The present invention relates to a device in screws, spindles or simila to effect at least two different displacements of the screw and/or one more bodies which are connected to the screw. ϊhe device coπprises a sc or spirrile body shewing two or more threads or similar of different pitches and at least a first body, in which the screw is arranged to ru or be displaced and or that the said first body is arranged to run or b displaced along the screw.

In a great number of devices and different situations^ such as working operations, there is a need to be able to rapidly displace a screw, spindle or similar and a nut, body or another device or means axially i relation to one another, for example in order to attain a quick engagem and a quick release action and removal or other rapid movement. It is a sometimes a need to be able to increase the tightening tension when, fo example, clamping objects. Areas where such a need exists are for exampl in clamping jaws, vices, puller tools, lifting jacks, sliding valves, o valves adapted to rapidly shut off large flews, etc.

A previously known device shows a screw with two threads with different pitches and a nut suited to the threads of the screw. By a radial turn o a part of the nut, an angular displacement of the threads is effected in said part in relation to the threads in the remaining part of the nut, whereby the nut can change fran a first thread to a second thread of the screw. However, it has been shown to be difficult to obtain a satisfacto operation in all positions of the screw snά ar nut because of the existence of the changing design. In addition the device requires manual handling and a turning of a nut part relative to the remaining part of t nut which, among other things, involves a circumstantial and ti e- consuming handling of the device.

ϊhe purpose of the present invention is to achieve a possible realizatio of a device of the kind in question and eliminate the disadvantages of t previously known device. Thus a device in accordance with the invention can be shaped to work and change over from one thread to another automatically, i.e. without the need to handle the device manually. In addition the device provides an improved tightening force when this is needed. Displacement and release of tightening or engagement conditions can be done more quickly, and the risk of operations being interrupted d to the device, is substantially reduced or completely eliminated.

Furthermore, the device is easily adapted to multiplicity of applications within widely differing fields.

The device in accordance with the invention has obtained the character- istics mentioned in claim 1.

Further characteristics of and advantages with the device in accordance with the invention will be apparent in the following description of the invention by embodiments, whereby a simultaneous reference will be made to the accompanying schematic drawings, of which Fig. 1 shows, from one side, an example of a device in accordance with the invention according to one embodiment and in one position, Fig. 2 shows the device in Fig. 1 in another position, Figs. 3 and 4 show, from one side, examples of spindles which can be included in a device in accordance with the invention, Figs. 5 and 6 show, in cross-section, examples of bodies or nuts, which can be included in a device in accordance with the invention, Fig. 7 a-e show schematically, from one side, examples of a working process for a device in accordance with the invention, Fig. 8 shews schematically pitches of a spindle, Figs. 9 and 10 shew schematically a part of a device in accordance with the invention, for example, the device in Figs. 1 and 2 and in respective positions, Figs. 11 - 14 show, from one side and partially in section, examples of a device in accordance with the invention in a working process, whereby a spring load sensing device, not shown in previous figures, is shown, Figs. 15 and 16 shew, from one side and partially in section, examples of further embodiments of a device in accordance with the invention shaped as ball screws, Fig. 17 shews from one side an embodiment of a ball holder which can be included in a device in accordance with the invention, Figs. 18 and 19 shew a spindle opened out in screw diagrams, which shew the pitches of the spindle as a functio of the spindle's angle of rotation and ball positions for balls, which a ball holder holds, Fig. 20 shows, from one side and partially in section, yet another embodiment of a device in accordance with the invention, Fig. 21 shows, from one side and also partially in section, a second embodimen of a ball holder, Fig. 22 shows, from one side, a screw according to another embodiment and Fig. 23 shews, from one side, a body or nut or a blank for bodies or nuts according to another embodiment.

