FR3109977A1 - Safety decompression equipment for hydraulic circuit - Google Patents

Abstract

Provided is a secure pressure relief equipment for removing existing residual pressure on a hydraulic circuit apparatus comprising a secure relief well and a secure drain well. Actuation of the drain well needle screw opens the circuit and collects hydraulic oil under residual pressure in the drain well using an associated receptacle. The invention finds applications in the technical field of agricultural machinery and public works machinery in particular.

Description

Safety decompression equipment for hydraulic circuit

The present invention relates to safe decompression equipment for hydraulic circuits. The term "hydraulic circuit" means a circuit which may include in particular a hydraulic pump, capable of pressurizing a hydraulic fluid, one or more hydraulic motors, for example a cylinder, a hydraulic distributor, for example a spool valve, and a certain number pipes, rigid or flexible, connecting the pump to the motors, via the distributor.

The invention finds applications for any type of hydraulic circuit, and in particular a hydraulic circuit of the type fitted to public works machinery or agricultural machinery.

State of the prior art

In hydraulic circuits of the aforementioned type, a hydraulic fluid and in particular a hydraulic liquid, sometimes referred to as “oil”, serves as an energy vector between a hydraulic unit, on the one hand, and actuators, on the other hand.

The hydraulic unit generally comprises a pump or motor-driven pump making it possible to pressurize the hydraulic fluid.

The actuators can be rotary actuators, also referred to as hydraulic motors, or hydrostatic. They can also be linear stroke hydraulic cylinders. The actuators transform the hydraulic power generated by the pump of the hydraulic unit into mechanical power.

The use of a hydraulic circuit on a public works machine or on an agricultural machine makes it possible to easily supply energy to various accessories with which the machine is likely to be equipped. These are, for example, buckets with cylinders for a construction machine.

All you have to do is connect the accessories to the machine's existing hydraulic circuit. The connection can take place in a simple way by means of flexible pipes provided with hydraulic couplers. The hydraulic couplers of the flexible pipes are associated with combined hydraulic couplers, in the form of bases, present on the hydraulic circuit.

Hydraulic couplings of complementary male and female form allow connection without tools, by simple insertion, like a plug.

A difficulty arises for the operation of hydraulic couplers when the hydraulic fluid present in the circuit is under pressure. Indeed, the pressure exerts sufficient forces on fluid couplings to prevent, or at least to make it difficult to couple or uncouple them. It should be noted that this phenomenon occurs even when the hydraulic unit is not in operation or when it is not under load. After switching off the pump, a residual pressure remains present in this hydraulic circuit. This only disappears gradually and proves to be sufficient to hinder the operation of the couplers.

For example, the difficulty of maneuvering hydraulic couplers typically manifests itself when changing buckets on a construction excavator. Or even more frequently when using breakers on these same excavators.

To circumvent this difficulty, hydraulic circuits are known provided with relief devices with return lines to the reservoir of the hydraulic unit. These devices, external to the couplers, make it possible to control a pressure drop in the hydraulic circuit prior to any operation of the hydraulic couplers. Such equipment, however, makes the hydraulic circuit more complex. They also constitute a cause of fragility of the circuit, in particular on construction machinery, due to their exposure to shocks or due to the risk of tearing.

Other decompression systems exist as described in patent FR 1901535 or patent FR 1903138 or even patent DE 38 22 806 A1, all of which have the disadvantage of comprising only one orifice and of not being secure. If the operator makes a mistake by forgetting, for example, to re-tighten the sealing plug of the discharge well, this will have the effect of projecting the oil under a pressure of 300 to 400 bars at a temperature of 80°, which constitutes a great danger.

The various devices of this patent avoid these drawbacks.

The invention proceeds from the identification of a practice of certain operators consisting in partially unscrewing hydraulic couplers prior to their operation, so as to rapidly drop the pressure of the hydraulic circuit in the vicinity of the couplers. This practice, in addition to being dangerous, given the pressures involved, is tedious. Indeed, a set of wrenches is required to loosen the couplers. There is also a risk of inappropriate tightening when reconditioning fluid couplings.

The partial unscrewing of the hydraulic couplers has, moreover, the disadvantage of letting a certain quantity of hydraulic fluid escape. Indeed, by loosening the fastening of the couplers, a variable quantity of hydraulic fluid tends to flow along the pipes and to spread on the ground or in the machine equipped with the hydraulic circuit.

This poses both problems of operator safety, durability of equipment and soil pollution.

