US3817154A

US3817154A - Apparatus for supplying fluid to a reversible drive organ

Info

Publication number: US3817154A
Application number: US00363168A
Authority: US
Inventors: L Martin
Original assignee: Poclain SA
Current assignee: Poclain SA
Priority date: 1972-05-31
Filing date: 1973-05-22
Publication date: 1974-06-18
Anticipated expiration: 1991-06-18
Also published as: GB1380226A; FR2187086A5; JPS4949084A; BR7303953D0; ES414629A1; AR198313A1; BE799230A; DE2327712A1; IT985983B

Abstract

Fluid supply system for a double acting fluid drive mechanism having first and second drive chambers, the system including a pump whose delivery is connected by a first conduit to the first chamber, a second conduit connecting the second chamber to a reservoir and including a one-way valve permitting flow only to the reservoir, a third conduit coupled to the second conduit, bypassing the one-way valve and including a flow limiter, a fourth conduit connected to the first conduit and to the flow limiter, which latter comprises a discharge valve operable to maintain pressure in the third conduit upstream of the discharge valve and an adjustable valve between the second chamber and the discharge valve operable to control the pressure delivered by the second chamber in response to pressure in the fourth conduit.

Description

United States Patent [191 Martin [45] June 18, 1974 APPARATUS FOR SUPPLYING FLUID TO A Primary Examiner-Edgar W. Geoghegan REVERSIBLE DRIVE ORGAN Attorney, Agent, or Firm-Nathaniel A. Humphries, [75] Inventor: Louis E. Martin, Senlis, France [73] Assignee: Societe Anonyme Poclain, Oise,

France [57] ABSTRACT [22] Filed: May 22, 7 Fluid supply system for a double acting fluid drive mechanism having first and second drive chambers, PP 363,168 the system including a pump whose delivery is connected by a first conduit to the first chamber, a second [30] Foreign Application p i i Data conduit connecting the second chamber to a reservoir M 31 1972 France 72 19573 and including a one-way valve permitting flow only to ay the reservoir, a third conduit coupled to the second conduit, by-passing the one-way valve and including a 5 flow limiter, a fourth conduit connected to the first [58] d /420, 60/477 conduit and to the flow limiter, which latter comprises 1e a discharge valve operable to maintain pressure in the third conduit upstream of the discharge valve and an [56] References Cited adjustable valve between the second chamber and the UNITED STATES PATENTS discharge valve operable to control the pressure delivl,972,462 9/1934 Schafer 91/420 X gred by the second chamber in response to pressure in 2,328,980 9/1943 Herman et al. h f h d i 2,470,778 5/1949 Lankovski et a1. 91/420 X 4 Claims, 3 Drawing Figures n -il 20 I n 7 /6 l T 1 APPARATUS FOR SUPPLYING FLUID TO A REVERSIBLE DRIVE ORGAN Fluid supply apparatus are already known which have, arranged in the delivery conduit, a flow-limiter operated by the pressure of the fluid contained in the intake conduit.

However, apparatus of this type have the disadvantage of being of unstable operation. Moreover, the very operating characteristics are often mediocre, the opening time of the flow-limiter being badly controlled and the closure time being too long.

In order to correct this state of affairs, a flow-limiter of a novel type is proposed, which has advantages over the previously known limiters, without having their above-mentioned disadvantages.

The object of the invention is therefore an apparatus for supplying fluid to a reversible drive organ, which is connected to a load which provides its forced drive during the operating phase in question and which has first and second chambers, this supply apparatus consisting of:

a fluid reservoir,

a pump connected to the said reservoir by a suction conduit,

a first conduit, which connects the delivery side of the pump to the first of the said chambers, this first chamber forming the fluid intake chamber during the abovementioned operating phase,

a second conduit, which connects the second of the said chambers to the reservoir, this second chamber forming the fluid delivery chamber during the said operating phase,

a non-return valve which is arranged in the second conduit and which only allows passage of the fluid towards the second chamber,

a third conduit, which is connected to the said second conduit on either side of the non-return valve and in which is arranged an adjustable flow limiter,

a fourth conduit, which is connected on the one hand to the first conduit and on the other to the flow adjustment organ of the said flowlimiter.

