2 integral therewith in a rightward direction as viewed in Figure 1 to separate the movable contact member 2 from the stationary contact member 8. At that time an electric arc 9 strikes across both contact members 2 and 8 within the arc-extinguishing chamber 6 as shown in Figure 2 while simultaneously the piston 3 is relatively moved toward the bottom of the cylinder 1 to compress an amount of an arc-extinguishing fluid such as sulfur hexafluoride (SF6) disposed in the cylinder 1. The fluid compressed to a high pressure blows against the electric arc 6 through the communicating holes 7 as shown at the arrow in Figure 2 resulting in the rapid extinction of the electric arc 6.
In conventional single-pressure puffer type switches such as shown in Figures 1 and 2 the puffer cylinder and the electrically insulating nozzle interlocking with the interrupt-ing operation have been large in weight resulting in the dis-advantage that a high-power operating mechanism is required to drive them. This disadvantage has been conspicuous parti-cularly with high capacity switches because .

r :1~;26;3iJL5 the compression chamber such as the chamber ~ needs a l~lrge volume and because heat due to the electric arc increases ,~, a pressure rise within the compression chamber thereby to increase a force tending to push back the piston with respect to the mating cylinder.
Contrary to switches such as described above, it ~:
has been previously proposed to extinguish the electric arc struck upon interrupting currents, only through the utilization of the arc-extinguishing fluid expanded with the electric arc without either the use of means for compressing the fluid to a high pressure or the compression of the fluid with an operating force. This measure has been disadvantageous in .
that the particular reservoir having accumulated therein the r~
fluid thus expanded rises excessively in temperature attended with a reduction in arc-extinguishing performance.
Figure 3 shows another conventional single-pressure ;~
puffer type switch. In the arrangement illustrated in ~, Figure 3 a puffer cylinder generally designated by the reference numeral 10 includes a terminal plate 12, a hollow cylindrical supporting member 13 fixed at one end to the terminal plate 12 and an electrically insulating member 14 in the form of a hollow cylinder fixed to the other end of ~.y the supporting member 13. The puffer cylinder 10 is kept ?~3 stationary by means of a supporting member (not shown) and r the insulating cylindrical member 14 includes an internal stepped cylindrical space having a large diameter space portion 14a located on that end portion thereof abutting ~.
against the supporting cylindrical member 13 the other end portion 14b flared toward its open end and an intermedi2te `S

- 14 _ cylindrical space portion interconnecting both end portions.
A puffer piston 15 is slidably fitted into the large cliameter space portion 14a oE the insulating member 14 and provided on that surface thereof remote from the supporting member 13 with a central raised portion forming a contact 15b. That surface of the puffer piston 15 exposed to an internal cylindrical space smaller in diameter than the space portion 14a of the supporting member 13 is connected to a guide rod 16 extending through the internal cylindrical space of the supportin~ member 13 and then slidably extending through a through hole 12a disposed on the terminal plate 12. The puffer piston 15, the contact 15a and the guide rod 16 form a stationary contact member generally designated by the !A
reference numeral 18. ,, The large diameter space portion 14a includes one end defined by an annular portion of the end sur~ace of the ,~
supporting member 13 exposed to the space portion 14a and ~
the other end defined by an annular round step 17b radially ~i inward extending from the inner wall surface of the large ii diameter space portion 14a and merged into the interface between that space portion 14a and the intermediate space , portion connected to the flaxed portion 14b.
A collector 19 is elected on the terminal plate 12 to abut resiliently against the outer peripheral surface of the guide rod 16 and a helical spring 20 is disposed within the internal cylindrical space of the supporitng member 13 l1 and between the terminal plate 12 and the puffer piston 15 , to encircle the guide rod 16 and the collector 19. The helical spring 20 tends normally to force the puffer piston 15 toward the annular step 17b.

1~ ,~-~ ;3:~5 ~

Then a movable contact member 21 is inserted into the internal stepped cylindrical space of the insulating member 4 from the flared end portion 14b until its free end abuts against the contact 15a of the stationary contact member 18. At that time the stationary contact member 18 "
is maintained at its position illustrated in Figure 3 against the resilience of the helical spring 20 to hold the ~
puffer piston 15 in engagement to the annular exposed end IJ
portion 17a of the supporting member 13. Under these circumstances, a compression chamber 22 is formed in the large diameter space portion 14a of the insulating member 1~
an~ connected in fluid communication with the exterior of the ~, cylinder 10 through an annular gap formed between the inner wall surface of the insulating cylindrical member 14 and the , outer peripheral surface of the movable contact member 21.
The movable contact member 21 includes the other end portion slidably extending through a through hole 23a '~
disposed on another terminal plate 23 and operatively coupled ~, to an operating mechanism (not shown). ~lso a collector 24 b is disposed on the terminal plate 23 to abut resiliently against the outer peripheral surface of the movable contact ~
member 21. L
The arrangement of Figure 3 is disposed within an t enclosure (not shown) to form therebetween a space filled b with an amount of an arc-extinguishing fluid such as gaseous sulfur hexafluoride tSF6). Therefore the compression chamber is filled with the arc-extinguishing fluid. This space is called hereinafter an "external space" because it is located ext nally cf the cylinder 10. The terminal plates 12 and 23 ¦

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are suitably fixed to respective stationary members (not shown) disposed in the enclosure (not shown).
As in the arrangement shown in Figures 1 and 2, the operatin~ mechanism (not shown) is operated to move the movable contact member 21 in the rightward direction as viewed in Figure 3. Since the stationary contact member 18 tends to be moved in the rightward direction by means of the action of the helical spring 20, the same is moved in that direction with the movable contact member 21 until the puffer ..
piston 15 abuts against the annular step 17b as shown in Figure 4. This prevents a further rightward movement of the piston 15 and therefore the stationary contact member 18.
During this movement the puffer piston 15 is effective for compressing the arc-extingu.ishing fluid within the compression chamber 22.
When the movable contact member 22 is further moved in the rightward direction, both contact members 18 and 22 are separated from each other whereupon an electric arc 25 ~
strikes thereacross within the internal cylindrical space of r;
the insulating member 14 as shown in Figure 4. Upon the electric arc striking across the separated contact members '.;
18 and 21, the arc-extinguishing fluid exposed to the electric arc 25 is expanded thereby to raise rapidly a fluid pressure .~
in the compression chamber 22. , After having disengaged from the stationary contact member 18 the movable contact member 21 is relieved of its load due to the contact member 18 and therefore is rapidly spaced from the stationary contact member 18 to spread rapidly the electric arc 25 until the free end of the movable contact 63~5 l .~' i, member 21 reaches the flared portion 14a of the insulating member 14 to widen the spacing formed therebetween. At that time, the arc-extinguishing fluid compressed within the compression chamber 22 is permitted to flow abruptly into the external space through the now widened spacing to be rapidly expanded and therefore cooled. Accordingly the electric arc 25 is blown out with the resulting stream of the cooled fluid. .
In the closing operation, the operating mechanism ~:
(not shown) responds to a command closure signal to move the L~
movable contact member 21 toward the stationary contact r member 18 to engage the former with the latter after which -~
the movable contact member 21 forcedly move the stationary ,.
contact member 18 with the puffer piston 15 in the leftward direction as viewed in Figure 3 or 4 against the action of .~
the helical spring 20 until the piston 15 is seated on the i.l annular end surface 17a of the supporting member 13 as shown '~;
in Figure 3. At that time the closing operation is completed.
During the closing operati.on the arc-extinguishing fluid from the external space is supplied via the spacing bet~7een the insulating cylindrical member 14 and the movable contact :~
member 21 to the compression chamber 22 to be ready for the .
next succeeding interrupting operation.
In conventional switches such as shown in Figures i., 3 and 4 the puffer piston 15 is operated over the entire volume of the compression chamber 22 between the annular end fi surface 17a and the step 17b so that, upon separating both contact members from each other, the volume of the compression chamber 22 becomes extremely small thereby to render a fluid pressu within the chamber 22 extremely high. This has ~., li ~fi3~5 ,'i ,,, resulted in the disadvantages that the helical spring 20 t is required to be of a high-power type while the closing operation requires a high power operating mechanism sufficlent to overcome such a high-power spring and tl~at the arc-extinguishing fluid within the compression chamber 22 can not absorbe a large quantity of arc energy emitted into the compression chamber 22 particularly upon interrupting any high current while the same remains at its low temperature.
Accordingly, the fluid is deprived of the arc-extinguishing ability because of an elevated temperature thereof.
Also such switches have been disadvantageous in the r'' following respects:
When the free end of the movable contact member 21 is moved to reach the flared insulating portion 14_, the fluid from the compression chamber 22 is rapidly delivered because of an extremely high pressure thereof. ~Iowever, due to the r small volume thereof, the compression chamber loses immediately the fluid resulting in a short blast time.
Accordin~ly, in the extreme case, a current can be interrupted only when the current passes through its zero point within such a short blast time.
Further it has been difficult to increase the ability to interrupt low currents and that to interrupt high currents simultaneously. ~lore specifically, if the volume of the compression chamber is determined so as to render the ~:
interrupting ability good for low currents then the interruption of a high current has resulted in the fluid within the compression chamber being heated and expanded with a large quantity of energy due to an electric arc struck across both contact members. This has caused the _ 1 9 _ ! .

