WO1995015448A1

WO1995015448A1 - Planetary gear system with continuous speed control

Info

Publication number: WO1995015448A1
Application number: PCT/EP1994/003990
Authority: WO
Inventors: Erhard BÜTTNER
Original assignee: Buettner Erhard
Priority date: 1993-12-02
Filing date: 1994-12-01
Publication date: 1995-06-08
Also published as: DE4341112C1

Abstract

The invention pertains to a planetary gear system (100) with continuous speed control, having a planet gear (50) whose planet wheel (11) meshes on one tooth trace both with a torque-transmitting planet gear part (10) and with another toothed wheel body (14) which is smaller than the torque-transmitting planet gear part that meshes with the planet gear on the same tooth trace and which is rotatably mounted excentric to the main axis (1) on a crank axle (15) that is linked to the drive shaft by a crank. The other torque-transmitting planet gear part (3) forms the control member of the speed control drive for continuous speed control and does not itself lie in the power flow of torque transmission through the gearing.

Description

Orbital gearboxes with stepless speed control

The invention relates to a planetary gear with stepless speed control, with a planetary gear on a main axis, which as a planetary gear part has a ring gear rotatably arranged on an input shaft provided coaxially to the main axis and a sun gear fixedly arranged on the input shaft, and with a planetary gear in meshing engagement with the ring and sun gear and with an output shaft coaxial to the input shaft.

Epicyclic gearboxes are receiving increasing attention for many purposes because they require a very small installation space in terms of the transferable power and can therefore be used as compact gearboxes with a high torque transmission capacity even under unfavorable spatial conditions. With very high gear ratios, only a relatively small number of gears are required.

In a preferred operating mode for such epicyclic gearboxes, the so-called three-shaft mode, there are three torques in equilibrium, which are assigned to the three gearbox shafts. The gear housing is kept free of attacking torques. Such a branching of force or torque makes it possible to influence the torques of the other shafts by changing one of the torques because of the force equilibrium. This basic law is exploited in that the torque ratios can be specifically changed and the torque and thus a speed of the output shaft can be regulated continuously.

From DE 37 13 722 AI such a continuously variable epicyclic gear is known. In this case, three planetary gear systems are combined with one another, one planetary gear system being assigned to each of the input and output shafts, and a compensating planetary gear system being arranged in a rotating housing rotatably mounted coaxially to the main axis. By coupling the drive side and the output side term planetary gear system via the central shaft and the coupling of these two planetary gear systems with the differential planetary gear system, there is a torque branching, so that a blocking of the transmission can be excluded. In addition, in the case of such a planetary gear transmission, there is also the possibility of increasing the output speed of the transmission from standstill to a speed corresponding to the load torque if the torque on the drive side remains the same by releasing a brake. Such a solution is disadvantageous in that the efficiency of the transmission is reduced by the frictional losses resulting from the braking effect. The arrangement of three planetary gear systems with the corresponding, structurally related arrangements also leads to a complex, voluminous construction.

From DE 38 06 292 AI a transmission is known in which a sun gear arranged on a driving shaft drives a planet gear which is firmly connected to another planet gear. This second planet gear meshes with another sun gear arranged on the driven shaft. The two planet gears, which are connected to one another, are arranged with an axis on a carrier serving as a rotating body. This is rotatably mounted on the driven shaft.

In another embodiment of this solution, the drive torque is transmitted to the planet wheels via a support body. The revolving body is designed as a ring gear which engages with the planet gears. The speed of the rotating body influences an actuating gear. Torque is transmitted from the drive shaft via a gear pair to the actuator designed as a friction gear. The speed is set by the friction gear and communicated to the circulating body by means of a worm gear. Accordingly, the circulating body is braked or the speed of the actuating gear is specifically changed. changes, so that the output speed can be continuously adjusted. In this solution, too, the relatively high losses in efficiency, which are caused here in particular by the friction gear or by the braking of the rotating body, are disadvantageous.

The above-mentioned solutions, which are essentially based on influencing one of the three elements of the torque branching for the speed setting, have the disadvantage that the gear branch used for the speed setting in the power flow between the input and output sides of the gear, i.e. lies in the transmission of torque, so that forces or torques on the transmission parts transmitting the torque, e.g. Braking forces must be transmitted so that the efficiency of the transmission and the power transmission are impaired.

