FR2562965A1 - INVERSION VALVE, IN PARTICULAR TO ORDER A HYDRAULIC CYLINDER - Google Patents

Abstract

REVERSE VALVE, IN PARTICULAR TO CONTROL A HYDRAULIC CYLINDER. THE BODY 1 OF THE VALVE INCLUDES SEPARATE CHANNELS 2, 4, 5, 9, 17 A 23 TO SELECTIVELY CONNECT A HYDRAULIC PUMP P AND A TANK TA TWO PIPES A, B OF A CYLINDER 26 AND HOUSES A SLIDE 3 IN WHICH ONE BALL 6 LIES ON A SEAT 7 PRESENTING NOTCHES LEAVING A THROTTLE PASSAGE. AN AUXILIARY PISTON 13, BORED BY A THROTTLE HOLE 14, MAY COME IN TIGHT SUPPORT AGAINST A BOSS 24, TO INTERRUPT THE FLOW OF THE LIQUID DOWNSTREAM OF THE BALL 6. EACH COMING OF THE PISTON 27 AT THE END OF THE RACE IN THE CYLINDER 26 INTERRUPTS THE FLOW OF LIQUID IN THE SLIDE 3. THE POSITION REVERSE OF THE SLIDE 3 IS PROVIDED BY THE INLET HYDRAULIC PRESSURE AND THE RETURN SPRING 12. APPLICATION TO THE RETURN OF TOOLS BY HYDRAULIC CYLINDERS.

Description

The present invention relates to a

  version, for controlling a hydraulic maneuvering apparatus

  such as a hydraulic cylinder, an actuating device

  rotation, or another type of hydraulic motor, by reversing the direction of action

  for example to rotate a reversible plow associated with

to the hydraulic cylinder.

  An inversion valve of the kind in question

  is essentially intended to allow a cylinder to

  to complete a complete race of work, from a first posi-

  end position at a second opposite end position and vice versa, for example to reverse the position of a tool, such as a reversible plow,

  connected to the cylinder. If the cylinder piston is initially

  fully retracted position, the provoking valve

  that the movement of the piston to the full extension position of the cylinder, then controls a reversal of movement of the piston so that it returns to its starting position. Whatever the end position of the piston of the cylinder at the beginning of a working stroke, it is necessary that the reversing valve which controls the jack forces the piston to perform a double complete working stroke, go-and-go. return, so that the piston returns then stop at its starting position. To order such

  cylinder operation, the reversing valve is con-

  particularly supplied with hydraulic fluid under pressure,

through a single inlet port.

  The reversal valves of the kind in question are most often of the so-called "pressure threshold" type, that is to say they control the inversion of the

  piston movement when the pressure of the hydraulic fluid

  that reaches a predetermined value. Under these conditions, a significant part of the useful pressure is used to control the valve, to the detriment of the pressure actually used for the operation of the associated hydraulic apparatus. If, for example, there is a hydraulic pressure of 150 bar at the inlet of the valve, it is not uncommon to

  reserve about 30 bars to control the valve itself.

  Thus, in view of the losses in charge related to the flow of the liquid through the valve, there is little

  than 100 to 110 bar for the operation of the hydrau-

  associated partner. If the reversing valve is used to reverse the direction of movement of the piston of a jack that controls the pivoting of a plow or reversible tool, it may be difficult to force the tool to

  crossing the neutral position of its connecting linkage

  at the end of the stroke of the cylinder rod, especially if this rod has to work in traction with some

  obliquity. In such a case, if an inverting valve is used

  pressure valve, this valve does not force the piston of the cylinder to restart in the opposite direction until the inlet pressure of the hydraulic fluid has reached

  predetermined value, in other words, the pivoting movement

  is necessarily interrupted for a certain period of time

  time, waiting for a sufficient increase in pressure

  in order to trigger the reversal of movement of the piston of the jack, the object of the present invention is to remedy

  to the disadvantage which has just been exposed concerning the

  pressure reversal pumps, to achieve a

  Reversing valve design simpler than the known inversion valves of the pressure threshold type, the new valve proposed reacting more smoothly and more quickly than the known valves. Compared with these known valves, the reversing valve according to the invention is suitable for the same applications, but without depending on an increase in the inlet hydraulic pressure for the change of position of its slide. As discussed below, the inversion valve contemplated by the invention, of the kind defined above, comprises a body in which are

  various separate channels, to connect selectively

  a pump, which delivers hydraulic fluid under pres-

  a reservoir, which serves to recover the fluid, two pipes that serve a cylinder to ensure the arrival of the hydraulic fluid under pressure, and the return of the fluid

  to the tank; the body of the valve contains a

  slat or drawer in which a bore serves as a housing for a movable shutter, such as a ball requested by a

  spring resting on a seat in the bore of the neck.

  lisseau; it is provided with passages such as canals

  and annular recesses for selectively cooperating with

  with the aforementioned channels of the valve body, when

  the slider is in one or other of its positions.

extreme conditions.

