Pressure switch and method of forming a diaphragm therein

Abstract

In a method of manufacturing a diaphragm with a contact, contact stocks each forming a movable contact on a stock formed out of a strip-shaped thin metal sheet material, or a rolled material are bonded at predetermined intervals to the stock by resistance welding, for example to form a diaphragm stock with a contact. Next, the stock of a diaphragm with a contact is subjected to continuous blanking with a predetermined diameter from each movable contact as center to produce a diaphragm with a contact.

Claims

1. A pressure switch, the pressure switch comprising: a housing to accommodate a connection terminal having a fixed contact therein, wherein the fixed contact includes a protruding portion, the fixed contact disposed in a recess on a first side of the housing and the connection terminal disposed in a cavity on a second side of the housing; a pressure-receiving chamber communicating with a duct to which an actuating pressure is supplied; and a diaphragm with a contact formed from a contact stock bonded to a diaphragm stock that is blanked to form the diaphragm with the contact, wherein the diaphragm is disposed as a partition between the pressure-receiving chamber and the recess in which the fixed contact is accommodated, wherein the diaphragm with the contact is configured to be displaced in response to a pressure inside the pressure-receiving chamber, wherein the contact stock forms a movable contact to be bonded to the diaphragm, the movable contact that comes into contact with the fixed contact when the pressure inside the pressure-receiving chamber is equal to or above a predetermined value, and the movable contact has electrical continuity with the diaphragm, wherein the movable contact protrudes from a surface of the diaphragm, wherein the movable contact includes an elevated portion and a recessed portion, wherein the elevated portion of the moveable contact is shaped and positioned to contact the protruding portion of the fixed contact at multiple non-contiguous positions and a contact face of the elevated portion of the movable contact is formed as a concave arc-shaped surface or a convex arc-shaped surface.

2. The pressure switch including a diaphragm with a contact according to claim 1, wherein a contact face of the movable contact of the diaphragm is formed into an annular shape, and a contact face of the fixed contact is formed substantially into a cross shape.

3. The pressure switch including a diaphragm with a contact according to claim 1, wherein a contact face of the movable contact of the diaphragm is formed into an annular shape, and a contact face of the fixed contact is formed substantially into a Y-shape.

4. The pressure switch including a diaphragm with a contact according to claim 1, wherein a contact face of the movable contact of the diaphragm is formed substantially into a cross shape, and a contact face of the fixed contact is formed into an annular shape.

5. The pressure switch including a diaphragm with a contact according to claim 1, wherein a contact face of the movable contact of the diaphragm is formed substantially into a Y-shape, and a contact face of the fixed contact is formed into an annular shape.

6. The pressure switch according to claim 1, wherein the contact stock is made of an alloy containing any one of tin, indium, zinc, and nickel.

7. A pressure switch including a diaphragm with a contact, the pressure switch comprising: a housing to accommodate a connection terminal having a fixed contact therein, wherein the fixed contact includes a protruding portion, the fixed contact disposed in a recess on a first side of the housing and the connection terminal disposed in a cavity on a second side of the housing; a pressure-receiving chamber communicating with a duct to which an actuating pressure is supplied; and a diaphragm with a contact formed from a diaphragm stock that is blanked, wherein the blanked diaphragm stock is bonded to a contact stock to form the diaphragm with the contact, wherein the diaphragm is disposed as a partition between the pressure-receiving chamber and the recess in which the fixed contact is accommodated, wherein the diaphragm with the contact is configured to be displaced in response to a pressure inside the pressure-receiving chamber, wherein the contact stock forms a movable contact to be bonded to the diaphragm, the movable contact that comes into contact with the fixed contact when the pressure inside the pressure-receiving chamber is equal to or above a predetermined value, and the movable contact has electrical continuity with the diaphragm, wherein the movable contact protrudes from a surface of the diaphragm, wherein the movable contact includes an elevated portion and a recessed portion, wherein the elevated portion of the moveable contact is shaped and positioned to contact the protruding portion of the fixed contact at multiple non-contiguous positions and a contact face of the elevated portion of the movable contact is formed as a concave arc-shaped surface or a convex arc-shaped surface.

8. The pressure switch including a diaphragm with a contact according to claim 7, wherein a contact face of the movable contact of the diaphragm is formed into an annular shape, and a contact face of the fixed contact is formed substantially into a cross shape.

