WO2007006940A2

WO2007006940A2 - Hydraulic jack safety device

Info

Publication number: WO2007006940A2
Application number: PCT/FR2006/001636
Authority: WO
Inventors: Jean-Paul Landier
Original assignee: Rassant Industries S.A.S.
Priority date: 2005-07-08
Filing date: 2006-07-07
Publication date: 2007-01-18
Also published as: WO2007006940A3; FR2888228A1

Abstract

The invention relates to a hydraulic jack safety device, in which the hydraulic jack comprises a housing containing at least: a reservoir (17) for a fluid; a piston which moves inside a cylinder; a pressurised chamber (16), a conduit (15) for returning the fluid to the reservoir; and a tool (26) which exerts an interlocking force, by means of contact maintained under the action of a user, in order to open a device (1, 2, 3, 4, 5, 6, 7, 8) that is used to open and close the return conduit. According to the invention, the aforementioned tool detaches from the return conduit opening/closing device when the force from the user is no longer exerted and the opening/closing device is closed by a return means when the interlocking force is no longer exerted.

Description

Safety device of a hydraulic jack

The present invention relates to the field of safety members of hydraulic jacks. It relates more particularly to a secure device for controlling the descent of a manually operated hydraulic jack manually.

A problem in the field of hydraulic jacks is the safety, during the phase of descent of the jack, for the people being close to the jack. Hydraulic jacks are known in the prior art and are lifted by means of a manual pump, which is actuated, for example, with a lever and makes it possible to lift a large load. A fluid under pressure allows the elevation of a piston sliding in a cylinder. The descent is performed by opening a conduit connecting the compression chamber and the liquid reservoir. The high load during the lifting phase is then lowered by driving the fluid out of the compression chamber.

This type of jack has a disadvantage in terms of safety, namely that the descent movement continues as soon as it has been triggered by the user. Stopping the descent, according to the prior art, is indeed achieved by a specific stop command or by an action of the user to disengage the descent command. An activation lever will remain, for example, in position under the action of its weight. Thus in the case where the user has a discomfort or accidental fall, the descent of the jack continues dangerously, the user can no longer control the stop of the descent of the hydraulic cylinder.

The present invention aims to overcome the disadvantages of the prior art by providing a jack whose descent mechanism is secure. That is to say that the jack comprises a safety device for the descent, controlled by the user and which stops the descent of the jack, in the case where the user does not exert a continuous control of descent of the jack hydraulic. This device thus prevents accidents occurring in the case where the user has a discomfort or accidentally falls. This object is achieved by a safety device of a hydraulic jack, the hydraulic jack comprising in a frame at least:

a reservoir containing a fluid,

a piston moving in a cylinder,

a pressurized chamber located in the cylinder and under the piston, containing fluid under pressure,

a fluid return duct connecting the pressure chamber to the tank, characterized in that it comprises a tool which exerts, by contact maintained under the action of a user, a latching force to open a device; opening and closing of the return duct, the tool disengaging from the opening and closing device of the return duct when the action of the user is no longer exerted while the opening and closing device of the return duct is closed by a return means when the engagement force is no longer exerted. According to another feature, the safety device is an entirely mechanical device.

According to another feature, the opening and closing device of the return duct comprises at least one non-return valve comprising at least one ball bearing against a circular orifice of a valve to close the return duct.

According to another feature, the ball of the check valve rests against the circular orifice of the valve in a rest position and is pushed back from the circular orifice of the valve by a needle controlled by the engagement force to open the return duct.

According to another feature, a spring is supported on the one hand on the bottom of a well forming the valve and on the other hand on the needle, tending to push the needle of the circular orifice of the valve.

According to another feature, the valve comprises a regulating orifice of a determined diameter, in connection with the reservoir, limiting the flow of the fluid to the reservoir and maintaining the pressurized fluid upstream of the regulator orifice.

According to another feature, the needle is in a needle chamber communicating with the return duct via a pressurization port located downstream of the non-return ball valve and upstream of the regulator orifice of the valve, the pressure exerted by the fluid on the needle tending to move the needle away from the circular orifice of the valve.

According to another feature, the engagement force is achieved by a force in rotation of the user on the tool converted into a translation movement by a pusher having a reversible pitch helical connection with the fixed frame, a first end pusher driving the needle in translation to move the ball of the check valve from the circular orifice of the valve and the needle pushing the pusher in a reverse helical movement when the action of the user is no longer exercised .

According to another feature, the helical connection, between the pusher and the frame, is made reversible by a screw length of determined length, having a fixed number of threads.

