Excessive pressure signaller, method for forming membrane profile for excessive pressure signaller

FIELD: measuring technologies.

SUBSTANCE: device has body with hermetically mounted elastic membrane made with concentric corrugation, enveloping upper portion of piston, being a rigid center and interacting with adjustable force spring and electro-contact device. Body also has an insert with central aperture, wherein a piston is mounted with concentric space, an elastic membrane is provided with second corrugation, placed above support surface in insert, separating peripheral portion of membrane, hermetically connected to insert, from its central portion, moving with the piston. Insert is made with stepped central aperture, while stepped transition in aperture serves as support surface for piston bottom, and depth of portion of aperture, wherein a piston is mounted, is equal to piston height, while contacting surfaces of insert and piston and membrane are of matching profile. Also, device has piston-insert pairs with matching parameters, but different effective areas, and springs interacting with piston of different rigidity are made replaceable and interchangeable in terms of mounting dimensions. Also described is method for forming membrane profile for device.

EFFECT: higher precision.

2 cl, 3 dwg

The invention relates to measurement devices, namely, devices for measuring the threshold pressure, and is designed to prevent overloading.

Known pressure switch (see, for example, Deakin and other Sensors control and regulation”. Engineering, M., 1965, s.626, fig.V, 92), comprising a housing, a sensing element made in the form of a piston located with clearance in the bore of the housing, the elastic membrane, the sealing gap. The movement of the piston under pressure is transmitted to the rod, which moves in guides and overcoming the spring force, causes the actuation element, such as a microswitch.

Known pressure switch has sufficient sensitivity by introducing elastic membrane and the accuracy provided by the piston, the area of which is stable. But it is possible jamming of the rod guides, and the amount of force developed by the piston in its initial stage, is insufficient to overcome jamming and to ensure smooth movement of the rod. Intermittent moving of the rod reduces the accuracy of pressure measurement.

Known pressure switch (see, for example, patent No. 2106611, CL G 01 L 19/12, 96, containing sensitive element made in the form of a piston located with clearance in the bore of the housing, the elastic membrane is, made with a concentric corrugation in contact with the piston and hermetically connected at the periphery of the housing, a rod located coaxially with the piston and cooperating with the spring and the electric contact element on the piston and the housing bore is made concentric with each other facets, between which is located the corrugation of the membrane, and the membrane is installed with a clearance relative to the body.

This pressure is taken as the prototype.

In the prototype, the elastic membrane is located with a clearance from the body, and in the initial stage of pressure on the rod operates the force developed by the membrane, the area of which is greater than the base area of the piston. Due to the large force is overcome becoming jammed effect in the guides of the rod. The rod is aligned and there is a smooth movement, which leads to a smaller error response, i.e. increasing the accuracy of measurement.

To reduce the influence of the stiffness of the membrane on the value of the setpoint response of the indicator membrane prototype has previously formed corrugation located above the support surface in the gap between the piston and the housing, but because of the manufacturing tolerances of the real sizes of previously formed corrugation of the membrane differ from the dimensions of the profile of the support surface, when exposed to a pressure value which is close to the value of setpoint actuation of the signaling device, corrugation changes its original shape, while in the areas of incompatibility is wrinkling or stretching, and depending on the amount of additional deformation cracks with subsequent loss of tightness of the membrane.

Besides this, due to the fact that the piston in the detector prototype is installed in the housing, making modifications for measurement is significantly different in pressure requires fabrication and modifications of the body of the detector, which is economically unprofitable.

The proposed solution is aimed at addressing these shortcomings.

To do this, in the case of the detector of excess pressure, which is hermetically installed elastic membrane made with a concentric corrugation, covering the upper part of the piston in the role of a hard center, interacting with adjustable force spring and the electric contact device, placed the insert with a Central hole, in which concentric with the clearance set the piston, and the elastic membrane is provided with a second bead located above the support surface in the box, separating the peripheral part of the membrane, tightly connected with the insert from moving together with the piston in its Central part, and the insert is made with a stepped center is inim hole, moreover, a stepped transition in the hole serves as a supporting surface for the bottom of the piston, and the depth of the hole, in which is mounted a piston equal to the height of the piston, while the contacting surface of the insert to the piston and membrane agreed on the profile. In addition, the detector overpressure agreed in diameter, but with different effective areas a pair of insert piston and cooperating with the piston springs of different stiffness are made removable and interchangeable on the landing.

The formation of the profile of the membrane for signaling excessive pressure occurs as follows: when assembling the original flat membrane cut from a polyimide film, hermetically mounted on the profiled surface of the insert to the piston, press it to their profiled surface, affecting her pressure ≥120 kg/cm²when this elastic membrane repeats and remembers the profile of the support surface due to the incident in her plastic deformation.

The invention is illustrated in the drawing, in which figure 1 shows the design of the detector excessive pressure, figure 2 and 3 shows the dynamics of changes in the shape of the corrugations in each of the salient provisions of the detector with a pre-made corrugation in the prototype and in the proposed detector excess is knogo pressure.