  Among some essential features of the reversing valve according to the invention, there is in particular the fact that: - means are provided on the seat formed in

  the bore of the slider, and / or on the bearing surface

  shutter, to prevent complete sealing of the shutter contact in support of the seat; we let

  to a relatively narrow passage between these two organizations.

  in the support position, so that the corresponding throttle

  dant ensures a pressure drop at the seat, when

  that there is a flow of fluid under pressure in the internal bore of the slider; this pressure drop then causes the slide to move from one to the other of

  its extreme positions; and the slide is intended to co-

  with an auxiliary piston, biased by a spring and provided with a hole of substantially smaller section than the internal bore of the slide; the arrangement is such that the piston hole acts as a throttling orifice,

  and that, in one of the extreme positions of the piston, the end

  the piston hole comes into sealing engagement with a boss provided for this purpose in the body of the valve, so as to seal the passage of the hydraulic fluid in the hole

  throttle, and to allow the return of the

  slid to its initial position as soon as the hydraulic fluid

  under pressure will cease to circulate with regard to the obtura-

  tor ,. - The slider and the piston are mounted in the extension of one another, in a bore of the body of the valve which is a housing for these two bodies; these are intended to take three main positions, namely an extreme position "right" and an extreme position "left", where the two bodies are at the end of stroke in support against each other, and a third main position, where the piston is at the end of the race

  in its extreme "left" position, the slide is

  then at the end of the race in its extreme position "on the right"; - The seat provided for the shutter in the inner bore of the slider can be constituted by notches, preferably arranged symmetrically to prevent a completely sealed contact of the shutter resting on the seat; and

  - the piston return spring is more

  that the return spring of the slide.

  Unlike the known inversion valves, of the pressure threshold type, the operation of which depends on a sharp increase in the arrival hydraulic pressure, the operation of the reversing valve according to the invention depends on the flow rate. hydraulic fluid. And a slight pressure drop (from 2 to 3 bar) at the seat in the inner bore of the slider is sufficient to hold the slider in one of its extreme positions. We can therefore use in an optimal way the

  hydraulic pressure available ,. On the other hand, with the

  Inverting poppet according to the invention, there is no need to provide a correspondence adjustment with a pressure

  determined operation ,. Indeed, the inversion valve

  sion according to the invention functions correctly at all

  pressures up to the maximum expected pressure.

  We will now describe an embodiment

  of the invention, presented hereinafter by way of illustrative example

  and in no way limiting, with reference to the

where,

  FIG. 1 is a diagrammatic section of a

  reversal valve according to the invention, associated with a hydraulic cylinder; Figure 2 is an enlarged detail of the valve of Figure 1; Figures 3 and 4 are sections of the valve, similar to the section of Figure 1, but corresponding to situations different from that of Figure 1, as to the positions of the cylinder and the positions of the slide of

  distribution, or drawer, and the auxiliary piston of the

  Pope. The reversing valve which is shown in the figures serves for example to control a hydraulic cylinder 26, to reverse the direction of operation of the piston 27 and the rod 28 of the cylinder, in order to pivotally drive a

  associated reversible plow (but not shown), the

  pope of inversion has a body 1, in which are

  Various separate passages 2, 17, 18, 19, 20, 21 serve to provide various modes of communication of the hydraulic cylinder 26 with a pump P and a hydraulic accumulator T 1. For this purpose, the cylindrical body of the cylinder 26 is connected to the body 1 of the valve by two pipes A and B, one of which ensures the arrival of hydraulic fluid to the cylinder, and the other the return of this fluid. In the body 1 of the valve is mounted a slider or drawer 3 of distribution, in which is formed a cavity 4, 4 'longitudinal open ,. This cavity contains a shutter, constituted for example by a ball 6 biased by a compression spring 10 which presses this ball against a seat 7 shutter 2 provided in the cavity 4, 4 '. The slider 3 further comprises channels 5, 9, and peripheral grooves 22, 23 for

