RU202842U1 - MECHANICAL REDUCER - Google Patents

Abstract

The invention relates to mechanical gearboxes for transmitting rotary motion and is a continuously variable transmission. The prior art knows various versions of mechanical gearboxes that allow the transmission of rotational force between two or more shafts. The purpose of these gearboxes is to coordinate the moments on the input (driving) and output (driven) shafts, from the driven shaft its torque is fed to the actuator. This construction of a mechanical gearbox is based on the ratio of the lengths of the circles of the pulleys installed on the input and output shafts. A belt made flexible in the form of a ring acts as a means of transferring mechanical force from one pulley to another pulley, which allows it to tighten the pulleys in an interference fit. The disadvantage of such solutions is the need for belt tension, which loses its elasticity and the force of compression of the pulleys during operation. This requires the provision of compensation for the elongation of the belt. It is also known to be selected for the main prototype, in which a transfer ring made in the form of a circle of metal, covered with rubber to increase the coefficient of friction with the surfaces of the pulleys, is used to transfer mechanical force between the shafts. The use of co-located tapered pulleys in a reciprocal arrangement ensures a constant angle of inclination in the gap between them. The transfer ring is made with an inclination of the edges having the same angle as the inclination of the side surfaces of the tapered pulleys, and can move along the axis of rotation of the pulleys. The disadvantages of this solution include adhesion on friction forces between surfaces. The proposed solution uses a transfer ring having a worm-type thread on both surfaces (external and internal), so that the angle of inclination of the worm thread turns corresponds to the inclination of the pulley threads. Thus, the transfer ring allows you to match the thread pitch of the two pulleys and ensure the transfer of force between them. The pulleys in the proposed solution are made with a worm-type thread, and are made with a different profile. The input (torque) pulley is made in the form of a cone, the receiving (output) pulley is made in the form of a cylinder with a uniform thread pitch. The thread of the input pulley, which has a tapered profile, has a constant angle of inclination, due to which its pitch changes along the axis of rotation of the pulley. Changing the diameter at an equal angle of inclination of the thread leads to a change in its pitch. Thus, in operation, when turning the rotating pulley in a different position of the transfer ring, it will correspond to a different angle of rotation of the receiving pulley. The angle of inclination of the threads on the transfer ring corresponds on each side to the angle of inclination of the pulley, and thread jamming does not occur.Depending on the position of the transfer ring between the pulleys, the conversion factor of the rotation of the input pulley to the output speed of rotation of the receiving pulley changes. In contrast to the belt variators known from the prior art, a rigid mechanical coupling of the two shafts is ensured. Thus, slippage of the shafts under high mechanical load is excluded, as well as the rupture characteristic of belt drives (increased reliability). In this case, the transmission ring serves as an intermediate link, equipped with two contact surfaces with different thread pitches.In automatic transmissions used in the industry, a stepped adjustment of the gear ratio of the gearbox is used, and in variators of snowmobiles and other vehicles, belts are used to provide traction due to friction - which reduces their ability to transmit large torques. The proposed solution makes it possible to implement a variator (gearbox) with a clutch through a mechanical transmission and smooth speed control. The proposed design provides an improved transfer of force to the worm gear of the clutch, which is expressed in a smooth course of the transfer ring and a decrease in its wear.

Description

Technical field to which the utility model belongs

The utility model relates to mechanical gearboxes for transmitting rotary motion, and is a continuously variable transmission.

State of the art

Known matching gearbox combined power plant [RF patent for utility model No. 116102], containing a drive pulley located on the shaft of the internal combustion engine, and a driven pulley located on the output shaft of the gearbox connected to the transmission. On the shaft of the electric motor there is a drive pulley, which is in constant engagement with it, and a support pulley, which are connected by a V-belt.

The disadvantages of this solution include the impossibility of adjusting the gear ratio of the gearbox, as well as stretching the belt in length, which leads to a deterioration in the adhesion of the pulley and the belt.

Also known is a coaxial helicopter belt reducer [RF patent for invention No. 2658745], containing a housing configured to drive the rotation in opposite directions of vertical coaxial hollow driven shafts from one drive shaft. The driving and driven shafts are made with pulleys fixed on them, and the driven shaft pulleys are located at different heights, while the drive is provided by two belt drives, one of which is made with a one-sided toothed belt, and the other belt drive is made with a double-sided toothed belt and with a block of auxiliary pulleys providing the opposite direction of rotation of one driven shaft relative to the other.

