DE2504146A1 - ELECTRIC SWITCH - Google Patents

Description

The invention relates to electrical switches and, more particularly, to a snap or push button switch with a blade contact mechanism with a pulling and a pushing element.

A whole range of pushbutton switches are available in stores « Such switches generally have a blade contact spring, which by a push button from a first position in a second position is moved. Part of the blade contact spring acts as a tension element and causes the spring to snap over via a middle position, while a pressure element pushes the knife

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The contact spring can snap back into its original position when the actuating force decreases.

Some switches of this type use a two- or three-piece blade contact spring. The when using Problems occurring with a blade contact spring consisting of several parts are, for example, manufacturing tolerances of the individual parts as well as the costs of manufacturing and assembling the individual parts. Also exhibit a number of these Blade contact springs have a small C-shaped compression spring, the exact manufacture of which poses problems and which are difficult to install is. It is also the use of a standard knife contact spring known, but which has a short service life and tolerance problems on throws. *

Many knife contact springs suffer fatigue fractures just below the area actuated by the push button. this is a common breaking point, as the maximum bending stress in the blade contact spring when it is pulled is directly below the Load point, i.e. the point actuated by the push button, whereby fatigue fractures occur under tensile load. A fatigue break begins as a crack on a surface under tension, with continued loading of the blade contact spring eventually leads to breakage as the crack progresses. Furthermore, the tensile forces exerted by the compression spring affect the blade contact spring an initial pull so that the pulling forces exerted by the push button increase the stress on the blade contact spring, which leads to fatigue failure.

Another reason for the short mechanical life of small switches is the manufacture of parts with Tolerances, which lead to a very strong compression of the spring element and thus to a large train. Is for example the optimal compression of the spring element approximately

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0.254 mm (0.01 inch), the tolerance of the construction of the Blade contact spring, the C-shaped compression spring and the yoke-like carrier approximately 0.5 mm (0.02 inch). This can lead to irregular forces, inoperative switches, or the need to set the switches individually.

The problems with prior art switches are particular serious if the blade contact spring is to work with a very small stroke, for example in the order of magnitude 0.025 mm (0.001 inch). For military requirements, a maximum motion differential of 0.038 mm (0.0015 inch) or 0.127 mm (0.005 inch) required depending on the respective switch, furthermore a feed maximum of 0.05 mm (0.02 inch), a minimum stroke excess of 0.1 mm (0.004 inch) and one Differential force from 28p - 56p (1 to 2 ounces). The requirements for the maximum movement differential and the differential force are difficult to meet for a number of switch manufacturers, and it is true that switches with the required minimum Overstroke are available, but a much larger overstroke is very desirable.

Most switches that meet military requirements, however, will encounter one or more of the following Problems on:

1) The switch has too many parts, some of them are complicated and expensive to manufacture.

2) The number of parts and their small size cause assembly difficulties.

3) Due to fatigue fracture, the switch has a relative short lifespan.

4) The total stroke of the switch is too small,

5) The differential of the switch is too high.

According to the invention, an electrical switch with a minimum

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Number of parts using a standard blade contact spring suggested. The blade contact spring has a pulling element with a pulled-down middle part and a pressure element, which biases the blade contact spring in a first position and a bias on the pulled down part of the tension element exercises. The push button engages with the pulled-down part and moves the blade contact spring to a second position, in which the bias in the pulled down part is subtracted from the pressure exerted by the push button, so that the remaining The tension within the blade contact spring remains relatively low and the probability of a fatigue breakage thus remains is reduced. In a preferred embodiment, the blade contact spring has a pair of legs that are separate from one another and a center tongue. Each of the legs has an S-shaped central part, which makes the blade contact spring very flexible and any manufacturing tolerances of the other parts can be easily compensated for when the blade contact spring is installed. Of the middle tongue part of the blade contact spring acts as a pressure element and exerts a bias on the downward or downward pulled down parts of the S-shaped legs.