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fluid within the compression chamber to be put under a very high pressure and also at an excessively elevated temperature resulting in an intense reduction in arc-extinguishing ability. Accordingly, even though the fluid at the excessively elevated temperature would blow against the ~;
electric arc, the latter has not heen blo~n out.
Furthermore, with both contact members separated from each other to strike an electric arc thereacross, the ., electric arc might further raise the fluid pressure within the compression chamber enough to overcome the resilience of the helical spring 20 tending to force the stationary contact member 18 toward the stationary contact member 21.
Under these curcumstances, the stationary contact member 18 tt~.
has been pushed back with the fluid pressure within the , compression chamber thereby to reduce the fluid pressure ., within the compression chamber and therefore the interrupting ability.
Also after the opening of both contact members, the re-closing operation is performed in such a manner that, ,~
upon both contact members 18 and 20 engaging each other, the stationary contact member receives a high impact force from the movable contact member so that this impact force cooperates with the resilience of the helical spring 20 to repeat the alternating disengagement and engagement .
between both contact members until the movable contact il member ultimately engages the stationary contact member. ~3 That is, in the process terminatinq at this ultimate , enaagement the chattering occurs~ and electric arcs repeatedly strikes across both contact members resulting in their being fused to each other.

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Figures 5 and 6 show one embodiment according to I, the switching device of the present invention at its closed and tripped positions respectively. The arrangement `~
illustrated is different from that shown in Figures 3 and ~ :, in that in Figures 5 and 6 the hollow cylindrical, electricall insulating member 14 illustrated in Figures 3 and 4 is replaced by a hollow cylindrical metallic housing member 26 ;
including one end open and the other end provided with a central opening into which a cylindrical electrically insulating nozzle 27 is firmly fitted.
More specifically, the hollow cylindrical member 26 is fixedly secured at the open end to the hollow cylindrical supporting member 13 and provided on the open end portion ~`
with a large diameter space 26a defining a compression chamber 29 with the annular end surface portion 28a of the supporting member 13 exposed to the large diameter space 26a and a circumferential round step 28_ disposed on the inner wall surface of the hollow cylindrical member 26 to be b spaced from the open end thereof by a predetermined length.
The puffer piston 15 is slidably fitted into the compression )L
chamber 29 to reciprocate between the annualr end surface r portion 28a and the circumferential round step 28_ serving as stoppers for limiting the movement of the puffer piston ~1 15 within the compression chamber 29. Therefore the piston ~-15 includes one peripheral corner nearer to the step 28b and complementary in shape to the step 28b and the other peripheral corner shaped into a right angle. ~he remaining space located within the hollow cylindrical member 26 , between the step 28b and the other end thereof forms a i3~
l ", ~s reservoir 30 somewhat smaller in diameter than the compression .' chamber 29 for the purpose as will be subsequently apparent.
The insulating nozzle 27 is substantially similar '.' to the free end portion of the electrically insulating member 14 shown in Figures 3 and 4 and includes a flared portion 27a simialr to the flared portion 14b as described above. ,~
In other respects, the arrangement is substantially .s identical to that shown in Figures 3 and 4.
From the foregoing it is seen that the arrangement ~;
shown in Figures 5 and 6 includes the compression cham~er 29 located on that side thereof adjacent to the supporting member 13 and the reservoir 30 located on the other side q thereof to be continuous to the compresison chamber 29.
The compression chamber 29 has a volume capable of reducing substantially to a null magnitude by the puffer piston 15 and the reservoir 30 serves to accumulate the arc-extinguishing fluid compressed wtihin the compression chamber 29. ~s As in the arrangement shown in Figures 3 and 4 the operating mechanism (not shown) is operated to move the v movable contact member 21 in the rightward direction as .
viewed in Figure 5 which is attended with the similar a movement of the stationary contact member 18 with the puffer r~
piston 15 resulting from the resilience provided by the -helical spring 20. This results in the compression of the fluid within the compression chamber 29.
When the movable contact member 21 is further moved .
in the rightward direction, the puffer piston 15 abuts against the stopper 28b whereupon the stationary contact member 18 is prevented from being further moved in the 63~5 rightward direction. Therefore both contact members 21 and 18 are separated from each other resulting in an electric farc 25 striking across both contact members as shown in Figure 6.
At that time, the volume of the compression chamber 29 becomes substantiall null while the reservoir 38 accumulates the fluid increased in pressure. However, the ~ctotal volume of the compression chamber 29 and the reservoir ,~30 has a small rate of change so that the fluid pressure is prevented from rising excessively. Also termal engergy resulting from the electric arc 25 struck across both contact members 21 and 18 is utilized to raise the fluid pressure within the reservoir 30 but due to the large volume of the :reservoir 30, the fluid is prevented from increasing excessively in both pressure and temperature even upon interrupting high currents. This means that the fluid .under a high pressure at a sufficiently low temperature tcan be accumulated in a large amount within the reservoir ~`30 for interrupting high currents. ~; Thereafter the process as described above in conjunction with Figures 3 and 4 is repeated to extinguish ,the electric arc 25. In the arrangement shown in Figures 5 and 6 it is noted that, because of the large volume of the reservoir 30, the arc~extinguishing fluid increased in ,lpressure within the reservoir 30 can blowagainst the electric ,1arc for a long time interval. This makes it possible to .~interrupt the particular current in the stable manner even 'though the current would pass through its zero point at any time point. r _ 23 -.i 1~ i3:~5 From the foregoing it is seen that the present invention comprises the compression chamber for compressing the arc-extinguishing fluid tllerein by decreasing its volume substantially to a zero magnitude and the reservoir adjacent to the compression chamber to be put in fluid communication therewith. Therefore it is possible to accumulate a large amount of the fluid having a proper pressure and a low temperature. This results in the ~i interrupting performance stabilized throughout a current range of from a low to a high magnitude.
Figures 7 and 8 illustrate a modification of the arrangement shown in Figures 5 and 6 at its closed and tripped positions respectively. The arrangement illustrated is different from that shown in Figure 5 principally in that in Figure 7, the stationary contact member 18 is disposed in the reservoir to be connected to the inner wall surface of the hollow cylindrical member 26.
More specifically, the stationary contact member 18 includes a hollow disc-shaped case 18a provided on the opposite surfaces with central aligned apertures and .
coaxially disposed within the reservoir 30 to be connected to the inner wall surface of the latter. Disposed in the case 18a is a split contact 18b having an inside diameter sufficient to permit the movable contact member 21 to extend therethrough and normally biased toward the central axis of the case 18a by leaf springs 18c disposed between the outer peripheral surface of the split contact 18 and the inner wall surface of the case 18a. As shown in Figure 7 the movable contact member 21 at its closed position extends i315 ,:

