FR2612600A1 - Testing device for hydraulic circuits - Google Patents

Abstract

The subject of the present invention is a testing device which is used for checking hydraulic circuits. A sampling element 1 includes a body 5 provided with means 20, 15 for sealed fixing onto a pipe 10, a head 6 for penetrating inside the said pipe 10 and a connector 3, 4 for a duct 11 made through the said body 5 and opening out from the said head 6. A spring 25 tends to close a valve 12 of conical shape towards a seat 17 formed in the said body 5, so as to block off the duct 11 by moving it away from the said head 6. The valve is held centred by a rod 23 which is mounted to slide in the said duct via splines interposed with recesses making longitudinal fluid passages 30 in the said duct. The connector 3, 4 includes an axial needle having an end for abutment on the said rod capable of pushing back the said valve away from its seat when the said connector is connected onto the said sampling element, the said needle internally forming an axial communication channel opening out laterally close to the said end via at least one lateral channel for communicating with at least one of the said passages.

Description

TESTING DEVICE FOR HYDRAULIC CIRCUITS
The present invention relates to a tester device which finds its utility in the control of hydraulic circuits.

 We know how to prevent many of the accidents that can occur on hydraulic systems that frequently involve industrial installations, by periodically checking their proper functioning by examinations carried out on the fluid circulating in the system piping. The most common verifications involve pressure measurements in which we will see, for example, abnormal pressure drops, temperature measurements which may indicate the appearance of heating, analyzes of the physical or chemical composition of the fluid intended to detect therein for example the presence of particles in suspension coming from a used element of the circuit.

 For this reason, the pipes are fitted with such circuits, with test devices which include, in a conventional manner, various sockets which fill these different offices by allowing each to connect a head for taking the fluid entering the pipe with a sensor or instrument. appropriate measurement, which can be reduced to a bottle for receiving a sample for analysis.

 It seems that the specialists have never been aware to date of all the interest which one would have to have elements of sampling of a single type which could be fixed permanently at various points of the piping to be interconnected at will, interchangeably, with one or other of the aforementioned measuring instruments. This situation seems to arise from the fact that it has never been envisaged that the measurement instruments can be interchanged on the same outlet (or sampling elements). The requirements specific to each type of measurement would rather suggest that they are mutually incompatible and that a special take is necessary for each one. We are then led to multiply the number of takes at each strategic location of the circuit, which increases considerably the complexity of the circuits and the cost of verification.

 In addition, it is a fact that the taps or sampling elements that comprise the current testing devices would not allow such an exchange.- For example, an element used as a pressure tap is not suitable for taking a sample of the fluid for analysis, and vice versa, while there is currently no device allowing precise measurement of the temperature of the fluid circulating in the piping.

These incompatibilities are explained in particular by the concern of taking only a very small quantity of fluid, but without pressure drop, for a pressure measurement, while in the case of a sample for analysis, it is especially important to allow free passage of particles in suspension in the fluid. In addition, the diversity of pressures prevailing in hydraulic systems raises other difficulties which lead manufacturers to propose for each function several models of devices, which are constructed to allow sampling under operating pressures lying in respectively different ranges. .

 The present invention essentially aims to simultaneously solve all of these difficulties by combining the different sampling functions in the same element to be fixed to a pipe, thanks to a special design of this element and of its means of connection with a measuring instrument. .

 The tester for hydraulic circuits according to the invention is conventional in that it comprises, like other prior devices, a sampling element comprising a body provided with tight fixing means on a pipe, a penetration head to the interior of said piping and a connection fitting with a measuring instrument for a conduit formed through said body and emerging from said head, and in that said element also includes a valve for closing said conduit, the opening of which can be caused to take a fluid sample inside the piping, when the measuring instrument is connected to the element by said fitting.

 In the novelty of its design, it is characterized in that said sampling element comprises a valve of conical shape cooperating to seal said conduit with a seat formed in said body around said conduit and a member for elastic biasing of said valve towards said seat by distance from said penetration head in the piping, as well as means for centering said valve constituted by a rod integral with said valve which is slidably mounted in said conduit by grooves interspersed with recesses providing longitudinal fluid passages in said conduit , and in that said connector comprises an axial needle having a stop end on said rod suitable for pushing said valve away from its seat against said elastic biasing member automatically when connecting said connector to said element sample, said needle internally forming an axial channel of communication with said measuring instrument (or with a sample reception bottle), opening laterally in the vicinity of said end by at least one lateral communication channel with at least one of said passages.

