WO1995012077A1

WO1995012077A1 - Periodically gearing drive with out-of-round cogs

Info

Publication number: WO1995012077A1
Application number: PCT/EP1994/003500
Authority: WO
Inventors: Friedrich Jarchow; Ming Liu
Original assignee: Gruner + Jahr Ag & Co.
Priority date: 1993-10-27
Filing date: 1994-10-26
Publication date: 1995-05-04
Also published as: DE4337413C1

Abstract

The drive has a flywheel store (v) and facilitates acceleration, deceleration and constant phases with unequal time components at a constant revolution speed (w1) at the drive shaft (II). During periodic operation, the motor is required to cover only the power losses and balancing power of the machinery. Special features prevent side changes in the gearing associated with jerkiness on changeover from an acceleration or stationary phase to a deceleration phase or vice versa.

Description

Periodic gearbox with non-circular gears

Gearboxes with non-circular gearwheels for power transmission between the engine and the machine implement periodically changing output speeds at a constant drive speed. Such gear transmissions are relatively compact compared to other mechanisms for generating periodic movements.

The problem with the pairing of non-circular gears is that when changing from an acceleration phase or stationary phase to a deceleration phase or vice versa, a flank change is associated with a shock. Such dynamic shocks reduce the load-bearing capacity and increase the noise level.

In the acceleration phase, the power flows from the engine to the machine and in the deceleration phase, conversely, from the machine to the engine. The motor and generator operation of the engine leads to speed fluctuations. Such changes in the speed of the engine can be disruptive. They cause e.g. B. in a work machine for a clock operation undesirable phase shifts.

According to DE 1 187 448 B, a non-circular gear rotating at a constant angular velocity is in engagement with two identical non-circular gear wheels, one of which is used to drive a periodically moving machine and the other, offset by 180 ", chwungradspeichers serves for the connection of a _S. If the design of the noncircular gears so that the sum of the kinetic energies of the system is constant and that the drive motor has to cover only the power loss. This undergoes this no speed fluctuations. With this arrangement, however, only a movement sequence with the same times for the acceleration and deceleration phases and with the same times for the constant phases lying in between can be realized, since at the same opposite phase angles of the mean non-circular gear rotating at constant angular speed, the same times belong.

DE 41 03 946 AI shows periodically translating gears with non-circular gears. The gearboxes shown are two-stage. The task is solved to adjust the periodic movement during the run. This is done with a suitable device, e.g. a hydrostatic twist clutch a relative rotation of the non-circular wheels sitting on the intermediate shaft.

DE 32 02 242 AI describes a periodically translating gear with round gears. Two gearwheels mounted parallel to one another on the output shaft are driven by gearwheels connected to the drive shaft in a rotationally fixed manner at different angular speeds, for example in opposite directions. The coupling of the two gearwheels mounted on the output shaft is carried out by a gearwheel segment with offset bearing journals, one of which is located eccentrically in a gearwheel and the other in an end groove on the other gearwheel. The gear segment of the coupling member is in engagement with a gear segment on the output shaft. These gearwheel segments lead to an oscillating movement of the output shaft at a constant speed of the drive shaft.

DE 25 07 844 A shows a three-shaft planetary gear, in which the round hollow gear and the web are used for positive running with the round planetary gears stored in it can be coupled with non-circular gears by means of a two-stage reduction gear. The variable ratio of the reduction gear creates the desired sequence of movements on the round sun gear connected to the output shaft.

The abovementioned prior art shows no measures which, as a result of the periodic accelerations and decelerations, avoid back flanking of the teeth associated with impacts.

Circuit test benches for carrying capacity tests on round gear wheels are known. For example, two parallel spur gear sets are clamped at a standstill with the help of a twist coupling, so that the front flanks of one wheel set and the rear flanks of the other wheel set are under the same load. During the run, the desired power circles between the two wheel sets, whereby the motor only has to cover the power loss. The load on the wheel sets remains constant during operation.

The bracing of two parallel gear sets with round wheels is also used to avoid backlash when the torque direction is reversed while maintaining the direction of rotation. To prevent flank lifting and thus backlash, the bracing torque must be at least equal to the maximum operating torque. This means that the gear pair transmitting the torque must in each case be designed for at least the double operating torque.

Taking into account the prior art shown, the invention has for its object to propose a gearbox with non-round gears and flywheel memory, the phases with constant drive angular speed on the output shaft during one revolution, ie during a period with constant, decreasing, constant and increasing angular angle ¬ speed or vice versa, the time shares of the different phases, in particular the phases with constant angular velocity are of different sizes. Furthermore, the problem is to be solved that there is no abrupt back flank wear of the tooth flanks when changing the movement phases.

According to the invention, a second wheel set with non-circular gear wheels is provided to implement the movement sequence of the output shaft with unequal time portions of the individual phases between the drive shaft and flywheel accumulator are that the sum of the system's kinetic energies remains constant. The rolling curves of the wheels of the second wheel set are different from those of the wheels of the first wheel set. In the acceleration and deceleration phases, the storage shaft connected to the flywheel accumulator or forming it with associated masses and the output shaft with associated masses exchange their kinetic energies, so that the motor only has to feed in the power loss and steady-state power. The flywheel spike can be formed by a separate flywheel or by a mass unit with the non-circular gear sitting on the storage shaft.

In order to avoid the abrupt flank change of the gearwheels in engagement, two identical gear sets are arranged in parallel and congruently with each other between the drive shaft and the output shaft on the one hand and between the drive shaft and the storage shaft on the other hand, which can be preloaded with a twist coupling at a standstill, whereby in accordance with the state of the art, it is possible to lift the flanks within the framework of the flank play of the unloaded tooth engagements. This can be achieved in that the elastic relative rotation of the two shafts in the respective wheel set is smaller than the torsional backlash of the relieved toothing due to the difference between the maximum operating torque and the preload torque. This measure significantly reduces the necessary preload torque and thus the maximum load on the individual tooth meshes.