The reference designation 1 in Figs 1, 2, 7, 11 - 14, shows devices in accordance with the invention, which comprise a screw 2 or a spirrile with a screw or spindle body 3 with one or more threads 4, 5, for example a

first thread 4 in the shape of a coarse thread and a second thread 5 in the shape of a fine thread, whereby the threads have different thread pitches 18 and 19, see Fig. 8. Thus a spindle body 3, as shown for exampl in Figs. 3 and 4, is provided with a fine thread 5. Then the fine thread can be eliminated in a spiral 6 extending helically around the spindle body, whereby the remaining fine thread 5 forms a threaded helical spiral 7 with several entrances, while the other spiral 6 forms a spiral path 6 or a ^' groove 16, which does not have fine threads or any threads but with the threaded spiral path 7 forms a coarse thread 4. In this way the coars thread 4 will divide the fine thread 5, which accordingly will have a riumiber of individual threads which, where appropriate, extend only over a part of the periphery of the spindle or screw body 3. Preferably the firs thread 4 is given a substantially larger pitch 18 than the individual threads in the second thread 5.

Furthermore, the device 1 comprises in accordance with the embodiments shown, a first and a second body 11 and 12 or nuts, which shew together with screw 2 suitable threads 8, 9 or similar, matching respectively the threads of the screw 2, i.e. in accordance with the embodiments shown in the figures, two threads with different pitches, see Figs. 5 and 6.

Bodies 11, 12 can be shaped by means of a nut blank, a body or a not bein threaded, such as with a thread with a small pitch or a so called fine thread, being provided with holes 51, openings, slots 52, recesses and th like by drilling and/or milling, see also Fig. 23, and further that the said thread being eliminated in a spiral 8, whereby the remaining thread forms a threaded spiral with several entrances, while the other spiral 8 forms a groove, which does not have fine threads or any threads. Threads in the said threaded spiral together form a coarse thread, i.e. that the threaded spiral exists in the first thread 4 or coarse thread of screw 2, when screw 2 and bodies 11, 12 are engaged in a first thread or coarse thread. The said second threads 5 or fine threads of screw 2, or the threaded spiral path 7 exist hereby in the said spiral 8 of bodies 11, 12, which is in the form of a non threaded portion. When screw 2 and bodies 11, 12 are engaged in a second thread or fine thread, at least some of th second threads 5 or fine threads of screw 2 are engaged with at least sam of the individual fine threads 9 of bodies 11, 12 and existing in the threaded spiral.

Holes 51 made in bodies 11, 12 can be used for receiving connecting devices 17, 35 aιx3 or load sensing devices 15, 35, pins, pegs, such as consisting, for example, of holding means, made recesses for arranging spring elements in load bearing devices and/or holding devices for load sensing devices or spring elements for them. Other recesses or slots 52 can be used instead for receiving connecting devices 17 between bodies 11, 12 in device 1 in order to limit the relative distance between the bodies 11, 12, rotation-lock bodies 11, 12 in relation to each other or make the nαn-turnable with one another for receiving wedges, a σveable wedge meant for a locking means in order to lock the bodies in an occupied, relative position in axial direction, etc. and other holes or openings for receiv¬ ing or forming a seat for locking elements in a locking device etc.

Device 1 or screw 2 is self-cleaning by any collected dirt or the like on screw 2 or screw body 3 being removed when the device is used. When screw 2 and bodies 11, 12 are engaged in the fine thread, and on movement between the screw and the bodies, the dirt will be transported to coarse thread 4 of screw 2, fall off or be scraped off by threads 9 of bodies 11, 12 or the said threaded spiral, when screw 2 and bodies 11, 12 are engage in the coarse thread.