The invention is therefore based on the object of improving an epicyclic gear of the type mentioned in such a way that the efficiency of the torque transmission of such gearboxes is improved and essentially on the introduction of torques into the power flow of the gearbox or the Ab¬ branching of such torques for the speed setting of the transmission can be dispensed with.

This object is achieved according to the invention in a planetary gear transmission of the type mentioned at the outset in that the planet gear is in meshing engagement on a flank line both with the one torque-transmitting planetary gear part and with a gearwheel, this gearwheel being smaller than that the same flank line meshing with the planet gear, torque-transmitting planetary gear part, this gear being rotatably mounted eccentrically to the main axis on a crank axis, the crank axis being assigned to the output shaft of the epicyclic gear via a crank and the remaining, non- torque transfer bearing planetary gear part forms the actuator of a speed actuator.

With such a solution, it is advantageously avoided to intervene in the power flow or in the torque transmission of the transmission for the stepless regulation of the output speed of the transmission. The actuator for setting the output speed only has to exert a minimal force to overcome the internal friction of the transmission.

The invention is based in particular on the consideration that it is possible with a planetary gear transmission on the basis of the principle of coupling two gear wheels, in particular ring gears, on a flank line of the toothing, by means of a pinion body covering these gear wheels, by controlling the " To control the ratio of the speeds of these gears on the covered gears without interfering with the torque transmission between the gears.

This control or torque setting is practically without power, i.e. it is only necessary to apply the actuating force required for the rolling of the pinion body, which is determined by the friction within the toothing and the bearing of the pinion body.

The present invention advantageously makes it possible to set the rotational speed of the output shaft of the epicyclic gear extremely precisely, since, in contrast to conventional controls or rotational speed positions, where quantities which are difficult to quantify, such as frictional forces, have an influence, according to the invention direct and reproducible Relationship between the speed of the actuator and the speed of the output shaft is present. The adjustment or control range is very large and extends from the nominal speed of the gearbox down to the value zero with stepless adjustment.

Preferred embodiments of the subject matter of the invention are set out in the subclaims.

The invention is explained in more detail below with reference to exemplary embodiments and associated drawings. In these show:

1 shows a sectional illustration of an exemplary embodiment of the epicyclic gear transmission, showing the power flow,

2 shows a section A-A of FIG. 1,

3 shows a simplified representation of the transmission diagram of the epicyclic gear according to FIG. 1,

4 shows a schematic illustration of the principle of operation of the speed setting of the transmission according to the present exemplary embodiment, and

FIG. 5 shows a simplified illustration of the transmission diagram similar to that in FIG. 3 for a further exemplary embodiment of the epicyclic gear transmission.

Before the explanation of a first exemplary embodiment of the epicyclic gearbox with reference to FIGS. 1 to 3 is discussed, the speed setting principle of this gearbox will be explained with reference to the schematic illustration in FIG. 4.

In Fig. 4, A denotes a first rack and B denotes a second rack, which are covered along a flank line by a pinion body C, which can roll on the rack pair in the circumferential direction. With such a construction, if the rack A is subjected to a force in the direction of the arrow, the other rack B is taken along accordingly, since the engaging teeth of the pinion body C act as a coupling member. The same applies to the application of forces to the rack B in the direction of the arrow, with the result that the rack A is then carried along by the coupling pinion body C. Nothing changes in such a forced coupling of the racks A, B even if the pinion body C is rolled back and forth on the racks A, B at the same time. The force required for rolling the back and forth movement of the pinion body C has nothing to do with the force to be transmitted between the two racks A, B. For the rolling movement of the pinion body C, only the frictional resistances of the toothings between the pinion body C and the toothed racks A, B have to be overcome. The above considerations, which are as obvious as they are surprising in terms of their practical applicability for the implementation of a stepless speed setting of a planetary gearbox, are used in the planetary gearbox, as explained in the exemplary embodiments below.

As can be seen from FIGS. 1 and 2, an epicyclic gear 100 has a sun gear shaft 2 coaxial with a fictitious main axis 1, to which a sun gear 3 is fixedly connected, an actuator drive wheel 4 being connected to the sun gear shaft 2 with a speed actuator, not shown here, for example a control motor.

A first ring gear 5 is arranged coaxially with the sun gear shaft 2, so that the rotatable sun gear shaft 2 in turn rotatably supports a hub 6 of the first ring gear 5 and the first ring gear 5 and the sun gear 3 are planetary gear parts of a planetary gear transmission 50 arranged as a speed-adjusting main gear of the epicyclic gear form. Non-rotatable on the Hub 6 is a coupling wheel 7 arranged as a gear, which is connected via a drive gear 8 to a drive shaft 9 of a drive motor, not shown here.

