WO2001090599A1 - Device for converting rotational movements into linear movements or vice versa - Google Patents

Abstract

The invention relates to a device (1) for converting rotational movements into linear movements or converting linear movements into rotational movements. Said device comprises a spindle (2) provided with a thread (5) and comprises several rollers (4) provided with annular projections. Said rollers are arranged between the spindle (2) and a housing (3), which comprises a thread (6) on the interior thereof. The housing (3), with a spindle (2) rotating in relation thereto, can be moved in relation to the spindle (2) in the axial direction thereof by the rolling engagement between the rollers (4) and the spindle (2) or the housing (3). The rollers (4) comprise a crowned shape or the interior of the circular ring-shaped housing (3) has a shape that is outwardly cambered toward the rollers (4) in order to reduce the contact pressure in both respective end areas (8, 9) of the rollers (4). The invention also relates to an actuating drive (23) which comprises a spindle and a connection to an actuating drive. A handwheel is provided for effecting a manual adjustment, and a motor-driven drive unit is provided for effecting a mechanical adjustment. The actuating drive is provided with a device as described in one of Claims Nos. 1 to 12 between the motor-driven drive unit or handwheel on one side and the actuator connection on the other.

Description

 Device for converting rotational movements into linear movements or vice versa

The invention relates to a device for converting rotary movements into linear movements, optionally of linear movements into rotary movements, with a threaded spindle and a plurality of rollers provided with ring projections, which are arranged between a threaded housing on the inside and the spindle, the Housing with spindle rotating relative to it by rolling engagement between the rollers and the spindle or the housing is movable relative to the spindle in the axial direction.

Furthermore, the invention relates to an actuator with a spindle and with a connection to an actuator, a handwheel being provided for manual adjustment and a motorized drive unit being provided for machine adjustment, wherein for the motorized drive unit e.g. an electric, pneumatic or hydraulic motor can be provided.

Devices for converting rotary movements into linear movements are generally known as spindle drives. Most of the time, such spindle drives have a trapezoidal spindle on which a nut secured against rotation is linearly adjusted. Such spindle drives are relatively robust and inexpensive to manufacture, but they are extremely maintenance-intensive and have an inconsistent efficiency.

In order to improve the efficiency of spindle drives, so-called ball and roller screw spindles have therefore already been proposed, in which a rolling motion transmission is generated via a type of planetary gear, which results in improved efficiency due to the reduced friction losses.

For example, US Pat. No. 3,884,090 A discloses a roller screw drive in which a plurality of cylindrical rollers are freely rotatably mounted in a cage and an improved efficiency is achieved by rolling the flanks of the thread of the spindle or the housing surrounding the rollers in the grooves of the rollers is achieved. However, such roller screws usually require extremely high manufacturing accuracies, which makes them relatively expensive to produce. The field of application of such roller screw drives is also in the area of high Precision settings, such as for adjusting the solar wings of satellites.

The aim of the invention is to provide a device of the type mentioned at the outset which has a constant efficiency which is improved compared to trapezoidal spindle drives and which requires little maintenance. Furthermore, the device should have a construction which, due to the possibility of reduced manufacturing accuracy, brings about a cost saving, but on the other hand has a high level of robustness in order to be able to transmit large axial forces.

Another object of the invention is to provide an actuator of the type mentioned at the outset, which is also inexpensive to manufacture and can transmit high axial forces and / or high (derived) torques due to its robust design.

The device according to the invention of the type mentioned at the outset is characterized in that the rollers have a spherical shape and the inside of the annular housing has a shape which is curved outward toward the rollers in order to reduce the contact pressure in both end regions of the rollers.

Due to the spherical or bulbous shape of the rollers (and / or, if applicable, the corresponding shape of the housing that bulges outwards towards the rollers), the contact pressure between the individual gear parts in the two end regions of the rollers, in which, depending on the direction of rotation of the spindle there is an absolute maximum, since the rollers are only in full contact with the thread of the spindle or the thread of the housing enclosing the rollers in the central region of the rollers when the axes of the spindle or the rollers are parallel. As a result, the requirements for the manufacturing accuracy can be reduced and the device can be designed cost-effectively. As such, it is also possible for the rollers to have a cylindrical shape and for the housing enclosing the rollers to have a shape which is curved outwards towards the rollers, as a result of which the maximum contact pressure is also shifted from the respective end regions of the rollers to the central region to be able to reduce the requirements for manufacturing accuracy, which in turn saves costs. Furthermore, there is still an efficiency of approx. 80%. In order to be able to transmit high axial forces, it is advantageous if the threads have a flank angle of less than 90 °, for example less than 70 °, preferably of approximately 60 °.