9. The pressure switch including a diaphragm with a contact according to claim 7, wherein a contact face of the movable contact of the diaphragm is formed into an annular shape, and a contact face of the fixed contact is formed substantially into a Y-shape.

10. The pressure switch including a diaphragm with a contact according to claim 7, wherein a contact face of the movable contact of the diaphragm is formed substantially into a cross shape, and a contact face of the fixed contact is formed into an annular shape.

11. The pressure switch including a diaphragm with a contact according to claim 7, wherein a contact face of the movable contact of the diaphragm is formed substantially into a Y-shape, and a contact face of the fixed contact is formed into an annular shape.

12. The pressure switch according to claim 7, wherein the contact stock is made of an alloy containing any one of tin, indium, zinc, and nickel.

13. A method of manufacturing a diaphragm with a contact for being used in a pressure switch, the method comprising: bonding a contact stock to a stock made of a thin metal sheet material to form a stock of the diaphragm with the contact for being used in a pressure switch that includes a fixed contact that includes a protruding portion, the contact stock forming a movable contact to be bonded to the diaphragm and having durability and providing electrical continuity with the diaphragm, wherein the movable contact protrudes from a surface of the thin metal sheet material; blanking the stock of the diaphragm with the contact for being used in a pressure switch to form the diaphragm with the contact for being used in a pressure switch, wherein the movable contact includes an elevated portion and a recessed portion, and wherein the elevated portion of the movable contact is shaped to contact the protruding portion of the fixed contact at multiple non-contiguous positions by an action of a fluid pressure and a contact face of the elevated portion of the movable contact is formed as a concave arc-shaped surface or a convex arc-shaped surface.

14. The method of manufacturing a diaphragm with a contact according to claim 13, wherein the contact stock is made of an alloy containing any one of tin, indium, zinc, and nickel.

15. A method of manufacturing a diaphragm with a contact for being used in a pressure switch, the method comprising: blanking a stock made of a thin metal sheet material into a diaphragm stock whose shape corresponds to the diaphragm; bonding a contact stock to the diaphragm stock to form the diaphragm with the contact for being used in a pressure switch, wherein the pressure switch includes a fixed contact that includes a protruding portion, the contact stock forming a movable contact to be bonded to the diaphragm and having durability and providing electrical continuity with the diaphragm, wherein the movable contact protrudes from a surface of the diaphragm stock, wherein the movable contact includes an elevated portion and a recessed portion, and wherein the elevated portion of the movable contact is shaped to contact the protruding portion of the fixed contact at multiple non-contiguous positions by an action of a fluid pressure and a contact face of the elevated portion of the movable contact is formed as a concave arc-shaped surface or a convex arc-shaped surface.

16. The method of manufacturing a diaphragm with a contact according to claim 15, wherein the contact stock is made of an alloy containing any one of tin, indium, zinc, and nickel.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a partial cross-sectional view which shows enlarged part of a configuration of an example of a pressure switch including a diaphragm with a contact according to the present invention;

(2) FIG. 2 is a cross-sectional view showing the configuration of the example of the pressure switch including the diaphragm with a contact according to the present invention;

(3) FIG. 3A is a perspective view showing a structure of the fixed contact shown in FIG. 1;

(4) FIG. 3B is a perspective view showing variations of the fixed contact shown in FIG. 3A;

(5) FIG. 4 is a cross-sectional view showing a structure of the fixed contact shown in FIG. 1;

(6) FIG. 5 is a cross-sectional view made available for explaining an operation in the example shown in FIG. 2;

(7) FIG. 6 is a perspective view including a cutaway view of a fixed contact and a diaphragm illustrated in FIG. 1;

(8) FIG. 7 is a diagram showing a relative position of the fixed contact to a movable contact of the diaphragm;

(9) FIG. 8A is a perspective view showing external appearance of another example of the fixed contact used in the example shown in FIG. 1;

(10) FIG. 8B is a perspective view showing variations of the fixed contact shown in FIG. 8A;

(11) FIG. 9 is a perspective view showing external appearance of still another example of the fixed contact used in the example shown in FIG. 1;

(12) FIG. 10 is a perspective view showing another example of the diaphragm used in the example shown in FIG. 1;

(13) FIG. 11 is a perspective view showing another example of the diaphragm used in the example shown in FIG. 1;

(14) FIG. 12A and FIG. 12B are partial cross-sectional views made available for explaining an example of a method of manufacturing a diaphragm with a contact according to the present invention;

(15) FIG. 13A is a plan view made available for explaining the example of the method of manufacturing a diaphragm with a contact according to the present invention;

(16) FIG. 13B is a front view corresponding to FIG. 13A; and

(17) FIG. 14A and FIG. 14B are views made available for explaining the example of the method of manufacturing a diaphragm with a contact according to the present invention.