  to cooperate in turn with the channels of the body 1 of the sou-

  In the two extreme positions of the slider 3, the hydraulic jack 26 comprises a piston 27, a piston rod 28 having an end 30, and a pivot point 29 for the cylindrical body of the cylinder, the axis of the cylindrical body of the cylinder 26 can take three reference positions. In position a of the axis of the jack 26, the piston 27 is completely set back in the starting position in the cylinder (FIG. 1). The position a2 of the axis of the jack corresponds to the maximum extension stroke of the rod 28 and the piston 27. The position a3 of the axis of the jack is the so-called inversion position, where the piston 27 has returned to her

  initial position of maximum retraction in the cylindrical body

  drique of the cylinder. The three main positions a1, a2, a3 of the axis of the jack 26 are schematically represented by lines in broken lines in FIG. 1. The end 30 of the rod 28 of the piston is articulated on a connecting rod 31 having a fixed point 32 of pivoting. and intended to bear against a fixed abutment 33 or 34, in each of the extreme positions of extension or retraction of the rod 28 and the piston 27 of the cylinder 26t. The end 30 of the piston rod is connected with a not shown to a tool such as a plow

  reversible, and serves to reverse this tool.

  The outline of the body 1 of the valve is shown schematically in phantom. A passage 2 for the entry of the high pressure hydraulic fluid communicates with the housing of the slider 3, by a vestibule 25 of section greater than that of the passage 2, but less than the section of the housing 'of the slider 3,. In the embodiment considered, the internal cavity of the slider 3 is constituted by two bores 4, 4 ', of slightly different diameters, so as to provide between the two bores a shoulder 7, which serves as a seat for a ball 6 of closing, thrust bearing on its seat 7 by a spring 10. As shown schematically in Figure 2, the support seat 7 comprises two symmetrical notches 8, which prevent complete sealing between the ball 6 and its seat 7. Radial channels 5, 9,

  are formed in the body of the slider 3, between the bores

  internal gages 4, 4 'and the lateral face of the slide.

  The end of the compression spring 10, intended to press the ball 6 shutter against its seat, is based on a

  stop ring 11 mounted in an annular groove of the

  internal wise 4 'of the slider 3. On the other side of the stop ring 11, is supported a second spring 12 whose other end urges a piston 13, pierced with a small axial hole 14, which opens in the center of an annular appendage 15 of pointed profile. A spring 16, more energetic than the spring 12, keeps the piston 13 resting against the slide 3, as already indicated, passages are formed in the body 1 of the valve, between the outer surface of this body and the housing internal 25 'provided for the slider 3, Such a passage 21 (Figure 1) communicates with the pipe A serving one end of the body of the cylinder 26, while another passage 17 communicates with the pipe B connected to the other end of the cylinder body ,. Other internal channels 18, 19, 20, formed in the body 1 of the valve, communicate with the return line which leads to the reservoir or hydraulic accumulator T, as seen in Figure 1, the channels 21 and 17 of the body 1 of the valve are connected to the pipes

  A and B each serving one end of the cylindrical body

  drique cylinder 26, to ensure sometimes the arrival of hydraulic fluid under pressure, and sometimes the return of the hydraulic fluid. In the considered system, the hydraulic cylinder 26 could be replaced by a rotary actuating device, or by another type of hydraulic motor. By way of example, the operation of the reversing valve according to the invention will now be described. invention, in the case where this valve is associated with a hydraulic cylinder, as shown in the accompanying figures, Initially (Figure 1), the cylinder 26 and the slider

  3 of the valve are in one of their two posi-

  For example, in the extreme "right" position, the pressurized hydraulic fluid enters the body of the valve through the passage 2 and the vestibule 25 to enter the bore 4 of the slider 3. Then, the fluid

  hydraulic system follows the path of least resistance in the

  wise 4, to cross the seat i and flow around the ball 6 in the bore 4 'of the slider; then the liquid passes through the axial hole 14 of the piston 13 and into the radial channel 18 of the body 1 of the valve, to arrive at the

tank T ,.