The longer stretch of the legs around the double bend creates more material along the length of the blade contact spring, so that the bending stress is distributed to a greater extent, while the S-shape of the legs helps maintain the line of tension of the Keep blade contact spring in the plane of the spring, and the necessary Space to create the other elements inside the counter. The greater flexibility of the blade contact spring is permitted also a relatively large stroke overrun. The switch can be made very sensitive, if necessary, and it Movement differentials of up to 0.0127 mm (0.0005 inch) can be achieved. The switch has only five parts within the switch housing on, of which only two are movable, namely the blade contact spring and the push button. The other three parts are fixed contacts. Accordingly, manufacturing tolerances

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and reduced parts and assembly costs.

An embodiment of a switch according to the invention will be explained in more detail below with reference to the drawings.
The drawings show in

1 shows a section through a switch according to the invention;

FIG. 2 shows a partial section, similar to FIG. 1, through the blade contact spring, to illustrate the switch in the actuating position; FIG.

3 shows an enlarged perspective illustration of the blade contact spring; .

4 is a side view of the blade contact spring without the contact;

Figure 5 is an end view of the blade contact spring along the line 5-5 of Figure 4;

6 shows a plan view of the blade contact spring according to FIG. 4;
Fig. 7 is a plan view of the common contact;

Fig. 8 is a side view of the common contact along the Line 8-8 of Figure 7;

Fig. 9 is a side view of the push button;

Fig. 10 is a plan view of the push button;

11 is a side view of the blade contact spring for illustration

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the tongue of the compression spring on the blade contact spring applied preload;

11A shows an enlarged partial section of the pulled-down part of the blade contact spring to illustrate the forces according to FIG Fig. 11;

FIG. 12 shows a view corresponding to FIG. 11 to show the limit prevailing in the blade contact spring when the push button presses on the blade contact spring; and in

FIG. 12A shows a view similar to FIG. 12 to illustrate the forces according to FIG. 12.

The electrical switch 15 shown in Fig. 1 has a housing 16 with three connection contacts 17, 18 and 19. The switch shown complies with military requirements and can be made in various designs and sizes will. The switch housing 16 has a base 20 with a pair of openings 21 and 22 and one attached to the base Cover 23 open. The three connection contacts 17, 18 and 19 extend through the base 20 into the space between the base 20 and the Lid 23, each contact having a radially enlarged, corrugated part 24 in frictional engagement with an opening having in the base.

A generally U-shaped bracket or common contact 26 is attached to the connection cone 17 and has a base part 27 and a pair of upstanding legs 28 and 29 with a V-shaped groove 30 and 31 are provided. With the connection contact 18 is an approximately Z-shaped, normally open contact 33 connected, a straight fastening part 34 and a straight Has contact part 35. At the connection contact 19 is a generally

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connected to my U-shaped, normally closed contact 36, which has a straight connecting part 37, an upstanding one Intermediate part 38 and a straight contact part 39, which above the contact part 35 with the normally open Contact 33 runs. All three contacts 26, 33 and 36 exist made of suitable, electrically conductive material, such as silver-coated Brass, with all three contacts attached to the top of the base 20 by riveting the top end 40 of the corresponding Connection contacts 17, 18 and 19 are attached.

An elongated, electrically conductive blade contact spring 42 made of flexible, elastic spring material is held movably by the common contact 26 within the switch volume. As 3, the blade contact spring 42 has a pair of flat end portions 43 and 44, a pair of separated ones Legs 45 and 46 and a tongue or middle part 47, which extends from the end part 44 between the two legs extends. The end parts of the two legs are flat and form an enlargement of the flat end parts 42 and 43, while the Intermediate portions of the two legs are generally S-shaped by a pulled down portion 48 which extends from the plane of the end portion 43 is curved downward, and by an upwardly curved part 49, which from the plane 'of the end part 44 is curved downwards. The bent part 49 generally has a smooth or domed curvature, while the drawn-down part 48 has a substantially flat central part 50, which runs parallel to the end parts 43 and 44 substantially.