Device 1 is arranged to be able to effect at least two different displace ments of screw 2 an Or one or more bodies 11, 12, such as, for example, rapid displacement of a screw 2 or a body 11, 12, whereby a low tension o tightening force action is certainly attained and a smaller load-bearing capacity but a rapid displacement, or a slow displacement, whereby a high tension or tightening force action is attained and an unproved or greater load-bearing capacity. Thus, a rapid transport can be carried out, when the loading is low, whereby when the load or an axial loading is received or an increased such, the device 1 changes over in a thread with smaller pitch or to a so called fine thread, whereby the load-bearing capacity increases. Accordingly it is a question of device 1 being able to change between at least two different displacements whereby, in accordance with the invention, this change can be carried out automatically. Thus, device 1 comprises a load sensing device 15, 35 which can be arranged to sense i a body 11, 12 obtains a resistance, a load 10 or similar. Furthermore, bodies 11, 12 are connected to each other by connecting devices 17, see Fig. 1, so that they cannot turn relative to each other but still be dis¬ placed with one another in the axial direction of screw 2. Connecting devices 17 can be formed by a number, for example three pins, pegs 27 or the like.

When bodies 11, 12 or their threads 9 run in the coarse thread 4 of scre 2, bodies 11, 12 are arranged at a distance 30 from one another and take up a first axial position 13 with one another, see also Fig. 9. With further reference to Figs. 7 a and 11, screw 2 or bodies 11, 12 are displaced in a direction 31 by means of a rapid displacement in the coar thread 4 of screw 2. It should be possible to say that device 1 is in a transporting position. When the first body 11 reaches a resistance or a load 10, i.e. that an axial loading is obtained between screw 2 and bodi 11, 12, see Figs. 7 b and 12, the load 10 is sensed by the load sensing device 15, 35, whereby the first body 11 climbs the second thread 5 or fine thread of screw 2. The second body 12 is still displaced in the fir thread 4 or coarse thread, i.e. in accordance with the condition shown i Fig. 9, until the second body 12 reaches the first body 11, see Figs. 7 and 13, whereby the second body 12 obtains a resistance, a load 10 or an axial load from the first body 11, which is sensed by a load sensing device 15, 35 in the second body 12. In this connection the second body also begins to climb the second thread 5 or fine thread of screw 2. When the second body 12 is engaged with the second thread 5 or fine thread of screw 2 the change f om the first thread 4 or coarse thread is carried out, see Figs. 7 d and 14. Bodies 11, 12 or their threads 9 are now runn ing in the fine thread 5 of screw 2, as shown in Fig. 7 e and in accord-, ance with the condition shown in Fig. 10, and are no longer situated at distance from one another but take up a second axial position 14 with on another, see also Fig. 2. The arrows 32 in Fig. 7 show the displacement the body or bodies 11, 12 or screw 2 in the first thread 4 or coarse thread of screw and the arrows 33 show the displacement of the body or bodies 11, 12 or screw 2 in the second thread 5 or fine thread of screw

When the resistance, load 10 or similar reduces, the bodies 11, 12 or their threads 9 return to the first thread 4 or coarse thread of screw 2 in the reverse way, i.e. beginning with the second body 12 _^ A change occurs again.

When both bodies 11, 12 are arranged in the second axial position 14 wit one another, i.e. when the bodies are connected or lie against each othe and are engaged with the fine thread, both bodies 11, 12 act as a unit o one body or nut, i.e. fine thread 9 or fine threads in one "body in connection with the other body, continue uninterrupted in the other body.

With such a device 1 a rapid transport can be carried out by means of engagement in the coarse thread, whereby however a reduced tightening force and load-bearing capacity exists. An improved tension or ti tening force action and load-bearing capacity is received fcy means of changing to another thread with a smaller pitch or to a fine thread, whereby precision is attained and that the device can be, or is, self-retarding. Furthermore the device can be contained in a small or limited space and can therefore also be utilized in further fields of application.

The load sensing devices 15, 35, which in accordance with the shewn embo¬ diment, are arranged in each body 11, 12, can cαrprise a controlling device 36, for example in the shape of a pilot ball and a spring device 37 which, in one controlling device 36, can be arranged to hold the controll¬ ing device 36 in a contact position against a base. Against the action of spring 37, controlling device 36 can be permitted to follow elevations in the base. In accordance with the embodiment in Figs. 11 - 14, the load sensing device 35 is controlled or run by means of a pilot ball 36 in the first thread 4 or coarse thread of screw 2 the displacement of the bodies