through the split contact l~b to be put in good enyagement with the latter by means o~ the action of the springs 1~_.
Further the movable contact memher 21 at its closed position has its free end somewhat producing from the case 18a to engage a slider generally designated by the reference numeral 150. The slider 150 is identical in both shape ,.
and operation to the stationary contact member 18 shown in Figures 5 and 6 excepting that no current flows through the slider 150. Therefore the slider 150 is formed of an electrically insulating material and the collector 19 shown in Figures 5 and 6 is omitted in Figures 7 and 8.
In other respects the arrangement is substantially identical to that shown in Figures 5 and 6.
Accordingly it will readily be understood that the arrangement of Figure 7 is substantially identical in operation to that shown in Figures 5 and 6 exdept for an electric arc 25 striking across the free end of the movable contact member 21 and the inner peripheral surface of the split contact 18_ as shown in Figure 8.
Since the slider 150 does not form a current- ~, carrying path and the associated collector is omitted, the same bears no contact pressure due to the collector. 1, Accordingly there are not caused a drag due to such a contact pressure and a repulsion resulting from a current which will otherwide flow through the slider. This permits the helical spring 20 to reduce in resilience. Further the chattering can be avoided because the stationary contact member 18 is located so as not to be struck by the movable contact member 21. This results in a reduction in wear and ,1~ .
~ fi3~5 tear of the contact members caused from electric arcs struck thereacross. ', The electrically insulating nozzle 27 way include its cylindrical hole increased in diameter and the stationary contact member lg is disposed in this large diameter hole.
The slider 150 may be partly or entirely formed of a metallic material.
Figure 9 shows a modification of the present r invention. In the arrangement illustrated the puffer cylinder 10 or the hollow cylindrical member 26 includes the large diameter space portion 26a disposed in the axially middle portion. An apertured terminal plate 12 in the form of a disc closes one end, in this case, the upper end as viewed in Figure 9 of the cylinder 10 and an electrically insulating nozzle 27 similar to the nozzle 27 as shown in Figures 5 and 6 screw threaded into the other or lower end portion thereof.
As tationary contact member 18 is substantially identical to that shown in Figures 5 and 6, and has a puffer piston 15 slidably fitted into the large diameter portion 26a forming a compression chamber 29 to reciprocate therein between a pair of circumferential flat steps 28a and 28b.
The stationary contact member 18 includes an arm portion slidably extending through a central hole on the terminal i' plate 12 and engaging a collector 19 disposed on the inner surface of the terminal plate 12 with a helical spring 20 as shown in Figures 5 and 6 omitted. Therefore the stationary contact member 18 is electrically connected to an external electric device through the collector 19 and the terminal plate The puffer piston 15 partitions the interior of the puffer cylinder 10 into a pair of upper and lower chambers 31 and 30 respectively equal in diame-ter to each other and somewaht smaller in diameter than the large diameter space portion 2~a. The upper chamber 31 communicates with , the arc-extinguishing fluid disposed in the external space ;?
through a plurality of holes 32 extending through the terminal plate 12. The lower chamber includes the compression chamber 29 formed of the large diameter space portion 26a and the reservoir 30 continuous to the compression chamber 29. r The puffer cylinder 10 is held at its position ~
illustrated in Figure 9 by a supporting member (not shown) :
where the puffer piston 15 abuts against the upper step 28a. ~
A movable contact member 21 operatively coupled to ~' an operating mechanism (not shown) slidably extends through an axial hole of the insulating nozzel 27 similar to that shown in Figures 5 and 6 to engage the stationary contact member 18 at its closed portion.
As shown in ~igure 9, a central raised portion 15a of the puffer piston 15 includes a tulip-shaped contact 33 pendent from the end thereof and tapered toward its end while the movable contact member 21 is provided on the free end portion with a recess 34 in the form of a bottle. At the closed position the stationary contact member 18 detachably engages the movable contact member 21 by having the tulip-shaped contact 33 resiliently inserted into the bottle-shape recess 34. Therefore the tulip-shape contact 33 forms a snap hook type coupling with the bottle-shaped recess 34.
This coupling is maintained in engaging state until it r r ~1~31 ~i3~5 l ~.' receives a force, in this case, a trip force of a predetermined l~
magnitude. For the trip force in excess of the predetermined magnitude the contact 33 oE the coupling disengages from the t recess thereof.
As in the arrangement of Figure 5, the operating mechanism (not shown) is operated to move the movable contact member 21 downward as viewd in Figure 9. As the tulip-shaped contact is maintained in engagement with the bottle-shaped recess 34, the stationary contact member 18 is also moved downward with the moving contact member 21 to cause the piston 15 to compress the fluid disposed in the compression r chamber 29 and the reservoir 30. When the piston 15 abuts r against the lower step 28b on the large diameter space portion 26b, the stationary contact member 18 is prevented r~
from further descending while the movable contact member continues to descend. As a result, a trip force in excess t~
of the predetermined magnitude as desdribed above is applied to the coupling 33-34 to cause the contact 33 to disengage from the recess.34 resulting in the separation of both ..
contact members 18 and 21. At that time an electric arc 25 strikes across both contact members as shown in Figure 10.
Thereafter the process as described above in r conjunction with Figures 3 and 4 is repeated to extinguish ., the electric arc 25 From the foregoing it is seen that, since the t operating mechanism (not shown) is required only to operate the stationar~ contact member 18 including the puffer piston 15 and the movable contact member 21, it is able to render the weight of operated components small as compared with the . ,, .~

ti315 ''~

prior art practice. In addition, in the duration of tlle electric arc for whlch a speed of separation of the movable i-contact member 18 is required to hold at the highest magnitude, it is sufficient to operate the movable contact member 21 alone. Therefore the speed oF separation can be sufficiently high with a force provided by a low-power operating mechanism. Accordingly the interrupting performance s can be improved with a small-sized, inexpensive consturction. ~
While the arrangement of Figure 9 includes the 5 tulip-shaped contact 33 formed of an electrically conductive material, it is to be understood that the contact 33 may be formed of an electrically insulating material. In the latter case, the re-engagement of the contact 33 with the recess 34 does not result in a current flowing therethrough upon the engagement. This causes a reduction in fear that an electric arc will strike across the two upon the engagement resulting in their fusion. Therefore the use of the ,~
electrically insulating contact 35 is advantageous for high rated current circuits.
The coupling as described above may be modified as shown in Figures 11 and 12. In the arrangement illustrated the stationay contact member 18 is provided on the free end surface portion with a hook-shaped depression 36 having a contracted portion located adjacent to its mouth to be sufficient to permit the recessed end portion of the movable i~
contact member 21 as shown in Figure 9 to be resiliently inserted into the depression 36 as shown in Figure 11. The tulip-shaped contact 33 is diposed at the bottom of the dep sion 36 and resiliently inserted into the recess 34 i315 at its closed position. Figure 12 shows the free end portions of both contact members 18 and 2] a-t their tripped positions.
In the arrangement shown in Figures 11 and 12, an electric arc strikes across the free ends of both contact members 18 and 21 so that the contact 33 is prevented from being exposed to the electric arc.
Also, as shown in Figures 13 and 14, the depression 36 can be provided on the inner peripheral surfade with a pair of diametrically opposite notches in which a pair of engaging members 37 formed of an electrically conductive material are disposed in diametrically opposite relationship with the tulip-shaped contact 33 omitted. Then a leaf spring s 38 is interposed between each engaging member 37 and the mating notch to bias normally the engaging element in a radially inward direction.
On the other hand, the movable contact member 21 j~
includes a pair of diametrically opposite notches 39 r located at their positions where the notches 21 engage the respective engaging members 37 when both contact members 18 and 21 engage each other as shown in Figure 13. To this end, the notch 39 is complentary in shape to the mating engaging .~
member 37. ii Figure 1~ shows the free end portions of both ,l contact member 18 and 21 at their tripped positions. ~d In Figures 15 and 16, the stationary contact member 18 has the free end portion shaped into a depression similar to that shown in Figure 11, that is, having a , contracted portion ~0 located adjacent to its mouth while the free end portion of the movable contact member 21 ~ 30 ~
~, lt ~1;2fii3.~L5 r~

includes a circumferential swelled portion 41 sufficient to pass resiliently throu~h the contracted portion 40 and tapered toward the free end substantially equal in diameter to the ~:~
main body of the movable contact member 21. As shown in Fi~ure 15, the free end of the movable contact member 21 at I~r its closed position rests at the bottom of the depression on ,~
the stationary contact member 18. Figure 16 shows the free end portions of both contact members 18 and 21 at their ,~
tripped positions. The arrangement shown in Figures 15 and 16 is advantageous over the arrangements shown in Figures 9, 10, Figures 11, 12 and Figures 13, 14 in that both free end portions are prevented from easily disengaging from each !l other without an additional component or components assembled into the stationary contact member 18.
The arrangement illustrated in Figure 17 is different i~
from that shown in Figure 9 principally in that in Figure 11, ,1 the stationary contact member is disposed within the resevoir q 30. More specifically, a pair of stationary contact members 18 are disposed in diametrically opposite relationship within the reservoir 30 by having their bottom located in associated notches disposed also in diametrically opposite relationship n on the inner wall surface of the reservoir 30. Then a leaf spring 42 is disposed in the mating notche to bias normally the associated stationary contact member 18 in the radially ~;' inward direction. Therefore, at their closed position the .;~
stationary contact members 18 are put in sliding engagement with the outer peripheral surface of the movable contact member 21 as having extended past the same (see Figure 17).
Further the tulip-shaped contact 33 is directly screw threaded 13~;2fi3~5 into the surface of the puffer piston 15 with the central raised portion thereof (see Figure ~) omitted, and the compression chamber 29 reaches to the terminal plate integral ,~
with the cylindrical member 26. Therefore, the upper chamber 31 (see Figure 9) is omitted. Because the stationary contact members 18 are disposed within the reservoir 30, the piston 15 and the guide rod 16 therefor forms an arc contact member 150 and also serves as the slider 150 as described above in L;
conjunction with ~igure 7. Therefore, the collector 19 (see Figure 9) is omitted.
In other respects, the arrangement is substantially identical to that shown in Figures 9 and 10.
In the opening operation 17, the tulip-shaped r contact 33 on the piston 15 first disengages from the recess 34 on the movable contact member 21 after the piston 15 has reached the lower step 28b. Then the movable contact .`
member 21 disengages from the stationary contact members 18 ,~
to cause an electric arc 25 as shown in Figure 18. ., In the closing operation, the movable contact r.
member 21 is moved upward as viewed in Figure 13 to fit the free end portion thereof into the spacing between the opposite stationary contact members 18 to engage it with the latter at that time, a current flows through both contact members 18 and 21 after which the movable contact member 21 abuts ,, against the piston 15 to force it upwardly until the piston 15 abuts against the step 28a on the terminal plate 12 to be prevented from ascending. At that time the tulip-shaped contact 33 on the piston 15 resiliently forced into the rr recess 34 on the movable contact member 21 to be returned 't ,, - 32 - '~

