RU2387599C1 - Piston designed for measuring volume of fuel - Google Patents

Abstract

FIELD: machine building. ^ SUBSTANCE: volume measuring device consists of pistons installed on connecting guide and performing reciprocal motions in cylinder measuring chambers connected between them and with specified volume under pressure created with fuel. When pistons move, fuel is transferred between an inlet aperture and outlet aperture connected with a fuel distributing gun; movement of pistons causes rotation of a crankshaft coupled with elements of detection for evaluation of fuel volume run through a measuring device depending on rotation of the crankshaft. Also the piston consists of a support element with an aperture in its central part with diametre less, than that of the measuring chamber, and of a round mono-block cleaning packing fabricated out of deformed material with the aperture in the central part enveloped with a curved rim on peripheral part; external diametre of the curved rim exceeds diametre of the measuring chamber. Components forming the piston are put on the end of the connecting guide. ^ EFFECT: efficient removing impurities and ice crystals in internal part of measuring chambers. ^ 12 cl, 5 dwg

Description

The object of the invention is a piston for a volumetric measuring device installed in a fuel distribution station, such as, for example, gasoline or liquefied petroleum gas (GPL).

Existing metrological rules require that volumetric measuring devices installed on fuel dispensers of gas stations calculate the amount of fuel delivered to the fuel tanks of road vehicles with an accuracy of the order of thousandths.

In order to satisfy such requirements, measuring devices must provide extremely accurate measurements.

To solve this problem, there are currently various types of volumetric measuring devices, in particular piston-type measuring devices.

Such measuring devices typically comprise pistons mounted in the interior of the measuring device body, in particular on connecting rails capable of reciprocating in interconnected cylindrical measuring chambers having a predetermined volume under the action of the pressure generated by the fuel flow.

This reciprocating movement of the pistons entails:

- on the one hand, the transfer of fuel between the inlet of the measuring device connected to the fuel storage tank using appropriate hydraulic equipment (such as pumps, filters, degassers, etc.) and the outlet of the same measuring device associated with the fuel dispenser a gun;

- and on the other hand, the rotation of the crankshaft associated with the detection bodies, which provide the ability to determine with fairly high accuracy the volume of fuel that has passed through this measuring device, as a function of this rotation.

More specifically, volumetric measuring devices mounted on fuel dispensers typically include one or two pairs of pistons that are capable of reciprocating movements in the measuring chambers, each of these pistons being connected to a connecting guide.

The connecting guide of the pistons is perpendicular and connected to the crankshaft by means of a gear rod of the crankshaft mounted eccentrically with respect to its central axis in such a way as to enable the alternating movements of the pistons to be converted into rotational motion, which can be detected by the detection organs.

At the same time, a piston volumetric measuring device of the type described above is equipped with an inlet spool rigidly fixed in a rotational motion on the axis of the crankshaft and provided with a set of openings that allow successive communication of various measuring chambers with an inlet and an outlet of this measuring device.

Thus, the set of passageways allows the fuel entering through the inlet of this measuring device and passing through the inlet spool to penetrate into one or another measuring chamber in order to create pressure on the piston installed in this chamber, while the opposite piston pushes fuel in the direction of the outlet.

At the same time, the transmission rod of the crankshaft moves this crankshaft in a rotational movement, which also entails a rotation of the intake spool.

In order to enable the detection authorities to determine the amount of fuel actually delivered to the user, with the accuracy specified by the rules established by law, it is important that the volume of the measuring chambers is known very accurately and that these chambers are hermetically sealed.

It is also important that each of the elements of the measuring device is equipped with gaskets, the nature of which ensures the best possible sealing in the sense that any leakage can introduce significant errors in the measurement of the volume of the transmitted fuel.

However, maintaining this complete sealing between said pistons and their associated measuring chambers is particularly problematic, given the fact that said pistons move in a reciprocating manner, which increases the risk of leaks.

In order to limit this risk, the pistons of volumetric measuring devices in the general case include:

- a support disk containing in its Central part of the hole and having a diameter slightly smaller than the diameter of the measuring chamber associated with this piston,

- at least one sealing ring having a diameter equal to the diameter of this measuring chamber.

The driving system formed by said support disk and one or more sealing rings is put on the end of the connecting guide and pressed against the abutment thickening made on this guide.