Since, depending on the direction of rotation of the spindle, the rollers move upwards or downwards relative to the housing when the spindle rotates, it is advantageous if the thread on the inside of the housing has at least one roller reset section which extends over the entire axial length of the housing in which the thread is interrupted. In this roll reset section, the rolls can e.g. after each revolution, related to the spindle, be set back by one thread.

If the flanks of the thread on the inside of the housing have a sloping transition towards the reset section, a smooth transition of the rollers between the reset section and the re-entry into the thread is advantageously achieved. The sloping transition into the reset section can be rounded off, but tangential sloping or moderately discontinuous sloping transitions are also possible in terms of production technology.

In order to achieve the most symmetrical possible wearing situation of the device, it is advantageous if two or more, preferably evenly arranged, rucksack sections are provided. In order to keep the rollers in an axially oscillating position relative to the housing, each roller is therefore e.g. set back by half a pitch of a two-start thread or according to the number of partial reset areas.

If the rollers are rotatably mounted in synchronization disks by means of pins provided at both ends, the rollers can advantageously not move against one another, as a result of which disadvantageous mutual contact between the rollers can be avoided.

In order to allow the rollers a certain freedom of movement in the radial direction, which is necessary in order to be able to enter and exit the reset partial area, it is favorable if the synchronization disks for receiving the pins have radial elongated holes.

In order to achieve a reset of the rollers in the reset partial areas in a structurally simple manner, it is advantageous if the rollers are assigned end-link link plates which each have at least one roller reset nose, each of which is assigned to a reset partial area.

In order to avoid slippage between the two synchronization disks, which would result in an inclined position of the rollers, it is advantageous if the synchronization disks are coupled to one another via at least one synchronization shaft.

If the synchronization disks are coupled to one another via two synchronization shafts arranged offset by 180 °, the reaction forces that occur do not result in friction losses on the circumference of the synchronization disks, but are advantageously supported by the shaft bearings located opposite each other.

For a slip-free, structurally simple synchronization of the two disks, it is expedient if the synchronization shaft engages with the two synchronization disks via intermeshing toothed rings.

If the synchronization shaft is freely rotatable in the cover or link plates, additional bearing points for the synchronization shaft can advantageously be omitted, which results in cost-effective production.

In order to reliably transmit the linear movement from the link plates to the housing, it is advantageous if the link plates are positively connected to the housing.

If the axes of the rollers are arranged obliquely with respect to the axis of the spindle, there are smaller difference angles between the grooved flanks of the rollers with respect to both the spindle and the nut thread, as a result of which advantageous rolling ratios and lower synchronization support torques are achieved. It is essential here that the desired inclination of the roller axes to the spindle axis remains constant, this being reliably achieved in a simple manner if the two synchronization disks for the inclination of the axes of the rollers are arranged offset with respect to the axis of the spindle.

In order to avoid an unfavorable point contact between the pins of the rollers and the elongated holes provided for their reception, it is advantageous if the pins have a bulbous shape.

The actuator according to the invention of the above Art is characterized in that a conversion device is provided as indicated above between the motor drive unit or handwheel on the one hand and the actuator connection on the other hand. In this way, an actuator is created which, with a cost-effective construction, is extremely robust and furthermore has a high degree of efficiency, in particular of approximately 80%.

Since the connection between the flanks of the threads of the spindle or the housing and the grooves of the rollers is not self-locking, but torque should not be transmitted from the actuator to the handwheel, it is advantageous if between a handwheel spindle connected to the handwheel and the spindle is provided with a device which transmits torques in both directions of rotation from the handwheel spindle to the spindle and has a blocking effect on torques in both directions of rotation from the spindle to the handwheel spindle. There is thus a type of freewheel device which acts in both directions of rotation, and such devices are known as so-called load torque locks.

