EP0053144A1

EP0053144A1 - Jack, particularly telescopic jack, provided with means for restricting the stroke

Info

Publication number: EP0053144A1
Application number: EP81901519A
Authority: EP
Inventors: Gérard LERAY; Jules Leray
Original assignee: Individual
Current assignee: Individual
Priority date: 1980-06-05
Filing date: 1981-06-04
Publication date: 1982-06-09
Also published as: FR2484031B1; FR2484031A1; JPS57501137A; WO1981003528A1; US4471944A

Abstract

L'invention concerne les verins, et en particulier les verins telescopiques. Suivant l'invention, le verin (10) comporte un cylindre (10A) avec des elements tubulaires coaxiaux (11), (12), (13), qui sont limites dans leurs deplacements par des moyens de fin de course avant et arriere. Le moyen de fin de course avant (50) etant, dans une position retractee desdits elements, loge dans une premiere depression a etages (43) menagee sur un premier element tubulaire, permettant l'obtention d'un jeu minimal entre cet element tubulaire et un element tubulaire voisin, tandis que, dans une position avancee dudit premier element tubulaire le moyen de fin de course avant (50) est en appui, pour partie, dans la depression precitee et pour partie dans une seconde depression (40) menagee a cet effet dans l'element tubulaire voisin. Application aux verins telescopiques.The invention relates to jacks, and in particular to telescopic jacks. According to the invention, the cylinder (10) comprises a cylinder (10A) with coaxial tubular elements (11), (12), (13), which are limited in their movements by front and rear limit switch means. The front limit switch means (50) being, in a retracted position of said elements, housed in a first step depression (43) carried on a first tubular element, allowing a minimum clearance to be obtained between this tubular element and an adjacent tubular element, while, in an advanced position of said first tubular element, the front end-of-travel means (50) is supported, in part, in the aforementioned depression and in part in a second depression (40) led to this effect in the neighboring tubular element. Application to telescopic jacks.

Description

TELESCOPIC CYLINDER

The present invention relates generally to cylinders, and more particularly to telescopic single-acting cylinders.

It is known that cylinders of the type under consideration comprise a cylinder, with a connection to a source of pressurized fluid, and inside this cylinder a series of coaxial tabular elements, which can occupy an advanced position for which they extend the said cylinder, or a retracted position inside the cylinder in question.

In practice, the above bular elements com¬ carry front and rear end-of-travel means so that, under the effect of the pressure of the fluid, the tubular element having the largest reaction surface causes on its course the other elements, then it is the turn of an adjacent element and so on, until said tubular elements occupy an advanced position for which they extend said cylinder. From such an advanced position, the process is exerted inversely towards the retracted position for which the said elements are housed inside the cylinder.

In a manner known per se, the aforementioned front and rear end-of-travel means are generally formed by heels fitted at the ends of the tubular elements; between these heels is thus formed an annular pressure in which a heel of a neighboring element can move, itself being able to comprise an annular groove with two end heels for the movement of another tubular element and thus following, the length of the abovementioned annular depressions defining the stroke of the tubular element, slidably mounted in the depressions. Currently the elements in question are obtained from conventional tubes, machined over their entire length both outside and inside to form the depressions and, therefore, the heels.

Such a technique is not free from drawbacks.

First, the tube machining operations are long and expensive; they also lead to a significant loss of raw material.

Then, the size of the telescopic jacks equipped with such tubular elements is important in particular because the depressions formed on the tubular elements - for the deflection of the heel create a large space between said elements.

Furthermore, the mechanical resistance characteristics of commercially available tubes currently entering the production of tubular elements, make it necessary to use tubes with a thickness suitable for absorbing pressures capable of prevailing inside the cylinders. In addition to the large footprint explained above, there is a significant weight due to the structure of the tubes used.

The object of the present invention is to solve the problem posed concerning the weight and the bulk, while retaining and even substantially improving the mechanical resistance of the jack, with means having practically no influence on the re price comes.