DESCRIPTION OF THE EMBODIMENTS

(18) FIG. 2 shows substantial part of an example of a pressure switch including a diaphragm with a contact, which is manufactured by a method of manufacturing a diaphragm with a contact according to the present invention.

(19) The pressure switch is attached, for example, to a not-illustrated hydraulic device or piping to supply air, a coolant, water, or the like via a connection joint 28.

(20) As shown in FIG. 2, the pressure switch is a normally-open switch. The pressure switch comprises, as its main constituents: a diaphragm assembly 20 joined to an end of the connection joint 28; a casing 10 connected to the connection joint 28 and incorporating a connection terminal 12 to be described later; and a fixed contact 13 of the connection terminal 12 provided inside the casing 10 and made capable of coming into contact with and being separated from a movable contact 20br of a diaphragm 20B to be described later in response to a displacement of the diaphragm 20B.

(21) The casing 10 as a housing is formed by using a resin material, for example, and is provided with a recess 10A located on inside of the casing 10 and designed to accommodate the fixed contact 13 of the connection terminal 12. An external connection part of the connection terminal 12 passes through a hole in the casing 10 and projects into a cavity which is formed on the outside. The external connection part of the connection terminal 12 is connected to a not-illustrated pressure detection circuit. Accordingly, when the movable contact 20br of the diaphragm 20B comes into contact with the fixed contact 13 as shown in FIG. 5 in response to inversion of the diaphragm 20B, a predetermined current is fed to the connection joint 28 via the diaphragm 20B, with the result that, the pressure detection circuit detects that a pressure inside a pressure-receiving chamber to be described later reaches a predetermined pressure.

(22) The diaphragm assembly 20 is disposed in such a way as to serve as a partition between a pressure-receiving chamber 28CH communicating with a flow passage 28a of the connection joint 28 and an open end portion of the casing 10. The diaphragm assembly 20 comprises, as its main constituents: an upper plate 20A in contact with a peripheral edge of the open end portion of the casing 10 and with an O-ring 18; a lower plate 20C in contact with a peripheral edge of the pressure-receiving chamber 28CH of the connection joint 28 and with an O-ring 25; and the diaphragm 20B sandwiched between the upper plate 20A and the lower plate 20C opposed to each other.

(23) The upper plate 20A is formed into an annular shape with a metal material, for example, and by press forming, cutting, die casting, forging, or the like.

(24) The lower plate 20C is formed into an annular shape with a metal material, for example, and by press forming, cutting, die casting, forging, or the like. An annular groove into which the O-ring 25 is inserted is formed in the connection joint 28 at a peripheral edge of a hole of the lower plate 20C concentrically with the peripheral edge of the pressure-receiving chamber 28CH of the connection joint 28. The pressure-receiving chamber 28CH communicating with the flow passage 28a of the connection joint 28 is formed from a surface of the diaphragm 20B, an inner peripheral portion of the lower plate 20C, and an inner peripheral portion of the connection joint 28. On this occasion, an outer peripheral edge of the diaphragm 20B is sandwiched between the upper plate 20A and the lower plate 20C.

(25) The diaphragm assembly 20 is produced by integrating the upper plate 20A and the lower plate 20C together while sandwiching the diaphragm 20B in between, by welding and thus bonding outer peripheral edges thereof. As a consequence, welded portions are formed on outer peripheral portions of the upper plate 20A and the lower plate 20C.

(26) The diaphragm 20B is formed from a thin metal sheet material such as a stainless steel plate, which has corrosion resistance to the fluid supplied through the flow passage 28a in the connection joint 28, for example.