For a translation of motion between the actuator drive, i.e. the handwheel or the motor drive unit, and the spindle, it is advantageous if a planetary gear with a sun wheel and several planet wheels is provided for adjusting the spindle. To translate the rotary movement from the handwheel into fast or from the motor drive unit to slow, it is advantageous if the spindle is connected to the sun gear or the handwheel spindle is connected to the planet gears.

On the other hand, it is favorable if the spindle is connected to the planet gears or the handwheel spindle is connected to the sun gear in order to obtain a translation from the motor drive unit to fast or a translation of the movement introduced by the handwheel to slow.

For a structurally simple transmission of movement from the motor drive unit to the spindle, it is advantageous if a worm wheel is provided for transmission of movement from a motor-driven drive shaft to the planetary gear. The connection between the drive shaft and the worm wheel can be self-locking in order to prevent unwanted turning back due to torques acting on the spindle. however, the motor drive unit can also be assigned a switchable locking element, possibly an electromechanical brake, in order to hold the actuator in the respective position.

To take advantage of the device for converting rotary movements into linear movements, also for converting into non-linear movements, e.g. To be able to use pivoting movements, it is advantageous to implement a shear force-free conversion, which is achieved when the cylindrical body rolls on a rail connected to the housing to convert the linear movement of the housing into a pivoting movement of a cylindrical body. In a structurally particularly simple manner, the cylindrical body can be connected to the housing with flexible elements, preferably two ropes, for transmitting motion from the housing to the cylindrical body. By crossing the cylindrical body with the ropes in a cross shape, the risk of possible tipping moments due to uneven settling in the rope can be avoided.

The invention is explained in more detail below on the basis of preferred exemplary embodiments illustrated in the drawing, to which, however, it is not intended to be limited. The drawing shows in detail:

Figure 1 partially a detailed view of a spherical roller between a spindle and a housing of a spindle drive.

2a schematically shows a diagram of the force profiles between the rollers and the spindle or the housing according to the prior art;

2b shows a diagram according to FIG. 2a with manufacturing inaccuracies;

2c schematically shows a diagram of the force profiles between the rollers and the spindle or the housing in the case of a spherical shape of the rollers and / or a shape of the inside of the housing that bulges outwards in the central region of the rollers towards the rollers;

FIG. 2d shows a diagram according to FIG. 2c with manufacturing inaccuracies as in FIG. 2b;

3 shows a plan view of the device according to the invention;

FIG. 4 shows a view according to FIG. 3, however, with the link plate removed;

5 shows a view according to FIGS. 3 and 4 with the upper synchronization disk removed; 6 shows a perspective view of a device modified from FIGS. 1 to 5 with the housing part removed;

7 shows a view of the device according to FIG. 6 with the housing closed;

8 shows a side view of the device according to FIG. 6;

9 shows a perspective view of a gearbox of an actuator with a device according to FIGS. 1 to 5;

FIG. 10 shows a broken view of this transmission according to FIG. 9;

11 shows an actuator according to FIGS. 9 and 10, wherein a linear rotation movement transmission device free of lateral force is provided;

FIG. 12 shows a perspective view according to FIG. 11 from the rear; and

13 shows in detail the course of ropes for the transverse force-free motion transmission device according to FIGS. 11 and 12.

1 shows a half section of a device 1 for converting rotational movements into linear movements, in which a plurality of rollers 4 are provided between a spindle 2 and a housing 3 and are provided for a rolling motion transmission. The spindle 2 and the housing 3 each have a thread 5 or 6, the flanks of these threads 5, 6 engaging in the grooves 7 of the rollers 4 and causing a rolling motion transmission. Since there is an uneven load transfer due to material elasticities in the movement transmissions, which usually cause increased stress in the areas 8 and 9, the roller 4 shown in FIG. 1 has a slightly convex shape in order to achieve the maximum stress of to shift the end regions 8 and 9 into the central partial region 10 of the roller 4, as a result of which lower manufacturing accuracies are required. Depending on the application, the crowning can be defined differently, e.g. -Convexities on the order of a few tenths of a degree have proven to be favorable.