According to a characteristic of the invention, one achieves such a result by using as starting material, to produce a telescopic jack, including the cylinder, tubular elements of drawn steel whose mechanical resistance characteristics are clearly superior to the tubes. usual, and do not require any resumption of machining for sliding apart from a light sanding. In association with such tubular elements, the invention provides front and rear end-of-travel means capable of allowing the progressive development of the exterior of the cylinder, or the progressive withdrawal of the interior of this cylinder from said elements, the said means of front limit switch being characterized in that they advantageously consist of at least one interrupted and elastically deformable ring which is, in a retracted position of the tubular elements, log

- - in a first depression formed in a first tubular element, thus allowing the obtaining of a minimum clearance between this first tubular element and a second neighboring tubular element, while in the advanced position of said first tubular element, the end means of front stroke is resting, in part, in the aforementioned depression and in part in a second depression provided for this purpose in said second tubular element. As for the rear end-of-travel means, they are advantageously, according to another characteristic of the invention, constituted by a rod engaged in a groove formed towards the rear end and on the inner surface of a tubular element , by having a protruding part thus constituting a stop for another tubular element in contact with the internal surface of the tooth.

The combination of tubular elements of drawn steel and the above end-of-travel means lead to the production of a jack having appré¬ able advantages compared to jacks of the same kind currently known.

The cylinders according to the invention are less bulky in that there is no lost space between the tubular elements, these being mounted to slide one on the other without significant play, namely just the play necessary for operation; they are lighter, due to the fact that the thickness of the tubes is less than in the past, and at the same time offer mechanical characteristics superior to traditional telescopic jacks. In addition, the machining operations are reduced to a strict minimum, namely, light sanding and machining of the depressions necessary for the front and rear abutment means, and for the various seals. All these construction features taken together lead to an actuator in which the disadvantages mentioned above are eliminated.

Other features and advantages of the invention tion will moreover emerge from the description which follows given by way of example with reference to the appended drawings in which: FIG. 1 illustrates in axial section an embodiment of a telescopic jack according to the invention, the tubular elements the constituent being positio retracted; FIG. 2 is a partial view, on a larger scale, showing an embodiment of the front limit switch means disposed between two neighboring tabular elements; Figure 3 is a view that a front limit switch means is in the active position; Figure 4 is a view showing the actuator according ^to Figure 1 5 with its tubular elements running end position before; Figures 5 to 8 show, partially schematically, the operation of the front end of course means when a tubular member is moved from an advanced position to a retracted position; Figures 9 and 10 show an alternative embodiment of the front end-of-travel means.

In the embodiment chosen and shown in FIGS. 1 to 7, a cylinder of the kind with teescopic elements 5 comprises a cylinder 10 and a certain number of tubular elements, for example three, respectively.

11, 12 eτj 13 in the example shown.

According to the invention, the cylinder 10, as well as the telescopic elements are obtained from 0 drawn steel tubes to which only surface treatment such as polishing is applied.

The cylinder 10 itself consists of two tubular sections 10A, 10B, assembled by welding 10C, while a bottom 10D attached by welding 10E on the free end of the tubular section 10B, seals the cylinder at one end. back.

The tubular section 10B also carries two diametrically opposed bolts 16, 17 intended to allow

fixing the jack to any support on which it can pivot about an axis XX, at least one of the pins, being moreover, in known manner, arranged to be connected to a source of pressurized fluid (not shown ).

The section 10A of the cylinder 10 has an inner diameter D smaller than the inside diameter Dl of the section 10B so that an annular recess 10F is thus formed between the interior surface of the section 10B and the tubular element 11.

The aforementioned recess is limited, on the one hand, by a circular shoulder 10G formed by the difference in diameters D, Dl and, on the other hand, by the front face 11B of an annular part 11A attached by welding to the end rear of the tubular element 11, the annular part being movable in the recess 10F; the aforementioned shoulder 10G as well as the bottom 10D thus form end-of-travel stops respectively front and rear of the first tubular element 11. In certain places on its periphery the annular part 11A comprises channels 11C, 11D allowing the admission of pressurized fluid to the reaction surfaces of elements 11, 12 and 13 respectively.

In the immediate vicinity of the end of travel stop 10G, the section 10A of the cylinder 10 comprises an annular housing 10H in which is placed a flat ring 20 for example of plastic material having a guiding role for the second tubular element 11.

At its end opposite the hinge axis XX, the section 10A of the cylinder 10 internally comprises first of all an annular housing 101 for a ring 21 similar to the aforementioned ring 20, then a housing 10J for a seal 23 and finally a clearance 24 for another lip seal 25. The first tubular element 11 is coaxial with the cylinder section 10A, a slight clearance, just necessary for operation, is formed between the cylinder and the first tubular element, which . can thus move axially- between the aforementioned end stops 10G and

10D.

It will be noted that the distance between a front face 11B of the annular part 11A and the shoulder 10G forming a front stop determines the length L of the stroke of the tabular element 11.