The disadvantages of this solution include the impossibility of regulating the gear ratio of the gearbox.

Also known from the prior art is a gear reverse variator [RF patent for invention No. 2546047], containing two pinion shafts in the form of conical multi-threaded equidirectional screws. The axes of the aforementioned gear shafts are located parallel to each other, and they themselves are facing counter-parallel, an intermediate gear enters into engagement with them, which moves along the gear shafts due to a helical pair, which is a hub and a screw, the helical pair is driven by a worm gear motor through the clutch. The limitation on the longitudinal movement of the intermediate gear along the screw is carried out by the end position sensors, the change in the operating mode of the gear reverse variator corresponding to the movement of the vehicle in the forward direction, in reverse or in place when the engine is running is achieved by a corresponding combination of gears of the drive of the drive shaft-gear.

The disadvantages of this solution include a small area in the contact zone outside the transfer ring and the pulley surface.

Also known from the prior art is a mechanical gearbox [RF patent for utility model No. 189572], containing two pulleys, one of which is leading, the other is driven. The said pulleys have a conical shape in longitudinal section to the axis of rotation, and are mutually reversed, so that the larger diameter of one pulley corresponds to the smaller diameter of the other, and one of the pulleys is installed inside a transmission ring having a diameter greater than the diameter of the pulley, and made with the inclination of the walls inward coinciding in angle with the angle of inclination of the working surfaces of the pulleys. The said transmission ring is equipped with a rubber coating on the inside and outside. In essence, this solution is the closest prototype.

The disadvantages of this solution include a small area in the contact zone outside the transfer ring and the pulley surface.

Disclosure of a utility model

Various variants of mechanical gearboxes are known from the prior art, allowing the transfer of rotational force between two or more shafts. The purpose of these gearboxes is to match the moments on the input (driving) and output (driven) shafts, from the driven shaft its torque is fed to the actuator. This construction of a mechanical gearbox is based on the ratio of the lengths of the circles of the pulleys installed on the input and output shafts. A belt made flexible in the form of a ring acts as a means of transferring mechanical force from one pulley to another pulley, which allows it to tighten the pulleys in an interference fit.

The disadvantages of such solutions are the need for belt tension, which loses its elasticity and the force of the pulley compression during operation. This requires the provision of compensation for the stretching of the belt.

Figure 1 shows a diagram of a belt-driven gearbox, which is the simplest variant of changing the gear ratio known from the prior art. In such devices, two cylindrical pulleys are spaced apart from each other at a certain distance. In this case, a flexible belt acts as a transmission of mechanical rotational movement, which serves to transfer the torque. In this case, the ratio of the pulley diameters determines the proportion of the rotational speed of the driving and driven shafts of the mechanical gearbox.

Such solutions have a number of disadvantages, including stretching of the flexible belt during operation, and subsequent slippage at high forces on the shaft. To this end, prior art solutions are known to improve the contact between the belt and the pulley, including all kinds of spring-loaded pulley systems for creating a constant force to extract the excess length of the flexible belt.

The flexible belt in such solutions is made, as a rule, of rubber and is installed on the pulleys in an interference fit. Over time, it begins to sag and can break under heavy mechanical stress.

In gearboxes like those shown in figure 1, different transmission ratios of the rotary motion (gear ratios) are possible. In general, the transmission of rotary motion will be proportional to the ratio of the diameters of the two pulleys to each other. This will transform the value of the moment of force on the driven (output) shaft, depending on the ratio of the diameters of the pulleys.

It is possible both to increase the speed of rotation of the driven (output) shaft, and to decrease the speed of its rotation - in the ratio of the sizes of the two pulleys. The transformation of speed is accompanied by a change in the moment on the shaft - thus, there is a mechanical transformation not only of speed, but also of effort, with constant power on the shaft.

In a number of practical applications, a smooth control of the rotational speed of the driven (output) shaft of a mechanical gearbox is required - examples of such applications can be various electric drives of mechanisms, as well as variators of vehicles. For example, variators are used in Yamaha snowmobiles and passenger cars, both imported and domestically produced.