In the ring gear 10 (internal toothing) of the first ring gear 5 meshes with the sun gear 3, at least one planet gear 11.1, which is part of a preferably two-part planetary gear 11 designed as a rigid body. The planet gear 11 therefore consists of the fixedly connected planet gears 11.1 and 11.2 and is rotatably mounted about the axis of a planet gear carrier 11.3. The second planet gear 11.2 of the integral planet gear 11 meshes with an internally toothed ring gear 14 which is rotatably supported by an inner ring of a roller bearing 13 and fitted into this. The ring gear 14 thus forms a second ring gear, in which the planet gear 11 also engages in meshing engagement. The roller bearing 13 supporting the ring gear 14 is arranged in a ring gear carrier 15.

Here, the arrangement of the ring gear or ring gear 14, which is smaller in diameter than the first ring gear 5, is such that the two planet gears 11.1, 11.2 of the integral planet gear 11 on the same flank line of the toothing, on the one hand, into the first ring gear 5 (planet gear 11.1) and secondly engage in the second ring gear or the toothed ring 14 (planet gear 11.2). This means that the gear pairs of the planetary gears 11.1 and 11.2, which are identical in terms of their geometric dimensions, are congruently arranged in the axial direction, and the second, smaller ring gear 14 is arranged and rotatably mounted such that its pitch circle is in the manner of an inner rolling circle is brought into agreement with the (larger) pitch circle of the first ring gear 5 at a circumferential point, so that the second ring gear 14 rolls with its pitch circle on the pitch circle of the first, larger ring gear 5. Returning to the explanatory illustration according to FIG. 4, in the first exemplary embodiment according to FIGS. 1 to 3 the first ring gear 5 forms the first rack A, which is driven here, and the second, smaller ring gear 14 forms the second entrained rack B, both of which Ring gears 5, 14 are covered in meshing engagement along the same flank line by the (divided) planet gear 11 (planet gears 11.1, 11.2), here the planet gear 11 corresponding to the pinion body C in FIG. 4.

As is clear from FIGS. 1 to 3, the body of the ring gear carrier 15 is rotatably mounted coaxially to the main axis 1, but the second ring gear 14 (ring gear) can be rotated eccentrically to the main axis 1 in connection with the roller bearing 13 supporting the second ring gear 14, so that the principle of a second ring gear 14 rotatably arranged on an eccentric axis results, which is firmly connected via a crank 15 (here formed by the ring gear carrier) to an output shaft 16 which is arranged coaxially with the main axis 1 or sun gear shaft 2 . The basic structure of the epicyclic gear 100 can be seen in particular from FIG. 3, with a distance a between a crank axis 20 which rotates the second ring gear 14 (in the present embodiment realized by the axis of rotation of the roller bearing 13) and the main axis 1 or output shaft 16 is the measure of the eccentricity of the rotary bearing of the second ring gear. As illustrated in FIG. 1, the planet gear carrier 11.3 is received with its axis of rotation in a support ring 19 rotatably mounted on the output shaft 16 and protrudes through a bore 17 in the ring gear carrier 15 so that a very compact arrangement is achieved in the axial direction.

The mode of operation of the epicyclic gear 100 according to the present embodiment with stepless speed adjustment is explained below. In Fig. 1 the arrows illustrate the force or torque flow through the epicyclic gear 100.

The epicyclic gear 100 is driven via the drive shaft 9, which e.g. is driven at a constant speed and transmits its torque to the ring gear 5 via the coupling gear 7, which is fixedly arranged on the hub 6 of the first ring gear 5. The internal toothing of the first ring gear 5 is in meshing engagement with the planet gear 11, more precisely with the first planet gear 11.1, which on the other hand is in meshing engagement with the sun gear 3. If the sun gear 3 is not driven by the sun gear shaft 2, the sun gear 3 has no influence on the gear ratio and is outside the torque flow, as is illustrated in FIG. 1. The torque is transmitted from the first ring gear 5 to the planet gear 11.1 and via the planet gear 11.2 rigidly coupled thereto to the second ring gear 14, which is meshed with the planet gear 11.2 in meshing engagement and in the inner ring of the roller bearing 13.