(27) As shown enlarged in FIG. 6, the diaphragm 20B comprises: a flange portion 20bf to be sandwiched between the upper plate 20A and the lower plate 20C; and a movable portion 20bm which is invertible, i.e., elastically deformable. The movable contact 20br having an annular contact face is bonded by resistance welding to be described later to a peak on a surface of the movable portion 20bm having a predetermined curvature radius and being opposed to the fixed contact 13. The movable contact 20br bulges upward by a predetermined height from the surface of the movable portion 20bm so as to come into contact with a cross-shaped contact face 13bt of the fixed contact 13 as shown partially enlarged in FIG. 1 and FIG. 7 when the diaphragm 20B is inverted.

(28) In the above-described example, the diaphragm assembly 20 includes the upper plate 20A, the lower plate 20C, and the diaphragm 20B. However, the present invention is not limited to this example. For instance, the diaphragm assembly may be formed from the upper plate 20A and the diaphragm 20B, or formed from the lower plate 20C and the diaphragm 20B. Alternatively, instead of providing the diaphragm assembly 20, only the diaphragm 20B may be sandwiched between the casing 10 and the connection joint 28 directly through the O-rings.

(29) As shown enlarged in FIG. 3A, the fixed contact 13 is made of copper-based metal or iron-based metal, for example, and includes a columnar portion 13A to be joined to a lower end of the connection terminal 12, and a contact portion 13B of a truncated cone shape integrally formed at a lower end of the columnar portion 13A. As shown in FIG. 4, a coating layer 13bs of a noble metal such as gold and silver having a predetermined film thickness is formed on a surface of the contact portion 13B.

(30) As shown enlarged in FIG. 3A, an end surface of the contact portion 13B includes the substantially cross-shaped contact face 13bt formed from portions radially diverging at intervals of 90. Cavities 13bd are formed at four positions around the contact face 13bt which is a flat end surface of the contact portion 13B.

(31) Thus, when the diaphragm 20B is inverted, the cross-shaped contact face 13bt of the fixed contact 13 comes into contact with the annular movable contact 20br at four positions as shown enlarged in FIG. 1. Accordingly, since the contact face 13bt comes into contact with the annular movable contact 20br at the four positions, it is possible to achieve reliable electrical connection between the diaphragm 20B and the fixed contact 13 in case a foreign substance is caught between the peak of the inverted diaphragm and part of the fixed contact 13. In addition, the cross-shaped contact face 13bt comes into contact with the annular movable contact 20br at the four positions with equal pressures as shown in FIG. 7. As a consequence, an impact at the time of the inversion of the diaphragm 20B is dispersed, and durability of the annular movable contact 20br of the diaphragm 20B is improved.

(32) Note that the contact face 13bt at the end surface of the contact portion 13B described above is not limited to this example. For instance, as shown in FIG. 3B, a contact face 14bt formed from a convex arc-shaped surface having a predetermined curvature radius may be provided instead.

(33) In FIG. 3B, a fixed contact 14 having the contact face 14bt is made of copper-based metal or iron-based metal, for example, and includes a columnar portion 14A to be joined to the lower end of the connection terminal 12, and a contact portion 14B of a truncated cone shape integrally formed at a lower end of the columnar portion 14A. A coating layer of a noble metal such as gold and silver having a predetermined film thickness is formed on a surface of the contact portion 14B. As shown enlarged in FIG. 3B, an end surface of the contact portion 14B includes a substantially cross-shaped contact face 14bt formed from portions radially diverging at intervals of 90. Cavities 14bd are formed at four positions around the contact face 14bt, which is the convex arc-shaped surface of the contact portion 14B.

(34) In the above-described configuration, when a pressure inside the pressure-receiving chamber 28CH is below a predetermined value, as shown in FIG. 2, the movable contact 20br of the diaphragm 20B is located away from the cross-shaped contact face 13bt of the fixed contact 13. Accordingly, the above-mentioned pressure detection circuit detects that the pressure inside the pressure-receiving chamber 28CH is below the predetermined value since a given current is not fed to the connection joint 28 via the diaphragm 20B. On the other hand, when the pressure inside the pressure-receiving chamber 28CH is equal to or above the predetermined value, the movable contact 20br of the diaphragm 20B comes into contact with the cross-shaped contact face 13bt of the fixed contact 13. Accordingly, the above-mentioned pressure detection circuit detects that the pressure inside the pressure-receiving chamber 28CH is equal to or above the predetermined value since the given current is fed to the connection joint 28 via the diaphragm 20B.