The object of the invention is to provide equipment making it possible to obviate these difficulties.

One aim is in particular to provide such equipment making it possible to drop the pressure of a hydraulic circuit quickly and in complete safety so as to allow easy connection or disconnection of the couplers.

An aim is also to provide such equipment making it possible to avoid any loss of hydraulic fluid, as well as any unexpected pollution.

Another aim is to provide equipment whose implementation is simple and rapid.

Another goal is to offer secure equipment that does not cause damage to the operator in the event of forgetfulness or incorrect operation.

Finally, an object of the invention is to provide reliable equipment which is suitable for machines working in difficult conditions and subjected to significant mechanical stresses.

To achieve these aims, the invention more specifically proposes a single decompression device of preferential but not exclusive cylindrical shape. Cylindrical equipment crossed axially by a hydraulic oil conduit connected to the existing hydraulic couplers.

Two side bores perpendicular to the duct ensure operation:

The first bore, called the relief well, contains a needle valve that is secured for opening or closing. The seat of the needle valve is connected in its distal part to the hydraulic conduit.

The second bore called drain shaft is specially arranged and connected by a channel to the discharge shaft. The drain well is threaded and suitable for receiving a receptacle by screwing, intended to contain the excess oil in an equally secure manner.

In the context of the invention, hydraulic fluid designates a liquid fluid at its operating temperature.

The relief shaft has two functions The first function consists of temporarily releasing the pressurized fluid in the pipe by unscrewing the needle valve from its seat. A second function is to collect a quantity of hydraulic fluid on the occasion of this actuation, in order to cause it to flow through a lateral channel in the direction of the hydraulic fluid receptacle secured to the drain well.

A non-removable flat broken ring arranged in a peripheral groove of the discharge shaft permanently prevents accidental unscrewing of the needle screw, thus protecting the operator from a jet of pressurized oil and ensuring his safety.

The threaded drain well which receives the receptacle by screwing is provided with a central stud arranged in its center forming a jet aerator and held in place by means of its threaded front part. At the periphery of the nipple an internal groove collects the hydraulic fluid and distributes it laterally through a bore or bores which pass through the groove and direct the fluid laterally inside the receptacle. Such an arrangement allows a very high safety in case of forgetting to close the needle screw which allows the filling of the receptacle. The jet will then not be directed towards the operator but will flow laterally into this jet-breaker nipple with much less force and violence, so much so that a simple cloth can be used without risk to collect the overflow. 'oil.

The hydraulic fluid container collects the released hydraulic fluid, thus preventing it from being released in an uncontrolled manner. After use, the receptacle can if necessary be emptied of its contents, for example by reintroducing the recovered hydraulic fluid into the hydraulic fluid reservoir upstream of the pump of the hydraulic unit.

The amount of hydraulic fluid flowing when the discharge needle is opened is relatively small, knowing that the discharge operation is carried out by cutting off the pump of a hydraulic unit from the hydraulic circuit provided with the decompressor. In other words, the discharge is carried out on the residual pressure of the hydraulic circuit. The capacity of the hydraulic fluid reservoir may be, for example, between 50 and 250 ml.

The engagement of the needle screw by screwing makes it possible to guarantee its precise positioning with respect to its seat to cause it to open without damage. Screwing in also makes it possible to reduce the needle actuation forces for a controlled and safe flow of the hydraulic fluid.

If necessary, the head of the conical screw can have a hexagonal recess centered on its screwing axis so as to allow the engagement of a socket wrench.

In a particular configuration, the hexagonal screwing socket spanner can be replaced by a hex bit inserted in the cap of an oil receptacle storage case.

The actuating head of the needle screw and the relief well have peripheral shoulders that come into mutual contact, in the actuating position. In their mutual contact, the shoulders fix the maximum stroke of the cone screw in the relief well. In this case, the needle length can be determined according to the position of the shoulders so as to let the oil pass by raising the needle just before the shoulders come into abutment. For a screwed actuating head, the position of the shoulders is relative to a screwing axis.

At least one of the shoulder of the relief well and the shoulder of the actuation head may have a seal and in particular a compressible seal. The seal makes it possible to seal the discharge well when the shoulders come into abutment and when the needle is resting on its seat. Outward loss of hydraulic fluid is thereby prevented.

It should be specified that a slight screwing range, corresponding, for example, to an amplitude of compressibility of the joint can advantageously be provided between a position in which the needle is released and a maximum screwing position fixed by the abutment of the shoulders. The actuation position is thus understood as a position included in this screwing range.