fi;~5 back to its original position as shown in Figur~ 17.
In Figures 17 and 1~ the stationary and movable con-tact members 18 and 21 respectively are shown as haviny respec-tive contacts attached to the free ends thereof. However, in the foregoing Figures and some of the subsequent Figures, those contacts are omitted only for purposes of illustration.
Also in some of the subsequent Figures such contacts are illustrated without the reference numerals identifying the same.
In Figure 19, the tulip-shaped contact 33 increases in axial length while the recess 34 increases in depth corres-pondingly. ~lso a clearance 32' is formed around the guide rod 16 for the piston 15 within the central hole on the terminal plate 12 to be substituted for the through holes 32 as shown in Figure 17.
In other respects, the arrangement illustrated is identical to that shown in Figure 17.
In Figure 19 it is seen that the tulip-shaped end portion of the contact 33 on the stationary contact member 18 can disengage from the recess 34 on the movable contact member 21 immediately after both contact members have disengaged from each other and an electric arc has been struck thereacross. This '~
permits a reduction in extent to which the puffer piston 15 tends to be moved away fxom the movable contact member 21 by means of the pressure of the compressed fluid upon the contact 33 disengaging from the recess 34. Accordingly, the more effective puffer action can be expected.

:

6~5 The arrangement of E'igure 5 can be modifi~d as shown in Figure 20. In Fiyure 20, the stationary contact member 18 includes an axial exhaust passageway 18A extending throughout its length and,axially aligned with an axial exhaust passageway 18B similarly extending throughout the ,, length of the movable contact member 21. Both exhaust passageways 18A and 18B serve to cause the compression chamber 29 to be connected in fluid communication with the external space therethrough. ~Iowever, with both contact ,, members engaged by each other, the compression chamber 29 ;~
is prevented from communication with the axial exhaust ,i passageways 18A and 21A. !2 The movable contact member 21 is separated from ,-the stationary contact member 18 in the same manner as ~.
described above in conjunction with Figure 5. At that time an electric arc 25 strikes across both contact members 18 and 21 while the compression chamber 29 communicates with the external space through the axial exhaust passageways 18A and 21A as shown in Figure 21. Under these circumstances, l' the are-extinguishing fluid compressed in the reservoir 30 is exhausted into the external space through the passageways t.
18A ~nd 21A while it cools the electric arc 25. For a low interrupted eurrent, the electrie arc 25 ean be extinguished only by means of the eooling action due to the blast of that eompressed fluid.
For a high interrupted current, however, the resulting electrie arc 25 has a large diameter sufficient to close the exhaust passageways 18A and 21A. Therefore, ~' a fluid pressure in the compression chamber 29 is not ~:

ll . ~ 3~5 .

lowered and inversely is raised because thermal energy due to the electric arc 25 is partly accumulated in the reservoir 30. However since one portion of the fluid is exhausted ':
into the external space through the exhaust passageways 18A
and 21A, the fluid within the reservoir 30 is prevented from increasing in both pressure and temperature excessively.
When the free end of the movable contact member 21 enters the flared portion 27a of the electrically insulating -nozzle 27, the fluid from the reservoir 30 is rapidly discharged to the external space as in the arrangement shown in Figures 5 and 6. The fluid thus discharged has a relatively high pressure and a relatively low temperature which cooperates with a large opening area of the nozzle 27 to permit a large amount of the ~luid to blow against the electric arc 25. As a result, the electric arc 25 is satisfactorily cooled and extinguished even though the particular interrupted current would be high.
From the foregoing it will readily be understood ;
that, after both contact members 18 and 21 have disengaged from each other, low currents can be rapidly interrupted by means of the piston action of the puffer piston 15 combined with the axial exhaust passageways 18A and 21A extending throughout the stationary and movable contact members 18 and 21 respectively. Also upon interrupting high currents, the fluid increased in both pressure and temperature due to the resulting electric arc is partly exhausted through the exhaust passageways 18A and 21A immediately after the occurrence of the electric arc. This to permits the interior of the reservoir 30 to be prevented from increasing ! ~63~5 ti' in both pressure and temperature excessively. ThereaEter t~
the free end of the movable contact member 21 enters the flared portion 27a of the insulating nozzle 27 whereupon the fluid having the sufficient arc-extinguishing performance can blow against the electric arc. This can smoothly cool and exhaust the electric arc.
Also since the contact member includes the axial t exhaust passageway, the convention is apt to occur when a current flows through the contact member. Where the exhaust ;
passageway extends through each of the stationary and movable contact members as in the arrangement of Figure 21, the t effect of this convection is particularly conspecuous.
In summary, the arrangement shown in Figures 20 ~
and 21 can realize the interrupting performance excellent ~Z
concerning to both low and high currents with a simple, inexpensive construction and still increase a current flowing through the stationary and movable contact members.
The arrangement illustrated in Figure 22 is different from that shown in Figure 7 in that the slider 150 is formed of a metallic material to form an arc contact member as in the arrangements shown in Figures 17 and 18 and that axial exhaust passageways 150A and 21A extend throughout the length of the arc and movable contact members 150 and 21 respectively.
Figure 23 shows another modification of the present invention. The arrangement illustrated is different from that shown in Figure 5 only in that in Figure 23, an encircling member is disposed to encircle the free end portions of the stationary and movable contact members and 'Z

_ 3~ _ 1~ .
~ 5 '., the stationary contact member includes the axial exhaust passageway extending throughout the length thereof. More ' specifically, the encircling member 42 includes an apertured partition 42a fixed at the outer periphery to a radially inward directed circumferential rib located on the inner !' wall surface of the hollow cylindrical member 26 between ~.
the compression chamber 29 and the reservoir 30 equal in diameter to each other. That lateral surface of the rib facing the piston 15 forms the circumferential step 28b or the stopper for the piston 15.
The encircling member 42 includes a relatively short sleeve 42_ extending from the central portion of the t-partition 42a toward the nozzle 27 and the partition 42a ij includes a plurality of radial openings disposed at ,.
predetermined equal angular intervals thereon to extend ~
from the outer periphery of the sleeve 42b to the outer edge b of the partition 42a (only one of which is illustrated) thereby to put the compression chamber 29 in fluid communication with the reservoir 30. The encircling member 42 is formed of an electrically insulating material. ~:
The sleeve 42b is so dimensioned that the ;
stationary and movable contact members 18 and 21 respectively can be inserted thereinto with a minute clearance formed therebetween as shGwn in Figures 23 and that the free end of the stationary contact member lg reaches very short of that end of the sleeve 42b nearer to the nozzle 27 upon the completion of the interruption as shown in Figure 24. 'c At their closed position, both contact members 18 and 21 engage each other within the sleeve 42b adjacent to the other P
end thereof. ~

- 37 - a ?;J
~3~

1~
~ S3.~5 ..