11, 12 during the rotation of screw 2 or vice verse. The direction of rotation of screw 2 or spindle 3 is shown with arrow 34. When a body 11,

12 is to climb a fine thread 5 of screw 2, the pilot ball 36 is pressed against the action of the spring 37 from the coarse thread 4 for contact against fine thread 5, i.e. the pilot ball 36 is moved aside and out of its controlling engagement with coarse thread 4. Bodies 11, 12 are thus mechanically operated by means of the load sensing device 35 or pilot ball 36 in the coarse thread 4 of screw 2 until a body 11, 12 or bodies reach a resistance, load 10 or similar and the load exceeds the limit load of pilot ball 36. In this connection the load sensing device or pilot ball is moved out of its controlling position and ceases the mechanical operation of the body 11, 12. It can be possible to say that pilot ball 36 forms a supplying device, when an axial force is directed against the bodies 11,

12. Besides as a controlling device load sensing device 35 or pilot ball 36 is accordingly a device of transfer and also runs a driving device, when screw 2 and bodies 11, 12 are engaged in coarse thread 4. In Fig. 22 a screw with a clamping part 53 is shewn and a shaped groove 54 or the lite in the first thread 4 or coarse thread for taking up or taking up part of, or contact of the pilot ball 36 in the load sensing device 35. On the side of the groove 54 exists surfaces 55 against the flanks of adja¬ cent other threads or fine threads 5. The distance 30 between the bodies 11, 12, when the bodies are displaced in the first thread 4 or coarse thread of screw 2, is a coarse thread pitch.

The shewn and described embodiments have referred to screws 2 and bodie 11, 12 with screw threads with a change-over between different thread pitches, and even an automatic one, and while maintaiiώig the advantage of device 1 in accordance with the invention. These can also be attaine with so called ball screws. In accordance with an embodiment of device according to the invention, an advantageous further development of the ball screw has been obtained. With a usual ball screw, balls run in a l path in a thread between a screw and a nut. The balls must be fed back means of special return leads. The design of the ball-screws involve, among other things, the consumption of a large number of balls, of whic half of these do not contribute to an improved bearing^capacity, since all the balls are in the thread of the nut at the same time. A ball scr in accordance with the invention, with a changing function, can almost b considered as a double ball screw, since the screw 2 has two threads 4, and for the change two nuts or bodies 11, 12, which are arranged in connection with each other to form a unit. In the unit scπe form of resilient, load sensing work is usually carried out which, at a predete mined axial loading between screw 2 and bodies 11, 12, permits the bodie in turn to change from the one or a first thread 4, and a second thread When low loading again occurs the change is carried cut in reverse. Bodi 11, 12 are not allowed to change at the same time, whereby at least one the bodies in a position is separated from the changing points. In this way screw 2 can always bear a load, which corresponds to what a body can bear. Hcwever, bodies 11, 12 must be able to move relatively to each oth so that when changing take place they displace in different pitches 18, whereby the relative movement between the bodies is carried cut under th angle of rotation of screw 2, as the changing is u der way. In accordanc with an embodiment of device 1 in accordance with the invention, the sai relative movement between the bodies 11, 12 is arranged to be carried ou in the axial direction of screw 2, i.e. it is an axial movement. It shou also be able to be a rotation or a combination of an axial movement and rotation.

In Figs. 15 and 16, embodiments of a so called ball screw or double ball screw are .shown, as the devices 1 are arranged for changing function. Th a screw 2 or a spindle body 3 is equipped with two or more threads 4, 5 with different pitches 18, 19. Two bodies 11 and 12 which primarily have the function of forming a path for balls 20, are arranged in order to tu between limiting devices 39 in the shape of flanges for limiting or uniting the bodies. Bodies 11, 12 are mounted in flanges 39 by means of