As mentioned earlier, the needle screw is fluidically connected with the hydraulic fluid receptacle.

According to a particular implementation of the relief well provided with its needle screw, the latter may comprise at least one lateral hydraulic fluid flow channel extending from the relief well to the drain well and its receptacle for hydraulic fluid. The flow channel or channels form in this case the fluidic link between the discharge well and the drain well provided with its receptacle.

The hydraulic fluid flowing from the seat of the needle valve at the time of its opening, is collected in the relief well and led to flow through a channel towards the receptacle fixed by screwing in the drain well. Preferably, the channel or channels have a reduced section compared to that of the discharge well, so as to cause a pressure drop in the hydraulic fluid reaching the receptacle.

The hydraulic fluid receptacle constitutes a hydraulic fluid manifold. In particular, a filler neck of the receptacle can be screwed onto the drain well. The removable nature of the hydraulic fluid receptacle makes it easier to empty the receptacle through its neck. Another possibility may consist in equipping the receptacle with a drain plug.

The cylindrical body of the decompressor may comprise an inlet end piece, and an outlet end piece, in mutual fluidic communication and in fluidic communication with the seat of the needle screw. This characteristic facilitates the serial assembly of the decompressor in a hydraulic circuit, the decompressor being traversed by the hydraulic fluid.

The terms "inlet endpiece" and "outlet endpiece" of the decompressor, still used in the remainder of the description, do not prejudge any connection direction of the decompressor to a hydraulic circuit. The direction of connection in a hydraulic circuit is free and has no effect on the operation of the decompressor.

When the decompressor is provided with an inlet fitting and an outlet fitting, it may be in the form of a straight connector, when the inlet fitting and the outlet fitting are coaxial, or of an elbow fitting when the inlet fitting forms an angle with respect to the outlet fitting.

The axis of the discharge well preferably forms a right angle with respect to the axis of the inlet nozzle and with respect to the axis of the outlet nozzle. In particular, when the inlet and outlet endpieces are coaxial, the discharge well and the drain well can preferably extend perpendicularly to a common axis of the endpieces.

The inlet end piece and the outlet end piece of the discharge coupler may comprise a thread.

According to another possibility, at least one of the inlet end piece and the outlet end piece may comprise or constitute a hydraulic coupler. Preferably, one of the inlet end piece and the outlet end piece may comprise a male hydraulic coupler and the other end piece may comprise a female hydraulic coupler. This configuration makes it very easy to insert the decompressor in series between an existing hydraulic base of a hydraulic circuit and a hydraulic coupler of a flexible pipe to be connected to the base.

The insertion of the decompressor in series in an existing hydraulic circuit, and in particular its coaxial insertion with the pipes of the hydraulic circuit, makes it particularly insensitive to shocks and possible stresses due to its cylindrical shape and the absence of any blunt external element such as as plug or nipple.

The needle screw has a hexagonal head at its proximal end. A slotted or recessed head with a hollow hexagonal recess is possible, as well as any other shape that would allow the screw to be rotated.

The receptacle is after use stored in a case fitted with a plug. To screw or unscrew the needle screw, a practical solution consists in equipping the cap of the case with a hexagonal socket socket, embedded in the cap, which allows you to always have the tool at hand.

To increase the tightening torque, a sliding rod can be added to the tool cap to allow better tightening of the needle screw on its seat.

Brief description of figures

Figure 1 is a cross-section of pressure relief equipment along a plane containing an axis of the relief well and an axis of the drain well and the oil receptacle.

Figure 2 is a 3D view of a decompression equipment according to the invention according to a plane containing the axis of the discharge well and the axis of the drain well and an axis of inlet and outlet nozzles. decompression equipment.

Figure 3 is a view of the needle valve, its gasket and the retaining split ring.

Figure 4 is a view of the central aerator pin for secure oil distribution in the drain well.

Figure 5 is a view of the respective positions of the needle valve in the closed or open position and of the associated position of the compressible seal.

Figure 6 is a view of the tool plug.

The figures are executed in free scale.

Detailed description of embodiments of the invention

Figure 1 is broken down into 3 main parts.

A first part which represents a section of the body of the decompression equipment. This body 1 is capable of being mounted in series in a hydraulic circuit. The threaded end 26 and the opposite threaded bore (not shown) of the base 30 of the equipment allow this coupling.

The body 1 of the decompression equipment can be made, for example, of metal, preferably of stainless steel, or else of a polymer.

