US2916568A - Contact air cooling system - Google Patents

Description

- Dec. 8, 1959 Filed Oct. 21. 1957 O. JENSEN CONTACT AIR COOLING SYSTEM 2 Sheets-Sheet 1 INVENTOR. flrra JE/VJE/V Dec. 8, 1959 o. JENSEN 2,916,563-

CONTACT AIR COOLING SYSTEM BY W 7; 4

Jrraovrxr United States Patent CONTACT AIR COOLING SYSTEM Otto Jensen, Malvern, Pa., assignor 'to I-T-E Circuit Breaker Company, Philadelphia, Pa., a corporation of Pennsylvania Application October 21, 1957, Serial No. 691,224 7 Claims. (Cl. 200-19) My invention relates to a novel means for cooling a pair of cooperable contacts as well as removing foreign particles from the cont-acting area, and more specifically relates to a cooling and cleaning system for contacts of the repetitively operated type, such as mechanical rectifier contacts.

Mechanical rectifiers and the contacts therefor are completely described in my copending applications Serial No. 307,067 filed August 29, 1952, now Patent No. 2,798,909, and Serial No. 558,350, filed January 10, 1956, now Patent No. 2,851,562 and assigned to the assignee of the instant invention.

As may be seen from reference to these copending applications, a mechanical rectifier, taken by way of example, utilizes a pair of cooperable contacts connected between an A.-C. source. and a D.- C. load. The contact is synchronously operated so that when the voltage of the A.-C. source is positive, the contact is closed, and this voltage is applied to the D.-C. load. When, however, the voltage of the A.-C. source reverses, the contact is open and the D.-C. load is disconnected from the A.-C. source. By synchronously operating the contact in this manner with respect to the frequency of the A.-C. source, the D.-C. load will have impressed thereon a unidirectional voltage of some predetermined average value.

Several serious problems are present in the utilization of this type of contact, primarily due to the relatively high contact currents which in some cases may be as high as 5,000 amperes, and also due to the fact that the contacts must operate sixty times every second, or 216,000 times every hour when rectifying a sixty cycle A.-C. source.

These problems primarily are excessive heat generation within the contact due to resistive heating of the contact material and resistive heating due to the contact resistance, and foreign material such as dust or specks of contact material which appear within the area of contact engagement. The latter noted problem of foreign material will, of course, increase the contact resistance so as to further increase the heat generated at the contact, but also may serve to initiate a small are immediately prior to contact closure, thus causing a weld which will be torn apart when the contact is open. Since this process is cumulative, after a relatively few operations the contact surfaces may be seriously damaged, and lead to a backfire or a high power are through the contact when the contact is opened. In a similar manner, a foreign particle may cause an arc to be drawn during contact opening.

The principal object of my invention is to provide a novel means for both cooling the contacts and dislodging foreign matter which appears within the contacting area.

In a preferred embodiment of my invention where a movable contact cooperates with a pair of relatively stationary contacts in a bridging arrangement, I drill a hole through the center of the movable contact. The

movable contact, which may have a biasing spring placed respect to the stationary contacts, then has a fluid conduit introduced through the aperture or hole in the contact and runs along the central axis of the spring to some outer source of high pressure fluid such as air.

The fluid conduit is terminated at a point substantially adjacent to the contact engaging area and within a depression in the head of an operating pushrod which moves the movable contact against the force of the biasing spring and out of engagement with the cooperating stationary contacts when disengagement is required.

This depression, in conjunction with other fluid passages in the pushrod head, then serves to deflect air or fluid brought through the fluid conduit into the contacting area.

By way of example, the portion of the pushrod head which engages the movable contact may be fluted whereby air rushes from the fluid conduit into the pushrod depression and then upwardly between the walls of the depression and the outer walls of the conduit through the fluted segments of the pushrod head and into the area formed by the disengagement of the cooperating con-- tacts.

It is to be noted that this air flow in the said area Willi be relatively turbulent so that the cooling eflect of the; air is amplified. Furthermore, this air will pick up any foreign particles within the area and blow them out of" the contact area.

Furthermore, the cooling effect may proceed even-r when the pushrod is removed from the movable con:- tact and the contacts are engaged, for with this condition air will be deflected by the pushrod depression and vmay escape through a passage formed by the outer por-- tion of the pushrod head and the outer portion of the engaged movable and stationary contacts. Hence, the cooling effect may proceed even though the cooperating contacts are engaged and the area formed by contact disengagement is not present.

