WO2024144644A1 - Cycloid reducer with eccentric roller - Google Patents

Abstract

The invention relates to a cycloidal reducer with eccentric roller used in low-clearance systems that require precise positioning, especially in robots. The invention is particularly related to a cycloidal reducer in which eccentric rollers are present and the conversion ratio can be increased by adding elements to the input and output shafts.

Description

SPECIFICATION

CYCLOID REDUCER WITH ECCENTRIC ROLLER

Technical field of the invention

The invention relates to a cycloidal reducer with eccentric roller used in low-clearance systems that require precise positioning, especially in robots.

The invention is particularly related to a cycloidal reducer in which eccentric rollers are present and the conversion ratio can be increased by adding elements to the input and output shafts.

State of the Art

Nowadays, gear systems that change the speed-torque ratio of a rotational movement with the help of gears are known as reducers. Structurally, reducers consist of parts such as gear wheels, shafts and bearings placed inside the body. Reducers containing a closed gear mechanism, designed to reduce the high rotation speeds of electric motors to the rotation speeds required for machines, are mostly used in applications where a lot of power is needed to move heavy objects. There are also reducers in production sectors such as cement, metal processing, mining, power transmission, railway, plastic, cement, etc. Worm screw reducers, spur gear reducers, helical gear reducers, cycloidal reducers, parallel gear reducers are widely preferred today.

Cycloidal reducers are used in low-clearance systems that require precise positioning, especially in robots. The speed reducer has a privileged place in sensitive systems where positioning is very important, such as CNC machines, satellite receivers and welding fixtures. With the development of technology in high-tech products with high positioning precision, it is desired to further reduce the gap in such reducers. Positioning accuracy largely depends on the working gaps of drive systems such as cycloidal reducers. Therefore, cycloidal reducers, which use mechanisms that reduce the gap and increase efficiency, are becoming more preferred and widespread. Cycloidal reducers are also highly resistant to wear and sudden impacts and offer extremely efficient operating performance. In the state of the art, there are many studies, patents and/or utility model applications regarding reducers and especially cycloidal reducers. One of these is the patent application numbered “TR 2021/020011”. In cycloidal reducers, a system is described that reduces the gap caused by geometric errors in the clutching area and increases transmission performance by creating pre-stress between the cycloidal profile and the pins working in contact with it. In cycloidal reducers, the system, which reduces the gap caused by geometric errors in the clutching area by creating pre-tension between the cycloid profile and the pins working in contact with it, in its most basic form comprises the body where the pins and the pre-tension mechanism are placed, the cycloid gear, the eccentric shaft, the pins, and the pre-tension mechanism as many as the number of pins.

Another document in the state of the art is the invention that is the subject of the patent numbered "WO2019090899". The invention relates to a precision cycloidal reducer with an eccentric roller, which is a device used for situations requiring high rotation precision, such as the rotary joint of a robot and the rotary table of a machine tool. The sensitive cycloidal reducer also allows two cycloidal discs to be added one after the other. The aim of the present invention is to provide a precision cycloidal rotary joint reducer with eccentric roller, which has a reasonable structure, low cost and interconnecting structure. The precision cycloidal rotary joint reducer includes pinion housing, planetary carrier, crankshaft, pin, cycloidal wheel, sun gear and planetary wheel. With the developed cycloidal reducer, the conversion ratio is equal to the number of gears of the disc.

The invention, which is the subject of the state of the art patent numbered "CN101907149", is related to the reducers used in industrial robots, especially the double cycloid single-stage reducer of an industrial robot. It is stated that the invention is planned to be used especially for industrial type areas. The feature of the industrial robot double cycloid single stage reducer is that there are cycloid wheels A and B between the left and right frames, and a set of balancers on the pin between the two cycloid wheels. The carrier ring plate placed in the pin holes of the two cycloid wheels and the column sleeve are of equal width. The equal load ring plate greatly increases the mechanical strength and rigidity of the pin. The article titled "A New Design of a Two-Stage Cycloidal Speed Reducer", which is in the state of the art, is about a new design of a two-stage cycloidal speed reducer. It is mentioned that the traditional two-stage cycloidal speed reducer can be achieved by the simple combination of single-stage cycloidal speed reducers. A single-stage reducer combines two identical cycloidal discs to balance dynamic loads and achieve uniform load distribution.