Returning to Figure 1, one can note inside the body of the decompression equipment a through bore 7 extending substantially parallel to the axis of the body 1 of the decompression equipment. The through bore 7 constitutes a hydraulic fluid pipe connecting an inlet and an outlet of the body 1 of the coupler. More precisely, the conduit 7 formed by the bore fluidically connects the inlet fitting 26 and the outlet bore (not shown) at the base of the decompression equipment.

A second part is designated as discharge shaft 2 and comprises a bore perpendicular to the axis of the fluid circuit 7. This bore 2 is able to receive the needle valve 4 of discharge

The duct formed by the through bore 7 is also in fluid communication through a channel 8 and at its end the seat 9 of the needle screw 4. This is a needle screw 4 made of steel or other material provided at its end of a needle 18 capable of forming by screwing pressure by the combined effect of a hex key on the hexagonal head of the needle screw 4 and the threads 17 of this same needle screw 4 a sufficient seal with the seat 9. This screwing prohibits the passage of oil under working pressure, generally 250 to 400 bars.

It can be observed that the needle valve 18 is located at the bottom of a relief well 2, made in the form of a bore perpendicular to the axis of the body of the decompression equipment. The discharge shaft 2 thus forms a depression with respect to the surface of the body 1 of the decompression equipment. It constitutes an access to the seat 9. The fact of unscrewing the needle screw 4 towards the outside of its housing makes it possible to release a passage of fluid between the needle 18 and the seat of the needle 9. This passage, allows, if necessary, to let a small quantity of hydraulic fluid escape, and consequently to cause the residual pressure to drop in the through conduit 7 and more generally to cause the residual pressure to drop in a hydraulic circuit connected to the decompression equipment 1.

A safety split ring 25 is installed in the peripheral groove 13 of the discharge well 2. This split ring, which cannot be removed once installed, ensures safety by preventing any inadvertent extraction of the needle valve which would be dangerous. This blocking takes place by contact and blocking of the collar 16 provided on the needle screw coming into contact with the split ring 25 held in the groove 13.

It should be noted that the groove 13 is configured so as to allow axial play in the movement of the broken ring 25 depending on the screwing or unscrewing of the needle screw 4. This play has the effect of allowing strong compression of the compressible seal 14 when the needle 18 is in contact with the seat 9 to block the strongest hydraulic pressure. On the other hand, in the open position the needle 18 moves back and the pressure on the seal 14 decreases but must remain sufficient to still ensure sealing with a lower residual oil pressure.

This organization is a step forward compared to existing needle decompression systems because this double compression of the seal, one strong when the pressure is at its maximum, i.e. 400 bars and the other weak when the needle 18 is detached from its seat. 9 with a residual pressure of a few bars, allows a great simplification in the construction of the sealing system of the decompressor compared to existing systems.

This configuration allows a double seal due to the strong compression of the needle 18 on its seat 9 and the strong compression of the compressible seal 14 at the same time. Moment which corresponds to the closing of the oil circuit which will be pressurized by several hundred bars when the hydraulic pump is restarted.

This innovative configuration is only permitted if the stroke of needle valve 4 is limited so as to allow effective sealing of seal 14 in both cases: maximum pressure and residual pressure. This limitation in the stroke of the needle screw 4 is obtained by the installation of the split ring 25 for blocking which ensures this double function of safety and compression with double effect on the compressible seal.

A third part is designated as a drain well 3. This drain well 3 is able to receive, by means of two threaded parts, a central cylindrical drain jet-breaker stud 5 equipped at its base with a threaded end piece 22 and a internal peripheral groove 20 connected to lateral channels 23 intended for a secure flow of oil under residual pressure.

The peripheral groove 20 is arranged opposite a flow channel 24 connecting the discharge well 2 and the drain well 3.

The main inlet threaded bore 40 of the drain well 3 is able to receive by screwing a bottle 6 or any other receptacle provided with a suitable threaded end. This pressurized fluid flow configuration is intended to ensure the protection of the operator who can no longer receive a dangerous direct jet of pressurized oil but with the aid of the jet-breaker nipple 5 a lateral flow of this oil. under pressure which will have lost its strength and will no longer present a danger. Even in the event of forgetting to close by tightening the needle screw 4, safety is thus ensured.

Figure 2 shows the arrangement of the safety elements such as the split ring 25 for retaining the needle screw 4 in the discharge well 2. Also the arrangement of the stud 5 for distributing oil in the drain well 3 . nipple 5 is screwed into the center of the discharge well using a specific tool using the two bores 28 allowing the threaded end piece 22 to be screwed into the threaded housing 19 (FIG. 1). For ultimate safety reasons, a pin 27 (not shown in FIG. 1) blocks the jet-breaker pin 5 in rotation, preventing any unscrewing or loss due to the vibrations of the machine.