  At the passage of the hydraulic fluid on the seat, through the notches 8, the ball 6 causes a pressure drop, of predetermined magnitude and substantially constant in the range of operating pressures for which the valve is provided, This pressure drop causes a displacement of the slider 3, the radial channel 9 of which then faces the channel 21 of the body 1 of the valve (FIG. 3), to allow the hydraulic fluid under pressure to pass into the pipe A to the jack 26, At the same time , a hydraulic pressure is established between the slider 3 and the auxiliary piston 13, because of the narrowness of the outlet hole 14 of the piston 13, relative to the section of the internal bores 4, 4 ', the slider. The exit hole 14 of the piston

  13 plays in this respect the role of a throttling orifice.

  This increase in hydraulic pressure in the slider 3 and the associated piston 13 is sufficient to push the piston 13, away from the slider 3, until the appendage 15 of the piston 13 bears against a boss 24 provided for this purpose on the bottom of the housing 25 'formed in the body 1 of the valve. This contact of the end 15 of the piston 13 on the boss 24 prevents the passage of the hydraulic fluid in the axial hole 14 of the piston 13, and thus the return of the liquid to the tank T by the radial channel 18 (FIG. 3). This results in a pressure increase in the valve, until the pressure reaches a high enough value to move the piston 27 in the cylindrical body of the cylinder 26. At the same time, the liquid contained in the part of the cylinder located on the side the end 30 of the rod out of the cylinder by the pipe B, connected to the radial channel 17 of the body 1 of the valve (Figure 3), facing

  which is a peripheral groove or an annular recess

  22 of the slider 2, which then communicates with a radial return channel 3 of the body 1, where the liquid joins the tank T. As long as the piston 27 continues to move in the same direction, in the cylindrical body of the jack 26, the pressurized liquid passes through the internal seat 7 of the valve, with a pressure drop sufficient to hold the slide 3 in the position shown in FIG. 3. When the piston 27 of the jack 26 reaches the end of the stroke extension, corresponding to the central position a2 of the cylinder axis (Figure 1), the hydraulic fluid under pressure can not cross the inner seat 7 of the valve. And the pressure then tends to equalize on both sides of the seat 7, thanks to the notches 8 (Figure 2), so that the slider 3 is then in equilibrium, as to the effect of the hydraulic pressure. Under these conditions, the spring 12 can push the slider 3 towards its initial position (FIGS. 3 and 4), while the auxiliary piston 13 remains at the end of the stroke, towards the left, its end remaining applied against the boss 24, under the effect of the pressure of the liquid interposed between the piston 13 and the slider 3. The movement that moves the slider 3 of the piston 13 (Figure 4) creates an increase in volume between the slide and the piston. The small amount of liquid needed for this increase in volume comes into

  passing through the notches 8 of the seat 7 (Figure 2) ,.

  In this new position of the slider 3 (FIG. 4), the hydraulic fluid under pressure which enters the valve exits via the radial channel 5 of the slider, and through the radial channel 17 of the body 1 of the valve, connected to the pipe B of the hydraulic cylinder 26 (Figure 1), the piston 2; the cylinder is thus pushed to the left, to its extreme position of retraction corresponding to the position a3 of the axis of the cylinder, At the same time, the liquid coming out of the cylinder 26 by the other pipe A (Figure 4 ), can pass through the radial channel 21 of the body 1 of the valve,

  and by another groove or annular recess 23 of the slide

  bucket 3, to return to the tank T by the radial channel 19, When the piston 2] has returned to the full retraction position in the cylinder 26, the mechanism has performed a complete cycle of work back and forth ,. A new complete cycle of work can then be initiated automatically, since the end 15 of the piston 13 carrying the hole 14 is in sealing abutment against the boss 24 of the body 1 of the valve, under these conditions, no flow of liquid n is possible at the seat of the valve. However, such a flow rate is necessary to ensure the pressure drop that allows displacement of the slider 3. The piston 13 thus remains in this position of FIGS. 3 and 4 until a pressure drop in the arrival channel 2 of the hydraulic fluid, In this case, the spring 16 pushes the piston 13 back to its initial position (FIG. 1), and the valve is then ready to command a new full forward-and-return movement of the piston 27 in the cylindrical body of the cylinder 26, corresponding to the displacement of the cylinder axis between the

  position a3 and position a1 of Figure 1 ,.