The axial displacements of the tubular elements 12 and 13 are limited by end-of-travel stops, both in the retracted position thereof (rear end-of-travel stop) and in the advanced position (front end-of-travel stops).

The rear end of travel stop of the tubular element 11 is constituted by an annular groove 11E formed on the inner face of the tubular element 11 in which is engaged a rod 30 intended to cooperate with a circular imprint 12A formed at the rear end of the tubular element 12. The aforementioned rod 30 has a protruding part thus constituting a rear end-of-travel stop at the tubular element 12, while a front end-of-travel stop at this tabular element 12 is formed by a device which will now be described with more particular reference to FIGS. 2 and 3.

As can be seen in these figures, the tubular element 11 comprises, on its inner wall, a first circular depression generally indicated at 40 having in cross section a generally oblique shape, comprising a notch in a quarter of a circle 41 extended rearward by a substantially flat section, forming a ramp 42; as for the tubular element 12 spaced from the previous one by a slight play as has been said before, it comprises on its external surface a second so-called depression with stages indicated generally in

43 comprising in cross section a first and a second stage formed by a groove substantially in a semicircle

44 extended rearwards by a groove 45 substantially in a quarter of a circle.

The device in question for end of travel stop

^~ R> ~ ~ T ^{".------.-I-.tWi} before is completed by a ring 50 housed in a groove 44 and, interrupted and elastically deformable whose diameter is, in the relaxed state,., substantially equal to the diameter D4 of the bottom of the first depression 40. In ^' the position of the elements shown in FIG. 2, the ring 50 is therefore compressed by the tubular element 11.

It will be noted that between the tabular elements respec¬ tively 12 and 13, front and rear end-of-travel abutment means are provided, similar to those which have been described above.

When the tubular elements 11, 12 and 13 are in the rear end-of-travel position, as shown in FIG. 1, the tubular element 11 is in abutment on the bottom 10D, while the tubular elements 12, 13 are in abutment by their respective rear ends on the rods 30; simultaneously, the front end-of-travel devices are inoperative because the rods 50 are compressed by the elements 11 and 12 and are housed in the groove 44 of the second depression 43.

When the fluid pressure is brought to the reaction surfaces of the tubular elements 11, 12, 13 and after the tubular element 11 has carried out its axial stroke L by driving the other tubular elements 12, 13, ie up to that it is in contact with the front end stop 10G, it is the turn of the tubular element 12 to be driven in axial displacement from its rear end position to a position front limit switch. At the start of the axial displacement (arrow F in FIG. 2) of the tubular element 12, the ring 50 slides on the interior wall of the tubular element 11 until the moment when (FIG. 3) arriving opposite the first depression 40 it relaxes and gradually penetrates therein under the combined effect of its elasticity and the ramp 42. It should be noted that the ring 50, in its operational position, that is to say that corresponding to FIG. 3, by part of its peripheral surface

WIPO as resting on the notch in a quarter circle 41 of the first depression • 40 and partly bearing on the groove 45 forming the second stage 45 of the. depression 43, the bearing zones being approximately diametrically opposite, owing to the fact that the depths p, pi, of the notch 41 and of the second stage 45 are approximately equal to l half the thickness of the ring 50 , at this momen the tubular element 12 is locked axially in the positio of the front end position, owing to the fact that the tubular element 1 is itself immobilized axially.

It is the same with regard to the tabular element 13 which, in the example shown, has at its front end a connecting fitting 60 with a passage 60A for fixing to any member, for example a vehicle skip or other, pivotally mounted while at its rear end, it is closed by a bottom 61, attached by welding 63 on a tubular section 13A.

When all the tubular elements 11, 12, 13 are brought to the end of the front stroke position, the jack is then in a position such as that shown in FIG. 4.

From the above, it therefore appears that the travel of tabular elements 11, 12, 13 is determined by the front and rear end-of-travel stops. For the tabular element 11 the axial stroke is equal to the length (Figure 1) between the front edge 11B of the annular part 11C and the circular shoulder 10G; for the tubular element 12 the axial stroke is equal to the pitch of the depressions 40, 43 and it is the same for the element 13.

From a position where all the tubular elements 11 12, 13 are in the front end-of-travel position (FIG. 4 at a rear end-of-travel position, the process is established in the following manner.

The tubular element 13 is moved towards the rear only, retracting at the start of its movement towards the rear, the ring 50 as it is clearly visible at

Figures 5 to 8.

