Field of the invention

The present invention relates to a planetary gear having a double eccentric disc . Furthermore , the invention also relates to this double eccentric grid .

State of the art

Planetary gears are used in numerous areas of li fe . They are gear or pinion mechanisms consisting of two sets of wheels . One wheel system has a fixed axis around which the sun wheel can rotate . The so-called bridge can also rotate around the same axis . The axles of the other wheel system are mounted in the bridge so that their teeth are connected to the sun wheel of the first wheel system. These planetary wheels both rotate around their own axis and also perform orbital motion . A more advanced version of such a planetary gear is also fitted with a ring gear, which is a gear with internal teeth placed around the planetary gears . The role of the ring gear is to change the direction of rotation of the output shaft . When using a ring gear, we have the possibility to move the planetary wheels through the sun gear by fixing the ring gear . However, by locking the sun wheel and unlocking the outer ring gear, the planetary wheels can be rotated in the other direction, thus changing the direction of rotation of the output axis .

Patent document CN106903684 A shows such a planetary gear used in a grid manipulator . This solution consists of a sun wheel and four planetary wheels of the same si ze . The disadvantage of the planetary gear is that it operates with a constant gear ratio and can break down i f overloaded .

Consequently, there is a need for a safety element that can be used with variable ratio and is protected against overloading, and that can be incorporated in planetary gears or in structures that act as hoists .

Short description of the invention

The present invention is based on the reali zation that the use of a double eccentric disc allows variable transmission in planetary gears or li fting structures . Furthermore , it dynamically adj usts and does not break under unexpected loads .

According to the foregoing, the present invention relates to a double eccentric disc having an inner disc fixed to an input shaft , characteri zed in that it further comprises an outer disc, said outer disc being connected to said inner disc by a flexible element .

According to a preferred embodiment of the double eccentric disc according to the invention, the inner disc is rotatably disposed in a cavity provided on the outer disc .

According to a preferred embodiment of the double eccentric disc according to the invention, the resilient member is a coil spring, an air spring or a servo mechanism .

The invention further relates to a planetary gear mounted on a base plate and having an input shaft , the double eccentric disc according to the invention being connected to the input shaft , the double eccentric disc being further connected to rollers , which are connected to levers , the levers being connected to planetary wheels , the planetary wheels surrounding a sun wheel , or the planetary wheels being surrounded by a ring wheel and the sun wheel or ring wheel being connected to an output shaft .

According to a preferred embodiment of the planetary gear according to the invention, the arms are connected to the planetary gears by a ratchet .

According to another preferred embodiment of the planetary gear according to the invention, the arms are connected to the planetary gears by a freewheel .

According to a preferred embodiment of the planetary gear according to the invention, the planetary gear comprises a sun wheel surrounded by the planetary wheels and a ring wheel surrounding the planetary wheels , both fixed to the output shaft .

The invention further relates to the use of a double eccentric disc in planetary gears .

The invention further relates to the use of double eccentric discs in elevators .

In the figures

Figure 1 shows a front view of the double eccentric disc according to the invention;

Figure 2 . a shows a front view of the inner disc of the double eccentric disc of the invention with the input shaft ;

Figure 2 . b shows a side view of the inner disc of the double eccentric disc of the invention with the input shaft ; Figure 3 shows a front view of the outer disc of the double eccentric disc according to the invention;

Figure 4 shows a front view of the minimum eccentricity of the double eccentric disc of the invention;

Figure 5 shows a front view of the maximum eccentricity of the double eccentric disc of the invention;

Figure 6a shows the planetary gear according to the invention with the minimum eccentricity of the eccentric disc ;

Figure 6b shows the planetary gear according to the invention with the maximum eccentricity of the eccentric disc ;

Figure 7 shows the use of the double eccentric disc as a lever .

Detailed description of the invention

The device according to the invention consists in varying the transmission by means of a double eccentric disc .