As can be seen from the content of the patent, utility model applications and articles given above, many studies have been carried out on cycloidal reducers. However, in the structure with eccentric rollers, there is no development for a cycloid reducer with reduced weight, where the number of bonds can be increased according to the user's wishes.

As mentioned above, the reducer structures in the current system are quite heavy. For this reason, the reducers are not portable and cannot be easily carried anywhere. It is designed according to the purpose for which it will be used, and then it is very difficult to transport and disassemble it for use elsewhere. For this reason, there is a need for a reducer that can be used both in mechanisms operating in low areas and in mechanisms operating in large areas with minimum space capacity.

Another disadvantage of the current system is the increase in friction force due to the gap between the mechanical parts in contact with each other in the reducer structures and the low surface roughness sensitivity of the gears produced with the traditional manufacturing method. In this case, the efficiency is low. For this reason, a reducer which has a the gear gap is below 1 arcmin and comprises elements obtained by precision milling processes.

As a result, due to the negativities explained above and the inadequacy of existing solutions on the subject, there is a need in the relevant technical field for a cycloidal reducer that has a high conversion ratio and offers the opportunity to be used both in mechanisms operating in low areas and in mechanisms operating in large areas with its minimum area capacity. Brief Description and Aims of the Invention

The invention relates to a cycloidal reducer that meets the above-mentioned requirements, eliminates all disadvantages, and brings some additional advantages and is used in low-gap systems that require precise positioning, especially in robots.

The most important aim of the invention is to provide a cycloidal reducer with high conversion ratio and torque value. For this purpose, a structure with eccentric rollers was created in the invention. The reducers, which are formed as a result of the combination of the inner body and the outer body, can be attached end to end with the help of elements placed on the input and output shafts. Since the bond ratios of the reducers added end to end are calculated by multiplying them with each other, the total bond ratio is increased.

Another aim of the invention is to provide the opportunity to make the desired cycloid reducer structure at the desired values. For this purpose, by providing input value to the user, the invention allows the user to change the value of the input parameters in the solid modelling environment. Wherein, by entering the hub diameter, the gear ratio, and the gear top diameter of the cycloidal gear as input parameters and by changing the input parameter values such as the outer diameter, inner diameter and eccentric misalignment of the cycloid disc and other parts such as the input body, output body, eccentric input shaft and output shaft, the user can make a cycloid reducer at the desired conversion ratio.

Another aim of the invention is to provide a portable cycloid reducer that can be easily carried anywhere. In the reducer developed with the invention, optimisations and unloading were made in a way that would not be affected by the strength requirements, and the weight was reduced to 4.5 kg. In this way, the space it occupies is small and its weight and cost are low. In order to reduce the weight, solid models of the existing reducer design samples were examined and material unloading operations were carried out based on the strength analysis in the parts of the samples that were found to be excessively durable. Reductions have been made in the wall thickness (wall) of some elements that shape the parts of the reducer, and an improvement in strength has been achieved by creating radius and chamfering on sharp edges. This advantage will lead to significant changes in the structure of products that require a large number of mechanical drives, such as eliminating the mechanical power needs of industrial puma type robots using elbows, producing them in narrow spaces, replacing speed boxes that require large physical spaces in all lifting and conveying machines and containing a large number of gear wheels. With its minimum space capacity, it provides the opportunity to use it in mechanisms that work in both small areas and in mechanisms that work in large areas.

Description of Figures:

FIGURE-1 is a drawing showing the front, back and side views of the cycloidal reducer with eccentric roller that is the subject of the invention.

FIGURE-2 is a drawing showing the A-A section of the cycloidal reducer with eccentric roller, which is the subject of the invention, and the parts in the internal structure of the cycloidal reducer, given in Figure 1 .

FIGURE-3 is a drawing showing the input body assembly view in the reducer with eccentric roller that is the subject of the invention.