The adjustable flow limiteritself consists of:

an adjusted discharge valve, which acts to maintain the pressure of the fluid which can be contained in the portion of the third conduit which is connected to the said discharge valve and is arranged directly downstream of this valve relative to the reservoir, substantially equal to a given value,

and a valve with adjustable opening, which is arranged between the drive organ and the discharge valve, which is distinct from this discharge valve, and the function of which is to regulate the value of the pressure of the fluid which can be delivered out of the second chamber during the abovementioned operating phase. This valve with adjustable opening includes an organ for adjusting its opening, which is in equilibrium under the antagonistic influences, firstly, of the pressure of the fluid contained in the fourth conduit and, secondly, of the fluid pressure which is substantially equal to the given value.

The valve with adjustable opening is also advantageously provided with a shock-absorber for its opening motion. The said shock-absorber consists of a piston, which is linked to the organ for adjusting the opening of the said valve with adjustable opening, being mounted slidably in the body of the said valve, and which, with the said body, defines on the one hand a first volume, which is freely in communication with the portion of the third conduit connected to the discharge valve and, on the other hand, a second volume. A nonretum valve allows passage of the fluid from the first volume towards the second volume, while a calibrated channel, forming a restriction, connects the two said volumes. A retaining organ tends "to keep the said piston and the said adjustment organ linked together.

Preferably, the organ for adjusting the opening of the valve with adjustable opening consists of a slide mounted slidably in the body of the said valve. This slide has a shoulder, the lateral adjacent wall of which can overlap the edge of a throat formed in the said valve body, one of the elements the lateral wall of the shoulder or the throatbeing provided with grooves having progressively vairable sections.

Finally, an elastic return organ :is often inserted between the organ for adjusting the opening of the valve with adjustable opening and the said valve body and has an effect antagonistic to that of the pressure of the fluid contained in the fourth conduit.

A better understanding of the invention will be obtained and secondary features and their advantages will become apparent in the course of the following description of embodiments offered by way of example.

It will be understood that the description and drawings are only given for guidance and are not limiting.

Reference will be made to the attached drawings, in which:

FIG. 1 is a diagram of a supply apparatus forming an application for a flow-limiter in accordance with the invention;

FIG. 2 is a sectional view of the adjustable flowlimiter with which the supply apparatus shown in FIG. 1 is fitted;

FIG. 3 is a section of a modification of a detail of the flow-limiter shown in FIG. 2.

In FIG. 1, the presence will be noted of a reversible drive organ which, in this particular case, consists of a double-acting, hydraulic ram l. The piston 2 of this ram defines with body 3 a first chamber 4 and a second chamber 5. The rod 6 of the piston is arranged substantially vertically, while a mass 7 is linked to it by means of a clevis 8 and pin 9, and constitutes a load which tends to return rod 6 into body 3. In this configuration, the first chamber 4 is arranged above the second chamber 5.

A pump 10 and a fluid reservoir 11 are connected by the suction conduit 12 of the pump. In addition, a three-position distributor 13 is connected, by a first conduit 14, to the delivery side of pump 10 and, by a second conduit 15, to reservoir 11.. A third conduit 16 connects the distributor to the first chamber 4, while a fourth conduit 17 connects this distributor to the second chamber 5.

Furthermore, a non-retum valve 18 is arranged in the fourth conduit 17, so as to allow passage of the fluid from the distributor 13 towards the: second chamber 5. It will also be noted that an adjustable flow-limiter 19, which is more particularly described with reference to FIG. 2, is arranged in a fifth conduit 20, which is connected to the fourth conduit 17 on either side of nonretum valve 18. A sixth conduit 21, which is connected to the third conduit 16, is also connected to the organ for adjusting the opening of flow-limiter 19, as will be observed below with reference to FIG. 2.

Finally the communications established by distributor 13 will be noted, which distributor connects:

in its first position, on the one hand, the first conduit 14 and the third conduit 16, and on the other hand, the second conduit 15 and the fourth conduit 17;

in its second position, on the one hand, the first conduit 14 and the fourth conduit 17 and, on the other hand, the second conduit 15 and the third conduit 16;

and which, in a third position, which is intermediate between the first and second positions, on the one hand, connects the first conduit 14 and the second conduit 15 and, on the other hand, isolates the third conduit 16 and the fourth conduit 17 at its position.