 It is further advantageous that the needle of the fitting has a narrowed end to form an annular chamber of fluid when the valve is opened by the needle, and thus improve the communication between said passages and the internal channel or channels of the needle. and avoid any risk of fluid stagnation.

 In a preferred embodiment of the tester device according to the invention, the connection of said fitting to said sampling element involves cooperating threaded portions provided respectively on the fitting and on the sampling element, which makes it possible to considerably reduce the effort that it is necessary to exert manually, during connection, to push the valve out of its seat, whatever the pressure of the fluid present in the piping which is added to that of the elastic member. The latter is advantageously constituted by a helical spring which rests on the one hand on an annular shoulder of the valve and on the other hand on an annular shoulder of the head of the sampling element.

 According to another advantageous characteristic of the device according to the invention, it comprises a safety plug adaptable to the body of the sampling element, in particular by screwing, which is replaced by the above connection when it is desired to make a measurement or a sample collection.

 According to another characteristic of the invention, the tester device advantageously comprises at least two interchangeable connectors which make it possible to connect two different measuring instruments (or bottles for receiving the sample) to the sampling element, respectively. Such couplings may in particular differ by the shape of the needle,; "incipally in the passage section offered to the fluid through this needle, as well as by the shape of a rear part of the needle which constitutes a junction end with a flexible tube leading to the measuring device, through a rotating cover allowing the fitting of the fitting to the threaded part of the body of the sampling element. We can thus distinguish in particular a pressure tap fitting in which the rear end of the needle forms an elongated cylindrical tail of small cross section suitable for engaging in a flexible capillary tube for connection with the measuring instrument (suitable here for pressure measurement), and a connection for taking sample in which the same tip is threaded externally to receive, by screwing, a tip engaged in a flexible tube of relatively large section to conduct the fluid withdrawn to a bottle for receiving the sample we. It will be noted here that for taking samples, the existence of an annular chamber around the end of the needle, according to a preferred embodiment of the invention, has the effect of promoting the maintenance in suspension of the particles contained in the fluid. We can also distinguish between sample taking connections suitable for taking samples at higher or lower pressures, in which the axial channel of the needle is respectively more or less narrow, with in the first case a single lateral channel and in the second case at least two lateral channels.

 According to yet another characteristic of the invention, the tester device comprises a temperature taking element, provided with a temperature sensor immersed in a fluid circulation pipe which connects in bypass of the piping to be checked on the element sampling point using the above pressure connection.

A particular embodiment of the invention will now be described in more detail which will make it better understand the essential characteristics and the advantages, it being understood however that this embodiment is chosen by way of example and that it is in no way limiting . Its description is illustrated by the accompanying drawings, in which
- Figure 1 shows schematically, in a partial sectional view, sampling element of the device of the invention equipped with its safety cap
- Figure 2 shows the same sampling element in the case where the safety cap is replaced by a fitting which allows the device to operate under pressure tap
- Figure 3 also shows the same sampling element, but here equipped with another connection by which the device of the invention operates by taking a sample
- Figure 4 schematically shows a temperature measurement element which advantageously comprises the device according to the invention.

 A tester for a hydraulic circuit according to the invention, as illustrated by the appended figures, essentially comprises, in the particular case considered, a sampling element 1 which appears in the first three figures, a safety plug 2 shown in FIG. 1, and several interchangeable connections with this plug, including the pressure connection connection 3 in FIG. 2 and the sample connection connection 4 in FIG. 4.

 We will begin by describing here the sampling element 1 in conjunction with FIG. 1. This element comprises a body 5, the shape of which is symmetrical in revolution and which has a front part 6, cylindrical and externally threaded at 20, a part rear 7, also cylindrical and externally threaded, and a central part 8 whose external contour is similar to that of a nut, to facilitate the rotation of the element on itself. This rotation is used to screw the element, by its front part 6, into a threaded radial tube 9 formed for this purpose on a pipe 10.

 Axially inside the body 5, there is formed a conduit 11 which passes through the element from one end to the other and which can be closed by a valve 12. The purpose of this conduit is to allow the removal of 'a fluid circulating in the pipe 10 when it is desired to carry out measurements. When the element is in place in the tubing of this piping, the front part 6 constitutes for the sampling a penetration head inside the piping. It ends, in this piping, by a conical end 13, from which opens the conduit 11. To ensure the tight connection of the sampling element in the correct position in the piping, the central part 8 of the element has a shoulder radial 14 which abuts on the end face of the pipe 9 while tightening a seal 15 housed in a groove 16 formed in the hollow of the shoulder.