FIGURE-4 is the drawing showing the output body assembly view in the cycloidal reducer with eccentric roller that is the subject of the invention.

FIGURE-5 is a drawing showing the isometric view of the cycloidal reducer with eccentric roller that is the subject of the invention, consisting of structures formed by the combination of the input body and the output body.

FIGURE-6 is a drawing showing the isometric view of the cycloidal reducers with eccentric roller that is the subject of the invention by adding them one after the other.

FIGURE-7 is a drawing showing the side view of the cycloidal reducers with eccentric roller that is the subject of the invention by adding them one after the other. Definition of Elements/Parts Composing the Invention

In order to better explain the eccentric roller cycloid reducer developed with this invention, the elements in the figures are numbered and the equivalent of each number is given below:

1 . Output body

2. Input body

3. Cycloidal disc

4. Output shaft

5. Input shaft

6. Pin

7. Eccentric roller

8. Output shaft bearing

9. Rotator bearing

10. Input shaft bearing

1 1 . Output body inner ring

12. Input body inner ring

13.0-gasket

14. Lubrication plug

15. Eccentric input shaft bolt

16. Eccentric input shaft washer

17. Needle ball bearing

18. Centring pin

19. Bolt

20. Cycloidal reducer with 1 :9 gear ratio

21 . Cycloidal reducer with 1 :10 gear ratio

22. Cycloidal reducer with 1 :1 1 gear ratio

23. Shaft

24. Ring

G. Main body Detailed Description of the Invention

The invention relates to a cycloid reducer used in low-gap systems that require precise positioning, especially in robots. Cycloidal reducer has a structure that can be added end to end; reducers with different conversion rates can be added one on top of the other. A cycloidal reducer with high conversion ratio and torque value is described, by means of its eccentric roller motion and force transmission structure.

The cycloidal reducer with eccentric roller comprises disc (3) in the cycloid, which allows the cycloidal reducer to make an oscillating movement, output shaft (4), to which eccentric rotation is transferred as linear rotation with the help of pins (6), input shaft (5), which enables the cycloidal disc (3) to make axial oscillation movement and to which the electric motor is connected, pin (6), which transfers between the cycloidal disc (3) and the output shaft (4), eccentric roller (7), which ensures the superficial contact of the axial pin (6) placed in the needle ball bearing (17) of the cycloidal disc (3) that makes eccentric oscillating motion, output shaft bearing (8), which enables the output shaft (4) to rotate, rotator bearing (9), which enables the misaligned cylinder area of the input shaft (5) to rotate, input shaft bearing (10), which enables the input shaft (5) to rotate on the linear axis, output body inner ring (1 1 ), which ensures that the output shaft bearing (8) remains fixed in the output body (1 ), input body inner ring (12), which ensures that the input shaft bearing (10) remains fixed in the input body (2), o- gasket (13), which provides oil sealing between the input body (2) and the output body

(1 ), lubrication plug (14) where the oil will be placed, eccentric input shaft bolt (15), which ensures that the input shaft (5) remains fixed between the rotator bearing (9), the eccentric input shaft washer (16) that allows it to be pressed together with the eccentric input shaft bolt (15) that keeps the input shaft (5) stable, and the needle ball bearing (17), cantering pin (18) and bolt (19) on which the eccentric roller (7) sits, minimising sliding friction.

Cycloidal reducer with eccentric roller consists of two units. These are the input body

(2) and the output body (1 ). First, the input shaft bearing (10) is driven into the central slot of the input body (2). The input body inner ring (12) is inserted into the ring slot in the input body (2) at the rear, ensuring that the input shaft bearing (10) does not come out of place. The non-misaligned shaft side of the input shaft (5) located on the cycloid disc (3) is placed at the centre of the input shaft bearing (10). Afterwards, the installation of the input body (2) is completed by driving the centring pin (18). In other words, the input body (2) is formed by assembling the eccentric shaft (5), the eccentric roller (7) and the cycloid disc (3). Thanks to these parts, the system moves axially.