In FIG. 5 the tubular element 13 has started (arrow FI) to return back, owing to the fact that.) The pressure of the fluid in the cylinder is gradually released, and this, until the end edge of the first stage 44 comes into contact with the ring 50 (Figure 6). The axial displacement, towards the rear of the tubular element 13 continuing the ring 50 is driven towards the rear (arrow F3) while being progressively compressed under the effect of the ramp 42 (FIG. 7) until 'that, having escaped from the ramp in question, it finds itself completely engaged in the first stage 44 (Figure 8). The tubular element 13 then continues, its axial stroke until it comes into abutment on the rod 30 carried by the tubular element 12, position for which said tubu¬ lar element 13 is retracted and in the end of stroke position back.

At this time, it is the tubular element 12 which is driven from its front end position to its retracted rear end position, in a manner similar to what has just been described for the tubular element 13.

It is also the same for the tubular element 11 apart from the fact that its rear end-of-travel position is determined by the annular part 11A coming into contact with the bottom 10D.

It will be noted that in such an embodiment the tubular elements are perfectly guided by the presence of the guide rings 20, and also by the fact that there is a very slight play between elements.

Reference will now be made to FIGS. 9 and 10 showing a variant embodiment of the front end-of-travel device, this variant having in particular the aim of allowing the admission of higher pressures, and, consequently, of increasing the capacities of loads of telescopic cylinders thus equipped.

It is in fact understood that the use of an elastic ring 50 as a means of end of travel before a tubular element, has mechanical resistance characteristics depending on its dimensions. As it is not possible to reduce the resistance of the tubular elements and providing deeper grooves for more substantial race rings, the invention provides to equip the tubular elements with two means of end of course before.

In FIGS. 9 and 10 above, two tabular elements have been shown partially such as, for example, the tubular elements 11 and 12 previously described, and it can be seen that the tubular element 11 has on its inner surface, a pair of depressions each indicated generally by 60 and 61, the generally oblique depression 60 having a section similar to the depression -4 previously described, while the multi-stage depression 6 has a section similar to the depression 43, described further, the deepest stage 62 being located towards the rear and extended towards the front by a second stage 6, the depth of which is substantially half of the stage 62. The depressions 60, 61 are spaced apart by a pitch PI.

As for the tubular element 12, it has on s external surface a pair of depressions indicated generally at 65, 66, the depression 65 located towards the rear comprising two stages 67, 68 similar to the depressurization 43 of FIG. 2, and the depression 66 situated towards the front comprising a groove substantially in a quadrant of circle 69 followed, towards the front, by a ramp 70, almost pe, planar, opening onto the external surface of the element 12. The step P2 of depressions 65, 66, is analogous to not PI of depressions 60, 61.

Note that in all the figures, the back is on the left and the front on the right for the reader.

According to this variant, and when the tubular elements are in the retracted rear end-of-travel position (FIG. 9), the depression 65, and more precisely in stage 67, houses an interrupted and elastically deformable ring 71 which is compressed when the elements 11 e 12 are in the rear end-of-travel position, while the depression 61 and more precisely the stage 62 houses a ring 72 which is expanded when the said elements are in the position indicated above. The ring 71 therefore tends to deploy radially along the arrow -F4 while the ring 72 tends to close on itself radially along the arrow F5.

When the elements 11 and 12 are in the front end-of-travel position after a displacement along the arrow F6 of the tubular element 12 (FIG. 10), a double front end-of-travel stop is obtained by the fact that the ring 71 is in support partly in depression 60 and partly in depression 65, while the ring 72 is partly supported in depression 61 and partly in depression 66.

From such a front end position, to a rear end position, the tubular element 12 moving backwards (arrow F7) while the tubular element 11 is stationary, the rings 71 , 72 respectively reintegrate the stages 62 - and 67, one, in this case the ring 72 being replaced in the tensioning position under the effect of the ramp of the depression 66 and the other, the 71 being instead replaced in the compressed position in the depression 65 under the effect of the ramp formed in the depression 60.

It will be understood that such an arrangement allows globally to double the force of the jacks, it being understood that the tubular elements will be calculated as a function of such an arrangement. Of course, the invention is not limited to the selected embodiments represented and which are instead subject to change without ^• the scope of the invention.

Thus in the examples shown, the front end-of-travel rings, that is to say the rings 50, 71, 72 have a circular section, but it is understood that these rings could have a different section, for example quadrangular, or oval, with of course,

! ? * depressions suitable for receiving such rings.