It will be understood that the hydraulic driven part supply circuit given as an example does not limit the application of the invention to this single embodiment. A particular alternative would be application to the case in which the pump has regulation of its flow, and this would then be a closed-circuit supply, which is conventional in hydraulics and does not require a reversing distributor.

The flow-limiter 19 shown in FIG. 2, comprises the two following, distinct elements:

a discharge-valve 22, which is guided by vanes 23,

which are arranged in a bore 24 formed in the body 25 of flow-limiter 19, and which can be in contact with its seat 26 under the influence of an adjusted spring 27;

a valve with adjustable opening, consisting of a slide 28, which is slidably mounted in body 25, and which has a shoulder 29, which is provided with grooves 30 of variable sections and the lateral wall 34 ofwhich overlaps the edge 31 of a throat 32 formed in body 25. A weakly adjusted spring 33 tends to return slide 28 in the direction of closure of conduit 20 by lateral wall 34, and does so by acting on an end surface 29a of slide 28.

In addition, slide 28 has a second end surface 29b and an intermediate surface 29c, which is directed in the opposite direction to surface 29b. It will be noted that conduit 20 is in fact divided into three sections, which are connected, one to second chamber 5 of ram 1 and to an intake conduit 35 of body 25, and another to distributor l3 and to an output conduit 36 of body 25 and, finally, an intermediate section, also known as the internal conduit, which connects throat 32 to dischargevalve 22. The pressure of the fluid contained in the said intermediate section of conduit 20 acts on surface 290, in the same direction as spring 33, and has an influence antagonistic to that of the pressure of the fluid contained in conduit 21, which acts on end surface 29b of slide 28.

FIG. 3 shows an advantageous modification of flowlimit'er 19, in which a complementary piston 37 is slidably mounted in body 25 at throat 32. A spring 38 is connected between piston 37 and body 25, and tends to keep surface 39 of the said piston 37 in contact with end surface 29a of slide 28.

A first channel 40 is formed in piston 37, through which it passes. It connects a first volume 41, which is defined by throat 32 and opens into the portion of conduit 20 connected to the discharge-valve, to a second volume 42, which is closed and is in fact, in this particular case, closed by a plug 43. A nonreturn valve 37a, consisting of a ball-bearing, its plunger and a return spring only allows passage of fluid in channel 40 from the first volume 41 towards the second volume 42. Moreover, the ball bearing and its plunger are guided by vanes 44 rigidly connected to piston 37. Furthermore, another, calibrated channel 45 connects the two volumes 4] and 42, in this particular case via a portion of first channel 40, and forms a restriction for the pas sage of the fluid.

The operation of the supply apparatus described above is explained below.

Distributor 13 is firstly arranged in its second position. The fluid drawn by pump 10 from reservoir 11 through suction conduit 12 is delivered into first and

fourth conduits

14 and 17. This fluid passes through non-return valve 18 and enters chamber 5 of ram 1. The effect of the pressure of the fluid in chamber 5 on piston 2 is to push this piston and, therefore, to lift load 7, which is linked to piston rod 6. Meanwhile, the fluid contained in chamber 4 is delivered into reservoir 11, through third conduit 16, distributor 13 and second conduit 15.

When load 7 has been lifted, distributor 13 is arranged in its third position. This results in the closure of third and

fourth conduits

16 and 17, and thus in shutting the fluid contained in chambers 4 and 5 in closed volumes. Load 7 is, therefore, immobilised, while pump 10 returns to reservoir 11 through first conduit 14, distributor 13 and second conduit 15.

The two operating phases just described were in fact already known themselves prior to the present invention and have only been recalled as a reminder.

On the other hand the operating phase which will now be described is novel and, of course, relates to the specific means in accordance with the invention. This operating phase corresponds to the distributor being placed in its first position.

It will firstly be stated that the fluid delivered by pump 10 enters chamber 4 via first conduit 14, distributor 13 and third conduit 16. Moreover, the fluid contained in chamber 5 cannot escape through the whole of conduit 17, as it is prevented from doing so by nonreturn valve 18. This fluid can therefore only escape from chamber 5 through conduit 20, and this through flow-limiter 19, in the manner which will be explained below.