Figure 3 shows the conical screw 4 and the broken safety ring 25 which has the particularity of not being removable.

Figure 4 shows in detail the peripheral internal groove 20 of the central aerator pin 5 of the drain well 3 and the threaded end piece 22 which allows screwing into the threaded bore 19 (Figure 1) the safety pin 27 which prevents any unscrewing is also represented.

Figure 5 shows an important aspect of the device concerning the simplification of this decompressor compared to more complex existing systems to ensure the tightness of the decompressor itself.

It should be noted that the groove 13 is configured so as to allow axial play in the movement of the broken ring 25 depending on the screwing or unscrewing of the needle screw 4. This play has the effect of allowing strong compression of the compressible seal 14 when the needle 18 is in contact with the seat 9 and the hydraulic pressure is the strongest. On the other hand, in the open position the needle 18 moves back and the pressure on the seal 14 decreases but must remain sufficient to still ensure sealing with a lower residual pressure of the oil to be evacuated.

This is an innovation compared to existing needle 18 decompression systems because this double compression of the seal 14, one strong when the pressure is at its maximum, i.e. 400 bars and the other weak when the needle 18 is detached from its seat with a residual pressure of a few bars, allows a great simplification in the sealing system of the decompressor 1 compared to existing decompressors.

This configuration allows a double seal due to the strong compression of the needle 18 on its seat 9 and the strong compression of the seal 14 compressible at the same time. Moment which corresponds to the closing of the oil circuit which will be pressurized by several hundred bars when the hydraulic pump is restarted.

This innovative configuration is only permitted if the travel of the needle valve is limited so as to allow effective sealing of the joint in both cases: maximum pressure and residual pressure. This limitation in the travel of the conical screw is obtained by the installation of the broken locking ring 25 which ensures this double function of safety and compression with the double effect of the seal 14.

Position A passage of oil under residual pressure: The needle 18 is detached from the seat 9 by retraction of the needle screw 4. The seal 14 is then slightly compressed against the collar 16 blocked by the broken ring 25 itself contained by the groove 13. Oil flows into channel 24.

Position B closing the oil passage: the needle screw 4 (Figure 1) compresses the needle 18 on its seat 9 and in doing so also strongly compresses the compressible seal 14 thus ensuring a double seal.

Figure 6 shows the tool imagined in combination with the closure cap 35 of a waterproof case intended to store the receptacle. A male or female hex socket 34 depending on the configuration of the needle screw head is crimped into the thickness of the cap 35. An O-ring 36 seals the storage case.

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A hexagonal recess 30, also visible in Figure 2, is made on the body of the decompression equipment, so as to be able to engage a tightening key.

Claims (5)

Decompression equipment comprising at least one discharge shaft (2) provided with the system for opening and closing a hydraulic circuit and a drain shaft (3) connected to the discharge shaft by a flow channel (8). Safety decompression equipment for hydraulic circuit according to claim 1 comprising a decompression device (1) provided with a pressure relief well (2) implemented by the actuation of a needle screw (4) the path of which is secured by a locking ring (25) and a drain well (3) connected by a channel (8) to the discharge well (2) which is secured by the addition of a central cylindrical jet aerator (5) grooved (20) pierced with peripheral bores (23) capable of distributing the hydraulic fluid in a secure manner in a receptacle (6). Decompression equipment according to claim 2, in which the discharge needle screw (4) is prevented from rotating by a non-removable split ring (25) embedded in a groove (13) of the bore of the discharge well (2) and ensures the safety of the hydraulic pressure relief preventing any withdrawal of the needle screw (4). Equipment according to claim 2, in which the drain well (3) is secured by a central jet aerator pin (5) made unremovable by a blocking pin (27), central cylindrical jet aerator pin (5) provided with a internal groove (20) and peripheral bores (23) allowing the oil to be distributed laterally under low pressure in a secure manner. Equipment, according to claim 2, in which the collar (16) of the needle screw (4) compresses a compressible seal (14) strongly when the needle screw (4) is in contact with the seat (9) and by contact with a ring broken (25) limits the withdrawal of the needle screw (4) while still ensuring sufficient compression of the compressible seal (14) to stop the fluid under residual pressure when the needle screw (4) is loosened.