In addition, it should be noted that the tubular elements 11, 12, 13 have decreasing health thicknesses, as is clearly visible in the drawings, the same is true of the rings 50, 71, 72 which themselves, decreasing sections as the diameter of the tubular elements decreases.

WIPO

Claims

1. Telescopic cylinder with a cylinder, and a series of coaxial tabular elements movable longitudinally one after the other, from a retracted position to an advanced position and vice versa, these elements being limited in their movements by means limit switches said below, front and rear, which are spaced longitudinally on the tubular elements, CHARACTERIZED in that at least one front limit switch means is housed, in a retracted position of said tubular elements, in a first depression formed on a first tubular element thus allowing the obtaining of a minimum clearance between this first tubular element and a second neighboring tubular element, while, in an advanced position of said first tubular element, the - end of stroke means before and resting, in part, in the aforementioned depression and - in part, in a second depression provided for this purpose in the second element tubular ent.

2. Cylinder according to claim 1, characterized in that the first depression is formed on the inner surface of a tubular element, while the second depression is formed on the outer surface of a tubular element in contact with the previous one.

3. Cylinder according to any one of the preceding claims, characterized in that the first depression has, in cross section, a generally oblique shape while the second depression is said to have stages.

4. Cylinder according to any one of the preceding claims, characterized in that the second depression comprises a stage suitable for making it possible to accommodate the end-of-travel means followed towards the rear, of another stage intended to form a surface d 'support to said means of limit switch.

5. Cylinder according to any one of the preceding claims, characterized in that the first depression comprises an oblique ramp starting from the rear towards

β — s * """i•" • -. ~ -. - the front extended by a notch substantially in a quarter circle, the end of the ramp and the notch opening onto the inner surface of the associated tubu¬ lar element.

6. Actuator according to any one of the preceding claims, characterized ^'in that the means of the forward end position is formed by a circular ring interrupted deformable elastically along its diameter.

7. Cylinder according to claim 6, characterized in that the ring has in cross section a cylindrical shape of revolution.

8. Cylinder according to any one of the preceding claims, characterized in that, as a variant, the front end-of-travel means is constituted by a series of balls subjected to the action of a spring means tending to push them back according to a radial direction.

9. Cylinder according to any one of the preceding claims, characterized in that the tubular elements, as well as the cylinder, are made of drawn steel with progressively decreasing thicknesses starting from the cylinder.

10. Cylinder according to any one of the preceding claims, characterized in that the inner surface of the cylinder and of the tubular elements comprise, towards the rear and towards the front, a housing for an annular friction and guide part.

11. Cylinder according to any one of the preceding claims, characterized in that the tabular elements comprise at their front end portions at least one housing for a seal.

12. Cylinder according to any one of the preceding claims, characterized in that the tubular element which is in the vicinity of the cylinder comprises at its rear end and on its external surface, an annular part capable, on the one hand, of moving in a recess formed by a circular shoulder formed in the cylinder constituting the end-of-stroke means ^' before said tabular element and, on the other hand, to allow the admission of fluid under pressure on the reaction surfaces of said tabular elements, said annular part further forming a rear end-of-travel means by cooperation with the bottom of the cylinder.

13. Cylinder according to any one of the preceding claims, characterized in that, as a variant, at least one tubular element, has on its external surface a stepped depression, and at a distance from the latter towards the front, a depression generally oblique, while a tubular element close to the previous one, has on its internal surface a generally oblique depression, and at a distance from the latter, towards the front a depression with stages.

14. Telescopic cylinder according to claim 13, characterized in that the aforesaid depressions formed on the tabular elements has an identical pitch, and are suitable for receiving for one, when the tubular elements are in the retracted position, a ring which is compressed , and for the other a ring which is expanding.

15. Telescopic cylinder with a cylinder and a series of coaxial elements movable longitudinally one after the other from a retracted position to one. advanced position, and vice versa, these elements being limited in their movements by end-of-travel means hereinafter called front and rear, which are spaced longitudinally on the tubular elements, characterized in that the means of end of rear stroke are, for at least one of the tubular elements, constituted by a rod engaged in a groove formed on the inner surface of a tubular element, at the rear end thereof, the said rod being partially projecting by relative to said surface and able to cooperate with the end of a tubular element in contact, when the latter is in the retracted position.

s -.- EU -----.- L.-i