EP0098323B1 - Oscillation mechanism for reciprocating machine parts, in particular for a support of print elements in a matrix line printer - Google Patents

Abstract

A rotational movement of a constant speed drive is translated into a linear reciprocating motion having two relatively long, constant slope sections within a cycle, such section occuring in between two sequential reversals, and representing a constant speed. The speed modification is obtained by a universal joint-cross link with oblique axes and a crank output having a linear phase.

Description

The invention relates to a pendulum mechanism for reciprocating machine parts according to the preamble of claim 1, in particular for a printing element carrier of a matrix time printer, which can be moved parallel to the printing abutment in forward and back passes and which is connected to a drive generating rotary movements.

Such pendulum mechanisms are used for the treatment, processing or observation, measurement and the like of objects extending along the pendulum path, with a speed curve with prescribed parameters always having to be observed via the effective path. Another requirement is the path-dependent actuation of the working means, tool or measuring instrument in order to avoid complicated position sensors and control loops.

Such a path-dependent system operating at constant speed is required in line printer type matrix printers. The dot-printing elements, usually hammer tips or wire tips, lie "horizontally" on a line which runs perpendicular to the direction of the movement of the recording medium through the matrix printer. During the printing, the hammers or wires are moved back and forth on the horizontal line. The dot printing elements are operated at predetermined locations to form a dot on the back of an ink ribbon. The timely and timely actuations determine the quality of the typeface and the performance of the matrix printer, which is tailored to the high volume of information to be printed at the output of an electronic data processing system.

Such a pendulum mechanism, which essentially consists of elliptical gears of a special phase position, is known from European Patent 44 415. Changes in speed within the back and forth movement of the print head are only possible to a very limited extent here.

In order to achieve similar movements, cam disks or camshafts have already been proposed. Pendulum mechanisms have also already been equipped with electromagnetic or electroinductive linear motors. Controlled motors take a different approach.

The disadvantages of cam disks or camshafts are the high demands on their manufacture. In addition, there is a high degree of wear with a short lifespan with positive connections. However, positive connections are not suitable for higher speeds.

Disadvantages of the linear motors or of the regulated motors and the electromagnetic coils lie in a high level of control expenditure, a high power consumption with poor efficiency and in a large space requirement.

The invention has for its object to convert a rotary movement of the drive into oscillating movements of the machine part or of the pressure element carrier with a number of predetermined parameters without great control effort in a pendulum mechanism of the type referred to, in particular in oscillating movements with a constant speed section.

The object is achieved according to the invention in that the superposition gear consists of a drive axis emerging from the rotary drive and a universal joint connected to it with an output axis, the drive axis and output axis being at a joint angle, and that the reciprocating movement of the machine part or Pressure element carrier can be generated by means of a crank which is driven by the output axis of the superposition gear and whose push rod is connected to the machine part.

This requires a minimal amount of regulation. The rotary motor only rotates in one direction. Inexpensive, low-noise, low-wear, technically proven, rotating machine elements can be used for the superposition gear.

In the interest of economic interchangeability of components, it is proposed that the universal joint consist of a universal joint.

The desired straight curve sections can be achieved in particular if the joint angle formed between the drive and driven axes of the universal joint is between 30 degrees and 50 degrees, preferably 40 degrees.

Another measure for generating suitable speed images is that the universal joint and the eccentric shaft are set out of phase with one another in their basic position.

The kinematics of the movements of the pendulum mechanism can also be improved in that the machine part or pressure element carrier, together with the devices carried by it, can be moved synchronously and in opposite directions to an equally large mass of a counterweight with respect to the phase position.

• Fig. 1 eine schematische Anordnung der Organe des Pendelmechanismus' als Draufsicht,
• Fig. 2 einen Teil der Antriebsorgane des Pendelmechanismus' im Bereich der Exzenterwelte, in Seitenansicht,
• Fig. 3 eine schematische Darstellung der Bewegungsverhältnisse an dem Universalgelenk,
• Fig. 4 ein Diagramm mehrerer Kurven, die modifizierte Sinuswellen darstellen und
• Fig. 5 eine Draufsicht auf einen Matrix-Zeilendrucker mit den wichtigsten Antriebsorganen des Pendelmechanismus' und ihre Zuordnung am Druckerrahmen.