According to another feature, a second end of the pusher comprises a cap below which is mounted a pin projecting from each side to form two cooperating nipples, when the engagement force is exerted, with a key having at one end a hole centering relative to the cap and two grooves housing the pins, the grooves starting at the end of the key by a portion whose axis of symmetry is parallel to the axis of the key and the pusher and extending, by a portion, corresponding to a half pin diameter, perpendicular to the axis of the key and in the opposite direction to the direction of rotation of the key exerting the engagement force, the key comprising at its other end a perpendicular handle for exercising the force and the cap being formed so that in the absence of action exerted by the user the key is disengaged from the pusher. Other features and advantages of the present invention will appear more clearly on reading the description below, made with reference to the accompanying drawings, in which:

- Figure 1 shows a sectional view of a portion of the secured descent device secured to a hydraulic jack;

- Figure 2 shows a sectional view of a ring of the device according to the invention;

- Figure 3 shows a sectional view of a valve of the device according to the invention;

FIG. 4 represents a front view of a needle of the device according to the invention;

- Figure 5 shows a sectional view of a decompression body of the device according to the invention;

FIG. 6 represents a decompression pusher of the device according to the invention;

- Figures 7 and 8 show a jack associated with a device according to the invention.

The invention will now be described with reference to FIGS. 1 to 8. Part of the safety device, integral with the hydraulic cylinder, shown in FIG. 1, intersects the return flow of the fluid flowing in a return pipe (15). during the descent of the jack to stop or allow the return of fluid from the piston to the reservoir (17). The return duct (15) connects the chamber (16) under pressure, arranged under a lifting piston (21), to the reservoir (17). Figures 7 and 8 show a hydraulic jack as a whole, comprising the part of the safety device secured to the jack, associated with a key (26) for lowering the jack, according to the invention. Pumping is performed by a pumping lever, incorporated in the cylinder, actuating a piston (19) for pumping suction fluid from the reservoir (17) to discharge it through a conduit (18) of supply, by a double valve mechanism . The fluid is sucked from the fluid reservoir (17) to the pumping piston (19) through a suction valve (22) and is then expelled to the pressure chamber (16) through a discharge valve (23). In a nonlimiting manner, the reservoir (17) communicates with the pump via the suction valve (22) and also via a bypass overload valve (24). The jack comprises a return duct (15) separate from the supply duct (18).

When the safety device of the invention opens the conduit (15) back, the fluid escapes from the chamber (16) under pressure to the reservoir (17). The load, lifted during the lifting phase, descends by pushing the piston (21) above the chamber (16) downwards and expelling the fluid from the chamber (16) under pressure. The pressure in the chamber can rise to values of the order of 600 bars.

Without limitation, the safety device has an axis of symmetry which is also the axis of rotation of a key (26) for controlling the descent, by which the control effort of the user is exerted. The device comprises a ball valve (4) non-return closing in the rest position the conduit (15) return. The ball (4) of the non-return valve is held by a spring (41) and a contact piece (42) resting on a circular orifice (201) of a decompression valve (2), shown in FIG. 3. On the other hand, the return duct (15) communicates with the reservoir (17) through this valve (2) through a hole (202) of determined diameter. Finally, the valve (2) comprises a pressurizing passage (203) through which the fluid flows to a chamber (101) of a needle (3) disposed in a decompression body (1), shown in FIG. 5, the body (1) of decompression being fixed, for example by screwing, in the frame. A thread (204) is formed on the valve (2), as a gripping means, in order to be able to disassemble this mechanism.

The needle (3) is movable, relative to the body (1) of decompression, in a translational movement or rotation along the axis (d1) of symmetry of the body (1) of decompression. A spring (5), shown in Figure 1, bears on the one hand on the valve (2) and on the other hand on a shoulder (32) of the needle (3). The needle (3) has at one end a head (31) and at the other end a rod of diameter smaller than that of the passage (203) in the valve (2). A seal (12) seals between the valve (2) and the return duct (15). Two seals (10, 11) seal at the decompression body (1). A first (10) seal provides the outer seal between the body (1) and the frame. A second (11) seal provides the internal seal between the body (1) and the needle (3). The surface of the wall of the needle chamber (101) is made with a determined roughness over a determined height (103) in order to ensure the seal between the needle (3) and the body (1) at the joint ( 11) in the chamber (101).

A pusher (6), shown in Figure 6, bears on the head (31) of the needle (3), shown in Figure 4. The pusher (6) and the body (1) of decompression comprise a complementary thread cooperating with a determined thread, to form together a helical displacement link (L81, L86). The pusher is limited in translation, in its recoil movement, by a housing (9) fixed, for example, non-limiting manner, by screwing on the body (1) of decompression. The casing (9) comprises, for this purpose, a bore whose outer diameter rests on a ring (13) blocked in a groove (61) of the pusher (6), shown in Figure 6. The pusher is controlled in rotation by means of connection with the key (26) for lowering the jack. The connecting means with the key (26) comprise, for example, an assembly formed by a ring (7) comprising a cap or a bevel mounted on the pusher (6) by a hole (T72) along the axis (d1) and held by a pin (8). The pin (8) passes through the ring (7) and the pusher (6) through a hole (T6, T71) perpendicular to the axis of symmetry of the device. The pin (8) being tightened by the ring (7) or the pusher (6), these three parts are integral.