  Of course, the invention is not limited to the embodiment just described, and can be made various modifications and / or various complements,

  entering into the frame and spirit of the invention. A party-

  its essential feature is that a permanent passage exists between the seat 7 and the ball 6, but such a passage can be made by means of grooves or indentations on the surface of the ball, and intended for cooperate with similar fingerprints of the seat; it is also possible to provide such impressions only on the ball, instead of the symmetrical notches 8 formed in the seat 7, as in the embodiment just described (FIG.

  2), the figures show the piston 13 of the

  pope immediately behind the slider 3, following a

  preferred embodiment of the valve according to the invention.

  However, this provision is not absolutely mandatory to ensure the proper operation of the valve, Indeed, one could mount the piston 13 in a housing located anywhere in the body 1 of the valve, provided that this housing of the piston 13 communicates with the same channels as in the embodiment shown in the figures,

  On the other hand, it is possible to complete the

  version according to the invention incorporating any other known type of valve or valve, to provide another possibly necessary function, for example, it can thus incorporate in the valve according to the invention a stop valve, and / or a protection valve against water hammers, As these auxiliary members do not themselves play any role in the operation of the reversing valve according to the invention, it was refrained from describing them and representing them in the figures,

Claims (4)

  - 1 reversing valve intended to control a   hydraulic operating device, such as a hydraulic cylinder   (26), a rotary actuator or other kind of hydraulic motor, by reversing the direction of the action exerted by this apparatus, for example to make   pivot a reversible plow associated with the hydraulic ram   than; this valve comprising a body (1) in which are provided various separate channels (2, 17 to 21) for selectively connecting a pump (P), which delivers a hydraulic fluid under pressure, and a reservoir (T), who serves   to recover the fluid, with two pipes (A, B) which   wind the cylindrical body of the cylinder (26), to ensure the arrival of hydraulic fluid under pressure, and the return of the fluid to the tank (T} the body (1) of the valve   containing a slider (3), in which an aluminum is   socket (4,4 ') serving as a housing for a movable shutter, such as a ball (6) which a compression spring (10) supports   against a seat (7) in the bore (4,4 ') of the slide   Bucket (3); the latter being provided with passages, such as channels (5,9) and annular recesses (22,23), for selectively cooperating with the aforementioned channels of the body (1) of the valve, when the slide is in one or the other of its two extreme positions; the valve being characterized in that means are provided on the seat (7) formed in the bore (4,4 ') of the slider (3), or on the associated bearing surface of the shutter (6), or-on the seat and on this surface, to prevent complete sealing of the shutter contact   (6) resting on the seat (7), so as to leave   a relatively narrow passage between these two bodies in the support position, so that the corresponding throat   ensures a pressure drop at the seat (7), when   there is a flow rate of fluid under pressure in the internal bore (4, 4 ') of the slider (3); this pressure drop then causing the slider (3) to move from one to the other of its extreme positions; and the slider (3) being intended to cooperate with an auxiliary piston (13), biased by a spring (16 ') and provided with a hole (14) of substantially smaller section than the internal bore (4,4' ) of the slider (3), the arrangement being such that the hole (14) of the piston (13) acts as a throttling orifice, and that, in one of the extreme positions of the piston (13), the end of the hole (14) of the piston comes into sealing engagement with a boss (24) provided for this purpose in the body (1) of   the valve, so as to block the passage of the hydraulic fluid.   in the throttle hole (14), and to allow the return of the slider (3) to its initial position, as soon as the hydraulic fluid under pressure ceases to circulate in shutter view (6).   2. Reversing valve according to claim 1, characterized in that the slide (3) and the piston (13) are mounted in the extension of one another in a bore (25 ') of the body (1). ) of the valve which constitutes a common housing for these two organs; these being intended to take three main positions, namely an extreme position "right" and an extreme position "left", where the two bodies are at the end of stroke in support against each other, and a third main position, where the piston (13) is at the end of its stroke in its extreme "left" position, the slide (3) being then in   end of stroke in its extreme position "right" ,.   3. Reversing valve according to claim 1, characterized in that the seat (7) provided for the shutter   (6) in the internal bore (4,4 ') of the slider (3) is con-   arranged by notches (8), preferably arranged symmetrically, to prevent contact completely.   sealing of the shutter (6) resting on the seat (7).   4. Reversing valve according to claim 1, characterized in that the spring (16) for returning the piston (13) is more vigorous than the spring (12) for returning the slide (3),