This propulsion system can be held with a tightening nut or with a tightening ring.

More specifically, said support disk is usually supported by a bulge, which is an abutment, by means of the first of its surfaces, provided with a groove on its peripheral part in which the first sealing ring is located.

In this case, the second sealing ring, essentially identical to the aforementioned first sealing ring, can be mounted on an annular ledge provided on the opposite or second side of this support disk, and is clamped between this support disk and the compression plate.

However, operating experience leads to the fact that such a propulsion system does not guarantee satisfactory tightness.

This problem is associated primarily with the inevitable presence of solid contaminants in the fuel circulating in the fuel dispenser between the storage tank and the fuel dispensing gun.

These contaminants, which are the result of the shortcomings of the methods used for cleaning fuel and the formation of deposits formed in the storage tanks of this fuel, essentially, under no circumstances can be completely eliminated, even if there is a filter installed at the inlet of the volumetric measuring device.

As a result of this, non-negligible amounts of solid contaminants having relatively small dimensions are deposited on the walls of the measuring chambers and thus become elements with very significant abrasive properties.

In addition, in the fuel present in the storage tank, there is always a small amount of residual water in a liquid state that can freeze and turn into ice at low temperature, forming ice crystals, which can also precipitate on the inner walls of the elements of the measuring device, in particular on the inner the walls of the measuring chambers in which the said pistons perform their reciprocating motion.

The presence of these solid particles (for example, contaminants or ice crystals) results in inhibition or obstruction of the reciprocating movement of the pistons in the associated measuring chambers, which causes a loss in the accuracy of measuring the volumetric amount of fuel delivered, which in this case may go beyond the limits set law regulations.

In addition, residual impurities and ice crystals can damage parts of the piston that are in contact with the inner surface of the measuring chambers, in particular the sealing o-rings, as well as the measuring chambers themselves, accelerating their abrasive wear.

This wear can significantly reduce the service life of these elements and can, in addition, cause leaks with the passage of fuel between the various compartments of the measuring chambers, thereby increasing the loss of measurement accuracy.

The technical task of the present invention is to eliminate these disadvantages and offer a piston designed for volumetric measurement of the amount of fuel and having a specific design, which guarantees a very effective removal of residual contaminants and ice crystals in the interior of the measuring chambers.

To solve this technical problem, the present invention provides a piston of the type mentioned above, characterized in that this piston contains a support element with a hole in its central part and having a diameter slightly smaller than the diameter of the measuring chamber associated with this piston, and a round one-piece cleaning seal a gasket made of a deformable material, containing a hole in its central part and surrounded by a curved rim on the peripheral part, has an outer diameter of yshayuschy diameter of the associated piston of the measuring chamber.

The driving system, formed by a set of structural elements of the piston, is worn on the corresponding end of the connecting guide.

In accordance with the invention, the cleaning sealing gasket is a part designed in the form of a single unit, divided into three parts.

The first of these parts corresponds to a flat washer having a diameter equal to the diameter of the said support element and slightly smaller than the diameter of the measuring chambers connected with the piston.

The second part corresponds to a circular hole, allowing the connection of this cleaning sealing gasket with a driving system at the end of the connecting guide.

The third part is formed by a curved rim having an outer diameter exceeding the diameter of the corresponding measuring chamber.

In accordance with another characteristic of the invention, at least one sealing ring having a diameter equal to the diameter of the corresponding measuring chamber is mounted on said support element.

The sealing ring (s) can advantageously be held onto said support element by means of a tightening plate having an opening in its central part.

In accordance with another characteristic of the invention, the cleaning sealing gasket is pressed against said support element and held by a constriction plate having an opening in its central part.

According to the invention, the plurality of elements forming the piston can advantageously be held by a tightening nut.

In accordance with the invention, it is important, in addition, that said cleaning gasket is made of a material flexible enough to allow the said outer rim to deform to a certain extent during the installation of the piston in the corresponding measuring chamber so that this rim was in reliable mechanical contact with the inner wall of the measuring chamber and slipped with some friction along this chamber wall in the process carried out I reciprocating motion of the piston.