Various gearboxes known from the prior art have either one fixed gear ratio or a limited range of values for the speed conversion stages. Such solutions are implemented, among other things, on gear wheels, which complicates the switching of speeds and the value of the gear ratio of the gearbox.

For example, the “automatic transmission” used in machines is essentially a stepped manual transmission with several gears, to which the output shaft gear wheel is connected (that is, connecting to the gear wheels on the input shaft that have different diameters - we we also change the total gear ratio of the mechanical gear). In the so-called variators, some kind of mechanical friction is used to transfer the rotational force from the input shaft to the output shaft.

The principle of operation of the solution chosen as the main prototype becomes obvious from figure 2. It shows two transmission pulleys in the form of a truncated cone. The working (side) surfaces of the pulleys have the same angle of inclination relative to each other. Thus, as can be seen from figure 2, being installed in the reverse order to each other, the said pulleys completely coincide with each other with their working surfaces. In this case, the gear ratio in the combination of tapered pulleys changes both in the direction of increasing or decreasing - depending on the point on the longitudinal axes where the characteristic is taken.

However, the transfer of moment between tapered pulleys when their working surfaces touch directly along the entire length of the longitudinal axes is impossible. This is due to different angular velocities - and hence the gear ratios of the reduction. On one extreme side of the pulleys, a reduction in the gear ratio will act, on the other hand, there will be an increase in the gear ratio. An equal gear ratio will act in the middle of the pulleys when the rotational speed of the driving and driven pulleys coincide. For this reason, it is possible to remove the mechanical rotational force only in a limited area of the working surface of the pulleys.

As a transfer of mechanical force between the drive and driven shafts, it was proposed to use a transfer ring made in the form of a circle of metal, covered inside and outside with rubber to increase the coefficient of adhesion to the surfaces of the pulleys (shown in figure 2 under the number 4).

Thanks to this, it becomes possible to remove the rotational force in the local area of the working surfaces of the pulleys. When moving the transfer ring along the axis of rotation of the pulleys, it allows you to change the gear ratio between the driven and driving pulleys. It is on this principle that the action of the main prototype is based.

The use of co-located conical pulleys in a mutually reverse arrangement provides a change in the ratio between them. The aforementioned transmission ring, due to the ability to move along the pulleys, implements a change in the gear ratio.

The main result achieved is a smooth control of the transmission ratio of the mechanical gear by moving the transmission ring along the axis of rotation. However, the coupling of the shafts in such a gearbox is not a rigid mechanical one, and works by means of friction.

Figure 3 shows a cross-section of the main prototype, from which it can be seen that the transfer ring covers one of the pulleys, which is located inside. This reduces the amount of space required to implement the solution. The diameter of said transfer ring must be greater than the largest diameter of the tapered pulley, but the degree of excess may be small. This makes it possible to reduce the size of the gearbox known from the prior art. The described features of the gearbox make it possible to increase the reliability of the operation of the means of transferring mechanical rotation (transfer ring), and to ensure the possibility of smooth regulation of the gear ratio from the minimum to the maximum value - with a passage through the section of equality of angular velocities (that is, equality of 1 gear ratio).

However, the configuration described in the main prototype has different operating conditions of the contact point of the pulleys and a single transmission ring, that is, a different contact area. When the transfer ring is made with a slight excess of the diameter over the largest diameter of the pulley, the pulley located inside will have a larger contact area with the rubber surface of the transfer ring, in comparison with that of the pulleys located outside the transfer ring. Since the outer pulley will work with the convex surface of the transfer ring, its contact area will be smaller - which means that the load permissible for the gearbox under the adhesion conditions will be less.

The proposed solution is a variator (mechanical gearbox) with a rigid coupling between the shafts through a worm thread on all shafts. Its design in a simplified version is shown in figure 4, which shows a longitudinal section of the proposed solution with a coupling at the edge of the transmission ring. The figure shows two transmission pulleys, one of which has a tapered shape, and the other is cylindrical, between them a transmission ring is used as a clutch, covering the drive pulley of a tapered shape, the cylindrical pulley is in contact with the transmission ring from the outside and is driven.

The principle on which the work of the proposed solution is based is simple, but it is inextricably dependent on a number of technical features that made it possible to implement smooth control.