Therefore the sleeve 42b can encircle the stationary contact member 18 over a predetermined length , measured in a direction of separation of the movable contact member 21 to the free end thereof.
The encircling member 42 serves to permit the arc-extinguishing fluid within the reservoir 30 to be .~.
delivered to the external space only after fluid has ~t penetrated the electric arc and to retain a low temperature fluid in the reservoir 30 w'lile the fluid in the reservoir .~
30 is prevented from increasing in temperature. In addition , the encircling member 42 is effective for blowing axially the low temperature fluid that has been accumulated in the reservoir 30 by the piston 15 even when the chattering r;,~
occurs between both contac, members 18 and 21 to strike electric arcs thereacross while the piston 15 is not engaged by the step 28_ due to a weak resilience of the helical ,~
spring 20 (see Figure 25). ,_ Therefore, when the fluid within the reservoir 30 ,,, increase ln pressure by expanding the same through the utilization of an electric arc struck upon interrupting the .
particular current, a temperature rise in the reservoir is limited by the partition defining the boundary between the reservoir and aspace where the electric arc strikes. This results in an increase in arc-extinguishing ability to L
interrupt electric arcs. ! 3 The arrangement illustrated in Figure 26 is t~, different from that shown in Figure 22 principally in that l~
in Figure 26 an encircling member similar to that shown in ~, Fig e 24 is disposed within tbe h~llow cylindrical member 26.

. .. , _.
.

,.
~ ~ l~
More specifically, the encircling member 42 is fixed to the inner wall surface of the hollow c~lindrical member 26 substantially identical to that shown in Figure 24 in the same manner as descri.bed above in conjunction with Figure 24 :;
excepting that its sleeve 42b is connected to the stationary contact member 18. The sleeve 42b is axially aligned with .
the through hole in the stationary contact member 18 having :
a diameter slightly smaller than the inside diameter of the sleeve 42b.
The slider or the arc contact member 150 has its free end portion reduced in diameter and adapted to be ,~
located within the sleeve 42b at the closed position as L
shown in Figure 26. Upon an electric arc 25 striking across both contact members 21 and 150 with the piston 15 abutting against the step 2~b as shown in Figure 27. That portion of ...
the contact member 150 following the reduced end portion has a predetermined length encircled by the sleeve 42 . ,.~
Figure 28 shows the slider or arc contact member ,:
15 not flowing up the movement of the movable contact member 21 due to a weak resilience provided by the helical spring 20.
The encircling member 42 or the sleeve 42b plays its role in preventing the arc-extinguishing fluid in the reservoir 30 from escaping to the external space until the fluid is completed to be compressed within the reservoir 30 through the movement of the piston 15 and in retaining the fluid at a low temperature in the reservoir until the electric arc is completed to be interrupted. Of course, the fluid from the reservoir 30 is permitted to be delivered to the external space only after it has penetrated the arc until the free ~

- 39 - ~, .

' .... ~, 3:~5 ., I ~`
end of the movable contact member 21 passes through the flared portion 27a of the nozzle 27.
Figure 29 illustrates a modification of the arrangement shown in Figure 20. The arrangement illustrated r~
is different from that shown in Figure 20 only in that in ,~
Figure 29 the axial exhaust passageway 18A extending through the stationary contact member 18 is selectively connected in fluid communication with the external space through at least two pairs of radial holes maintaining a predetermined axial distance therebetween. ~ore specifically, the axial s exhaust passagesay 18A includes a first plurality of radial holes 18B disposed at predetermited equal angular intervals in the stationary contact member 18 to be located just under the terminal plate 12 at the closed position of the stationary contact member thereby to put the axial exhaust passageway 18A in fluid communication with the exterminal space therethrough. In Figure 29 a pair of radial holes 18B is shown as opposing to each other. When the stationary contact member 18 is moved upward as viewed in Figure 29, the radial holes 18B are closed with a sleeve 12b sungly fitted into the opening 12a on the terminal plate 12 to run toward the puffer piston 15 and form a small clearance between the sleeve 12a and the stationary contact member 18.
Therefore the axial exhaust passageway 18A is prevented from communicating with external space.
On the other hand, when the stationary contact r member lS is moved upward and then stopped through the engagement of the puffer piston 15 with the step 28b, the axial passageway 18A is arranged to communicate with the ,,. .

llZ6315 external space through a second plurali-ty of radial holes ,;' 18C disposed in the contact member 1~ in the same manner as lr the radial holes 18~. To this end, the second pair of radial holes 18C are located below the first plurality of b radial holes 18B to form a predetermined distance ~ -substantially equal to an axial length of the compression chamber 2~ shown in this case as being equal in diameter to the reservoir 30. Then an L-shaped closure block 12b is pendént from the terminal plate 12 so that one leg of the 'IL" is parallel to the latter. That leg is provided with f a through opening 12c axially aligned with the sleeve 12a ,i through which the stationary contact member movably extends.
A closed position of the stationary contact member 18, the second radial holes 18C face the opening 12c adjacent to i, the bottom of the closure block 12b to be prevente~ from communicating with the external space as shown in Figure 29 wherein both contact members 18 and 21 are illustrated as being put at their closed position. That is, the axial exhaust passageway 18A is not connected in fluid communi- r cation with the external space. The opening 12c has an axial length dimensioned so that, when the puffer piston 15 does not engage the step 28b as shown in Figure 30, the second t radial holes 18C face the opening 12c to prevent the axial f exhaust passageway 18A to communicate with the external space.
The axial exhaust passageway 18A terminals at the same level as the lowermost wall of the second radial holes 18C.

1 ~ 6315 ,, .

In the interrupting operation the movable contact member 21 is separated from the stationary contact member 18 to strike an electric arc 25 thereacross within the reservoir 30. At that time the reservoir 30 communicates with the external space through the axial exhaust passageway 18A and the second radial holes 18C. If an electric arc strikes across both contact members 18 and 21 while the former does not flow up the latter as shown in Figure 30 then the reservoir 30 does not cor~muncate with the external space and instead the fluid pressure is accumulated within the reservoir 30 until the puffer piston 15 engages the step 28b. Under these circumstances, if the fluid pressure is excessively accumulated within the reservoir 30 with a high arc current then the stationary contact member 18 is moved away from the movable contact member 21 to reach its lowermost E
position as viewed in Figure 29. In this case, the pressure within the reservoir 30 is released through the axial exhaust passageway 18A and the first radial holes 18~.
In the arrangement of Figure 29, the electric arc struck upon the separation of both contact members is also utilized to expand the fluid within the reservoir to raise ~' the fluid pressure therein after which the fluid from the reservoir is rapidly delivered thereby to cool and extinguish the electric arc. In addition, the first and second radial holes are responsive to the movement of the stationary contact member to communicate and block the reservoir with and against the external space. This permits the reservoir to be prevented from rising in temperature and to have a sufficient fluid pressure accumulated therein. Therefore the interrupting '.
.` i,, performance can be improved. Also the resilience exerted on the stationary contact member can reduce, and a force for driving the movable contact member may be low while the ~.
construction is simplified. ~J
The arrangement of Figure 22 can be modified in ~.
the same manner as described above in conjunction with Figures 28 and 29 resulting in that illustrated in Figure 31.
In the arrangement illustrated, the slider 150 also serving !-;
as the arc contact member is identical in construction to the stationary contact member 18 shown in Figures 28, 29 and 30 to be substituted for the latter. Therefore an axial passageway 150A, first radial holes 150B and second radial b holes 150C correspond to the axial passageway 18A, the first radial holes 18B and the second radial holes 18C as shown in Figures 28 and 29 respectively.
Also Figures 31 and 32 show the arrangement at its closed and tripped positions while Figure 33 corresponds to Figure 30.
Figures 34 and 35 show two modifications of the arrangement illustrated in Figures 31 and 32 wherein Figure 34 shows the arc contact member 150 including only the second radial holes 150C and Figure 35 shows the arc contact member 150 including only the first radial holes 150B with the closure block 12b omitted.
The first radial holes 18B or 150B cooperate with the sleeve 12b to serve as a release valve for releasing a pressure in response to a large rise of pressure in the reservoir. On the other hand, the second radial holes 18C
or 150C cooperate with the sleeve 12b to control the operation o~ an exhaust opening at will in accordance with _ 43 _ ll 3~5 ',' a movable member, which opening exhausts only an electric r arc at an elevated temperature.
Figure 36 shows still another modification of the present invention. The arrangement illustrated is substantially similar to that sho~m in Figures 5 and 6 expecting that in Figure 36 there is provided latching means .
for holding the puffer piston in its position where the piston i~
has completed to compress the arc-extinguishing fluid in -the compression chamber and therefore in the reservoir. -r More specifically, the latching means includes a plurality ;r, of latches 43 disposed at predetermined equal angular intervals on the inner wall surface of the compression chamber 29 adjacent to the circumferential step 28b which is formed of a radially inward directed rib defining a boundary '3 between the compression chamber 29 and reservoir 30 equal tj in diameter to each other. To this end, a plurality of .
recesses are disposed on the inner wall surface of the compression chamber 29 at positions coinciding with those of latches 43 and then the latches 43 are disposed in the rl respective recesses through leaf springs 44 interposed .
between the same and the bottoms of the recesses. Therefore .
each of the latches 43 tends to be normally forced radially ' inward by means of the action of the mating leaf spring 44 so that it normally protrudes in the radially inward direction from the inner wall surface of the compression chamber 29. i~
The latching means also includes a circumferential tC
groove 45 disposed on the peripheral surface of the piston 15 at such a position that, when the piston 15 engages the .~