The output body assembly is formed by mounting the pin (6) and the output shaft (4) to the output body (1 ). Six pins (6) are driven into the output shaft (4) with a tight fit. Then, the output shaft bearing (8) is driven into the output body (1 ). In order for the output shaft bearing (8) to remain fixed in place, the output body inner ring (1 1 ) is removed, ensuring that the output shaft bearing (8) remains fixed in place. Subsequently, the assembly is completed by placing the shaft part of the output shaft (4) into the output shaft bearing (8) slot. By means of these parts, the axial movement coming from the input body assembly, and by means of the pins (6), the outlet body

(1 ) rotate in linear motion.

There are seven cavities within the cycloidal disc (3), which has a curved structure formed by the intersection of the epicycloid and hypocycloid curves of the cycloid disc (3), having a unique gear profile, which makes eccentric oscillating movements. The bearing (9) is mounted in the centre of these spaces, and the input shaft (5), which has an axial structure, is mounted inside the bearing (9). In order for the input shaft (5) to remain in the bearing (9), the eccentric input shaft washer (16) and the eccentric input shaft bolt (15) are placed and fixed. After all these procedures, the assembly of the cycloid disc (3) is completed.

The electric motor is connected to the input shaft (5) and also enables the cycloidal disc (3) to make axial oscillation movement. The eccentric roller (7) is mounted in the remaining six spaces. Needle ball bearing (17) is used to seat the eccentric roller (7) and to minimise sliding friction.

The main body (G), which consists of combining at least one outlet body (1 ) and at least one inlet body (2) end to end, is shown in Figure-2. In order to increase the bond rate, the number of main body (G) consisting of the output body (1 ) and the input body

(2) can be increased as shown in Figure-6. For example, the triple structure is shown in Figure-6. At the junction of the input shaft (5) and the output shaft (4) are an eccentric input shaft bolt (15) that keeps the input shaft (5) fixed between the rotator bearing (9), and an eccentric input shaft washer (16) that ensures that the input shaft (5) is pressed by the eccentric input shaft bolt (15) that keeps it fixed.

The eccentric roller (7) is placed inside the needle ball bearing (17) and the ball bearing

(16). As the eccentric roller (7) slides friction lessly by means of the needle ball bearing

(17), the torque increases. The eccentric roller (7) is produced with an outer diameter sufficient to cover the inner diameter of the point contact pin (6) of the needle ball bearing (17), ensuring superficial contact at all points. In this way, torque losses are prevented.

In the reducer developed with the invention, there is also a lubrication plug (14) at the bottom of the outlet body (1 ) where the oil will be placed and the o-gasket (13) is placed in the o-gasket channel on the input body (2), which provides oil sealing in the part where it contacts the input body (2). Then, the outlet shown in Figure-4 is inserted into the body (1 ) in such a way that the six pins (6) correspond to the pin holes on the 6 eccentric rollers (7). By inserting three bolts (19) through three empty holes in the output body (1 ) in such a way that the surface of the output body (1 ) presses against the o-gasket (13) on the input body (2), the guide thread is tightened to the corresponding location on the input body (2) with a torque value of 9Nm. Before tightening the bolt (19), the centring pin (18) is driven in to ensure axial misalignment. This assembly is shown in Figure-5.

In order to ensure that the oil in the reducer remains in the system, the output shaft bearing (8) and input shaft bearing (10) are covered and sealed. In addition, the rotator bearing (9) is selected without a cover to ensure oil transfer between the input body (2) and the output body (1 ). The output body (1 ) and the input body (2) are combined by means of their compatible structures.

In the system developed with the invention, when the engine connected to the eccentric input shaft (5) is started, the eccentric end of the eccentric input shaft (5) starts to rotate. The movement of the eccentric input shaft (5) is transferred to the rotator bearing (9). The rotator bearing (9) then transfers the outer ring movement to the inner ring and the cycloidal disc (3), which takes motion from the outer ring, starts to swim in a sinuous manner on the solid pins into the input body (2) by making an axial oscillation movement as much as the axial misalignment, by means of the eccentric end of the input shaft (5). In a way that sliding friction within the needle ball bearing (17) is minimised, the eccentric roller (7) transfers the axial oscillation movements to the output shaft (4) with the help of pins (6) turning it into linear motion. The desired bond value is obtained by means of the "+" element of the output shaft (4) connected to the output body (1 ). Following all these processes, oil is poured from the location of the lubrication plug (14) bolt and teflon tape is wrapped around the lubrication plug (14) bolt and tightened.