At rest the ball (4) of the valve is compressed against a hole (201) circular, thus closing the conduit (15) back. The ball (4) is compressed both by a spring mechanism and also by the fluid. The pressure inside the chamber (16) compression is then exerted on the ball (4) of the valve.

The device according to the invention allows the lowering of the jack when the non-return ball valve (4) is open. The liquid then flows from the room (16) compression, through the conduit (15) back to the reservoir (17) through the ball valve (4) and the hole (202) calibrated valve (2).

To open the ball check valve (4), the needle (3) pushed by the pusher (6), moves the ball (4) away from its seat and releases the orifice (201) of the valve (2) decompression. To move the needle (3), in a translation movement, a user transmits, for example, a rotational movement to the pin (8) and the ring (7) connected to the pusher (6). The translational movement of the pusher (6) towards the needle results from the helicoidal movement of the pusher (6) with respect to the body (1), activated by a force torque exerted by the user by means of the control key (26). of the descent. The pusher (6) which bears on the head (31) of the needle (3), transmits this translational movement to the needle (3), which then moves the ball (4) away from the circular orifice (202) of the valve (2). The key (26) is rotated through handles or other gripping means.

When the rotational force on the pusher (6) is interrupted, the pusher exerts a small force determined on the needle (3) which is then pushed back from the orifice of the valve (2) on the one hand under the action spring (5) disposed in the needle chamber (101) and secondly under the action of the pressure exerted by the fluid. The ball (4) is then pressed again against the circular orifice (202) of the valve and closes the conduit (15) for returning the fluid.

The needle (3) pushes the pusher (6) which undergoes a helical recoil movement relative to the body (1) of decompression. In one embodiment, this helical movement caused by a translation movement of the needle (3) is possible only because the thread of the pusher (3) is important. Indeed, the thread of 8mm, comprising four threads, avoids excessive friction forces. In another embodiment, the frictional forces at the helical link (L86, L81) are avoided by a ball bearing screw.

Advantageously, if the user stops performing his action, for example by ceasing to exert a force torque on the key, the return flow is stopped and therefore the descent of the hydraulic cylinder is also stopped. The needle (3) is separated from the valve (2) by the combination of two forces exerted on the one hand by the pressure of the liquid on the needle (3), and on the other hand by the spring (5) resting on the valve (2) and the needle (3). The combination of these two forces constitutes a restoring force, towards the rest position, of the device. The chamber (101) of the needle in the decompression body (1) in fact communicates with the valve (2) through an orifice (102) for pressurizing the chamber (101). The chamber (101) of the needle is therefore filled with pressurized liquid and is at the same pressure as the chamber (16) in the cylinder (20) of the jack. This pressurized liquid exerts a force proportional to the load lifted by the hydraulic cylinder, pushing the needle (3) away from the orifice of the valve

(2).

The liquid filling the chamber (101) of the needle (3) is pressurized relative to the reservoir (17) due to its location upstream of the hole (202) whose diameter is determined to regulate the flow rate in the valve (2). The hole (202) has in fact a determined diameter, made in an exemplary embodiment at a value between 0.5 and 0.9 mm. The function of the regulator hole (202) is therefore twofold. The regulator serves both to control the rate of descent of the jack by controlling the fluid flow and to pressurize the chamber (101) of the needle (3).

The safety device comprises an automatic disengagement if the control force is no longer exerted by the user. Indeed the control key of the descent falls if the user releases it. For example if the user releases the key to move away from the hydraulic cylinder or in the event of a fall of the user, the descent of the hydraulic cylinder is stopped. In an exemplary non-limiting embodiment, the pin (8) protrudes from each side of the ring (7) and the assembly consisting of the ring (7) and the pin (8) serves as a key hold (26). activation of the device. The activation key (26) drives the compound consisting of the pusher (6), the ring (7) and the pin (8) in a rotational movement. The ring (7) is centered in a hole (261) for centering the key (26). The pin (8) is inserted into a passage (262) parallel to the axis (d1) of the device and continuing with a portion perpendicular to the axis (d1) of the device of dimension of the order of diameter of the pin and going in the opposite direction to the direction (263) of rotation of the rotational control force. Once the pin (8) abuts in the portion perpendicular to the axis (d1), the rotational movement exerted by the user is transmitted to the assembly consisting of the pin (8), the ring (7) and the pusher (6). In addition the pin (8) being in a portion of the passage (262) perpendicular to the axis (d1) of the device, the key (26) of activation is locked in translation. This drive means is similar to a bayonet mechanism and has the advantage of disengaging automatically if the user releases the key (26) activation. Indeed, in the case where the user releases the key, following an accidental fall or discomfort, the beveled shape of the ring and that of the pin (8) allow the key (26) to switch. The key (26) driven by its weight tilts and thus releases from the pin (8). Once the activation key (26) has fallen, the force torque previously exerted on the pusher vanishes, the needle is pushed back and the check valve closes the return duct (15) again.