3~S

step 28b, the g~oove 45 faces the latches ~3. ~s the groove a 5 is made complementary in shape to each latch 43, they are fitted into the groove 44 and resilitnly held in engagement with the latter. The latches 45 and therefore the groove 45 are so shaped that the resilience of the helical spring 20 can easily put the groove 45 in engagement with the latches 43 while groove 4 5 can not disengage from the latches 43 unless a force higher than resilience of the helical spring 20 is applied to the groove 45.
As shown in Figure 36, a receptacle 15a in the form of a hollow cylinder is fixedly secured to the flat surface ~;
of the piston 15 facing the reservoir 30 at the center.
The receptacle 15a includes a centracted portion near to t;
its mouth to permit the free end portion of the movable contact member 21 to be forced thereinto. The receptacle 15a acts as a contact attached to the stationary contact member 18.
In the interrupting operation, the puffer piston 15 engages the step 28b to be prevented from being further moved while at the same time the groove 45 on the piston 15 engages the latches 43 on the inner wall surface of the compression chamber. Then the movable contact member 21 disengages from the receptacle 15a to strike an electric arc 25 thereacross as shown in Figure 37. The electric arc 25 causes the fluid pressure in the reservoir 30 to be further increased thereby to increase a force tending to force the stationary contact member 18 in the leftward direction as viewed in Figure 37. However, even though this force would be higher than the resilience of the helical spring 20, the i~

i3:~5 stationary contact member 18 is dlsabled -to be moved leftward as viewed in Figure 37 because the groove 45 is in engagement with the latches 43 to hold the stationary contact member 18 to be maintained fixed to the hollow cylindrical member 26.
Therefore the reservoir 30 can be maintained under a high fluid pressure.
When the fluid pressure in the reservoir 30 increases beyond a fluid pressure sufficient to extinguish the electric arc, the groove 45 disengages from the latches 43 to move the stationary contact member 18 toward its original position against the resilience of the helical spring 20. This prevents the fluid pressure in the reservoir 30 from increasing unnec-essarily. Upon the fluid pressure within the reservoir 30 reducing, the stationary contact member 18 is again moved rightward until it is again locked by the latching means 43, 44, 45.
Thereafter the movable contact member 21 is further separated from the stationary contact member resulting in the extinction of the electric arc as described above.
When the movable contact member 21 at its open posi-tion is moved to engage the contacts 15a on the stationary contact member 18, a current immediately flows through both contact members to generate an electromagnetic repulsion there-between. Under these circumstances, the groove 45 on the piston 15 is in engagement with the latches 43 to prevent the stationary contact member 18 from moving leftward as viewed in Figure 37. Accordingly, both contact members are not separated from each other so that no electric arc strikes there-across. Accordingly the movable contact i, ~ ~ i31S
l ~, member 21 and the contact 15a on the st~tionary contact member 1~ are prevented from fusing to each other due to an electric arc struck thereacross Then the free end of the movable con-tact member 21 is forced into the receptacle 15a after which the movable contact member 21 is pushed in the le~tward direction as viewed in Figure 37. This causes the grooves 45 to disengage from the latches 43 thereby to permit the moved components to be returned back to their original positions as shown in Figure 36.
While the stationary contact member 18 is formed t' integrally with the piston 15, it is to be understood that, '1 as shown in Figure 7, the stationary contact member 18 in ,, the form of a split contact may be annulus and disposed in the reservoir 30 and slidably engage the outer peripheral surface of the rnovable contact member. Further the latching means is not required to be disposed on both the piston 15 Y
and the compression chamber 29 but it may be disposed on the guide rod for the piston 15 and that portion of the terminal plate 12 slidably engaged thereby.
In the arrangement shown in Figures 36 and 37, the , puffer piston can be held in its posltion where the piston has just completed to compress the arc-extinguishing fluid.
Therefore the piston is prevented from retrograding forcedly Y
resulting in improvements in the interrupting performance.
In addition, both contact members in the clsoing process are prevented from being again separated from each other due to an electromagnetic repulsion generated therebetween resulting in an increase in current capacity. Therefore, a :1 ~ 3~5 the resulting device is small-sized inexpensive an~ hic3h in current capacity as compared with the prior art practice.
The arrangement illustrated in Figure 38 is different from that shown in Figure 9 only in that in Figure 38 latchina means including latches 43, leaf springs 44 and a groove 45 is disposed in the same manner as described above in conjunction with Figure 36 with the receptacle 15a f omitted.
The arrangement illustrated in Figure 39 is different from that shown in Figure 17 only in the same respect just described in conjunction with Figure 38.
The arrangement illustrated in Figure 40 is different from that shown in Figure 9 principally in that in Figure 40, a check valve is operatively coupled to each of through holes on the terminal plate through which the stationary contact member slidably extends. As shown in Figure 40, the check valve designated by the reference numeral 46 includes a valve body 46a normally closing an open end of an associated one of the through holes 32 on the terminal plate 12 facing the chamber 31 now called a "back pressure chamber" and a valve stem 46b connect at one to the valve body 46a to extend boosely through the associated hole 32 and having the other end portion protruding beyond the terminal plate 12. The other end portion is folded into a "L" forming a stopper 46c for preventing the check valve from falling into the back pressure chamber 31.
Also a receptacle 15a such as shown in Figure 36 is fixedly secured to the puffer piston 15 in the same manner as described above in conjunction with Figure 36.
'~
,, ,~, - 48 - , l ~ 63~5 In other respects the arrangement is identical to that shown in Figure 9.
When the movable contact memher 21 is descending with the stationary contact member 18 to compress the arc-extinguishing fluid in both the compression cha~ber 29 and the reservoir 30, the check valves 46 open the associated through holes 32 due to a pressure difference between the , external space and the back pressure cham~ier 31. Therefore the fluid pressure in the back pressure chamber 31 does not impede the descent of the piston 15 and others.
Then the piston 15 abuts against the step 28b as shown in Figure 41 until the recess 34 on the movable contact member 21 disengages from the tulip-shaped member 33, in this case, formed of an electricall~ insulating material. Also the movable contact member 21 is separated from the stationary contact member 18 resulting in an electric arc striking thereacross. This electric arc is operated to increase further the fluid pressure in the reservoir 30 until the piston 15 is forced to retrograte.
This results in the closure of the check valves 46. Therefore the fluid pressure in the back pressure chamber 31 increases to suppress the retrogradation of the piston 15. As a result, the reservoir 30 is maintained under a high fluid pressure.
Thereafter the movable contact member 21 reaches its position illustrated in Figure 42, and then the electric arc 25 is blown out with a stream of the arc-extinguishing fluid designated at the arrows a side the electric arc 25.
As shown also in Figure 42, the electric arc 25 spreads ~1~6315 across the ends of both contact members 21 and 18 so that the tulip-shaped member 33 is prevented from being directly exposed to the electric arc 25.
From the Loregoing it is seen that the check valves are disposed to suppress the retrogra~ation of the piston. Therefore it is possible to perform the puffer action more effectively resulting in improvements in interrupting performance. , The arrangement illustrated in Figure A 3 is different from that shown in Figures 40, 41 and 42 only in that in Figure 43 a pair of stationary contact members are ~
disposed in diametrically opposite relationship within the t, reservoir while the stationary contact member 18 shown in Figures 40, 41 and 42 serves as a slider or arc contact !~
member with the receptacle 15a on the piston 15 omitted. t' In the arrangement illustrated a pair of recesses are disposed in diametrically opposite relationsip on the inner wall surface of the reservoir 30 and have inserted thereinto t respective stationary contact members 18. The stationary t contact members 18 tend to be radially inward moved by means of the action of mating leaf springs 42 interposed between the same and the bottoms of the associated recesses.
Therefore both stationary contact members 18 are arranged F
to engage slidably the outer peripheral surface of the movable contact member 21.
The arrangement illustrated in ~igure 44 is different from that shown in Figures 41, a2 and 43 only in that in Figure 44 a tension spring 47 is disposed around the t stationary contact member 18 between the puffer piston 15 ~63:~S
f and the terminal plate 12 by having hoth ends suitably fixed to the two with the checK valves 46 and the through holes 32 omitted. The tension spring 47 serves to hold the piston 15 and therefore the stationary contact member 18 IJ
in the inoperative position illustrated in Figure 44. -The piston 15 along with the stationary contact member 78 and the movable contact member 21 is moved downward as viewed in Figure 44 against a tension provided by the tension spring 47 to compress the arc-extinguishing fluid r, in both the compression chamber 2~ and the reservoir 30 after which an electric arc struck cross the movable contact member 21 and the receptacle or the contact 15a on the , stationary contact member 18 is extinguished as described ;
above.
It is noted that, after the tulip-shaped member 33 on the stationary contact member 18 has disengaged from -3 the recess 34 on the movable contact member 21, the puffer 'i~
piston 15 receives not only the tension of the tension spring ,J
47 but also a pressure due to the arc-extinguishing fluid ~
compressed by the piston 15 thereby to tend to be returned ;J
back to the ter~inal plate 12. ~owever, since the puffer piston 15 has a null initial speed at the beginning of this return-back and the tension spring 47 is required only to provide a low tension, the piston 15 is forced to be moved toward the terminal plate 12 by a very small distance until r the electric arc is extinguished.
Accordingly, an increase in volume of the reservoir ~
30 results in the fluid pressure therein and hence an amount b of the fluid blowing against the electric arc being reduced to a substantially negligible extent. l ~, , ~, ~63:~5 It will readily be understood that the tension i~
spring 47 aids in returning the piston 15 back to its ~,' inoperative position.
While an electromagnetic repulsion is generated between the movable and stationary contact arms 21 and 18 .
upon the two engaging each other, the same is disabled to move the stationary contact member 18 toward the terminal plate 12 because the piston 15 is in engagement with the , step 28a. ~herefore the stationary contact member 1~ can not be separated from the movable contact member 21. This t prevents an electric arc from striking across both contact members. Accordingly, both contact members are not fused to each other with the result that the tulip-shaped member 33 is permitted to be smoothly inserted into the recess 34.
While the arrangement of Figure 44 utilizes the tension of the tension spring, a helical spring 48 may be , disposed around the movable contact member 21 put at its closed position in both the compression chamber 29 and the reservoir 30 as shown in Figure 45. In the latter case, ~, a resilience provided by the helical spring 48 is utiliæed to attain the same purpose as the tension of the tension spring 47.
Figure 46 shows a different embodiment of the present invention. In Figure 46, the arrangement similar to that shown in Figures 5 and 6 includes the terminal plate 23 closing an opened of an enclosure 49 and the movable contact member 21 put at its closed position to be engaged at the other end by locking means generally designated by ;~
the reference numeral 50 aDd disposed in the enclosure 49.