(35) In the above-described example, the end surface of the contact portion 13B of the fixed contact 13 has the cross-shaped contact face 13bt. However, the fixed contact is not limited to this example. For instance, as shown enlarged in FIG. 8A, an end surface 23B of a fixed contact 23 may have a substantially Y-shaped contact face 23bt.

(36) The fixed contact 23 having the contact face 23bt is made of copper-based metal or iron-based metal, for example, and includes a columnar portion 23A to be joined to the lower end of the connection terminal 12, and a contact portion 23B of a truncated cone shape integrally formed at a lower end of the columnar portion 23A.

(37) The substantially Y-shaped contact face 23bt is formed from portions radially diverging at intervals of 120, for example. Cavities 23bd are formed at three positions around the contact face 23bt which is a flat end surface of the contact portion 23B.

(38) In this case, when the diaphragm 20B is inverted, the Y-shaped contact face 23bt of the fixed contact 23 comes into contact with the annular contact 20br at three positions.

(39) Note that the contact face 23bt at the end surface of the contact portion 23B is not limited to this example. For instance, as shown enlarged in FIG. 8B, a contact face 24bt formed from a convex arc-shaped surface having a predetermined curvature radius may be provided instead.

(40) A fixed contact 24 having the contact face 24bt is made of copper-based metal or iron-based metal, for example, and includes a columnar portion 24A to be joined to the lower end of the connection terminal 12, and a contact portion 24B of a truncated cone shape integrally formed at a lower end of the columnar portion 24A.

(41) The substantially Y-shaped contact face 24bt is formed from portions radially diverging at intervals of 120, for example. Cavities 24bd are formed at three positions around the contact face 24bt which is the convex arc-shaped surface of the contact portion 24B.

(42) In this case, when the diaphragm 20B is inverted, the Y-shaped contact face 24bt of the fixed contact 24 comes into contact with the annular movable contact 20br at three positions.

(43) Furthermore, the fixed contact is not limited to the examples shown in FIG. 3A, 3B and FIG. 8A, 8B. For instance, as shown enlarged in FIG. 9, a fixed contact 34 may be made of copper-based metal or iron-based metal, for example, and may include a columnar portion 34A to be joined to the lower end of the connection terminal 12, and a contact portion 34B of a truncated cone shape integrally formed at a lower end of the columnar portion 34A. A cavity 34bc is formed at a central part of an annular (donut-like) contact face 34bt at a flat end surface of the contact portion 34B. On this occasion, the contact face 34bt at the end surface of the contact portion 34B is not limited to this example. For instance, the contact face 34bt may be formed from a convex arc-shaped surface having a predetermined curvature radius.

(44) In this case, as shown enlarged in FIG. 10, a diaphragm 30B to be combined with the fixed contact 34 is formed from a flange portion 30bf to be sandwiched between the upper plate 20A and the lower plate 20C, and a movable portion 30bm which is invertible, i.e., elastically deformable. A cross-shaped movable contact 30bc is bonded by resistance welding at a peak on a surface of the movable portion 30bm, which is formed to project toward the lower plate 20C, has a predetermined curvature radius, and is opposed to the fixed contact 34. The movable contact 30bc bulges by a predetermined height from the surface of the movable portion 30bm so as to come into contact with the annular contact face 34bt of the fixed contact 34 when the diaphragm 30B is inverted. Note that the contact face of the movable contact 30bc is not limited to this example. For instance, the contact face may be formed as a concave arc-shaped surface having a predetermined curvature radius.

(45) In addition, a diaphragm 40B to be combined with the fixed contact 34 is not limited to the above-described example. For instance, as shown in FIG. 11, the diaphragm 40B is formed from a flange portion 40bf to be sandwiched between the upper plate 20A and the lower plate 20C, and a movable portion 40bm which is invertible, i.e., elastically deformable. A Y-shaped movable contact 40by is bonded by resistance welding at a peak on a surface of the movable portion 40bm, which is formed to project toward the lower plate 20C, has a predetermined curvature radius, and is opposed to the fixed contact 34. The movable contact 40by bulges by a predetermined height from the surface of the movable portion 40bm so as to come into contact with the annular contact face 34bt of the fixed contact 34 when the diaphragm 40B is inverted. Note that the contact face of the movable contact 40by is not limited to this example. For instance, the contact face may be formed as a concave arc-shaped surface having a predetermined curvature radius.