 The valve 12 is movable longitudinally in the axis of the conduit 11. It is a conical valve, which closes the conduit 11 when it is applied to a seat 17 formed around the conduit in the body of the element.

In a conventional manner in itself, the valve 12 and the seat 17 are both made of hard metal alloy, but with a lower hardness for the seat 17 than for the valve itself.

 The seat 17 is in fact formed at one end of a tube 18, which is mounted inside the body 5 by a ring 19 screwed into the rear part 7, so that it is kept wedged between an internal shoulder of the ring 19 and an internal shoulder of the body 5 against which a seal 21 is interposed. It can also be seen that at the rear of the tube 18 the ring 19 forms an annular groove containing a seal 22 of which the utility will appear later.

 In the axis of the element, the valve 12 is extended towards the rear of the edge of the element, inside the tube 18, by a rod 23 which keeps it permanently centered in the axis of the element while traveling. This rod 23, of generally cylindrical shape, has three longitudinal flats, so that it forms three grooves sliding in contact with the internal wall of the tube, interspersed with three recesses which, during sampling, provide passages 30 for the fluid between the flats and the wall of the tube 18. At the opposite end, the valve 12 is extended along its axis by another rod 24, engaged inside a helical spring 25. The role of spring 25 is to elastically urge the valve 12 towards its seat 17, in the direction of closing of the conduit 11.It bears at its two ends respectively on a radial shoulder 26 formed inside the head 6 and on a shoulder 27 which separates the rod 24 of the valve itself. It therefore tends to push the valve 12 towards its seat away from the end of the head 6, in an elastic action which is exerted in the same direction as the pressure prevailing inside the piping 10.

 Outside of the verification periods which require taking samples of fluid in the piping, the sampling element 1 is out of service and the valve 12 closes the internal duct. The element is then protected by the safety cap 2, connected to the element in the position illustrated in FIG. 1. This cap comprises a bell hood 28 which is screwed onto the rear part 7 of the body 5 of the element . For this purpose, the cover 28 has an internal thread cooperating with the external thread of the part 7 and its annular end forms a nut 29. A shutter 31 is rotatably mounted in an axial hole in the cover 28, so as not to be driven in rotation with the latter when the plug is screwed onto the element 1. Beyond a shoulder (40) which abuts on the end face of the ring 19, this shutter 31 forms a finger 32 which penetrates into the conduit 11 far enough to close it at the seal 22 already mentioned, in its extreme position, without however reaching the rod 23 of the valve, which therefore remains closed. This additional closure prevents any leakage that may occur at the valve.

 Opposite finger 32, the shutter 31 protrudes from the cover 28. At this level is fixed the end of a chain 33, the other end of which is fixed to the body 5 of the element 1. This chain has quite naturally the object of retaining the plug 2 permanently near the element 1.

 Referring now to Figure 2, we will describe a first type of fitting cooperating with the element 1 in substitution for the plug 2. Like the other fittings described below, the fitting 3 combines the functions of automatic opening of the valve 12 , to ensure a fluid sample, and connection to a flexible tube 36. In the case of FIG. 2, the tube 36 is a capillary tube, which conducts the sampled fluid to a pressure measuring instrument, of the type pressure gauge or piezoelectric probe for example.

 The fitting 3 comprises a cover 37, in the shape of a bell like that of the plug 2, and like the latter, terminated by a crown in the shape of a nut 39 and fitted internally with a thread 38. This allows the fitting of the fitting on the body of the element 1 by screwing on the cooperating thread of the rear part 7 of the element.

 In the axis of the cover 37 is mounted a needle 41, around which a central annular rim 42 of the cover is crimped in an annular housing of the needle, so that the needle is fixed in axial position relative to the cover , but that the latter can rotate freely around it.

 The diameter of the needle 41 is substantially equal to the internal diameter of the ring 19. It therefore enters the conduit 11 when the connector is connected, and provides a sealed connection at the joint 22. It nevertheless has an external shoulder 43 which determines its extreme position by abutment on the end face 44 of the ring 19.

In the axial direction, the needle 41 is of a length such that it abuts by an end 45 on the rod 23 of the valve 12 and push the valve out of its seat 17 against the spring 25. The valve opening is thus automatic when the fitting is connected, and it is easy to overcome both the resistance of the spring and the pressure of the fluid present in the piping by the force exerted manually to screw the cover 37 onto the body of the item 1.