As can be seen from the force transmission profiles 17, 18 shown in FIG. 2a between the spindle 2 and the rollers 4 or the rollers 4 and the housing 3, the force transmission maxima 17 ′, 18 ′ occur in the roller end regions 8, 9 in conventional devices , whereby such transmission devices react extremely sensitively to the slightest manufacturing inaccuracies. It can be seen from FIG. 2b that a significant increase in the absolute maximum 18 ′ occurs in the case of manufacturing inaccuracies.

In contrast, in a device according to the invention, as shown in FIG. 2c, the maxima 17 ', 18' of the force transmissions 17, 18 between the spindle 2 and the rollers 4 or the rollers 4 and the housing 3 are shifted into the central region 10. As a result, the device according to the invention exhibits a significantly less critical behavior towards manufacturing inaccuracies, as can be seen from FIG. 2d. 2d shows manufacturing inaccuracies as in FIG. 2b, but these manufacturing inaccuracies only lead to an increase in the pressure in the edge regions 8, 19, while the pressure maxima 17 ', 18' remain unchanged. As a result, the requirements for manufacturing accuracy, which in the prior art are in the 0.001 mm range, can be reduced by a power of ten in the 0.01 mm range, and significant cost savings can thus be achieved.

In order to be able to transmit high axial forces between the spindle 2 and the housing 3, the flanks of the threads 5 or 6 and the corresponding grooves 7 of the roller 4 have a flank angle of e.g. approx. 60 ° (90 ° flank angles are common in the state of the art).

At the two ends of the roller 4 there are pins 11, which serve to mount the rollers 4 in synchronization disks 12 (cf. FIG. 4). This mounting of the rollers 4 in the synchronization disks 12 has the primary purpose of preventing the rollers 4 from colliding with one another, which could possibly destroy the device, and of guiding the rollers 4 parallel to the system axis. The two synchronization disks 12 each have link disks

13 on. In order to couple the rotary movement of the two synchronization disks 12 to one another, a synchronization shaft 14 is provided, which prevents rotation slip between the two synchronization disks 12. The synchronization wave

14 has two ring gears 15, which bring about an identical speed via a meshing engagement in ring gears 16 of the synchronization disks 12. This prevents the rollers 4 from sloping between the spindle 2 and the housing 3 become. The synchronization shaft 14 is freely rotatably mounted in openings in the link plates 13, which further have control cam-like ratchet lugs 13 'for resetting the rollers.

In Fig. 3, the device 1 is shown in a plan view, wherein the spindle 2 and the rollers 4 rotatably mounted in the synchronization disks 12 can be seen within the housing 3, but partially from the link disk 13 in which the synchronization shaft 14 is mounted , are covered.

The synchronization shaft 14 engages with the ring gears 15 in the ring gears 16 of the synchronization disks 12 and thus forces synchronization of the synchronization disks 12, which prevents the rollers 4 from jamming. As can further be seen from FIG. 4, the pins 11 of the rollers 4 are mounted in radial elongated holes 20, as a result of which the rollers 4 can move in the radial direction, which is particularly evident when the entry and exit in FIG 21 is desired. FIG. 5 also illustrates the rolling engagement of the rollers 4 with the thread 5 of the spindle 2 or with the thread 6 of the housing 3. The rounded transitions 22 of the thread 6 in, the thread-free reset partial regions 21 can also be seen, as a result of which a smooth entry or exit of the rollers 4 in or out of the respective reset portion 21 is made possible. It is expedient here if the thread 6 of the housing is not cylindrical, but is widened in the reset partial areas 21, as a result of which a torque which is as continuous as possible for generating the axial force (or vice versa) is achieved.

6 shows a somewhat modified device 1 'compared to the device 1 shown in FIGS. 1 and 3 to 5, in which the synchronization disks 12 are coupled to one another via two synchronization shafts 14 arranged offset by 180 °. The housing 3 is composed of two separate housing parts 3 ', one of the two housing parts 3' being removed in the exemplary embodiment shown in FIG. 6. With the aid of the diametrical arrangement of two synchronization shafts 14, the reaction forces that arise do not result in friction losses on the circumference of the synchronization disks 12, but are advantageously supported via the synchronization shaft 14 located opposite each other.