However, before examining the operation of the actual flow-limiter 19, it will briefly be mentioned that the necessity for the insertion of this limiter is linked with the fact that load 7 is such that it tends to drive the pis ton in the same direction as the fluid which enters chamber 4 tends to do itself, but more rapidly than the said fluid can do so. In other words, in the absence of a flow-limiter, such as limiter 19, the flow of fluid conveyed by conduit 16 would be insufficient to compensate for the increase in volume of chamber 4, due to the driving of piston 2 and the piston-rod by load 7. There would therefore be a risk of cavitation in chamber 4, cavitation always being detrimental to the maintenance of the wholeness of the organs which give rise to it and to the maintenance of satisfactory operating conditions. The reason for the presence of flow-limiter 19 is to avoid such disadvantages.

It will also be noted that, if the example selected is one in which the reversible drive organ linked to load 7 consists of ram 1, all reversible drive organs can be supplied by means of the apparatus which has been described. Thus, in particular, a reversible hydraulic motor attached to a winch drum, could be driven by the load suspended from the connecting line wound on the said drum. The apparatus which has been described in the example of the supply of ram 1 could, of course, find a well-advised application in the supply of the said motor for driving the winch.

The operation of flow-limiter 19 will now be explained. The fluid delivered from chamber 5 arrives opposite shoulder 29 of slide 28. The position of this slide has been governed by the equilibrium of the antagonistic influences, on the one hand, of the pressure of the fluid contained in third conduit 16, which, by acting through sixth conduit 21 on surface 29b, tends to cause opening of a passage between edge 31 and the lateral wall 34 and grooves 30 of shoulder 29 and, on the other hand, of the pressure of the fluid contained in the portion of conduit 20 between throat 32 and dischargevalve 22, and of spring 33. Furthermore, spring 33 has a very small and negligeable influence relative to that of the pressure of the fluid in the said portion of conduit 20, which pressure corresponds to the adjustment of spring 27 of discharge-valve 22. The purpose of spring 33 is in fact limited to returning slide 28 to the position corresponding to closure of the abovementioned passage between edge 31 and shoulder 29, when the pressure in the various conduits becomes substantially zero following prolonged stoppage of operation.

A given passage is therefore formed between the two portions of conduit 20 which can be isolated by shoulder 29. The size of this passage is directly governed by the pressure in sixth conduit 21. Now this pressure is either low, when load 7, driving piston 2, tends to form a vacuum in chamber 4 and consequently in third conduit 16 and sixth conduit 21, or high, when, on the other hand, load 7 does not drive piston 2 more rapidly than compensation is effected for the volume increase in chamber 4 by addition of fluid delivered by pump 10.

When the pressure of the fluid in the sixth conduit 21 is initially low, there is a reduction in the said passage, under the influence of the pressure of the fluid contained in the portion of conduit 20 arranged between throat 32 and discharge-valve 22, which pressure is maintained substantially constant by the said discharge-valve 22, which is adjusted. This passage reduction causes a reduction in the flow of fluid conveyed in conduit 20, and therefore deceleration of the motion of the piston 2. The increase in the volume of chamber 4 therefore also decreases until the fluid delivered by pump 10 can compensate for this volume increase. Only then, the pressure in third conduit 16 and, consequently, in sixth conduit 21 again adopts a higher value until the, pressure drop in chamber 4, which results from this rapidity of descent of piston 2, causes a drop inthe pressure of the fluid contained in sixth conduit 21 and, in this way, causes the return of slide 28 to its median position in which the flow-rate in conduit 20 corresponds to the required value of the descent velocity of piston 2 and load 7.

Flow-limiter 19 acts in two distinct phases: a phase in which the pressure of the fluid contained in chamber 5 is reduced, by possible throttling of the fluid between edge 31 and the lateral wall 34 and grooves 30 of shoulder 29, during which phase there is a consumption of power due to throttling, which is equal to the product of the flow-rate and the pressure differential between the fluid contained in chamber 20 on either side of shoulder 29;

a phase in which the pressure of the fluid contained in the portion of conduit 20 between throat 32 and adjusted discharge-valve 22 is stabilized, which stabilization corresponds to the value of the adjustment of spring 27 of the said discharge-valve 22.