 Internally, the needle 41 has an axial channel 46 which crosses it longitudinally as far as a tip 47 projecting outside the cover 37, and which opens in the vicinity of the end 45 by a lateral channel '48, oriented at an angle. At this level, the end 45 is narrowed, to have a diameter much smaller than that of the conduit 11 at this location. These arrangements have the effect of forming an annular chamber 49 thanks to which the fluid easily circulates passages 30 formed around the rod 23 at the channel 48, and from there at the axial channel '46, without risk of seeing stagnation zones appear.

 At the rear end of the needle '41, the endpiece 47 forms a cylindrical tail of small section which provides the junction with the capillary tube 36, which is clamped thereon by a ring 50.

 While the fitting 3 which has just been described transforms the element 1 into a pressure tap, the fitting 4 of FIG. 3 is more suitable for taking a sample for analysis.

 In the same way as the previous connector, the connector 4 comprises a cover 51 rotatably mounted on a needle 52, and the cover is shaped to be screwed onto the rear part 7 of 11 element 1 while the needle enters the conduit 11 to open the valve 12.

 A first difference is in the shape of the rear part of the needle 52, which is more broadly dimensioned at the level of the crossing of the cover and which ends in a tip 53, threaded externally to receive a tip 54, of the type conventional, engaged in the end of a flexible tube which has not been shown. This tube leads the fluid taken to a bottle receiving the sample.

 Other differences, which do not appear clearly in the figures, relate to the design of the internal channels of the needle. In the variant illustrated in Figure 3, the axial channel 55 remains relatively narrow and there is provided a single lateral channel 56 opening towards the passages 30, in an annular chamber 57 formed around the narrowed end 58 of the needle. Nevertheless, the conditions thus ensured for the ciculation of the fluid during the sampling guarantee the maintenance in suspension of the particles which it may contain and the absence of losses or stagnation. The particular design of the device, the shape of the valve (12) and of the hollow opening control needle (52) ensure an integral sweeping of the oil passage chamber and therefore avoid oil storage. polluted.

 However, this variant is preferably used for taking samples when the fluid present in the examined piping is under high pressure. Otherwise, where the pressure is relatively low, it is preferable to connect to the element 1 another variant of the connector 4, in which the needle 52 has an axial channel 55 of wider section, with two similar lateral channels 56, opening symmetrically into the directory chamber 57.

 FIG. 4 illustrates yet another function of the device of the invention, using the same sampling element, but taking the temperature. This sampling element does not appear in the figure. The connection used in this case to open the valve is no longer shown; it is identical to the pressure tapping connector of FIG. 2 and it provides the junction with a capillary tube 58 which conducts the withdrawn fluid to a temperature taking element shown in FIG. 4.

 The temperature taking element 60 is mounted in derivation with respect to the piping examined. It is essentially constituted by a section of tube 61 which forms a fluid circulation pipe by the fact that it is associated with two sampling elements 62 and 63, identical to element 1 of the preceding figures, which are mounted symmetrically in the tube 61 by screwing their respective heads into the ends of the tube, internally threaded for this purpose. In operation, the element 60 is connected to the tube 58 coming from the examined piping, by a fitting 64 identical to that of FIG. 2, which is mounted at the end of the flexible tube 58 and which is connected by screwing on the element 62 by screwing by opening the corresponding valve. At the other end of the tube 61, the valve of the element 63 and opened in the same way by an identical fitting 65, ensuring the junction with a flexible tube 66 which discharges the fluid towards u # n tank 67 belonging to the hydraulic installation to be checked.

 The element 60 also comprises a temperature probe 68 which is mounted laterally in the tube 61 in the middle part thereof, so as to make its sensor member 69 penetrate inside the pipe through which the element circulates. fluid. The temperature taking element thus constituted makes it possible to carry out particularly reliable measurements of the temperature of the pipes, owing to the fact that one operates on circulating fluid, continuously sampled from the pipes.

 Of course, the device according to the invention, as described above in a particular embodiment, can also be supplemented to perform other functions for verifying the operation of the hydraulic circuits, as well as can modify it in various alternative embodiments without departing from the scope of the present invention.