Accordingly, an important object of my invention is to provide a novel cooling system for contacts wherein a fluid conduit is connected to the area of contact engagement when the cooperating contacts are disengaged.

Another object of my invention is to provide a novel cooling means for mechanical rectifier contacts wherein the top of the pushrod head serves to form a passage for deflection of air from a fluid conduit which passes through an aperture in the movable contact into the area created by contact disengagement.

Another object of my invention is to provide a novel cooling system for contacts wherein cooling and cleaning proceeds when the contact is in an open position.

These and other objects of my invention will become apparent from the following description when taken in conjunction with the drawings, in which:

Figure 1 shows an exploded perspective view of the preferred embodiment of my novel invention taken in conjunction with a mechanical rectifier contact.

Figure 2 is a side view of one possible modification of the pushrod head of Figure 1.

Figure 3 is a cross sectional view of the pushrod head of Figure 2 when, taken across lines 33.

Figure 4 is an assembled cross-sectional view of the embodiment of Figure 1 when the cooperating contacts are in their engaged position.

Figure 5 is similar to Figure 4 with the cooperating contacts in a disengaged position.

Figure 6 is a schematic circuit diagram of a threephase half-wave mechanical rectifier circuit wherein the contacts are adapted in accordance with my novel invention.

Referring now to Figures 1, 4 and 5 which show a typical mechanical rectifier contact of the type set forth inmy above noted copending applications Serial No. 307,067 filed August 29, 1952, now Patent No. 2,798,909 and Serial No. 558,350 filed January 10, 1956, now Patent No. 2,851,562, a pair of stationary contacts 10 and 12 are clamped by a clamping means (not shown) to an A.-C. bus 14 and a D.-C. bus 16 which buses are subsequently connectable to an A.-C. source and DC. load respectively.

In order to connect the A.-C. source and DC. load (not shown), when the polarity of the A.-C. source is of a desired value a movable contact 18 is brought into bridging engagement-with respect to stationary contacts 10 and 12 in a manner to be described hereinafter.

Movable bridging contact 18 has an aperture '20 therein which passes a fluid conduit 22, as will be more fully described hereinafter.

Movable contact 18 is normally biased into contact engagement with respect to stationary contacts 10 and 12 by means of biasing spring 24 which bears against a relatively stationary spring support member 26. In order to achieve contact disengagement a pushrod device 28, which is operated from a motor 30 in such a manner as to impart linear motion as indicated by the arrow 32 to the pushrod 28, is in a lower position when disengaged with respect to the movable contact 18. When, however, the motor 30, operating through an operating linkage of the type which is completely described in my above noted copending application Serial No. 307,067 filed August 29, 1952, now Patent No. 2,798,909 drives pushrod 28 upwardly, the top of pushrod 28 or the pushrod head is brought into engagement with the underside of contact 18, and moves the contact 18 to a disengaged position against the force of biasing spring 24-. (See Figure 5.)

Figures 1, 4 and further show the top of the pushrod 28 as having a depression 34 therein which depression receives the open end of fluid conduit 22. The top of pushrod head 28 is fluted, as seen by fluted portion 36, so that even through the top portion 36 of pushrod head 28 engages the under side of contact 18, it will be in a non-airtight manner.

Clearly, the opposite end of fluid conduit 22 will have a source of high pressure fluid connected thereto so that this fluid will move through conduit 22 to emerge within the depression 34 of the pushrod 28 at a point which is substantially intermediate an area created by the movement of the cooperating contacts to a disengaged position.

The cooling and cleaning effect of my novel system may be best understood by reference to Figure 5 where the air flow through conduit 22 is indicated by the arrows. Thus, the air flow proceeds down the conduit 22 and into depression 34 where it is deflected by the bottom of the depression and then flows upwardly through a passage defined by the inner walls of depression 34 and the outer surface of conduit 22. The fluid then reaches the fluted top portion 36 of pushrod 28, which fluted portion defines passages leading from the depression 34 to the area formed between the movable contact 18 and the stationary contacts and 12 when the movable contact is disengaged.

Thus, the relatively high pressure fluid emerges through the fluted section 36 into this area in a turbulent manner, as indicated by the arrows in this area, so that both cooling of the contact surfaces of contacts 10, 12 and 18 and removal of foreign particles in this area is achieved.