(46) The diaphragms 20B, 30B, and 40B described above are each manufactured in accordance with an example of a method of manufacturing a diaphragm with a contact of the present invention to be described below.

(47) In the case of manufacturing a diaphragm 56 with a contact (see FIG. 14B), contact stocks 50ai (i=1 to n, n is a positive integer) each forming a movable contact on a stock 52 formed out of a strip-shaped thin metal sheet material (a rolled material) shown in FIG. 12A are bonded at predetermined intervals as shown in FIG. 12B to the stock 52 by resistance welding, for example. Each contact stock 50ai has a shape corresponding to any one of the movable contact 20br shown in FIG. 6, the movable contact 30bc shown in FIG. 10, and the movable contact 40by shown in FIG. 11, for example. Each contact stock 50ai has a diameter in a range from 2.6 mm to 3.0 mm inclusive, for instance. The contact stocks 50ai may be formed from a noble metal such as gold or silver, which is excellent in abrasion resistance and electrical continuity. Or, the contact stocks 50ai may be formed from a clad material containing a noble metal such as gold or silver. The contact stock may be formed from an alloy containing any one of tin (Sn), tin oxide, indium (In), indium oxide, zinc (Zn), zinc oxide, and nickel, for example, in order to improve abrasion resistance. Or, the contact stock may be formed from any one of silver alloys including, for example: an alloy of silver and zinc; an alloy of silver, tin, and indium; and an alloy of silver and nickel. Thus, the movable contacts having an excellent ability of abrasion resistance and electrical continuity than those of the movable contacts subjected to plating are obtained as a consequence.

(48) Accordingly, as shown in FIGS. 13A and 13B, a plurality of movable contacts 50ai (I=1 to n, n is the positive integer) are formed in a line at predetermined intervals on the stock 52. The stock 52 has a width slightly larger than the diameter of each diaphragm 56, and a predetermined length sufficient to produce a plurality of diaphragms 56 therefrom. The stock 52 may be either a single plate material having the predetermined length or a continuous plate material such as a rerolled material, which is rolled and has the predetermined length. As a consequence, a stock 54 of a diaphragm with a contact is formed from the plurality of movable contacts 50ai and the stock 52 as shown in FIGS. 13A and 13B.

(49) Next, as shown in FIG. 14A, the stock 54 of a diaphragm with a contact is placed on a given press machine (not illustrated), and is then subjected to continuous blanking with a predetermined diameter from each of the movable contacts 50ai as center as indicated with dashed lines in FIG. 14A. Thus, the diaphragm 56 with a contact is produced as shown in FIG. 14B.

(50) Accordingly, characteristics of the movable contact 50ai of the diaphragm 56 with a contact including its abrasion resistance and continuity reliability are improved as compared to those of the diaphragm with a contact which is subjected to plating.

(51) In the above-described example, the diaphragm 56 with a contact is produced by forming the stock 54 of a diaphragm with a contact and then blanking the stock 54 of a diaphragm with a contact by using the press machine. However, the diaphragm 56 with a contact does not always have to be manufactured as described above. For example, the stock 52 may be first formed into a circular piece by blanking and then the contact stock 50ai may be bonded by resistance welding to the circular stock produced by blanking. On this occasion, the contact stock 50ai may be bonded to the stock 52 not by resistance welding but by other bonding methods including brazing, diffusion bonding, and the like.

(52) The example of the pressure switch according to the present invention is applied to the normally-open switch. However, the present invention is not limited to this example and may naturally be applied to a normally-closed switch, for instance. Moreover, the diaphragm with the contact manufactured by an example of a method of manufacturing a diaphragm with a contact according to the present invention is applied to the pressure switch to be connected to the piping via the connection joint 28. However, the present invention is not limited to this example. For instance, the present invention may also be applied to a pressure switch disclosed in Japanese Patent Laid-Open No. H 02-220320 (1990) or Japanese Patent No. 3,031,679.

(53) While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.