1 to 6 explain the transmission according to the invention using the example of a traction sheave with a periodically changing speed for a conveyor belt.

1 contains the kinematic variables of the output shaft II or the drive pulley IV which are dependent on the time t. The cycle time, ie the time of a period of 0.13 seconds corresponds to one revolution of the drive shaft I or the output shaft II ¬ indicate ε _n angular deceleration or angular acceleration, ω _n angular velocity and α rotation angle. The constant phases for ε _n = 0 have different lengths.

2 schematically represents the system. The wheel set with the non-circular wheels 1, 2 connects the drive shaft I with the output shaft II and the wheel set with the non-circular wheels 3, 4 connects the drive shaft I with the storage shaft III. The output shaft II includes the drive pulley IV with the conveyor belt (not shown) and the storage shaft III the flywheel V. tύ _τ denotes the constant angular velocity of the drive shaft I, ω _n the variable angular velocity of the output shaft II and cι) _ιn the variable angular velocity of the storage shaft III .

The wheel set with the non-circular gear wheels 1, 2 according to FIG. 3 fulfills the kinematic conditions specified in FIG. 1. 3 shows the axes of rotation or _fulcrums 0 _lf O _{H of} the wheels, shows the rolling curves rolling on one another with the variable radii r _wl , r _wl , further teeth and the current position of the rolling point C in which the rolling curves touch and which is always on the connecting line of the pivot points O _τ , O _u . The radius ratio r _w2 / r _wl forms the periodically changing transmission ratio (II _T / Ö _{H of} the wheelset.

The current position of the non-circular gears shown in FIG. 3 corresponds to the time t = 0 in FIG. 1. With reference to the rotational angle position of the traction sheave IV or the output shaft II, the conveyor belt E for the sheet-like material not shown means the loading phase, V the deceleration phase, A the Design phase and B the acceleration phase. The rolling curve parts belonging to phases E and A are circular arcs. The radii r _{wlπax limit} the phase E on the wheel 1 and the radii r _wlmin the phase A and vice versa on the wheel 2 r _w2min the phase E and r _w2max the phase A. FIG. 3 also gives those belonging to the individual phases or areas Amounts of the angles of rotation α _x and α _π on.

Analogously to FIG. 3, FIG. 4 shows, according to the invention, the wheel set for connecting the drive shaft I to the storage shaft III or to the flywheel V. FIG. 4 again identifies the axes of rotation O _τ and O _{m of} the wheels 3 and 4 , the radii r _w3nax , r _w3min and r _wmin , r _wιmuc and also the areas E, V, A and B for the traction sheave IV with the respectively associated angular ranges _τ and _m and the angular velocities ω _∑ and ω _m . The instantaneous pitch point C again corresponds to the time t = 0 in FIG. 1. The pitch curves of wheels 1 and 3 on the one hand and 2 and 4 on the other hand differ in their shape.

5 shows, analogously to FIG. 1, the angular accelerations or decelerations ε _IXI , the angular velocities ω _nι and the _{angles of} rotation α _{m of} the storage _shaft III depending on the time t.

With reference to FIG. 2, FIG. 6 shows between drive shaft I and output shaft II parallel to wheel set 1, 2 the same wheel set 1 ', 2' and between drive shaft I and storage shaft III parallel to wheel set 3, 4 a same wheel set 3 ' , 4 '. The parallel wheel sets are each congruent. In the sense of the invention, the wheel sets 1, 2 and 1 ', 2' with the twist coupling K _n and the wheel sets 3, 4 and 3 ', 4' with the twist coupling K _{UI can} be pre-tensioned at a standstill so that the Backlash a flank change of the engaged teeth is avoided.

Claims

claims

1. Periodically translating gear with a first gear set with non-circular gears (1, 2) and a flywheel memory (V) for generating a movement sequence, the period of which corresponds to one revolution of the drive shaft (I) or the output shaft (II) and that at a constant angular velocity the drive shaft (I) shows, in chronological order on the output shaft (II), a phase with constant angular velocity, a phase with decelerating angular velocity, again a phase with constant angular velocity and then a phase with accelerating angular velocity or has a reversed phase sequence in chronological order, characterized in that the time components have different sizes, at least for the phases with constant angular velocity, and that between the drive shaft (I) and the storage shaft (III) with flywheel storage (V) there is a second gear set with non-circular gears ( 3, 4), whose pitch curve en differ from those of the first wheel set, the rolling curves of the gears (3, 4) of the second wheel set being designed so that the kinetic energy of the system is always constant, and the system consisting of the drive shaft (I), the Ab¬ drive shaft (II) and the storage shaft (III) with the associated masses.

2. Periodically translating transmission according to claim 1, characterized in that between the drive shaft (I) and the output shaft (II) on the one hand and between the drive shaft (I) and the storage shaft (III) on the other hand two identical sets of wheels (1, 2; 3 , 4; 1 ', 2'; 3 ', 4') are provided in a cover-identical arrangement, with the first pair of wheelsets (1, 2; 1 ', 2') with a first rotary coupling (K _n ) and the second pair of wheelsets (3, 4; 3 ', 4') is pretensioned with a second rotary coupling (K _IU ) so that the elastic relative rotation of the shaft sections between see the wheelsets (1, 2; 1 ', 2') of the first pair of wheels on the one hand and between the wheelsets (3, 4; 3 ', 4') of the second pair of wheels on the other, each due to the difference between the maximum operating torque and preload torque is smaller than the backlash of the relieved toothing concerned.