An embodiment of the invention is shown in the drawing and will be described in more detail below. Show it

• 1 is a schematic arrangement of the organs of the pendulum mechanism as a top view,
• 2 shows a part of the drive elements of the pendulum mechanism in the area of the eccentric world, in a side view,
• Fig. 3 is a schematic representation of the Movement conditions on the universal joint,
• Fig. 4 is a diagram of several curves that represent modified sine waves and
• Fig. 5 is a plan view of a matrix line printer with the main drive elements of the pendulum mechanism and their assignment on the printer frame.

In the exemplary embodiment, the reciprocating machine part 1 consists of the pressure element carrier 1, which is set into oscillating movements by the drive 2 in the form of the rotary motor 2a.

• (1) x = B cos(ω₂t)
• wobei bedeuten:
  • x = Verschiebeweg (mm)
  • B = Kurbellänge (mm)
  • ω₂ = Winkelgeschwindigkeit (1/sec) der Abtriebsachse 6
  • t = Zeit (sec)
  • A = Schubstangenlänge (mm) der
  
  Schubstange 1a.

The frequency is z. B. for the pressure element carrier 1 to 30 / sec and more. The path of movement is approximately 12.7 mm (5/10 ^” ). The rotary motor 2a drives the superposition gear 3, which consists of a universal joint 3a, and the crank 4 (FIG. 1). The crank (Fig. 2) produces a sinusoidal movement according to the relationship of a crank drive, which is:

• (1) x = B cos (ω ₂ t)
• where mean:
  • x = displacement (mm)
  • B = crank length (mm)
  • ω ₂ = angular velocity (1 / sec) of the output axis 6
  • t = time (sec)
  • A = push rod length (mm) of
  
  Push rod 1a.

(The so-called handlebar ratio λ = A / B is assumed to be relatively large.)

The speeds on the machine part 1 according to FIG. 2 are therefore, without taking into account the superposition gear 3, corresponding to those in the case of a sinusoidal curve shape, ie. H. the speeds periodically approach a maximum and a minimum. The superposition gear 3 (FIGS. 1 and 3) converts the non-uniform speeds into uniform ones. The universal joint 3a (also called universal joint or universal joint) is provided as the superposition gear 3. The drive axis 5 is at the output axis 6 at the joint angle a, which is between 30 degrees and 50 degrees, preferably 40 degrees.

The rotary motor 2a drives the drive axis 5 with the movement parameters ϕ ₁ ω ₁ , where ϕ _{1 represents} the angle of rotation (°) of the drive axis 5 and ω ₁ the uniform angular velocity.

• (2) tan ϕ ₂ = tan ϕ₁ cos a
• wobei bedeuten:
  • ϕ₁ = Drehwinkel (°) der Antriebsachse 5
  • ϕ₂ = Drehwinkel (°) der Abtriebsachse 6
  • a = Gelenkwinkel (°) zwischen der
  
  Antriebsachse 5 und der Abtriebsachse 6

The output angle of the output axis 6 thus results from

• (2) tan ϕ ₂ = tan ϕ ₁ cos a
• where mean:
  • ϕ ₁ = angle of rotation (°) of drive axle 5
  • ϕ ₂ = angle of rotation (°) of the output axis 6
  • a = joint angle (°) between the
  
  Drive axis 5 and the output axis 6

The ratio of the angular velocities is determined as follows:

The universal joint 3a (FIG. 3) has an axis 7 which is driven by the drive axis 5 and which rotates at the rotational speed ω ₁ . Due to the articulation angle a, the uniform rotational speed ω _{1 is converted} into a non-uniform rotational speed o ₂ on the axis 8. Depending on the position of the eccentric shaft 4, which is phase-shifted by the crank angle y from the position of the axis 8, uniform speeds result in sections.