As explained, the transmission of the torque takes place on the same flank line, so that both planet gears 11.1 and 11.2 form a single-sided double lever and mesh with the first ring gear 5 and with the second ring gear 14 along the same flank line, so that the torque ment on the planet gear 11 and transferred to the second ring gear 14. Under this condition of the "tapping" of the torque along the same flank line with regard to the meshing engagement of the planet gear 11 with the first and second ring gear 5 and 14, it is possible to the planet gear 11 with the two parts ll.l and 11.2 in the ring gear 5 under An ¬ driven by the sun gear to run more slowly, without interfering with the torque flow. The planetary gear 11 rotates about its own axis in accordance with the given gear ratio between the planetary gear 11 and the sun gear 3 and at the same time becomes inside the ring gear 5 brought into a circular orbit, this orbital movement, mediated by the first ring gear 5, transmitted by the second planet gear 11.2 to the second ring gear or the ring gear 14. The second ring gear or ring gear 14 with the roller bearing 13 thus rotates about its own axis, the crank axis 20, and at the same time moves according to the transmission ratio with the planet gear 11 and its own drive by the sun gear 3 on a circular, by the crank 15 with the radius a determined orbit around the main axis 1 or around the output shaft 16. This circular movement of the second ring gear 14, which is transmitted via the crank axis 20, the crank 15 to the output shaft 16, determines the output speed.

In the event that the sun gear shaft 2 is not driven, i.e. the speed control device is out of operation, the epicyclic gear 100 acts as a transmission gear with the transmission ratio predetermined by the transmission ratios. The epicyclic gear 100 is non-positive and positive.

For infinitely variable speed control, the sun gear shaft 2 and thus the sun gear 3 firmly connected to it are driven via the actuator gear 4, so that the planet gear 11 with the planet gears 11.1 and 11.2, which are only parts of the one, integral planet gear 11, are driven via the sun gear 3 , driven with increasing speed, which is transmitted to the second ring gear (internal toothing) 14 and leads to a compensation of the rotational movement of the second ring gear 14 transmitted by the first ring gear 5, so that the speed of the sun gear shaft 2 increases with increasing speed Output shaft 16, which represents the rotational speed of the second ring gear 14 about the main axis 1, can be adjusted continuously to zero and to a standstill of the output shaft 16. It is thus possible in a very simple and practically low-power or low-power manner, without intervention in the torque flow through the gearbox to continuously adjust the speed of the output shaft. The additional rotational movement about its axis conferred by the sun gear 3 to the planet gear 11 with the planet gears 11.1 and 11.2 corresponds to the rolling movement of the pinion body C on the pair of racks A, B, which was explained schematically with reference to FIG. 4, within the present epicyclic gear arrangement the racks A, B which are formed to form the first and second ring gear 5, 14 are each rotatably mounted in FIG. 4. It is essential that the speed control element (sun gear 3) remains completely free of the torque flow to be transmitted, so that the output torque is not reduced by the speed control device compared to the drive torque. By rotating the sun gear 3, the rotational speed of the planet gear 11 can thus be reduced to a standstill by converting the sun gear speed completely into rotation of the planet gear 11, so that the second ring gear 14 no longer rotates around the main axis 1 and the output speed at the output ¬ drive shaft 16 can be continuously reduced to zero. The eccentric rotary bearing of the smaller second ring gear 14 (internal toothing 14) is necessary in order to take up the torque on the same meshing tooth (same flank line) of the planet gear 11 (11.1, 11.2), at the same time to take over the inherent rotation of the planet gear 11 and thus practical to allow additional torque-free movement of the planet gear 11 by the sun gear 3.

A further embodiment of the transmission gear 100, which is shown here only schematically on the basis of the gear scheme, is shown in FIG. 5.

This exemplary embodiment differs from the exemplary embodiment according to FIGS. 1 to 3 only in that in this case the first ring gear 5 is part of the speed actuator, while the torque transmission via the Internal gear shaft 2 connected drive and therefore takes place via the sun gear 3.

In this case too, the torque on the planet gear 11 must be taken off on the same flank line. Since the sun gear 3 transmits the torque to the planet gear 11 (planet gear 11.1) in this embodiment, the second ring gear 14 also meshes with the sun gear 3 with the planet gear 11.2 of the planet gear 11 in this embodiment. The crank arm a is correspondingly enlarged compared to the first exemplary embodiment. While the transmission of the torque near the main axis 1 of the transmission via the sun gear 3, the planet gear 11 and the ring gear 14 to the output shaft 16, which runs coaxially to the main shaft 1, takes place in this exemplary embodiment, the speed setting is via an actuator drive shaft 9, the first ring gear 5 is driven by the gear 8 connected to it and the coupling gear 7 in order to cause the planet gear 11 to rotate about the axis of the planet gear carrier 11.3, and in this way a stepless speed setting by slowing the rotational speed of the crank 15 to reach the main axis 1 rotatable ring gear 14. In this case too, the speed control element (first ring gear 5) is arranged outside the torque flow through the transmission, so that there is no need to intervene in the flow of force through the transmission for the speed adjustment.