Figure 1 shows a double eccentric disc 6 comprising an input shaft 7 to which an inner disc 6a is fixed . The inner disc 6a is connected to an outer disc 6b via a flexible element 8 .

Figures 2 . a and 2 . b show the relative positions of the inner disc 6a and the input shaft 7 at rest . Perpendicular to the plane of the inner disc 6a, and laterally to the centre of the inner disc 6a, the input shaft 7 is connected by an unreleasable bond .

Figure 3 shows the outer disc 6b provided with an eccentrically disposed nest 6c, which is adapted to rotatably receive the inner disc 6a . Figure 4 illustrates the minimum eccentricity between the inner and outer discs 6a , 6b and Figure 5 illustrates the maximum eccentricity .

Figures 6a and 6b show the planetary gear 100 according to the invention, which is arranged on a base plate 1 . The planetary gear 100 comprises planetary wheels 2 around a sun wheel 5 driven by the planetary wheels 2 . This forms the output for the planetary gears 100 .

The retract contains an input shaft 7 ( Figure 2 ) to which the double eccentric disc 6 is connected . The double eccentric disc 6 is connected to the rollers 4 , which move the arms 3 , which are connected to the planetary wheels 2 by a freewheel (not shown) .

During the operation of the planetary gear 100 , the double eccentric disc 6 mounted on the input shaft 7 drive the rollers 4 and the arms 3 connected to them . The arms 3 drive the planetary wheels 2 by means of the freewheel . The fastest of the planetary wheels 2 drives the sun wheel 5 mounted on the output shaft (not shown) .

The double eccentric disc 6 comprises an inner disc 6a and an outer disc 6b, which are flexibly coupled to each other, for example by a spring, and the inner disc 6a is located in a nest 6c on the outer disc 6b . The inner disc 6a is rotated via the input shaft 7 , which drives the outer disc 6b via its flexible coupling . This outer disc 6b drives the arms 3 via the rollers 4 . Depending on the current position of the outer disc 6b, the rollers 4 move the planetary wheels 2 connected to them at varying speeds . The speed of the fastest planetary wheel 2 determines the speed of the sun wheels 5 driven by the planetary wheels 2 . This is because the arms 3 drive the planetary wheels 2 via a freewheel . The planetary wheels 2 move together because they are connected and the planetary wheel 2 with the highest angular speed drive the sun wheel 5 , all the other planetary wheels 2 rotate at the same speed, but the other planetary wheels 2 are not driven by the movement of the arms 3 because the double eccentric disks 6 move the inactive arms 3 slower . During a complete revolution of the input shafts 7 , each of the arms 3 is driven, but only one of the arms 3 is driven at a time .

The position of the inner disc 6a and outer disc 6b in relation to each other and to the input shaft 7 is determined by their eccentricity . I f the eccentricity is zero , the inner disc 6a and the outer disc 6b form a regular circle and the sun wheel 5 is stationary . The planetary gear according to the invention has an internal diameter, which can be calculated from the geometric dimensions , which is provided by the solution according to the invention at the maximum eccentricity .

The relative position of the double eccentric disc 6 gives the amplitude of the swing of the arms 3 . When the inner disc 6a and the outer disc 6b of the double eccentric disc 6 are connected by a preloaded spring, an automatic transmission is obtained . The double disc is automatically adj usted in response to an increase in the load on the eccentric . When the torque of the double eccentric disc 6 reaches the preload of the connecting spring, the set eccentricity and ratio start to decrease , even to zero , at unchanged input speed .