In order to help explain the invention, Figure-6 shows the cycloid reducer (20) with a 1 :9 ratio, the cycloid reducer (30) with a 1 :10 ratio, and the cycloid reducer (40) with a 1 :1 1 ratio. The 1 :9, 1 :10 and 1 :1 1 mentioned here refer to the gear ratios. As shown in Figure-6, the structure added end to end is formed by installing three reducers with different gear ratios, one after the other, the input shaft (5) and the output shaft (4). The reducers are kept fixed by maintaining the axial misalignment with the shaft (50) supported by the ring (60) shown in this figure. The reducers are connected to each other with a tight fit consisting of male and female, shown in Figure-1 . The gear ratio after the connection is established is 1 :9*1 :10*1 :1 1 =1 :990. That is, when the input shaft (5) turns 990 turns, 1 turn is taken from the output shaft (4). Likewise, this number can be increased by four, five, six or according to the gear ratio the user wants to reach.

By means of the parametric cycloid reducer structure, input value is provided to the user. Wherein, by entering the hub diameter, the gear ratio, and the gear top diameter of the cycloidal gear as input parameters and by changing the input parameter values such as the outer diameter, inner diameter and eccentric misalignment of the cycloid disc and other parts such as the input body, output body, eccentric input shaft and output shaft, the user can make a cycloid reducer at the desired conversion ratio. In other words, the structure can be changed by changing the value of the input parameters in the solid modelling environment.

In the cycloidal reducer with eccentric roller, the efficiency is increased by cutting the cycloidal disc (3) with the wire erosion method, in which the workpiece is cut by means of a wire through which high-intensity electric current is passed, and by processing the surface roughness value of the gears on the input body (2) with a precision close to 0.8 m. Increasing the efficiency here is achieved by giving precision machining tolerances to slot surfaces such as bearings on vertical machining machines and closing the tolerance gaps that will occur due to rough machining. In this way, factors that reduce efficiency due to the gap created between the parts in mechanical contact with each other and the low sensitivity of the surface roughness "Ra" in the gears produced with the traditional manufacturing method, as well as the increase in the friction force between the mechanical parts, are prevented.

It is ensured that the gear gap of the cycloidal reducer is below 1 arcminute (1/60 of a degree - arcminute), the friction between the gears is reduced by the cycloidal disc (3) produced by the wire erosion method and the input body gears milled by precision machining having a surface quality of Ra = 0.8 mm and below, and the efficiency is increased.

The aim of the gear gap of the cycloidal reducer being 1 arcminute is to increase the torque transmission rate, strength and efficiency by minimising the gap between the gears. Aiming below 1 arcminute is to capture gaps such as 10 arcmin and 5 arcmin in similar reducers other than cycloid (harmonic, planetary reducers). The most important feature of the cycloidal reducer developed with the invention is that its efficiency is high by keeping the gear gap below 1 arcmin, and the invention aims to achieve the quality of similar cycloidal reducers with a gap below 1 arcmin with CNC machines capable of precision machining.

Holes of diameter of the shaft (50) are drilled on the outermost parts of the reducer input body (2) and output body (1 ), with angle differences of 120 degrees and after the reducers are mounted back-to-back, axial misalignment is prevented by placing pins in the holes of the input body (2) and output body (1 ).

The developed cycloid reducer can be used in any sector thanks to its portable (light and low volume) structure. Because the space occupied by the reducer is small, its weight and cost are low. Because the weight was reduced to 4.5 kg by optimising and unloading the input body and outlet body in a way that the strength requirements were not affected. The reduction in specified wall thickness by emptying is the reduction in outside diameter at the pin and other parts. In addition, by using the cycloidal disc (3), other parameters can be designed smaller by ensuring that the diameter passing through the centre of the pins (6) is minimum and the conversion ratio is maximum. That is, a reducer with a high bond ratio at low volume has been developed. This advantage will lead to significant changes in the structure of products that require a large number of mechanical drives, such as eliminating the mechanical power needs of industrial puma type robots using elbows, producing them in narrow spaces, replacing speed boxes that require large physical spaces in all lifting and conveying machines and containing a large number of gear wheels.