According to another embodiment, the activation key comprises a first housing, for example of hexagonal section, coming around a complementary shaped head disposed at the outer end of the pusher (6). Disengagement means of the key comprise for example a retractable central rod in a second housing opening at the bottom of the first housing. The central rod thus leaves its housing when the key is not maintained by the user, pushing the key of the pusher (6). Conversely, the central rod is pushed into its housing under the action of the user, the connection made between the key and the pusher (6) then allowing the user to exert a descent control force.

The safety device is advantageously made by mechanical elements interacting with each other and not requiring an external source of energy, such as for example an electric generator. Thus the device according to the invention remains portable and the security does not depend on external conditions, such as the state of the power supply network. It should be obvious to those skilled in the art that the present invention allows embodiments in many other specific forms without departing from the scope of the invention as claimed. Therefore, the present embodiments should be considered by way of illustration, but may be modified within the scope defined by the scope of the appended claims, and the invention should not be limited to the details given above.

Claims

1. Safety device of a hydraulic jack, the hydraulic jack comprising in a frame at least:

a reservoir (17) containing a fluid,

a piston (21) moving in a cylinder (20),

a chamber (16) under pressure located in the cylinder (20) and under the piston (21), containing fluid under pressure,

a conduit (15) for returning the fluid connecting the chamber (16) under pressure to the reservoir (17), characterized in that it comprises a tool which exerts, by contact maintained under the action of a user, a force engagement device for opening a device (1, 2, 3, 4, 5, 6, 7, 8) for opening and closing the return duct, the tool being disengaged from the device for opening and closing the duct return when the action of the user is no longer exercised while the opening and closing device of the return duct is closed by a return means when the engagement force is no longer exerted.

2. Safety device according to claim 1, characterized in that it is an entirely mechanical device.

3. Safety device according to claim 1 or 2, characterized in that the opening and closing device of the return duct comprises at least one non-return valve comprising at least one ball (4) bearing against an orifice (201) circular valve (2) for closing the conduit (15) return.

4. Safety device according to claim 3, characterized in that the ball (4) of the non-return valve rests against the orifice (201) of the circular valve (2) in a rest position and is pushed back. the circular orifice of the valve by a needle (3) controlled by the engagement force to open the conduit (15) return.

5. Safety device according to claim 4, characterized in that a spring (5) is supported on the one hand on the bottom of a well forming the valve (2) and on the other hand on the needle (3). ), tending to push the needle (3) of the orifice (201) circular valve (2).

6. Safety device according to claim 4 or 5, characterized in that the valve (2) comprises a orifice (202) of a determined diameter, in connection with the reservoir (17), limiting the flow of fluid to the reservoir ( 17) and maintaining the pressurized fluid upstream of the regulator orifice (202).

7. Safety device according to claim 6, characterized in that the needle (3) is in a chamber (101) of the needle communicating with the conduit (15) return by a pressurization port located downstream of the ball valve ( 4) anti-return and upstream of the orifice (202) regulating the valve (2), the pressure exerted by the fluid on the needle (3) tending to move the needle (3) away from the orifice (201) circular valve (2).

8. Safety device according to one of claims 4 to 7, characterized in that the engagement force is achieved by a force in rotation of the user on the tool converted into a translational movement by a push rod (6) having a helical link (L81, L86) reversible with the fixed frame, a first end of the pusher (6) driving the needle (3) in translation to move the ball (4) away from the check valve of the orifice (201) circular valve and the needle (3) pushing the pusher (6) in a reverse helical movement when the action of the user is no longer exercised.

9. Safety device according to claim 8, characterized in that the connection (L81, L86) helical between the pusher (6) and the frame, is made reversible by a screw length of determined length, having a determined number of nets.

10. Safety device according to claim 8 or 9, characterized in that a second end of the pusher (6) comprises a cap in below which is mounted a pin (8) projecting from each side to form two cooperating pins, when the engagement force is exerted, with a key (26) having at one end a hole (261) for centering with respect to the cap and two grooves (262) for housing the pins, the grooves (262) starting at the end of the key (26) by a part whose axis of symmetry is parallel to the axis of the key ( 26) and the pusher (6) and extending, by a portion, corresponding to a half pin diameter (8), perpendicular to the axis of the key (26) and in the opposite direction to the direction (263) of rotation the key exerting the engagement force, the key (26) having at its other end a perpendicular handle for exerting the force and the cap being formed so that in the absence of action exerted by the user the key (26) is disengaged from the pusher (6).