In FIG. 7 the device 1 'according to FIG. 6 is with both Housing parts 3 'shown. In particular, it can also be seen in the broken-open section of the synchronization disk 12 that the rollers 4 are not arranged parallel to the axis of the spindle 2, but rather that the axes of the rollers 4 are inclined slightly relative to the main system axis defined by the axis of the spindle 2 is (see also Fig. 8). This can be achieved, for example, by rotating the two synchronization disks 12 with respect to one another before the rollers 4 are installed. The oblique arrangement of the axes of the rollers 4 with respect to the axis of the spindle 2 results in smaller difference angles between the grooved spindle flanks 7 of the rollers 4 on the one hand and both the spindle thread 5 and the nut thread 6 on the other hand, which results in advantageous rolling ratios and lower synchronization support torques.

As can also be seen in FIG. 8 in the broken-open areas of the synchronization disks 12, the pins 11 of the rollers 4 have a bulbous shape, as a result of which it does not occur even when the axes of the rollers 4 are inclined relative to the axis of the spindle 2 there is an adverse point contact between the pins 11 and the elongated holes 20 receiving the pins 11. Of course, other rounded shapes of the pins 4, e.g. a double cone shape or the like, conceivable.

9 shows a perspective view of an actuator 23 (without a motor drive unit and without a handwheel) with a device 1 for converting rotational movements of the spindle 2 into a linear movement of the housing 3, which is connected to an actuator (not shown). The spindle 2 is connected to a sun gear 24 of a planetary gear 25, whereby a rotational movement translation of planet gears 26 of the planetary gear 25 is effected. The planet gears 26 are either driven by a worm drive, which can be self-locking (not shown), for example by an electric motor (possibly not equipped) with a braking device (not shown), or moved by a handwheel spindle 27. A load torque lock 28 is provided between the handwheel spindle 27 and the spindle 2, which enables the torque to be transmitted from the handwheel spindle 27 to the spindle 2 in both directions of rotation, but from the spindle 2 to the handwheel spindle 27 acting torques blocked.

FIG. 10 shows a partially broken perspective view of the actuator according to FIG. 9. In particular, the movement conversion from the planet gear carrier 29 to the sun gear 24 via the planet gears 26 can be seen. Furthermore, the positive connection of the link plate 13 to the housing 3 of the device 1 can be seen.

An actuator 23 is shown in FIG. 11, in which the linear movement of the housing 3 of the device 1 is in turn converted into a pivoting movement for the actuator. In contrast to FIGS. 9 and 10, the spindle 2 is connected to the planet gear carrier 25 and the handwheel spindle 27 to the sun gear (not shown), which leads to a speed reduction from the handwheel spindle 27 to the spindle 2.

This movement conversion between the housing 3 and a cylindrical connecting piece 32 takes place in the embodiment shown without lateral force, for which purpose a rail 30 is provided on the housing 3, which is provided with four grooves 31 for guiding two cables 33. For the transverse force-free movement conversion, the cylindrical connection piece 32 is connected to the housing 3 via the two cables 33 looped around the connection piece 32, as a result of which a rolling movement occurs between the connection piece 32 and the rail 30 when the housing 3 is displaced linearly. The ropes 33 are connected in detail to the rail 30 via an adjustable latching device 34, as can be seen in particular from FIG. 12. The tension of the ropes 33 can be adjusted by adjusting a screw 35.

FIG. 13 shows the course of the ropes 33 around the cylindrical connecting piece 32, not shown in FIG. 13, in detail. It is important here that the crossed wrapping of the two ropes 33 around the connecting piece 32 enables the rope forces, which may possibly occur due to uneven setting of the ropes, to be balanced, and thus the introduction of tilting moments into the device 1 can be avoided.