The alerter overpressure contains (see figure 1) housing 1, which is installed insert 2 with a piston 3, the elastic membrane 4 with corrugations 5, 6, is located above the insert 2 and the piston 3, the lid from fitting 7, the spring 8 and the electric contact device 9, shown conventionally.

In the alerter excess pressure as a sensitive element that converts pressure into force, is used the piston 3 mounted in a cylindrical insert 2 with some radial clearance. Sealing a radial gap of a pair of piston-insertion is achieved by use of the elastic membrane 4 made of polyimide film and hermetically connected at the periphery of the insert 2.

To reduce the influence of the stiffness of the membrane 4 by the value of setpoint actuation of the signalling device, the membrane 4 has a corrugation 5, separating it fixed peripheral part from moving together with the piston 4 of the Central part, and the corrugation 6 covering the upper part of the piston, preventing its displacement in the radial gap. Agreed on the profile of the surface of the membrane 4 and the surface of the insert 2 with a piston 3, which support surfaces for busy handling the pressure membrane, protect it from unauthorised deformation and, ultimately, destruction.

On figa (see figure 2) shows the membrane with pre-manufacture the major corrugation not yet installed in the detector.

In the absence of excess pressure piston 3 is pressed by a spring 8, which regulates the actuation setting value, to the bottom cover with the socket 7. In order at the specified position of the piston of the corrugation 6 is located in the gap between the insert 2 and the piston 3, it must change its shape (see figb). In this position, the detector is in storage.

Under pressure, the value of which is close to the value of setpoint actuation of the detector, the applied pressure, tightly compressing the membrane 4 to the box 2 and the piston 3, again changes the shape of the corrugations 6 (see figv).

When exposed to handling the pressure of the lower surface of the piston 3 is pressed against the stepped transition in the Central hole in box 2, while between the Central part of the membrane and the surface of the piston remains conventionally shown in Figg region incompatibility, inside of which is the collapse of the membrane 4. However, depending on the size of the area of incompatibility during subsequent cyclic loading can develop cracks with loss of integrity of the membrane.

To address this shortcoming in the proposed detector consists of two flute: bumps 5 are located near hermetic sealing membrane, the purpose of which is to ensure movement of the Central part of the membrane 4 for the odd Flexural deformation of the corrugations, and corrugation 6, fixing the axial position of the piston relative to the membrane 4.

Corrugations in accordance with the proposed method form as follows:

During Assembly of the detector flat workpiece elastic membrane 4, obtained by the cutting of the polyimide film (see figa), tightly set on the surfaces of the insert 2 with a piston 3 and act on it high blood pressure ≥120 kg/cm²side cover with the socket 7, the lower surface of the piston 3 is pressed against the stepped transition in the Central hole in the insert 2 and the upper surface of the piston 3 together with the insert surface 2 forms a profiled support surface for the membrane 4, which due to tension in excess of the limit of elasticity, is formed by the profile of the membrane 4 with corrugations 5, 6 (see figb that follows the profile of the support surface of the insert to the piston.

The piston 3 by a spring 8 is pressed against the bottom of the grooves in the lid with the fitting 7 (see Figg). The membrane of the detector due to the rigidity of the formed corrugations when tracking a movement of the piston is slightly lifted above the surface of the piston, in addition curving line of contact with the boundary grooves.

Thus, the proposed detector excess pressure due to the removal of the corrugations of the radial clearance of the piston-insert eliminates the effect is changing the shape of the corrugations of the membrane on the stability of a setpoint value triggering alarm after setting.

In addition, providing the possibility of making modifications to measure considerably different in pressure reduces the cost of manufacturing.

1. The alerter excess pressure, comprising a housing in which is hermetically installed elastic membrane made with a concentric corrugation, covering the upper part of the piston in the role of a hard center, interacting with adjustable force spring and the electric contact device, characterized in that the housing of the detector placed the insert with a Central hole in which the piston is installed with a concentric gap, and the elastic membrane is provided with a second bead located above the support surface of the insert with the possibility of separating the peripheral part of the membrane, tightly connected with the insert from moving together with the piston in its Central part.

2. The alerter overpressure according to claim 1, characterized in that the insert is made with a stepped Central bore, and a stepped transition in the hole serves as a supporting surface for the bottom of the piston, and the depth of the hole, in which is mounted a piston equal to the height of the piston.

3. The alerter excess pressure in one of claim 1 or 2, characterized in that the contacting surface of the insert to the piston and membrane according to the negotiated profile.

4. The alerter excess pressure in one of claims 1, 2 or 3, characterized in that the agreed diameters, but with different effective areas, a pair of insert piston and cooperating with the piston springs of different stiffness are made removable and interchangeable on the landing.

5. The method for forming the profile of the membrane for signaling excessive pressure, which consists in the fact that during Assembly of the detector of the original flat elastic membrane made of polyimide film, hermetically mounted on the profiled surface of the insert to the piston, press it to their profiled surface, affecting her pressure ≥120 kg/cm²with the possibility of repetition and memorization elastic membrane profile of the support surface due to the incident in her plastic deformation.