The material of the eccentric roller (7) and pin (6) is tempered steel with high hardness and wear resistance and having the same strength properties as bearing steel. Since the material of the eccentric roller (7) and the pin (6) is the same as the needle ball bearing (17), they do not cause wear-based damage to each other.

Claims

1. A cycloidal reducer used in low-gap systems requiring precise positioning, comprising

• the outlet body (1 ) that comprises the pin (6) that transfers between the cycloidal disc (3) and the output shaft (4) and the output shaft (4) where the eccentric rotation is transferred as linear rotation with the help of the pins (6), and is combined with the input body (2) by passing the pins (6) to the eccentric roller (7) in the input body (2), and

• the input body (2) that enables the cycloidal disc (3) to make axial oscillation movement, comprises the input shaft (5) to which the electric motor is connected, the eccentric roller (7) which ensures the superficial contact of the axial pin (6) placed in the needle ball bearing (17) of the cycloidal disc (3) that makes eccentric oscillating movement, and cycloidal disc (3) that allows the cycloidal reducer to make an oscillating movement, and is connected to the outlet body (1 ) by passing the pins (6) on the output body (1 ) to the eccentric roller (7).

2. A cycloidal reducer according to claim 1 , comprising at least one main body (G) that increases the ratio of the reducer by adding the output body (1 ) and the input body (2) end to end.

3. A cycloidal reducer according to claim 1 , comprising input shaft bearing (10) driven into the centre slot of the input body (2) for the input shaft (5) to rotate on the linear axis.

4. A cycloidal reducer according to claim 3, comprising input shaft bearing (10) with a cover and felt structure to keep the oil in the cycloidal reducer in the system.

5. A cycloidal reducer according to claim 3 or 4, comprising input shaft bearing (10) associated with the input body internal ring (12) to remain fixed in the input body (2).

6. A cycloidal reducer according to claim 1 , comprising output body inner ring (1 1 ) that ensures that the output shaft bearing (8) remains fixed in the output body

7. A cycloidal reducer according to claim 6, comprising output shaft bearing (8) with a cover and felt structure to keep the oil in the cycloidal reducer in the system.

8. A cycloidal reducer according to claim 1 , comprising eccentric input shaft bolt

(15), at the junction of the input shaft (5) and the output shaft (4), which ensures that the input shaft (5) remains fixed between the rotator bearing (9) to which the movement of the input shaft (5) is transferred.

9. A cycloidal reducer according to claim 8, comprising coverless rotator bearing (9) to ensure oil transfer between the input body (2) and the output body (1 ).

10. A cycloidal reducer according to claim 1 , comprising the eccentric input shaft bolt (15) that keeps the input shaft (5) fixed and the eccentric input shaft washer

(16) that allows it to be pressed.

11. A cycloidal reducer according to claim 1 , comprising needle ball bearing (17) so that the eccentric roller (7) can slide without friction.

12.A cycloidal reducer according to claim 11 , comprising the eccentric roller (7) produced with an outer diameter sufficient to cover the inner diameter of the needle ball bearing (17) of the point contact pin (6) to ensure superficial contact at all points.

13. A cycloidal reducer according to claim 1 , comprising the lubrication plug (14) at the bottom of the output body (1 ) where the oil will be placed.

14. A cycloidal reducer according to claim 1 , comprising o-gasket (13) that provides oil seal between the input body (2) and the output body (1 ).

15. A cycloidal reducer according to claim 1 , comprising the eccentric roller (7) and pin (6) selected from the same material so that they do not cause abrasionbased damage to each other.

16. A cycloidal reducer according to claim 15, comprising eccentric roller (7) and pin (6) that are made of tempered steel.