It is based on the constancy of the angle of inclination of the worm-type thread on the driving and driven pulleys - however, the driving pulley is made in the form of a cone, and has a variable diameter along the length of its axis of rotation. This leads to a change in the thread pitch from one end of the cone to the other - as shown in figure 5. Figure 5 shows the development of the surface of the cone in a plane and the thread on it - it can be seen that the thread pitch in the narrow part of the cone narrows, that is, with the same inclination threads on a smaller diameter, one thread gives a smaller longitudinal pitch. This is very important for the implementation of the proposed solution - since the equal angle of inclination means the consistency of the pulley thread with the thread of the transfer ring, in any position on the longitudinal axis of rotation, which guarantees the absence of locking and biting of the thread. It also means that in one revolution of the drive pulley, the transmission ring will make a different number of turns, depending on its position along the axis of rotation - which means the possibility of adjusting the transmission coefficient of the proposed solution. Figure 6 shows a cross-section of the transmission ring of the proposed solution, where it can be seen that a worm-type thread is made inside and outside of it, and around the circumference on the transfer ring it is enough to make one thread turn.

The driven (output) pulley is cylindrical in shape, since the transmission ratio is provided by the tapered shape of the input (driving) pulley. The task of the driven pulley is to receive the mechanical force of rotation from the transfer ring, from the outer surface of which there is a corresponding thread corresponding to the worm thread of the driven pulley, the pitch of which and the angle of inclination correspond to the thread of the driven pulley, ensuring the absence of biting and locking of the thread, as well as its smooth running.

A smooth change in the rotation of the pulleys is provided for the first time among the known industrial solutions, and the solution chosen for the main prototype works due to mechanical friction, which is realizable, but has limitations on the limiting moment of the shafts. The described result is achieved by the totality of the measures and design solutions used. The main one is the variable pitch for the thread on the tapered drive pulley, which made it possible to remove the rotational force at different points along its axis of rotation. In this case, biting and locking of the thread of the transfer wheel does not occur, since their angle of inclination is coordinated with each other. The external thread of the transfer ring allows the transfer of the rotational force to the driven shaft, the shape of which gives an equal thread run and accepts the rotational force. The transfer ring acts here as an intermediate link, which can have different thread pitches at the same time, since it has two sides, external and internal. To move the transfer ring along the surface of the pulleys, a clutch is used, equipped with two rollers, one on each side, which ensure the retention of the transfer ring during its rotation. The movement of the clutch is provided by a helical gear known from the prior art, which is a threaded shaft passing through the base of the clutch with a corresponding thread. When the screw drive rotates, the coupling moves along with the transfer ring clamped in it. The location of the clutch as in Figure 4 is approximate, as are the dimensions of the clutch.

Shown in figure 4, the clutch is operable, providing rotation of the transfer ring and at the same time its rotation. Figure 4 shows the rollers located inside the clutch and allowing the transfer ring to slide around the circumference (rotation). Also, the helical gear provides correction of the clutch position, that is, its movement, which makes it possible to smoothly regulate the gear ratio of the variator.

The difference between a clutch with a single-shaft screw drive, and a clutch with a four-shaft one, as in Figure 8, lies in the smoothness and symmetry of the position when the transfer ring moves. In practice, the power on the pulleys depends on this, which can be transmitted to the output of the gearbox. The clutch in figure 4 will ensure the operation of lower power variators, and as in figure 8 will ensure the operation of high power variators of large machines and processing lines. This is the advantage for the proposed solution - improving the smoothness of the transfer ring when changing the gear ratio, reducing friction from the skewed thread of the transfer ring and reducing its wear.

For the coordinated movement of the four helical gears, figure 7 shows a system of gears forming a gear train. The shaft in the center rotates a common gear, which receives an external rotational control force when changing the position of the clutch. The four gears are in mechanical engagement with the central gear, rotating synchronously and in accordance. However, the design of this node is not the essence of the proposed solution, and is shown to demonstrate the operation of the entire solution as a whole and its feasibility. It is important that it is possible to transmit the rotational force simultaneously to all four shafts of the helical gear, which, with an equal pitch of their threads, also ensures equal movement of the coupling angles.