bearings 29 and have ball paths 28 for balls 20, whereby the ball paths lack pitches. Balls 20 are arranged in a ball holder 21 for each body 11, 12, see also Fig. 17. The ball holder 21, which can be in the shape of a sleeve 22, has positions 23 or throu openings 24 or holes for the balls 20. Furthermore, each ball holder has one or more load sensing devices 15, 35 or openings 25 or holes by means of which a load sensing device 15, 35, for example in the shape of a pilot ball 36, can project for engagement with screw 2 or its thread 4 or threads 4, 5. The load sensing device 15, 35 can instead be arranged in one or both of the said limiting devices 39 and be comprised of a spring loaded ball 36. Ey means of an adjustment device 38 in the shape of, for example, an adjustment screw, the load sensing device 15, 35 can be set. Since the bodies 11, 12 in Figs. 15 and 16 are shewn connected to each other, the bodies are changed to the secon thread 5 or fine thread of screw 2, i.e. have occupied a second axial position 14 with one another.

Screw 2, a body 11, 12 and the ball holder 21 are united by the rolling movements of the balls 20.

The engagement of the balls 20 or position in screw 2 is shown in Figs. 1 and 19, whereby Fig. 18 shows the d_ placement of the bodies 11, 12 in a first thread 4 or a coarse thread, while Fig. 19 shows the displacement o the bodies 11, 12 in a second thread 5 or fine thread. This is also shown in the earlier Figs. 9 and 10, where the threads of the bodies 11, 12 correspond by balls 20, and the changing is also evident. In Figs. 18 and 19 the position of the load sensing device 15, 35 or a pilot ball 36 is shown. In the bottom part of Fig. 19 it can be seen that body 11, 12 or balls 20 are located in fine thread 5 or at bodies 11, 12 with the screw thread, the fine thread 9 of bodies 11, 12 engaged with the fine thread 9 of screw 2. In the case of ball screws the corresponding body 11, 12 has only one thread or fine thread but ball holder 21 has a pitch, which corresponds to the first thread 4 or coarse thread of screw 2 and second thread 5 or fine thread.

In the top part of Fig. 19 a displacement in the coarse thread 4 of the screw is shown, as well as in Fig. 18.

For device 1 in accordance with the invention, it is shown that it is possible to eliminate the previously mentioned limiting devices 39 or flanges for uniting the bodies 11, 12 or holding together the bodies and

the ball holders 21 in the intended position. Since ball paths 28 in bodies 11, 12 do not have pitches and balls 20 are held in ball holders in a spiral araϊ in predetermined, spaced positions, the ball holders 21 will have a planetary function if the driving occurs onΦodies 11, 12. Accordirigly, bodies 11, 12 and ball holders 21 with balls 20 will mainta their intended position in device 1. Ball holders 21 are, in the ball screw or double ball screw, connected to each other by means of a connecting device 17 similar to that described in ∞πnectiαn with previously embodiments for bodies 11, 12, i.e. that ball holders 21 are not turnable relative to each other but are displaceable in the axial direction of screw 2, whereby changing function is attained. The corinecting device 17 can be formed of one or more clutch couplings 26 or similar, whereby one ball holder 21 is equipped with a projecting part, which is displaceable in the axial direction of screw 2 in a recess, groove or the like in the other ball holder 21, see for example the embodiment in Fig 21. The distance 30 shewn in the figure, shews that bodies 11, 12, ball holders 21 or balls 20 are in the first thread 4 or coarse thread of screw 2. By reducing distance 30 or allowing the bodies 11, 12 or ball holders 21 to connect with each other, a change to a seco thread 5 or fine thread is accordingly achieved. Furthermore, it can be seen that ball holders 21 do not have a load sensing device 15, 35 or openings 25 or holes for such a device. Thus, changing can be carried cut without such a device for ball screws with a changing function or double ball screws in accordance with the invention. However, there is a risk of the changing jamming in isolated or on same occasions. Therefore, in addition, for double screws, double ball screws ought to or should have a least a load sensing device 15, 35, for example in the shape of a pilot ball 36. Normally, a load sensing device 15, 35 must exist to produce changing function, or automatic changing function, but can*be in form of device other than a pilot ball 36 or similar. Such a device 15, 35 will b seen in connection with the description of the embodiment in Fig. 20.