Claims

claims 1.Device (1) for converting rotary movements into linear movements, if necessary of linear movements into rotary movements, with a spindle (2) provided with a thread (5) and several rollers (4) provided with ring projections, which have a thread between them on the inside (6) housing (3) and the spindle (2) are arranged, the housing (3) rotating relative to it by rotating engagement between the rollers (4) and the spindle (2) or the housing (3) can be moved relative to the spindle (2) in the axial direction thereof, characterized in that the rollers (4) have a spherical shape or the inside of the circular ring Housing (3) have a shape curved outwards towards the rollers (4) in order to reduce the contact pressure in each of the two end regions (8, 9) of the rollers (4). 2. Device according to claim 1, characterized in that the threads (5) have a flank angle (a) smaller than approximately 90 °, preferably approximately 60 °. 3. Device according to claim 1 or 2, characterized in that the thread (6) on the inside of the housing (3) has at least one roller reset portion (21) extending over the entire axial length of the housing (3), in which the thread (6) is interrupted. 4. The device according to claim 3, characterized in that the flanks of the thread (6) on the inside of the housing (3) to the reset portion (21) towards a falling, e.g. have rounded transition (22). 5. Apparatus according to claim 3 or 4, characterized in that two or more, preferably evenly arranged on the circumference, reset partial areas (21) are provided. 6. Device according to one of claims 1 to 5, characterized in that the rollers (4) are rotatably mounted in synchronization disks (12) with the aid of pins (11) provided at both ends. 7. The device according to claim 6, characterized in that the synchronization disks (12) for receiving the pins (11) have radial slots (20). 8. The device according to claim 6 or 7, characterized in that the rollers (4) are associated with end link discs (13), each of which has at least one roller reset nose (13 '), each of which has a reset portion (21). assigned. 9. Device according to one of claims 6 to 8, characterized in that the synchronization disks (12) are coupled to one another via at least one synchronization shaft (14). 10. The device according to claim 9, characterized in that the synchronization disks (12) are coupled to one another via two synchronization shafts (14) arranged offset by 180 °. 11. The device according to claim 9 or 10, characterized in that the synchronization shaft (14) with the two synchronization disks (12) via meshing ring gears (15, 16) is in engagement. 12. The apparatus according to claim 11, characterized in that the synchronization shaft (14) in the link plates (13) is freely rotatable. 13. Device according to one of claims 9 to 12, characterized in that the link plates (13) with the housing (3) are positively connected. 14. Device according to one of claims 1 to 13, characterized in that the axes of the rollers (4) with respect to the axis of the spindle (2) are arranged obliquely. 15. The apparatus according to claim 14, characterized in that the two synchronization disks (12) for the inclination of the axes of the rollers (4) with respect to the axis of the spindle (2) are arranged offset from one another. 16. The apparatus of claim 14 or 15 with claim 6, characterized in that the pins (11) have a bulbous shape. 17. Actuator (23) with a spindle and with a connection to an actuator, wherein for manual adjustment a handwheel and for mechanical adjustment a motor drive unit are provided, characterized in that a device according to one of claims 1 to 14 between the motor drive unit or handwheel on the one hand and the actuator connection on the other hand is provided. 18. Actuator according to claim 17, characterized in that a device (28) is provided between a handwheel spindle (27) connected to the handwheel and the spindle (2), which torque in both directions of rotation of the handwheel spindle (27) transmits to the spindle (2) and has a locking effect in both directions from the spindle (2) to the handwheel spindle (27). 19. Actuator according to claim 17 or 18, characterized in that a planetary gear for adjusting the spindle (2) (25) with a sun gear (24) and a plurality of planet gears (26) is provided. 20. Actuator according to claim 19, characterized in that the spindle (2) with the sun gear (24) or the handwheel spindle (27) is connected to the planet gears (26). 21. Actuator according to claim 19, characterized in that the spindle (2) with the planet gears (26) and the handwheel spindle (27) is connected to the sun gear (24). 22. Actuator according to one of claims 19 to 21, characterized in that a worm wheel is provided for transmitting motion from a motor drive shaft to the planetary gear (25). 23. Actuator according to one of claims 17 to 22, indicates that the cylindrical body (32) rolls on a rail (30) connected to the housing (3) in order to convert the linear movement of the housing (3) into the pivoting movement of a cylindrical body (32). 24. Actuator according to claim 23, characterized in that for the transmission of motion from the housing (3) to the cylindrical body (32), the cylindrical body (32) with at least one flexible element (33), preferably two cables, with the housing (3 ) connected is.