The blade contact spring 42 is provided with a pair of circular relaxation openings 52 at the points where the lateral edges of the tongue 47 converge with the end portion 44 and the legs 45 and 46, both lateral edges of the Tongue 47 is generally tangential to the respective opening

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extend. The openings 52 prevent a concentration of pressure in the areas in which the tongue 47 and the legs 45 and 46 would otherwise meet. In the illustrated embodiment, the openings 52 are 0.635 mm (0.025 in.) In diameter inch), which are significantly larger than corresponding openings in comparable switches, which usually only have an opening diameter of 0.127 mm (0.005 inch). The end part '44 however, despite the relatively large openings 52, it has sufficient strength by a pair of side flanges 53 extending downwardly from the side edges of end portion 44. The flanges 53 also reinforce the end portion 44 in the area around the generally rectangular opening 54 (see FIG. 6), in which an electrically conductive contact 55 is attached. The existing in the form of the flanges 53 material is also used Heat dissipation from the contact.

The blade contact spring 42 is actuated by a push button 56, which is slidably held in a cylindrical collar 57 in the cover 23 of the switch housing 16. According to Figs. 1, 9 and 10 has the push button 56 has a generally cylindrical finger 58 with a round head 59 and an elongated actuating member which extends downward from the cylindrical finger 58 and shoulders 61 and 62 carries. The cylindrical finger 58 is in a correspondingly shaped cylindrical part of the collar 57 of the cover 23 displaceable, with an upward movement of the push button 56 beyond the position shown in FIG the engagement of the shoulders 61 and 62 with the top of the lid 23 is prevented. The lower part of the cylindrical collar 57 is slotted to conform to the laterally outwardly extending actuation portion 60 of the push button 56, where "the engagement of the diaphragm walls with the. Actuating part 60 prevents rotation of the push button 56 relative to the other parts of the switch.

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Through the collar 57, the push button 56 is above the pulled down Part 48 of the legs of the blade contact spring arranged, wherein the actuating part 60 is a pair of spaced apart, V-shaped parts 63 and 64 on v / eist, those with the drawn down Parts of the legs 45 and 46 come into engagement. A centering part 65 extends downward between parts 63 and 64 into the slot between the two separate legs. 45 and 46 of the blade contact spring 42 in order to center the push button 56 with respect to the blade contact spring 42.

The switch is installed by fitting the connection contacts 18 and 19 into the base 20 of the switch housing 16, fitting of contacts 26, 33 and 36 over the upper ends of the corresponding Connection contacts and by riveting the upper ends 40 of the connection contacts 17, 18 and 19 for fastening the contacts. To facilitate the connection of the common contact 26 with the connection contact 17 its upstanding leg 28 can run parallel to the axis of the connection contact 17, until the upper end 40 of the connection contact 17 is riveted around (see. Fig. 7). The leg 28 can then in the direction of the other leg 29 are bent, i.e. into the position according to FIGS. 1 and 2.

The blade contact spring 42 is then placed on the common contact 26 by fitting the tongue 47 into the groove 31 of the leg 29 and the inner edge 67 of the end part is fixed in the groove 30 of the other leg of the common contact 26, the grooves 30 and 31 serve as stops for tensioning the knife contact spring 42.

Subsequently, the cover 23 can with the push button 56 over the ■.

Base 20 are arranged and attached to this. .

The non-actuated position of the switch is shown in FIG. Acting as a pressure element tongue 47 of the tactile or Snap switch 15 presses the open from the blade contact spring

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engaged contact 55 upwardly into firm electrical engagement with contact portion 39 of normally closed contact 36. The push button 56 is in engagement with the middle part of the two pulled down parts 48 of the blade contact spring 42 and is under the action of the blade contact spring in a position (see. Fig. 1) in which his shoulders 61 and 62 with the Top of the lid 23 are engaged. The blade contact spring 42 is advantageous over the common contact 26 arranged so that the tongue 47 is substantially extended when the switch is in the position of FIG. 1, however the tongue 47 can be bent down slightly to ensure that the tongue moves when the switch is actuated bends in the right direction.