Claims (15)

 1. Tester device for hydraulic circuits comprising a sampling element (1) comprising a body (5) provided with means (20, 15) for sealingly fixing to a pipe (10), a head (6) for penetrating inside of said piping (10) and a connector (3, 4) for connection with a measuring instrument for a conduit (11) formed through said body (5) and emerging from said head (6), characterized in that said element sampling (1) comprises a valve (12) of conical shape cooperating to close said conduit (11) with a seat (17) formed in said body around said conduit and a member (25) of elastic biasing of said valve towards said seat by distance from said head (6) for penetration into the piping, as well as means for centering said valve constituted by a rod (23) integral with said valve (12) which is slidably mounted in said conduit (11) by intercalated grooves with recesses providing long fluid passages tudinaux (30) in said conduit, and in that said fitting (3, 4) comprises an axial needle (41, 52) having an end (45, 58) of abutment on said rod (23) suitable for pushing said valve ( 12) away from its seat (17) against said elastic biasing member (25) automatically during the connection of said connector on said sampling element (1), said needle internally forming an axial channel (46, 55 ) of communication with said measuring instrument (possibly a sample reception flask), opening laterally in the vicinity of said end (45, 58) by at least one lateral channel (48, 56) for communication with at least one of said passages (30).  2. Device according to claim 1, characterized in that the needle (41, 52) of the connector has a narrowed section in the vicinity of said end (45, 58) to form an annular fluid chamber (49, 57) communicating said passages (30) with said axial channel (46, 55) when the valve is opened by the needle.  3. Device according to claim 1 or 2, characterized in that it comprises at least two interchangeable connections (3, 4), respectively for a pressure tap and for a sample tap.  4. Device according to any one of claims 1 to 3, characterized in that said elastic urging member of the valve is constituted by a helical spring (25) which rests on the one hand on an annular shoulder (27) around d 'a rod (24) extending said valve (12) and on the other hand on an annular shoulder (26) inside the head (5) of the sampling element.  5. Device according to any one of claims 1 to 4, characterized in that said connector comprises a cover (37, 51) in which said needle (41, 52) is rotatably mounted and in that said cover and a rear part (7) of said sampling element have cooperating threaded parts making it possible to connect the connector to the element by screwing, by opening the valve by the needle.  6. Device according to claim 5, characterized in that said needle (41, 52) forms outside of said cover (37, 51) a nozzle (47, 53) for joining with a flexible tube suitable for conducting the withdrawn fluid to a measuring instrument, possibly consisting of a simple bottle for receiving a sample.  7. Device according to any one of claims 1 to 6, characterized in that said sampling element (1) comprises a seal (22), mounted between a tube (18) forming said seat (17) and a ring (19) for fixing said tube (18) in the body (5) of the element, and in that said needle (41, 52) is shaped to cooperate with this seal (22) to seal around said conduit (11) when connecting the connector to the element.  8. Device according to claim 7, characterized in that said needle (41, 52) has means (43) for abutment on an end face (44) of said ring (19), in an extreme position where the valve is open .  9. Device according to any one of claims 1 to 8, characterized in that it comprises at least one connector (3) for pressure measurement in which said needle (41) has a nozzle (47) forming an elongated cylindrical tail of small section suitable for engaging in a flexible capillary tube (36) connecting with a pressure measuring instrument.  10. Device according to any one of claims 1 to 9, characterized in that it comprises at least one connection (4) for taking a sample in which said needle (52) has a nozzle (53) threaded externally to receive , by screwing, an end piece (54) of a flexible tube of relatively large cross-section to conduct the fluid withdrawn up to a bottle for receiving the sample.  11. Device according to claim 10, characterized in that it comprises at least two interchangeable connections (4) for taking a sample, suitable for taking samples at higher or lower pressures, in which the axial channel (55) of the needle (52) is respectively more or less eons', with in the first case a single lateral channel (56) and in the second case at least two similar lateral channels.  12. Device according to any one of claims 1 to 11, characterized in that said element it further comprises a temperature taking element (60), provided with a temperature sensor (69) immersed in a pipe (61) for circulating fluid which is connected in derivation of the piping to be checked on said sampling element.  13. Device according to Claim 12, characterized in that the said pipe (61) has internally threaded ends for receiving the respective heads (6) of two connectors according to Claim 9.  14. Device according to any one of claims 1 to 5, characterized in that it further comprises a safety plug (2) adaptable to the body (5) of the sampling element, in particular by screwing, to which comes replace said fitting (3, 4) when it is desired to take a sample.  15. Device according to claim 14, characterized in that said plug (2) comprises a shutter (32) rotatably mounted in a cover (28) for screwing on said sampling element (1), said shutter having means (40) abutment on said sampling element (1) and comprising a finger ((32) able to penetrate into said conduit (11) to close the latter in a sealed manner in an extreme position where the valve (12) remains closed.