A double ball can be driven in various ways, for example by means of driving on the ball holder, which can most closely be desctibed as direct driving. It can also be driven on the said bodies, whereby the ball holde with balls acts as planets and planet holders, i.e. a planetary driving. An example of such a double ball screw will be described below.

Device 1 in Fig. 20 shews a double ball screw, in which the one or first body 11, 41 shows, at one end, a projecting sleeve 43 or similar, in whic

the second body 12, 42 is located, i.e. integrated in the first body 11. Between the bodies 11, 12, a load sensing device 15, 35 is arranged in the shape of a pair of 0-rings 46. Screw 2 shews a coarse thread 4 and a fine thread 5 in the shape of inner ball paths 45 for balls 20. The balls 20 are held by ball holders 21, which in similarity with previous embodiments are axially displaceable relative to each other in the axial direction of screw 2 but not turnable with one another. The ball holders 21 are connected with each other by means of a connecting device 17, such as a clutch coupling 26 or similar and keeps the balls 20 in predetermined, spaced positions in a spiral, which corresponds to the pitch of the coarse thread 4 of screw 2. Guiding edges 47 or similar can be formed on ball holders 21 or formed in the clutch coupling 26 for relative axial control of ball holders. The bodies 11, 12 have outer ball paths 28 for balls 20 and which lack pitch, i.e. balls 20 have the same pitch as ball paths 28 in bodies 11, 12. The distance 30 between bodies 11, 12 and the distance 40 between ball holders 21 in the axial direction of screw's 2 spaced position 13, is the same as half the pitch or the centre distance between two adjacent balls 20 in ball holder 21, or a cam width of spindle 3 in screw 2. With the reference designation 44 an end wall is shown which can be formed as a locking ring, which is threaded in the sleeve 43 projectin from the first body 11, 41. The end wall 44 can be arranged or used to adjust or fine set the distance 30 between bodies 11, 41 and 12, 42 and thus form an adjustment element, which is shown with the reference designation 48. Thus, end wall 44 can be screwed further into sleeve 43 o in the opposite direction for adjustment of the said distance 30. To facilitate such an operation, end wall 44 can show an engagement device 49, for example a hook spanner. In the same way, or at the same time, an adjustment of the running of balls 20 in coarse thread 4 can be performed. In position 13, shown in Fig. 20, device 1 is in coarse thread 4, but wit ccatiπued displacement towards load 10 and, when this is reached, the first body 11 enters the fine thread 5 of the screw airl then the second body 12, whereby bodies 11, 12 are held in the fine thread as long as loa 10 exists. The device 1 is not self-obstructing in cases when the pitch o the coarse thread 4 is small and the adjustment element 48 can also or instead be shaped as a sensing device or similar.

Without exceeding the sccpe of the concept of the invention, modification of the device in accordance with the invention should be possible. The device or each body can comprise at least one load sensing device, for example a load sensing device in each body, two load sensing devices in

each body etc. The thread length in the coarse thread of the screw for a ball screw and between the transposition between a first thread or coars thread and a second thread or fine thread is, or is preferably, greater than half the length between balls in the coarse thread. In this way even running is ensured. The wall thickness between the threads or groov in the bodies is so dimensioned that it will not be negative, which is w the ball sizes and thread pitches are adapted so that a maximum number o thread entrances can be used. The ball density namely increases quadratically with the number of thread entrances. Accordingly, it is desirable to have a maximum ball density and as large a difference betwe the pitch of the fine and coarse threads as possible. A double ball scre can be arranged to work with rolling friction, which gives a high efficiency and less wear in comparison with existing ball screws. Furthermore, a higher displacement velocity can be reached through the lack of ball return leads. Furthermore, the device can otherwise be adapted in its design form with regard to the multiplicity of different fields of application which can be utilized. The device in accordance wi the invention is thus not restricted to that shewn and described in connection with the embodiments but solely by the following claims.