The length of the blade contact spring 42 and the length of the tongue 47 is relative to the distance between the two grooves 30 and 31 in the two legs 28 and 29 of the common contact 26 so dimensioned that the tongue 47 exerts a train on the legs 45 and 46 of the blade contact spring 42, which the bent parts 48 and 49 of the legs 45 and 46 seeks to stretch or level. According to Figures 11 and 11A a tensile stress T1 is exerted by the tongue 47 on the stretched parts of the leg exerted, causing a tension T2 on the fibers in the upper half of the bent portion 48 and a compressive stress C1 the fibers in the lower half of the pulled-down part. Similar tensile and compressive stresses are in the upper part 49, which need not be discussed further.

The switch 15 is operated by depressing the push button 56. The push button 56 acts on the central part of the pulled down part 48 of the two legs 45 and 46 and moves the both spring legs down. During the movement of the blade contact spring 42 from the position according to FIG. 1, the spring legs are standing under tension and stretch somewhat while compressive stress is exerted on tongue 47. Reaches the blade contact spring

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a position that goes beyond the middle, the elastic leg the contact 55 in engagement with the contact part 35 of the normally open contact 33 snap (see. Fig. 2). In this position the pressure element is the tongue 47 bent and provides a restoring force to the blade contact spring 42 to push back into the position of FIG. 1 as soon as the acting on the push button 56 force decreases.

In Figs. 12 and 12A, that is when the push button is depressed 56 the load voltage exerted on the blade contact spring 42 is indicated by the arrow L; this load causes a pressure " tension C2 on the fibers in the upper part of the pulled down part 48 of the two legs and a tension T3 on the fibers in the lower area of the pulled down part 48. In the usual blade contact springs causes the tensile stress T3 caused by the push button after a certain number of Operations of the push button cause a fatigue fracture. In the proposed blade contact spring, however, this is in the Pre-tensioned area on which the push button 56 acts (cf. Fig. 11), so that the actual load within the blade contact spring 42 below the push button 56 during actuation is significantly lower. The one generated by prestressing Tensile stress T2 is subtracted from the compressive stress C2 generated during actuation, while that generated by preload Compressive stress C1 is subtracted from the tensile stress T3 generated during actuation. Although other switches also have blade contact springs have with bent parts, so far no switch is known in which the push button in "the way with the bent. Part of the blade contact spring comes into engagement that the fatigue fractures that occur during actuation and often lead to leading tensile stresses are reduced.

Although the illustrated blade contact spring 42 is a pair of curved Has parts, one part 48 below the plane of the straight end parts and the other part 49 above the plane

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of the straight end parts of the blade contact spring 42, good results can also be achieved with a blade contact spring a single bent portion in each leg corresponding to the pulled down portion 48. However, it turned out that the upwardly curved part 49 is advantageous in that the line of tension in the blade contact spring 'in general runs in the plane of the straight parts of the blade contact spring and desired space in the vicinity of the other parts within of housing 16, such as near leg 29 of common contact 26. The distance between the legs is sufficient, however, to arrange the leg 29 in the legs even without the raised part 49.

The double bend in the legs of the blade contact spring 42 also increases the excess travel of the switch, i.e. the Distance by which the push button 56 is displaceable when the contact 55 is engaged with the normally open contact 35 is brought. The elasticity created by the bends in the legs enables the push button 56 to be depressed further, than would be the case with straight legs of the blade contact spring. Furthermore, due to the increased overall length of the blade contact spring due to the bends in the legs, more material is present - see above that the bending load can be distributed to a greater extent.

The possibility of significantly exceeding the stroke is particularly important when the blade contact spring is used in an arrangement in which the spacing of the parts or their tolerances are different. The elasticity of the blade contact spring ensures greater reliability and operational safety and avoids further adjustments when a large number of installations he follows. If necessary, the blade contact spring can also be designed to be very sensitive, so that movement differentials of up to 0.0127 mm (0.0005 inches) can be achieved.