Solid particles of pollution and ice crystals that are located on the inner walls of the measuring chambers during the operation of the measuring device can thus be completely removed as they are deposited as a result of the friction of the rim of the cleaning gasket on the walls of the measuring chambers.

Due to this circumstance, the presence of a cleaning gasket allows to increase the accuracy of measuring the volume of fuel delivered to the user, while not allowing the pistons to be delayed in their movement, and at the same time to increase the service life of the pistons and, in particular, the sealing rings of the seal, slowing their abrasive wear.

The use of a cleaning sealing gasket in accordance with the invention is particularly preferred from the point of view of providing sealing: indeed, one or more sealing sealing rings are less worn and provide better sealing and satisfactory mechanical contact at the level of the walls of the measuring chambers with a cleaning sealing gasket, providing additional sealing added to the sealing that usually provides using one or more sealing o-rings.

This result is particularly advantageous when the volumetric metering device is intended for a fuel dispensing station of type GPL, in which the danger of leaks is particularly significant, taking into account the relatively low viscosity of such fuel. This helps to ensure the highest accuracy in quantifying the amount of fuel delivered.

In accordance with another characteristic of the present invention, the piston comprises an auxiliary cleaning sealing gasket similar to the main cleaning sealing gasket and installed between said supporting element and an abutment-thickening made on the connecting guide.

The rims of the main cleaning seal and the auxiliary cleaning seal are oriented in opposite directions.

This characteristic has the advantage of allowing the cleaning of the internal walls of the measuring chambers, that is, the removal of solid contaminants that can be deposited on these internal walls during the implementation of each phase (in one or the other direction) of the reciprocating movement of the piston, that is, to help ensure the best sealing of the system and the best protection of the piston structural elements from wear, and to promote the best sealing of this system.

In accordance with another characteristic of the invention, said auxiliary cleaning sealing gasket is held by means of an auxiliary tightening plate between said supporting element and an abutment-thickening made on the connecting guide.

It should be noted here that in accordance with the invention, a piston equipped with one or preferred method of two cleaning sealing gaskets mounted on said support element and not containing additional sealing rings of sealing may provide the possibility of obtaining a level of sealing sufficient in the framework of using such a device for distribution of liquid fuel having a sufficiently high viscosity.

However, such a configuration may also be preferable from a financial point of view.

In accordance with another characteristic of the invention, one or more cleaning sealing gaskets are made of a polymeric material such as polytetrafluoroethylene containing graphite.

Particularly preferred results were obtained using cleaning gaskets containing about 15% graphite.

This choice allows you to give the rim of the cleaning gasket sufficient flexibility to ensure satisfactory contact along the entire peripheral part of the inner wall of the measuring chambers.

The presence of graphite in parallel allows us to guarantee sufficient resistance of the cleaning gaskets during the movement of the pistons, that is, an improvement in their friction coefficient and an increase in their service life.

The characteristics of the piston intended for the device for measuring the volumetric amount of fuel, which is the subject of the invention, will be described in more detail in the following statement, which gives references to the drawings given in the appendix and which are not restrictive, including:

- figure 1 is a perspective view of a volumetric measuring device with four pistons;

- figure 2 is a view of such a measuring device in cross section;

- figure 3 is a view in parsing of the first method for implementing the piston in accordance with the invention;

- figure 4 is a sectional view of a cleaning gasket;

- figure 5 is a view in profile of a second method for implementing a piston in accordance with the invention.

It should be noted here that if the figures shown in the appendix show a measuring device with four pistons, pairwise connected to each other and able to respectively reciprocate in four measuring chambers, arranged in such a way that two successively adjacent adjacent chambers form each other angle 90 °, the present invention is in no way limited to a measuring device having just such a configuration, and can also be used in rshnevyh measuring devices having other configurations, particularly in measuring devices with two parallel pistons.

As can be seen in FIG. 1 and 2, the volumetric measuring device 1 comprises a housing 4 of the measuring device, a bottom cover 19 and a top cover 20.

The top cover 20 is equipped, on the one hand, with an inlet 2 connected to the storage tank and with hydraulic elements not shown in the drawings shown in the appendix and allowing fuel to be introduced into the interior of the measuring device 1 in the direction shown by arrow A, and on the other side, an outlet 3 associated with the dispensing gun and providing the ability to remove fuel in the direction shown by arrow B.