This arrangement has considerable advantages. In

fact it will be clearly understood that better operational stabilization is obtained than by the use of the previtially constant, which is not the case of the return force of a spring.

Furthermore, it is very easy to adjust the opening time of the abovementioned passage, as a function of the values of the useful sections of surfaces 29b and 290.

Finally, the operating pressiire of the fluid contained in sixth conduit 21 is in fact maintained at a substantially constant value which, moreover, is lower than in prior apparatus. These two points are naturally advantageous in themselves.

To perfect the stabilization obtained from the operation of flow-limiter 19 of FIG. 2, it is possible to advantageously add a shock-absorber for the motion of slide 28 corresponding to the opening of the abovementioned passage, such as the shock-absorber described with reference to FIG. 3.

Supposing that slide 28 has initially been entirely pushed until second volume 42 has become minimal, an examination will firstly be made of the following phase, in which slide 28 slides in the direction opposite to the initial direction, and then of the phase after this following phase, in which slide 28 again slides in the direction of reduction of second volume 42.

While slide 28 moves in the direction opposite to the initial displacement direction, piston 37 moves under the influence of spring 38 in the same direction as the slide. The pressure of the fluid contained in first volume 41 has the effect of pushing back the ball-bearing and the plunger of non-return valve 37a and thus allow ing free transfer of the fluid from the first volume 41 into the second volume 42, via channel 40.

When the closure movement of slide 28 has been terminated, another opening movement takes place. However, this opening movement is braked by the fluid which, enclosed in second volume 42, can only now escape from it through calibrated channel 45, channel 40 then being re-closed by non-return valve 37a. It will therefore be understood that piston 37, non-return valve 37a and calibrated channel 45 in fact form a true shock-absorber for the motion of slide 28 corresponding to the opening of the passage. This shock'absorber naturally perfects stabilization of the motion of slide 28 and also, therefore, the operation of the assembly.

Of course, it will be noted that an equivalent would be to form non-return valve 37a and calibrated channel 45 in body 25 of the flow-limiter, seeing that the functions provided remain identical.

Also, if the example described corresponds to the open-circuit supply of a ram 1 by means of a distributor 13, the present invention is also applicable to the case of closed-circuit" supply by means of a reversible pump with flow-rate regulation. In a conventional manner, such a pump is connected to the supply circuit by two main conduits which, depending on the position of the flow-regulating organ, constitute either one suction conduit and the other the delivery conduit, or, conversely, one the delivery conduit and the other the suction conduit. The portion of the circuit connected to the suction conduit, by analogy with the case of the open circuit, then constitutes the fluid reservoir. It is worth noting that, in the case of the closed-circuit, the organ for regulating the flow-rate of the pump selects the delivery direction of the said pump and, in that respect, can be considered as equivalent to the distributor 13 of the open-circuit.

The invention is not limited to the description given above but, on the contrary, covers all the modifications which could be made to it, without departing from its scope or spirit.

l claim:

1. Apparatus for supplying fluid to a reversible drive organ, which is linked to a load which provides its forced drive during the operating phase in question and which has first and second chambers, this supply apparatus consisting of:

a fluid reservoir,

a pump connected to the said reservoir by a suction conduit,

a first conduit which connects the delivery side of the pump to the first of the said chambers, this first chamber forming the fluid intake chamber during the above-mentioned operating phase,

a second conduit which connects the second of the said chambers to the reservoir, this second chamber forming the fluid delivery chamber during the said operating phase,

a non-return valve which is arranged in the second conduit and only allows passage of the fluid towards the latter chamber,

a third conduit which is connected to the said second conduit on either side of the non-retum valve and in which an adjustable flow-limiter is arranged,

a fourth conduit which is connected, on the one hand, to the first conduit and, on the other hand, to the flow-regulating organ of the said flowlirniter, characterised in that the adjustable flowlimiter itself consists of:

an adjusted discharge-valve, which acts to maintain the pressure of the fluid which can be contained in the portion of the third conduit which is connected to the said discharge-valve and is arranged directly downstream of this valve relative to the reservoir, substantially equal to a given value,

and a valve with adjustable opening, which is arranged between the drive organ and the dischargevalve and is distinct from this discharge-valve, and the function of which is to regulate the value of the pressure of the fluid which can be delivered out of the second chamber during the above-mentioned operating phase, while this valve with adjustable opening has an organ for adjusting its opening, which is in equilibrium under the antagonistic influences, on the one hand, of the pressure of the fluid contained in the fourth conduit and, on the other hand, of the fluid pressure which is substantially equal to the given value.