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In a special embodiment of the switch there was Blade contact spring 42 made of a beryllium copper alloy with 0.0762 mm (0.003 inch) thick. The total length of the blade contact spring was 11.5 mm (0.453 inch) and the width of the spring between the outer edges of the separated legs 2.667 mm (0.105 inches), while the width of the two Legs each 0.635 mm (0.025 inch) and the distance between the legs were 1.397 mm (0.055 inches). The flat central portion 50 of the two pulled down portions 48 had one Length of 0.762 mm (0.03 inch) while the left end of the. flat portion 2.032 mm (0.08 inches) from the inner edge 67 of the end portion 43 was removed. The right end of the flat part 50 had a distance of 1.42 mm (0.056 inch) from the center of the raised Part 49. The bent parts 48 and 49 had the same vertical distance up and down from the end parts 43 and 44, this vertical distance between the bottom of the pulled down portion and the top of the raised portion were 1.9 mm (0.075 inches). The pressure relief openings 52 were 0.635 mm (0.025 inch) in diameter, which is approximately eight times the thickness of end portion 44, "during the reinforcement flanges 53 were 3.3 mm (0.130 inches) long and 0.62 mm (0.03 inches) wide. The diameter the openings 52 can be changed according to the thickness of the blade contact spring. The diameter of such openings has heretofore generally been limited to about three or four times the thickness of the blade contact spring, but the reinforcement flanges allow the one used herein Blade contact spring a considerable increase in the diameter of the openings compared to the thickness of the blade contact spring. These flanges 53 are particularly useful when the diameter of the openings 52 is more than five times the thickness of the blade contact spring is increased, the ratio of diameter to thickness being the dimensions of the end portions 44 and the flanges 53 accordingly to significantly more than eight times

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can be increased.

Although in the preferred embodiment, the pulling elements Pair of separate outer legs and the pressure elements have a central tongue, the blade contact spring also train so that the tension elements are arranged between a pair of pressure elements. In this case it shows Tensile element still has a pretensioned part below the push button, in which the actual stress is very slight during actuation.

Claims: - 15 -

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Claims (23)