Thus , when the double eccentric disc 6 is used in the planetary gear 100 , the inner disc 6a of the double eccentric disc 6 is fixed to the input shaft 7 . The outer disc 6b is in contact with the arms 3 , which it li fts as ball lever . The inner disc 6a and outer disc 6b could rotate relative to each other i f they were not connected by a flexible element 8 . In the normal state , the flexible element 8 connecting the inner disc 6a and outer disc 6b are at rest , and the relative positions of the inner disc 6a and outer disc 6b give the maximum eccentricity . When the outer disc 6b starts to work, the arms 3 exert resistance to the movement of the outer disc 6b . This resistance stretches the flexible element 8 and the relative positions of the inner disc 6a and outer disc 6b move towards the minimum eccentricity . I f the resistance on the load side increases further, the flexible element 8 is stretched further until the eccentricity is at a minimum, thus reducing the output speed to zero . As the load decreases , the force on the flexible element 8 decreases , and the flexible element 8 starts to pull the inner disc 6a and outer disc 6b back towards the maximum eccentricity . Equilibrium is reached where the spring force and the return force from the arms 3 are in equilibrium . This implies a certain transmission and therefore a certain torque .

The planetary gear 100 can also be designed with a ring gear, which is a gear with internal teeth and it surround the planetary wheels 2 and are fixed to the output shaft . I f a ring gear is used, it is possible to move the planetary wheels 2 through the sun wheel 5 by fixing the ring gear . However, by locking the sun wheel 5 and unlocking the outer ring gear, the planetary wheels 2 can be rotated in the other direction, thus changing the direction of rotation of the output shaft . As shown above , the ring gear can also be used to replace the sun gear 5 i f only a unidirectional output shaft is required .

The double eccentric disc 6 shown in Figure 1 can be used not only in the planetary gear 100 . For example , it can also be used to operate a double-arm or single-arm as shown in figure 7 , where one hal f of the lever 8 is li fted by the lateral surface of the outer disc 6b through a ball bearing . The other hal f of the lever 8 performs its function under load .

As in the operation of the planetary gear 100 , the input shaft 7 is rotated, which forces the inner disc 6a, which is in an unbreakable connection with it , and the outer disc 6b, through the flexible element 8 , to rotate around the input shaft 7 . The lever 8 exerts a radial force on the lateral surface 3 through the ball bearing, causing the flexible element 8 to deform and thus rotate the outer disc 6b and the inner disc 6a relative to each other .

As the position of the outer disc 6b and the inner disc 6a relative to each other changes , the eccentricity of the lateral surface 3 relative to the input shaft 7 will change . Figure 3 shows the minimum eccentricity ( 0 mm for a suitable geometry) and Figure 4 the maximum eccentricity . The position of the structure between the two end positions is determined by the characteristics of the elastic element 8 and the magnitude of the force acting on the lateral surface . The relative displacement of the outer disc 6b and the inner disc 6a must be kept within a certain range in order to achieve the desired operation, one endpoint of which is zero eccentricity and the other endpoint is the maximum eccentricity to be achieved .

I f the force acting on the lateral surface is too high, the flexible element 8 will allow the two discs to move towards zero eccentricity, i . e . the amplitude of the movement of the lever 8 will decrease , to zero in the extreme case . When the load returns to its operating value , the flexible element 8 allows the inner and outer disc 6a and 6b to move towards their maximum eccentricity, i . e . the amplitude of the movement of the lever 8 increases .

The double eccentricity disc 6 according to the invention provides , inter alia, the possibility of so-called soft starting . Since at the moment of start forces greater than the operating force are applied, the eccentricity falls to a value close to 0 , the input drive rotates almost without load . The movements start , the start forces are reduced, the flexible element 8 set the eccentricity to the operating value .

The flexible element 8 regulate the operation of the structure according to the invention without external intervention . By varying the characteristics of the flexible element 8 , the operation of the mechanism can be modi fied, since the flexible element 8 determine the relative position of the inner and outer disc 6a and 6b . Such flexible element 8 can be a coil spring or a simple rubber band . Preferably, the flexible element 8 is an air spring or servo mechanic, which devices also allow feedback in the system .

An advantage of the solution according to the invention is that it is suitable for so-called soft start .

A further advantage of the solution according to the invention is that in the event of overloading, the system does not break, but only disengages .

A further advantage of the solution according to the invention is that it can also be used in planetary gears or li fting devices .