Four cylindrical measuring chambers 5 of a given volume are limited by the inner part of the housing 4 of this measuring device.

These measuring chambers 5 are diametrically opposed to each other in pairs and arranged so that two adjacent adjacent chambers 5 are offset from each other by an angle of 90 °.

Each of these measuring chambers is hermetically closed at its end by means of a cover 6.

As can be seen in figure 2, the measuring device 1 contains two pairs of pistons 7a, 7b, only one of which is presented in this figure; these pistons 7a, 7b, the configuration of which will be described in more detail in the following description, are able to move in a reciprocating manner in the respective measuring chambers 5.

As can be seen in FIG. 2 and 3, the pistons 7a, 7b of each pair are mounted at the respective ends of the connecting guide 8 provided with a transverse hole 8a having an elongated shape and allowing the transmission rod of the crankshaft 17a to pass through which the crankshaft 17 is articulated.

This crankshaft 17 is mounted in an eccentric manner with respect to the rod 17a and parallel to this rod so that the reciprocating movement of the pistons 7a, 7b leads to a rotational movement of this crankshaft.

The crankshaft 17 is guided by a bearing 18 and is connected to a crank 17b inserted into the bottom cover 19 of the measuring device 1.

In addition, this crankshaft 17 extends beyond the top cover 20 of the measuring device 1 and is connected at this level with detection bodies not shown in the drawings in the appendix, which allow determining the amount of fuel passing through this measuring device 1 as a function of the number of revolutions crankshaft 17.

As can be seen in FIG. 2, the top cover 20 of the measuring device 1 contains four holes 21a, 21b, only two of which are shown in the figure and which are respectively connected with holes 21c, 21d made in the housing 4 of the measuring device so that provide a consistent message inlet 2 and outlet 3 with each of the measuring chambers 5.

At the same time, the upper cover 20 is equipped in its inner part with an inlet spool 22, rigidly rotationally connected to the crankshaft 17 by means of a ring 23 and a rotating ring 24.

A spring 25 mounted inside the rotary ring 24 allows the inlet spool 22 to be held.

In accordance with an embodiment not shown in the drawings, the inlet spool 22 is equipped with two diametrically opposite elongated holes, each of which extends a quarter of the circumference (in the range from 0 to 90 ° and in the range from 180 to 270 °).

These elongated openings have the function of ensuring that the inlet and outlet openings 2, 3 communicate with the measuring chambers 5 through the openings 21a, 21b and the openings 21c, 21d and, as a result, provide the possibility of introducing fuel into one of the measuring chambers 5 and removing this fuel from the diametrically opposite measuring chamber 5, and also provide blocking the transfer of fuel through two other measuring chambers 5, which are perpendicular to the said measuring chambers.

As can be seen in FIG. 1 and 2, the covers 6 of the measuring chambers 5, as well as the bottom cover 19 and the top cover 20, are fixed to the housing 4 of the measuring device using screws 26.

In addition, the measuring device 1 is equipped with gaskets 27, allowing to ensure tightness between the various structural elements of this measuring device.

As can be seen in figure 2, each of the covers 6 of the measuring chambers 5 is equipped with an adjusting screw 6a, the rotation of which allows you to change the cyclic volume of this measuring chamber before operating this measuring device.

To this end, the adjusting screws 6a engage with the end of the respective connecting guides 8 so as to limit the working stroke of the pistons 7a, 7b.

The movement of these adjusting screws 6a is indicated by disks 6b equipped with risks corresponding to fractions of the volume of the measuring chambers 5.

Next will be described a method of functioning of the previously presented measuring device.

As can be seen in FIG. 1 and 2, liquid fuel coming from a storage tank, not shown in the drawings shown in the appendix, enters the measuring device 1 through an inlet 2 made in the top cover 20, in the direction shown by arrow A.

Thus introduced fuel passes through the first opening of the inlet spool 22, then passes through the opening 21a, 21b of the upper cover 20, which is located opposite this first elongated hole, so as to penetrate into the first measuring chamber 5 through the associated hole 21c, 21d.

In this case, the first measuring chamber 5 is filled with fuel, which exerts pressure on the piston 7a located in this chamber, which under the influence of this pressure is pushed in the direction opposite to the cover 6.