Figure 8 shows a complete clutch assembly with a transfer ring, separate from the rest of the variator. The figure shows the rollers that are located around the circumference of the coupling from the inside and ensure the sliding of the transfer ring during rotation.

Otherwise (except for the gears in figure 7 and the clutch assembly in figure 8), the proposed solution is identical to the simplified version in figure 4. When operating the proposed variator, the same operating principle is provided as in figure 4. Thus, the difference between the proposed solution lies in the holding mechanism and the movement of the transmission ring, which gives the control of the transmission ratio of the entire variator as a whole. Shown in figure 7 gears of four shafts with a thread of the screw drive of the clutch allow movement of the clutch and the transfer ring.

The introduction of four threaded shafts in the screw drive of the coupling ensures uniform movement of the transfer ring, regardless of the force on the pulleys of the proposed variator. Reducing various misalignments and misalignment deviations reduces the friction of the thread channel on the transfer ring and the counter thread on the pulleys, which reduces wear.

The presented solution is simple and therefore practically applicable, which makes it possible to apply it in industry.

The proposed technical solution is new, having the following fundamental differences from the prototype:

- the clutch is installed on a helical gear with four threaded shafts rotating at equal speed;

- the coupling is made square on the outside and has a round cut on the inside;

- threaded shafts pass through the coupling at the corners of the square through the threaded holes;

- a round cutout inside the coupling is larger in diameter than the largest diameter of the drive pulley;

- the clutch has roller pairs on both sides of its inner cavity along the entire circumference;

- the clutch has two walls, between which there is a transmission ring;

- roller pairs coincide with a flat side surface on the transfer ring between its external and internal threads.

Thus, the totality of essential distinctive features of the utility model leads to a new technical result - an improvement in the smoothness of the transmission ring and a decrease in wear, and was previously unknown from the prior art.

Brief description of the drawings. Figure 1 shows a classic belt drive. Here 1 is a pulley, 2 is a belt. Figure 2 shows a longitudinal section of a mechanical gearbox known from the prior art. Here 3 is a tapered pulley, 4 is a transmission ring. Figure 3 shows a cross-sectional view of a mechanical gearbox known from the prior art in a transverse plane. Here 3 is a tapered pulley, 4 is a transmission ring. Figure 4 shows a section of a variant with a simplified design of the clutch in a plane longitudinal to the axis of rotation. Here 3 is a tapered pulley, 4 is a transmission ring, 5 is a cylindrical pulley, 6 is a helical gear, 7 is a clutch. Figure 5 shows the course of the thread on the tapered pulley of the proposed solution. Figure 6 shows a cross-section of the transmission ring of the proposed solution in a plane transverse to the axis of rotation. Here 8 is an external thread, 9 is an internal thread. Figure 7 shows the gear unit of the control force to the helical shafts of the clutch of the proposed solution. Figure 8 shows the assembly of the helical gear, clutch and transfer ring assembly for the proposed solution. Here 4 is the transfer ring, 6 is the helical gear, 7 is the clutch, 10 are the gears of the gear drive.

Claims (1)

A mechanical gearbox containing two pulleys, one of which is driving, the other is driven, as well as a transfer ring put on one of the mentioned pulleys and moved along the pulleys due to a helical transmission through a clutch, and the driving pulley has a tapered shape, the driven pulley has a cylindrical shape, both pulleys are equipped with a worm-type thread, and the pitch of the turns on the tapered pulley changes along the axis of rotation, and the transfer ring is put on the drive pulley and is made with one turn of the worm-type thread on the inner and outer surfaces, so that the thread of the inner side corresponds to the thread on the drive pulley, and the thread of the outer side corresponds to the thread on the driven pulley, the pulleys and the transfer ring are installed together, in mechanical engagement with each other, forming a worm gear together, characterized in that the said coupling is installed on a helical gear having four shafts rotating at equal speed with threaded, and the coupling itself you is made square on the outside and has a round cutout on the inside, and the mentioned threaded shafts pass through it at the corners of the square through threaded holes, the round cutout inside the coupling is larger in diameter than the largest diameter of the drive pulley, the coupling itself has roller pairs on both sides of its inner cavity throughout circle, having two walls between which the transfer ring is located, the said roller pairs coincide with the flat side surface on the transfer ring in the interval between its external and internal threads.

Images