, 1 ~ i3~S ;;
~ 't The locking means 50 includes a locking memeber 50a shown in Figure 46 as abutting against the other end of the t`
movable contact member 21 by means of the action of a ~;
spring 50b. T}-us the locking means 50 detachably locks the movable contact member 21 at its closed position.
At its closed position the other end of t~ne movable contact member 21 is somewhat inserted into closure driving means generally designated by the reference numeral 60.
~lore specifically, the closure driving means 60 includes f a cylinder 60a having an open end and a spring looded piston 60b slidably fitted into the cylinder 60a. The closure , driving means 60 is normally put in its energized state by lAi a lifting member (not shown) and the free end of the movable contact member 21 at its closed position is located within 1~
the cylinder 60a adjacent to the open end. !' With the movable contact member 21 engaged by the c stationary contact member 21, the locking member 50a is pulled downward as viewed in Figure 46 against the action of the spring 50b. Therefore the helical spring 20 is ,~
operated to move the stationary contact member rightward as viewed in Figure 46 with the movable contact member 21 to strike an electric arc 25 across both contact members 18 and 21 in the manner as described above in conjunction with Figure 3, 4, 5 and 6 as shown in Figure 47. Then the t~, electric arc 25 is extinguished as described also above. t At that time, the movable contact member 21 has the free end spaced from the nozzle 27 and the other end abutting agains he piston 60b as shown in Figure 48.

llZ6;315 Under these circumstance, the closure driving means 60 discharges its energy in responce to a command closure signal. This results in both contact members engaging each other in the manner as described above in conjunction with Figures 3 and 4. At that time the movable contact ,~
member 21 engages the loc~ing means 50 to be locked at its closed position resulting in the completion of the closing operation. Also the closure driving means 60 is put in its energized state by the lifting member tnot shown). Therefore -s the moved components are returned back to their original ?, position shown in Figure 46. ,1 Since the closure driving means is required only 5 to perform the closing operation, it can be constructed simply and inexpensively. Also, both contact members are maintained in engagement with each other under a pressure by means of the action of the spring so that the contact ,-~
members are possible to carry a high current. Further, in E
the interrupting operation,; both contact members are operated from each other only after they have reached predetermined -.
positions resulting in the stabilized interrupting E
performance. If the movable contact member has a large inertia then the same performs stably the separating ~.
operation. This results in the more reliable interruption.
In the arrangement illustrated in Figure 49 a .l hollow cylindrical stationary member 10 formed of an ti electrically insulating material includes one end surface, , in this case, the lefthand end surface as viewed in Figure 49 provided with a central small hole, an inner cylindrical u space lOa having a large cross sectional area, and the other ' . v~ 1 - 54 - .' '~

1 ~ 5 :
.

or righthand end surface provided with a central hole lOb having a small cross sectional area. This hole lOb is so , dimensioned that the movable contact member 21 movably extends there-through with a small spacing formed therebetween.
The puffer piston 15 or a slider is slidably fitted into the inner space lOa and tends to be moved toward the righthand end surface by means of the action of the helical spring 20 disposed between the lefthand end surface and the piston 15. `
The terminal plate 12 is extended and sealed through the peripheral wall of the hollow member 10 to be E
perpendicular to the longitudinal axis of the hollow member 10. The terminal plate 12 defines a boundary between the compression chamber 29 and the reservoir 30 and forms one part of the stationary contact member 18 fixedly secured to ' the inner peripheral wall surface of the reservoir. The stationary contact member 18 includes a leaf spring 18_ disposed in a recess disposed on the radially inner surface thereof and a contact 18b fitted into the recess and on the leaf spring 18a. Therefore the contact 18_ slidably engages the movable contact member 18 put at its closed position by means of the action of the leaf spring 18a. At its closed position the movable contact member lS includes one end, in this case, the lefthand end as viewed Figure 49 engaging the puffer piston 15 and the other or righthand end , somewaht fitted into the cylinder 60a of the closure driving means 60 and engaging the locking means 60 movably protruding beyond the peripheral wall of the cylinder 60a. The locking means 50 serves to lock the stationary contact member 18 at . n .1, 31L5 ~

r its closed position. The closure driving means 60 further includes a piston 60_ slidably fitted into the cylinder 60_.
As shown in Figure 49 a collector 24 is located t;adjacent to the open end of the c~linder 60a to abut against the movable contact member 21.
When the locking means 50 is retraced as shown in Figure 50, the helical spring 20 is operated to move the piston 15 in the rightward direction as viewed in Figure 49 r with the movable contact member 21 to compress the arc- ir extinguishing fluid in the compression chamber 29 and the reservoir 30 until the piston 15 abuts against the terminal ;;
plate 12 to be prevented from further moving (see Figure 50).
Thereafter, the movable contact member 21 continues to be moved in the rightward direction due to its inertia. Then the movable contact member 21 is separated from the stationary contact member 18 to strike an electric arc 25 thereacross 3 as shown in Figure 50. The electric arc 25 is extinguished as described above and the righthand end of the movable i~
contact member 21 abuts against the piston 60b of the closure , driving means 60 as shown in Figure 51.
In the closing operation, the piston 60b is moved in the leftward direction manually or with a mechanical ~3 force resulting, for example, from a spring (not shown) to move the movable contact member 21 in the leftward direction.
The movable contact member 21 engages the stationary contact L
member 18 and then abuts against the piston 15 thereby to 3 receive the puffer action from the helical spring 20 while the latter accumulates energy. ~7hen the helical spring 20 is completed to accumulate energy, the locking means 50 3~

l ~ i3J,5 engages the righthand end of the movable contact member 21 to lock the contact member 21 at is closed position. Then the piston 60b is returned back to its original position whereupon the closing operation is completed. ~hat is, the moved components are returned bac~ to their pisitions shown ',.
in Figure 49.
From the foregoing it is seen that by providing ;`
the piston or slider and a resilient mernber or the helical spring for pushing the slider, a simple closure driving means can be incorporated into a simple, inexpensive switch ,:
to improve its interrupting performance.
While the present invention has been illustrated ,,`
and described in conjunction with several preferred ;~
embodiments thereof it is to be understood that numerous changes and modifications may be resorted to without departing from t spirit and scope of the present invention.