At the same time, the second elongated opening of the inlet spool 22 releases the opening 21a, 21b of the upper cover 20 and the opening 21c, 21d associated with the second measuring chamber opposite the first chamber, and thus forms a message of the second measuring chamber with the outlet of the upper cover 20.

Given the connection between the pistons 7a and 7b located in the first and second measuring chambers 5, the fuel present in this second measuring chamber is pushed out of the measuring device 1 through the outlet 3 in the direction indicated by arrow B.

At the same time, the movement of the pistons 7a and 7b entails the rotation of the crankshaft 17, as well as the intake spool 22, rigidly connected with this crankshaft during its rotation.

The configuration of the elongated openings of the intake spool 22 allows you to continue the introduction of fuel into the first measuring chamber 5 and its removal from the second measuring chamber 5 during this rotation.

Indeed, the dimensional parameters of these elongated holes having the shape of a quarter of a circle are determined so as to overlap the holes 21a, 21b of the top cover 20 and the associated holes 21c, 21d made in the housing 4 of the measuring device, in the case when the pistons 7a, 7b are at the end of their working stroke.

The first elongated opening of the inlet spool 22 thus opens the opening 21a and the opening 21c connected with the third measuring chamber 5 adjacent to the first chamber and offset by an angle of 90 ° with respect to this first chamber.

At the same time, the second elongated opening of the inlet spool 22 opens the opening 21b and the opening 21d associated with the fourth measuring chamber 5 in order to enable the removal of fuel contained in this chamber through the outlet 3.

This movement is then reproduced as follows: the first inlet of the inlet spool 22 opens successively the openings 21a, 21b and the openings 21c, 21d associated with each of the four measurement chambers 5 in order to allow the introduction of fuel into these chambers and their removal from these diametrically opposite cameras. Knowing the amount of fuel transmitted through each of the measuring chambers 5, it is possible to determine the amount of fuel supplied to the vehicle’s fuel tank by counting the number of revolutions of the crankshaft 17.

It should be noted here that, in view of the fact that the various structural elements of this measuring device are adapted to withstand a working pressure of approximately 16 bar and a peak pressure of approximately 25 bar, such a measuring device can be integrated in a fueling installation Type GRL.

As can be seen in FIG. 2 and 3, each of the pistons 7a, 7b is mainly formed by a support disk 9 having an opening in its central part and worn on the corresponding threaded end of the connecting guide 8. This support disk 9 has a diameter slightly smaller than the diameter of the corresponding measuring chamber 5, and provided on its peripheral part with a groove in which the first sealing ring 10 is located.

As can be seen in FIG. 3, the support disk 9 rests on a stop-forming thickening 30 made on the connecting guide 8, using the first of its sides and by means of a toroidal gasket 31, and is equipped on its second side opposite to its first side, peripheral ledge into which the second sealing ring 11 is inserted.

These sealing rings 10, 11 have a diameter equal to the diameter of the corresponding measuring chamber 5, and are pressed against the inner wall 5a of this chamber during the reciprocating movement of the piston 7a, 7b.

The first constriction plate 12, having a diameter similar to the diameter of the support disk 9, and also containing a hole made in its central part, is pressed against the second sealing ring 11 and determines, together with this ring and the supporting disk 9, equipped with the first sealing ring 10, system worn on the end of the connecting guide 8.

As can be seen in FIG. 3 and 4, the piston 7a also comprises a circular monoblock cleaning gasket 13 in the form of a bowl, which is clamped between the first constriction plate 12 and the second constriction plate 14 similar to said first constriction plate.

The washer 15 associated with the nut 16 tightening, allows you to hold these various elements and their fixation on the corresponding threaded end of the connecting guide 8.

As can be seen in FIG. 3 and 4, the cleaning sealing gasket 13, which is made of polytetrafluoroethylene containing graphite, is formed by a flat washer 13a, having a diameter equal to the diameter of the supporting disk 9 and the compression plates 12 and 14, containing a circular hole 13b in its central part and continuing in its peripheral part, a curved rim 13c having an outer diameter exceeding the inner diameter of the corresponding measuring chamber 5.