In this case, the second ring gear 14 can also be replaced by a spur gear likewise rotatably mounted on a crank.

A kinematic reversal of the movement with respect to the drive through of the torque through the transmission is possible, so that in the examples explained the drive side can be interchanged with the driven side.

Claims

claims

1. epicyclic gear with continuously variable speed setting, with a planetary gear on a main axis, which as planetary gear parts has a ring gear rotatably arranged on an input shaft provided coaxially to the main axis and a sun gear fixedly arranged on the input shaft, with a planetary gear in meshing engagement with the hollow and Sun gear and with an output shaft coaxial to the input shaft, characterized in that the planet gear (11) is in meshing engagement on a flank line with the one, a torque-transmitting planet gear part as well as with another gear (14) which is smaller than that on the same flank line with the planet gear (11) meshing, torque-transmitting planetary gear part and which is rotatably mounted eccentrically to the main axis on a crank axis (20) which is assigned to the output shaft (16) via a crank (15), the remaining, non-torque transmitting planet nradgetriebeteil actuator ei¬ nes speed actuator.

2. epicyclic gear nch claim 1, characterized gekennzeich¬ net that the torque transmitting planetary gear part is a first ring gear (5) which is rotatably mounted on a sun gear shaft (2) of the sun gear (3) and with a drive gear (7) with a torque-transmitting drive (8, 9) is connected, is provided.

3. epicyclic gear according to claim 2, characterized gekennzeich¬ net that a speed actuator (4) is connected to the sun gear shaft (2).

4. epicyclic gear according to claim 1, characterized gekennzeich¬ net that the torque-transmitting planetary gear part is the sun gear (3) which is connected to a torque-transmitting drive, while a first, the sun gear (3) surrounding ring gear (5) which is rotatably mounted on a sun gear shaft (2) and has a drive gear (7) is connected to a speed actuator.

5. epicyclic gear according to at least one of the preceding claims 1 to 4, characterized in that the further gear re is a ring gear (14).

6. epicyclic gear according to at least one of the preceding claims 1 to 4, characterized in that the further gear re is a spur gear.

7. epicyclic gear according to at least one of the preceding claims 1 to 6, characterized in that the planet gear (11) integrally integrally has a first planet gear portion (11.1) and a second planet gear portion (11.2), the first planet gear portion ( 11.1) is part of the planetary gear (50) in meshing engagement with the sun gear (3) and the first ring gear (5) and the second planetary gear section (11.2) is on the same torque-transmitting flank line of the meshing engagement of the first planetary gear section (11.1) with the ring or sun gear (5, 3) in meshing engagement with the further gear (14).

8. epicyclic gear according to claim 5, characterized gekennzeich¬ net that the second ring gear (14) is an in an inner ring of a rolling bearing (13) inserted ring gear which has the same tooth pitch as the first ring gear (5).

9. epicyclic gear according to at least one of the preceding claims 1 to 8, characterized in that the planet gear sections (11.1 and 11.2) of the integral planet gear (11) are arranged on a planet gear carrier rotatable about a planet gear axis (11.3).

10. epicyclic gear according to claim 9, characterized gekennzeich¬ net that the planet carrier (11.3) through a recess (17) of a ring gear carrier (15) and is received in a rotatable support ring (19).

11. epicyclic gear according to claim 10, characterized gekenn¬ characterized in that the ring gear carrier (15) is fixedly connected to the Abtriebs¬ shaft (16) and eccentrically supports the roller bearing (13), the outer ring of which is fixed in the ring gear carrier (15) is.

12. epicyclic gear according to at least one of claims 1 to 10, characterized in that the planetary gear (11) in a ring gear (10) of the first ring gear (5) and in a ring gear of the second ring gear (14), the is received in the roller bearing (13) arranged eccentrically to the output shaft (16), revolving, with a rotational speed of the second ring gear (14) about the main axis (1) corresponding to the output speed.