It is to be noted that in the case of Figure 4 where the movable contact 18 is closed an air passage is still formed between depression 34 and an area external of the stationary contacts 10 and 12 through which a fluid can pass. That is to say, fluid may pass through the .fluted section 36 and then between the outer portion of the. top of the pushrod 28 and the inner surface of stationary contacts 10 and 12 whereby cooling of this portion of the stationary contacts is achieved.' Further air may escape 4 in a direction parallel to the adjacent surfaces of the stationary contacts 10 and 12 and against the lower surface of the movable contact 18 (Figure 1) so as to achieve cooling of the movable contact 18 as well as portions of stationary contacts 10 and 12, even though the contacts are engaged. I

While Figures 1, 4 and 5 have shown the pushrod as having a fluted top portion 36 to define air passages leading from the pushrod to the external area, it is clear that these passages could be formed in many different ways. By way of example, Figures 2 and 3 show a second embodiment of a pushrod head 38 which has a depression 40 therein which is similar to depression 34 of Figures 1, 4 and 5. However, instead of fluting the top of the pushrod head, a plurality of apertures such as apertures 42, 44, 4-6, 48, 50 and 52 are drilled from the side of the top of the pushrod head and into the depression 40.

Accordingly, air or fluid from fluid conduit 22 may be directed into the contacting area through the plurality of apertures 42 through 52 in a manner similar to that of Figures 1, 4 and 5.

Figure 6 shows the manner in which my novel aircooled contact may be applied in a mechanical rectifier system. More specifically, in Figure 6 an A.-C. source of voltage 54 is connected to the primary of a delta-Y connected rectifier transformer which has a center tap brought out from the Y connected secondary to negative D.-C. terminal 56.

The other terminals of the Y connected secondary are then connected in series with a first, second and third respective rectifier phase each of which includes series connected commutating reactor 58 and contact 60. A complete description of the operation of commutating reactors, such as the commutating reactor 58, is set forth in copendin application Serial No. 301,880, now Patent No. 2,759,128, filed July 31, 1952 and assigned to the assignee of the instant invention.

Each of contacts 60 are of the type above described in conjunction with Figures 1, 4 and 5 and comprise stationary contacts 10 and 12 which cooperate with a movable contact 18.

The movable contacts are, as previously described, moved out of engagement with respect to their cooperating contacts 10 and 12 by means of a pushrod 28, and the pushrods of the various phases are operated in a predetermined sequence by a linkage schematically indicated in Figure 6 by a dotted line which is driven from the motor 30.

Each of the contacts 12 are then tied together and brought out to a common positive terminal 62 whereby a D.-C. load is thereafter connectable between terminals 56 and 62.

As has been previously described in Figures 1, 4 and 5, each of contacts 60 has a fluid conduit 22 associated therewith. In Figure 6 I prefer to connect each of conduits 22 to a common conduit 64 having one end 66 closed and the other end connected to a compressor 68 or some similar source of high pressure fiuid.

Accordingly, the compressor 68 will drive fluid through the main conduit 64 and into the individual conduits 22 whereupon the air cooling and cleansing effect will be achieved in a manner described above for each of the contacts.

Although I have described preferred embodiments of my novel invention, many variations and modifications will now be obvious to those skilled in the art, and I prefer therefore to be limited not by the specific disclosure herein but only by the appended claims.

What is claimed is:

1. In a mechanical rectifier contact means comprising a movable contact movable into and out of engagement with respect to a pair of relatively stationary contacts spaced apart from one another; said movable contact having biasing means asso'ciated therewith for biasing said movable damned.

contact into bridging contact engagement with respect to said pair of spaced stationary contacts; pushrod means engageable with the side of said movable contact adjacent said stationary contacts for moving said movable contact against the force of said biasing means and to a disengaged position with respect to said stationary contacts; an aperture in said movable contact and a fluid conduit means extending through said aperture and being directed toward said pushrod; said pushrod being constructed to define a path for fluid flow from said fluid conduit means to the area between said movable contact and each of said pair of stationary contacts created when said movable contact is moved to said disengaged position.

2. In a mechanical rectifier contact means comprising a movable contact movable into and out of engagement with respect to a pair of relatively stationary contacts spaced apart from one another; said movable contact having biasing means associated therewith for biasing said movable contact into bridging contact engagement with respect to said pair of spaced stationary contacts; pushrod means engageable with the side of said movable contact adjacent said stationary contacts for moving said movable contact against the force of said biasing means and to a disengaged position with respect to said stationary contacts; an aperture in said movable contact and a fluid conduit means extending through said aperture and being directed toward said pushrod; said pushrod being constructed to define a path for fluid flow from said fluid conduit means to the area between said movable contact and each of said pair of stationary contacts created when said movable contact is moved to said disengaged position; said pushrod having a fluted head engaging said side of said movable contact to mechanically engage said movable contact in a non-airtight manner to thereby define said fluid flow path to said area.