.~

- 57 - ~1

Claims (36)

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

1. A self-extinguishing type switch comprising a hollow cylindrical member, an amount of arc-extinguishing fluid accomodated in said hollow cylindrical member, at least one pair of contact members disposed in said hollow cylindrical member to be relatively movable to engage and disengage from each other, a reservoir disposed in said hollow cylindrical member to accumulate the arc-extinguishing fluid increased in pressure due to an electric arc struck across said contact members separated from each other, a compression chamber disposed in said hollow cylindrical member to be connected in fluid communication with said reservoir, a piston movably disposed in said compression chamber and operable on separation of said contact members from each other to compress said arc-extinguishing fluid within said compression chamber and deliver the compressed fluid to said reservoir, and a nozzle disposed to be connected in fluid communication with said reservoir, said nozzle discharging said arc-extinguishing fluid located in said reservoir and increased in pressure after said contact members are separated from each other by a predetermined dis-tance.

2. A self-extinguishing type switch as claimed in claim l, wherein said contact members comprise a movable contact member and a stationary contact member disposed inte-grally with said piston.

3. A self-extinguishing type switch as claimed in claim 2, wherein said piston tends to be moved in a direction of action of the compression by means of a resilient member and wherein when said contact members are in their closed position, said movable contact member locates said piston at a position of initiation of the compression action against a force provided by said resilient member.

4. A self-extinguishing type switch as claimed in claim 2, wherein at least one of said movable and stationary contact members includes a fluid passageway for connecting the exterior of said hollow cylindrical member in fluid com-munication with a space where an electric arc strikes upon the separation of said two contact members.

5. A self-extinguishing type switch as claimed in claim 4, wherein said fluid passageway opens on a contact surface of said contact member.

6. A self-extinguishing type switch as claimed in claim 4, wherein a sleeve supported by the hollow cylindrical member surrounds the stationary contact member over a predeter-mined length extending in a direction of movement of said movable contact member such that when the contacts are engaged the sleeve also surrounds a terminal portion of the movable contact member.

7. A self-extinguishing type switch as claimed in claim 4, wherein said fluid passageway includes a hole for connecting and disconnecting said fluid passageway to and from the exterior of said hollow cylindrical member attendant upon the movement of said contact member.

8. A self-extinguishing type switch as claimed in claim 7, wherein said fluid passageway extends through said stationary contact member and includes a plurality of holes located for selectively connecting and disconnecting said fluid passageway to and from the exterior of said hollow cylindrical member in accordance with a distance of movement of said stationary contact member due to movement of said piston.

9. A self-extinguishing type switch as claimed in claim 2, wherein a sleeve supported by the hollow cylindrical member surrounds the stationary contact member over a pre-determined length extending in a direction of movement of said movable contact member such that when the contacts are engaged the sleeve also surrounds a terminal portion of the movable contact member.

10. A self-extinguishing type switch as claimed in claim 2, wherein there are provided a resilient member for causing siad piston to tend to be moved in a direction of the action of compression and imparting a separation force to said movable contact member, closing means for moving said movable contact member toward said stationary contact member to put both contact members in engaging relationship and locking means for holding said movable contact member in its closed position.

11. A self-extinguishing type switch as claimed in claim 2, wherein said stationary contact member is connected to said movable contact member through a coupling held in connected relationship until a tripping force in excess of a predetermined magnitude is applied to said coupling.

12. A self-extinguishing type switch as claimed in claim 11, wherein said tripping force is applied to said coupling at a postion where said piston completes the compression action.

13. A self-extinguishing type switch as claimed in claim 11, wherein said piston is returned back to a position where the compression action is initiated.

14. A self-extinguishing type switch as claimed in claim 13, wherein a resilient member returns said piston back to a position where the compression action is initiated.

15. A self-extinguishing type switch as claimed in claim 1, wherein said contact members comprise a movable contact member and a stationary contact member engageable with-in said hollow cylindrical member.

16. A self-extinguishing type switch as claimed in claim 15, wherein said piston tends to be moved in a direction of action of the compression by means of a resilient member and wherein when said contact members are in their closed posi-tions, said movable contact member locates said piston at a position of initiation of the compression action against a force provided by said resilient member.

17. A self-extinguishing type switch as claimed in claim 15, wherein at least one of said movable contact member and said piston includes a fluid passageway for connecting the exterior of said hollow cylinder to said reservoir.

18. A self-extinguishing type switch as claimed in claim 17, wherein said fluid passageway includes a hole for connecting and disconnecting said fluid passageway to and from the exterior of said hollow cylindrical member attendant upon the movement of said contact member.

19. A self-extinguishing type switch as claimed in claim 18, wherein said piston is provided with both said fluid passageway and an arc contact member engaging and disengaging from said movable contact member.

20. A self-extinguishing type switch as claimed in claim 19, wherein said fluid passageway includes a plurality of holes for selectively connecting and disconnecting said fluid passageway to and from the exterior of said hollow cylindrical member in accordance with a distance of movement of said piston.

21. A self-extinguishing type switch as claimed in claim 15, wherein a sleeve supported by the hollow cylindrical member surrounds the stationary contact member over a pre-determined length extending in a direction of movement of said movable contact member such that when the contacts are engaged the sleeve also surrounds a terminal portion of the movable contact member.

22. A self-extinguishing type switched as claimed in claim 15, wherein said piston includes an arc contact member for engaging and disengaging from said movable contact member and wherein a sleeve supported by the hollow cylindrical member surrounds the stationary contact member over a predetermined length extending in a direction of movement of said movable contact member such that when the contacts are engaged the sleeve also surrounds a terminal portion of the movable contact member.

23. A self-extinguishing member as claimed in claim 15, wherein there are provided a resilient member for causing said piston to tend to be moved in a direction of the action of compression and imparting a separation force to said movable contact member, closing means for moving said movable contact member toward said stationary contact member to put both contact members in engaging relationship, and locking means for holding said movable contact member in its closed position.

24. A self-extinguishing type switch as claimed in claim 2, wherein said piston is connected to said movable contact member through a coupling held in connected relationship until a tripping force in excess of a predetermined magnitude is applied to said coupling.

25. A self-extinguishing type switch as claimed in claim 24, wherein said movable contact member is separated from said stationary contact member before said piston disconnects from said movable contact member.

26. A self-extinguishing type switch as claimed in claim 24, wherein said movable contact member is separated from said stationary contact member when the connection of said piston to said stationary contact member is released.

27. A self-extinguishing type switch as claimed in claim 15, wherein said stationary contact member slidably engages an outer peripheral surface of said movable contact member.

28. A self-extinguishing type switched as claimed in claim 15, wherein said piston is returned back to a position of initiation of the compression by said movable contact member upon both contact members engaging each other.

29. A self-extinguishing type switch as claimed in claim 15, wherein said stationary contact member is disposed in said reservoir.

30. A self-extinguishing type switch as claimed in claim 1, wherein there is provided a coupling capable of engaging said piston at a position where said piston completes the compression action.

31. A self-extinguishing type switch as claimed in claim 30, wherein said coupling engages said piston with a force less than that required for the coupling to disengage from said piston.

32. A self-extinguishing type switch as claimed in claim 30, wherein said coupling is disposed on both an outer peripheral surface of said piston and an inner peripheral surface of said compression chamber.

33. A self-extinguishing type switch as claimed in claim 1, wherein said hollow cylindrical member includes a back pressure chamber for said piston on a side of said compression chamber remote from said reservoir and connected in fluid communication with the exterior of said hollow cylindrical member through an opening, and a check valve disposed in said opening to permit the arc-extinguishing fluid only to flow into said back pressure chamber from the exterior of said hollow cylindrical member.

34. A self-extinguishing type switched as claimed in claim 1, wherein the interior of said hollow cylindrical member is partitioned into said compression chamber and said reservoir through a step against which said piston abuts at a position where said piston completes the compression action.

35. A self-extinguishing type switch as claimed in claim 1, wherein said nozzle includes a portion flared toward an open end thereof.

36. A self-extinguishing type switch as claimed in claim 1, wherein said contact members engage and disengage from each other in said reservoir.