Claims '' by a housing, by an elongated blade contact spring with a pair of ends, with a pulled-down part between the ends and with a contact part disposed in the housing, which is between a first and is movable to a second position, by means for biasing the contact part of the blade contact spring in the first position, a tensile stress on the blade contact spring to stretch the pulled-down part exercise, and by a movable in the housing, arranged actuating device that of the pulled-down part the blade contact spring added and with this in Can be brought into engagement and from a first position is movable into a second position in the direction of the pulled-down part of the blade contact spring, the Movement of the actuating device from the first position into the second position, a movement of the contact part forces the blade contact spring from its first position into the second position. 2. Switch according to claim 1, characterized in that g e k 'e η η ζ e i' net that a tongue part forms the pretensioning device, which is made in one piece with the blade contact spring. ' 3. Switch according to claim 1, characterized in that g e k e η η ζ e i c h net that the blade contact spring has a pair of end parts and a pair of spaced legs therebetween having the end parts, both legs being provided with the pulled-down part. · 4. Switch according to claim 3, characterized in that g e k e η η ζ e i c h net that the one-piece with the blade contact spring is made - 16 509832/0327 "., Λ put tongue forming the pretensioning device, which is extends from one of the end portions between the two legs. 5. Switch according to claim 4, characterized in that that the tongue is substantially flat in the first position of the contact part, and that the movement of the Contact part in the second position, the tongue bends. 6. Switch according to claim 1, characterized in-r net that the pulled down part is below the connecting line the two ends of the blade contact spring extends and that the blade contact spring has a curved part between has its ends, which extends above the connecting line between the two ends of the blade contact spring. 7. Switch according to claim 1, characterized in that that the blade contact spring has a pair of end portions and a pair of separate legs, respectively has a pulled-down part between the end parts that one is made in one piece with the blade contact spring Tongue forms the biasing device extending from one of the end portions between the legs and a pair of lateral edges that the blade contact spring at the connection points between the two lateral ones Edges of the tongue and one end part each have an opening on τ has, and that one end part with a pair of lateral Flanges are provided which extend generally at right angles to the plane of the one end portion. 8. Switch according to claim 1, characterized in that that the blade contact spring has a pair of substantially planar end portions and a pair of separated from one another. th legs between the two end parts, one end part forming the contact part, and that the two legs generally have an S-shape that of a - 17 -509832/0327 first part bent down from one of the end parts and formed by a second part bent upwards from the other end part, the first bent part in each case Part of the two legs forms the pulled-down part of the blade contact spring. 9. Switch according to claim 8, characterized in that the integral with the blade contact spring produced Tongue forms the pretensioning device which extends from one end part between the two legs. 10. Electrical push button, marked by a housing with a common contact, with a normally closed contact and with a normally open contact, through one located in the housing and movable blade contact springs engaged with the common contact and comprising a pair of substantially flat end parts, a pair of separate legs arranged between the end parts, each with one extending below the planes of the end portions, pulled down portion and a tongue extending from one of the end portions extends between the legs, through first and second stop parts in the housing, which are connected to the tongue and one of the end parts, respectively are engaged and which put the pulled down parts in tension, while the other end part is in engagement with biased to the normally closed contact, and by a movable bearing arranged in the housing above the pulled-down parts of the legs of the blade contact spring actuating device that can be moved in the direction of the pulled down parts between the two end parts and with the pulled down parts can be brought into engagement and thereby the other end part with the normally closed Kon- " tact disengages and engages the normally open contact. . - 18 - V. 50 98 32/0327 11. Switch according to claim 10, characterized in that that the common contact has at least one of the stop parts. 12 .. switch according to claim 10, characterized in that that the common contact is generally U-shaped and has a pair of legs, one of which Leg of the common contact the first stop and the other leg of the common contact the second Stop forms. 13. Switch according to claim 10, characterized in that that both legs of the blade contact spring each have an upwardly curved part adjoining the pulled-down part Have part which is above the levels of the end parts substantially at the same distance as the pulled down Extend parts below the levels of the end parts. 14. Switch according to claim 10, characterized in that that the operating device has a pair of separate operating parts and one between the operating parts having downward centering part, wherein each actuating part with a pulled-down part of the two legs of the blade contact spring is in engagement and that Centering part extends downward between the legs. 15. Switch according to claim 10, characterized in that that both pulled down parts have a substantially straight central part which is generally parallel extends to the end parts. 16. Switch according to claim 10, characterized in that the tongue is substantially extended when the second end portion is engaged with the normally closed contact. - 19 509832/0327 250A146 17. Switch according to claim 10, characterized in that that the tongue has a pair of side edges and the knife contact spring one opening each at the connection points between the two side edges of the tongue and one end part, and that one end part with a pair of ropes see nf! is provided which are generally perpendicular to the plane of one end portion. 18. Switch according to claim 17 »characterized in that that each opening at the junctions between. The two side edges of the tongue and the end part have a diameter of at least 5 times the thickness of the blade contact spring having. 19. An electrically conductive blade contact spring for an electrical switch with a blade contact spring actuator, characterized by a pair of end portions, by extending between the end portions ^tensile: element and by from one of the end portions of outgoing pressure element, the tension member of an elastic, consists of flexible material and has a pulled-down part below the end parts of the knife contact spring, and further characterized in that the knife contact spring is arranged in the switch so that the pulled-down part is pretensioned by the pressure element and is arranged below the actuating device so that when actuated of the pulled-down part by the actuating device for moving the blade contact spring, the actual tension within the pulled-down part is reduced. 20. The device according to claim 19, characterized in that the blade contact spring je.eine opening in one end part at the connection points between the tension element and the pressure element, the diameter of which 509832/0327 -20- _Λ 2504Η6. is at least five times the thickness of the end part. 21. The device according to claim 20, characterized by a reinforcing flange extending from one end portion generally at right angles thereto. 22. The device according to claim 19, characterized in that the tension element consists of separate legs extending between the end parts, each with ^{a pulled-down part:} that a tongue made in one piece with the blade contact spring forms the pressure element that extends from the one end part between the Leg extends that the tongue has a pair of side edges and the blade contact spring each has an opening in one end part at the connection points between the two side edges of the tongue and the two legs, and that one end part is provided with a pair of side flanges, extending generally perpendicular to the plane of the one end portion. 23. The device according to claim 22, characterized in that the openings have a diameter have, which is at least 5 times the thickness of the end part. 50983 2/0327 Blank page