As can be seen in FIG. 5, the piston 7a also comprises an additional cleaning sealing gasket 28 having a configuration similar to that of the main cleaning sealing gasket 13 and equipped with a curved rim oriented in the opposite direction with respect to the curved rim 13c.

This additional cleaning sealing gasket 28 is sandwiched between the first side of the support disk 9 and the auxiliary constriction plate 29, similar to the first and second constriction plates 12, 14, which is pressed against the abutment thickening 30 formed on the connecting guide 8.

Another possible implementation method, not shown in the drawings in the appendix, is to install two cleaning sealing gaskets 13 and 28, the orientation directions of the curved rims of which are opposite, on the supporting disk 9 of appropriate sizes, held by clamping plates 14, 29 and pressed against an abutment thickening 30 made on the connecting guide 8, but without a sealing ring.

All four pistons of the switchgear represent, of course, a similar configuration.

Claims (12)

1. A piston for a volumetric measuring device mounted in a column for distributing fuel such as gasoline or liquefied petroleum gas (GPL), this volumetric measuring device (1) comprising pistons (7a, 7b) mounted, in particular, on a connecting guide (8) with the ability to reciprocate in interconnected cylindrical measuring chambers (5) with a given volume under the pressure created by the fuel in such a way that this displacement of the pistons entails her:
on the one hand, the transfer of fuel between the inlet (2) associated with the storage tank and the outlet (3) associated with the fuel dispensing gun;
and on the other hand, the rotation of the crankshaft (17) associated with the detection bodies, which provide the ability to determine the amount of fuel passed through this measuring device (1), depending on the rotation of this crankshaft (17), characterized in that this piston contains a support element (9) with an opening in its central part and having a diameter slightly smaller than the diameter of the measuring chamber (5) connected with this piston, as well as a round monoblock cleaning sealing gasket (13) made of defo material with an opening (13b) in its central part and enveloped on its peripheral part by a curved rim (13c) having an outer diameter exceeding the diameter of the measuring chamber connected to this piston (5), the set of elements forming this piston being worn on the corresponding end of connecting guide (8). 2. A piston according to claim 1, characterized in that at least one sealing ring (10, 11), having a diameter equal to the inner diameter of the corresponding measuring chamber (5), is mounted on said supporting element (9). 3. A piston according to claim 2, characterized in that the sealing ring (s) are held onto said supporting element (9) by means of a compression plate (12) with an opening in its central part. 4. A piston according to any one of claims 1 to 3, characterized in that the cleaning sealing gasket (13) is pressed against said support element (9) and held by a tightening plate (14) with an opening in its central part. 5. A piston according to any one of claims 1 to 3, characterized in that the set of elements of this piston is held by means of a tightening nut (16). 6. A piston according to claim 4, characterized in that the set of elements of this piston is held by a tightening nut (16). 7. A piston according to any one of claims 1 to 3 and 6, characterized in that it comprises an additional cleaning sealing gasket (28), essentially similar to the main cleaning sealing gasket (13) and installed between said supporting element (9) and the generatrix emphasis by a thickening (30) made on the connecting guide (8), and the curved rims of the main cleaning seal and the additional cleaning seal are oriented in opposite directions. 8. The piston according to claim 4, characterized in that it contains an additional cleaning sealing gasket (28), essentially similar to the main cleaning sealing gasket (13) and installed between the said support element (9) and the thickening (30) forming a stop made on the connecting guide (8), and the curved rims of the main cleaning seal and the additional cleaning seal are oriented in opposite directions. 9. A piston according to claim 5, characterized in that it comprises an additional cleaning sealing gasket (28), essentially similar to the main cleaning sealing gasket (13) and installed between said supporting element (9) and a thickening (30) forming an abutment made on the connecting guide (8), and the curved rims of the main cleaning seal and the additional cleaning seal are oriented in opposite directions. 10. A piston according to any one of claims 7 to 9, characterized in that the additional cleaning sealing gasket (28) is held by means of an auxiliary clamping plate (29) between said supporting element (9) and an abutment thickening (30) made on the connecting guide (8). 11. A piston according to any one of claims 1 to 3, characterized in that the cleaning sealing gaskets (13, 28) are made of a polymer material containing graphite. 12. The piston according to claim 4, characterized in that said polymer material is polytetrafluoroethylene.

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