3. In a mechanical rectifier contact means comprising a movable contact movable into and out of engagement with respect to a pair of relatively stationary contacts spaced apart from one another; said movable contact having biasing means associated therewith for biasing said movable contact into bridging contact engagement with respect to said pair of spaced stationary contacts; pushrod means engageable with the side of said movable contact adjacent said stationary contacts for moving said movable contact against the force of said biasing means and to a disengaged position with respect to said stationary contacts; an aperture in said movable contact and a fluid conduit means extending through said aperture and being directed toward said pushrod; said pushrod being constructed to deflect fluid flow from said fluid conduit means to an area between said movable contact and each of said pair of stationary contacts created when said movable contact is moved to said disengaged position.

'4. In a mechanical rectifier contact means comprising a movable contact movable into and out of engagement with respect to a pair of relatively stationary contacts spaced apart from one another; said movable contact having biasing means associated therewith for biasing said movable contact into bridging contact engagement with respect to said pair of spaced stationary contacts; pushrod means engageable with the side of said movable contact adjacent said stationary contacts for moving said movable contact against the force of said biasing means and to a disengaged position with respect to said stationary contacts; an aperture in said movable contact and a fluid conduit means extending through said aperture and being directed toward said pushrod; said pushrod being constructed to define a path for fluid flow from said fluid conduit means to the area between said movable contact and each of said pair of stationary contacts created when said movable contact is moved to said disengaged position; said fluid flow to said area cooling each of said stationary contacts and said movable contact and dislodging foreign particles from said area.

5. In a mechanical rectifier contact means comprising a movable contact movable into and out of engagement with respect to a pair of relatively stationary contacts spaced apart from one another; said movable contact having biasing means associated therewith for biasing said movable contact into bridging contact engagement with respect to said pair of spaced stationary contacts; pushrod means repetitively engageable with the side of said movable contact adjacent said stationary contacts for moving said movable contact against the force of said biasing means and to a disengaged position with respect to said stationary contacts; an aperture in said movable contact and a fluid conduit means extending through said aperture and being terminated in a depression in said pushrod in a position substantially aligned with the area created between said movable and stationary contacts when said movable contact is moved to said disengaged position; said pushrod having a fluted head engaging sa d side of said movable contact to mechanically engage said movable contact in a non-airtight manner to thereby define said fluid flow path to said area.

6. A contact device comprising a relatively stationary contact and a cooperating movable contact movable between a contact engaged position and contact disengaged position with respect to said relatively stationary contact; a pushrod means operatively connectable to said movable contact for moving said movable contact to at least one said contact engaged or contact disengaged positions; an aperture in said movable contact and a fluid conduit means extending through said aperture and having an open end terminated in a depression in the end of said pushrod operatively connected to said movable contact; said pushrod means having a fluid passage therein for directing fluid received by said depression in said pushrod end from said fluid conduit means to the area created between said movable and stationary contacts when said movable contact is moved to said contact disengaged position.

7. A contact device comprising a relatively stationary contact and a cooperating movable contact movable between a contact engaged position and contact disengaged position with respect to said relatively stationary contact; a pushrod means operatively connectable to said movable contact for moving said movable contact to at least one of said contact engaged or contact disengaged positions; an aperture in said movable contact and a fluid conduit means extending through said aperture and having an open end terminated in a depression in the end of said pushrod operatively connected to said movable contact; said pushrod means having a fluid passage therein for directing fluid received by said depression in said pushrod end from said fluid conduit means to the area created between said movable and stationary contacts when said movable contact is moved to said contact disengaged position; said pushrod end having a fluted head engaging the side of said movable contact engageable with said stationary contact to mechanically engage said movable contact in a non-airtight manner to thereby form said fluid passage; said fluid flow to said area cooling each of said stationary and movable contacts and dislodging foreign particles from said area.

References Cited in the file of this patent UNITED STATES PATENTS 1,612,318 Riley Dec. 28, 1926 2,039,838 Sandicoeur May 5, 1936 2,072,112 King Mar. 2, 1937 2,634,341 Rosen Apr. 7, 1953 2,741,735 Wasserrab Apr. 10, 1956 2,863,112 Kleinvogel Dec. 2, 1958 FOREIGN PATENTS 897,409 France May 22, 1944 615,727 Germany Apr. 19, 1956

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