• (4) x = B. cos [ arctan (tan (ω₁. t). cosa) + y] Gemäß Fig. 4 sind einige Beispiele der erreichten modifizierten Sinuskurven mit gleichförmigen Geschwindigkeitsabschnitten dargestellt. Auf der Abszisse ist die Zeit t in sec und auf der Ordinate der Verschiebeweg x in mm aufgetragen. Die einzelnen Kurven basieren jeweils auf unterschiedlichen Parametern mit den folgenden Werten:
  • Kurve 10: Gelenkwinkel a = 70 Grad;
    • Kurbelwinkel y = 0 Grad
  • Kurve 11: Gelenkwinkel a = 40 Grad;
    • Kurbelwinkel y = 0 Grad
  • Kurve 12: Gelenkwinkel a = 40 Grad;
    • Kurbelwinkel y = 90 Grad
  • Kurve 13: Gelenkwinkel a = 70 Grad;
    • Kurbelwinkel y = 90 Grad

These speeds can be determined from the displacement equation for displacement x as follows:

• (4) x = B. cos [arctan (tan (ω _1. T). Cosa) + y] According to FIG. 4, some examples of the modified sine curves achieved are shown with uniform speed sections. The time t in sec is plotted on the abscissa and the displacement x in mm is plotted on the ordinate. The individual curves are based on different parameters with the following values:
  • Curve 10: joint angle a = 70 degrees;
    • Crank angle y = 0 degrees
  • Curve 11: joint angle a = 40 degrees;
    • Crank angle y = 0 degrees
  • Curve 12: joint angle a = 40 degrees;
    • Crank angle y = 90 degrees
  • Curve 13: joint angle a = 70 degrees;
    • Crank angle y = 90 degrees

As can be seen, curve 12 has a remarkably straight and very long path section between points 12a and 12b, which represents a constant speed. In this section, it is particularly advantageous to print with a matrix line printer. Curve 10 comes into consideration for applications which are based on a speed dependent on the feed for the recording medium. As can also be seen, a large number of pairing sizes, consisting of the joint angle a and the crank angle y, can be selected.

5 shows the application of the invention to a matrix printer, the pressure abutment 15 being provided on the printer frame 14 in the form of a rotatably mounted printing roller over which the recording medium 16 is guided. As described, the pressure element carrier 1 is connected to the crank 4, which forms part of a crank mechanism 17 which is rotatably supported in bearings 18 and 19. The pressure element carrier 1 is articulated to the crank 4 by means of the first push rod 20. The drive 2 is also superimposed on the printer frame 14 provided rotary bearings 21 and 22. The superposition gear 3 is provided as described. The counterweight 23, which is articulated to the crank mechanism 17 by means of the second push rod 24, serves to balance the total mass of the pressure element carrier 1. The eccentricity and the phase position of the eccentric shaft 24a is the same as that of the crank 4 with a push rod 20. A parallel movement of the pressure element carrier 1 and the counterweight 23 enables leaf springs 25 and 26 or 27 and 28, on which the pressure element carrier 1 and the counterweight 23 respectively support.

Claims (5)

1. A PENDULUM MECHANISM

for a machinery part (1) capable of moving to and fro, especially a print element carrier (1) of a matrix line printer,

arranged parallel to the roller (15) and movable in forward and return passes or runs, connected to a rotating drive (2) producing a uniform rotary motion with an associated transmission gearing (3), the non-uniform speeds of the machinery part/print element carrier (1) being convertible into uniform speeds in the straight sections deviating from the sinus characteristic curve between the positive and negative maximum points of the sinus wave, this assembly being characterized by:

the superposed transmission gearing (3) consisting of an input drive shaft (5) protruding from the shaft extension end of the rotating drive (2) and an associated universal joint (3a) with an output shaft (6), the input and ouput shafts forming an angle (alpha), the forward and backward motion of the part/carrier (1) being generated with the aid of a crank (4) driven by the output shaft (6) of the superposed transmission gearing(3) with push rod(s) (1a, 20) connected to the selfsame part/carrier (1).

2. A PENDULUM MECHANISM

to Claim 1,

characterized by:

the universal joint (3a) being a cardan joint.

3. A PENDULUM MECHANISM

to Claim 1 or Claim 2,

characterized by:

Angle (alpha) formed by the input and output shafts (5 and 6) of the univeraal joint (3a) being generally in the from 30 to 50 degree range but preferably an exact 40 degreea.

4. A PENDULUM MECHANISM

to one or several of Claims 1 to 3,

characterized by:

the universal joint (3a) and eccentric shaft (4) being dephased relative to each other in their respective home positions.

5. A PENDULUM MECHANISM

to Claims 1 to 4,

characterized by:

the part/carrier (1), with the equipment arranged thereon or carried along thereby, being movable in synchronism with and opposed to the phase relation relative to a counterweight or balancing weight (23) of equivalent mass.

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