2. Supply apparatus in accordance with claim 1, characterised in that in addition the valve with adjustable opening is provided with a shock-absorber for its opening motion, in that the said shock-absorber consists of a piston, which is linked to the organ for adjusting the opening of the said valve with adjustable opening, being mounted slidably in the body of the said valve, and which defines with the said body, on the one hand, a first volume, which is freely in communication with the portion of the third conduit connected to the discharge-valve, and, on the other hand, a second volume, in that the non-retum valve allows passage of the fluid from the first volume towards the second volume, while a calibrated channel, forming a restriction, connects the said two volumes, and in that a retaining organ tends to keep the said piston and the said adjustment organ linked together.

3. Supply apparatus in accordance with claim 1, characterised in that the organ for adjusting the opening of the valve with adjustable opening consists of a slide mounted slidably in the body of the said valve, in that the said slide has a shoulder, the adjacent lateral wall of which can overlap the edge of a throat formed in the said valve-body, and in that one of the elements, lateral wall of the shoulder or edge of the throat, is provided with grooves of progressively variable sections.

4. Supply apparatus in accordance with claim 1, characterised in that in addition an elastic return organ is inserted between the organ for adjusting the opening of the valve with adjustable opening and the body of the said valve and has an influence antagonistic to that of the pressure of the fluid contained in the fourth conduit.

Claims

1. Apparatus for supplying fluid to a reversible drive organ, which is linked to a load which provides its forced drive during the operating phase in question and which has first and second chambers, this supply apparatus consisting of: a fluid reservoir, a pump connected to the said reservoir by a suction conduit, a first conduit which connects the delivery side of the pump to the first of the said chambers, this first chamber forming the fluid intake chamber during the above-mentioned operating phase, a second conduit which connects the second of the said chambers to the reservoir, this second chamber forming the fluid delivery chamber during the said operating phase, a non-return valve which is arranged in the second conduit and only allows passage of the fluid towards the latter chamber, a third conduit which is connected to thE said second conduit on either side of the non-return valve and in which an adjustable flow-limiter is arranged, a fourth conduit which is connected, on the one hand, to the first conduit and, on the other hand, to the flow-regulating organ of the said flow-limiter, characterised in that the adjustable flow-limiter itself consists of: an adjusted discharge-valve, which acts to maintain the pressure of the fluid which can be contained in the portion of the third conduit which is connected to the said discharge-valve and is arranged directly downstream of this valve relative to the reservoir, substantially equal to a given value, and a valve with adjustable opening, which is arranged between the drive organ and the discharge-valve and is distinct from this discharge-valve, and the function of which is to regulate the value of the pressure of the fluid which can be delivered out of the second chamber during the above-mentioned operating phase, while this valve with adjustable opening has an organ for adjusting its opening, which is in equilibrium under the antagonistic influences, on the one hand, of the pressure of the fluid contained in the fourth conduit and, on the other hand, of the fluid pressure which is substantially equal to the given value.

2. Supply apparatus in accordance with claim 1, characterised in that in addition the valve with adjustable opening is provided with a shock-absorber for its opening motion, in that the said shock-absorber consists of a piston, which is linked to the organ for adjusting the opening of the said valve with adjustable opening, being mounted slidably in the body of the said valve, and which defines with the said body, on the one hand, a first volume, which is freely in communication with the portion of the third conduit connected to the discharge-valve, and, on the other hand, a second volume, in that the non-return valve allows passage of the fluid from the first volume towards the second volume, while a calibrated channel, forming a restriction, connects the said two volumes, and in that a retaining organ tends to keep the said piston and the said adjustment organ linked together.